DEFF Research Database (Denmark)
Ravn, Jacob; Thorup, Niels; Nielsen, Poul
2001-01-01
A tricyclic nucleoside is synthesised from a bicyclic nucleoside precursor by applying a stereoselective dihydroxylation, a regioselective tosylation and an intramolecular ether formation. This tricyclic nucleoside is constructed as a conformationally locked thymidine analogue and has been analys...
Desulfurization of 2-thiouracil nucleosides: conformational studies of 4-pyrimidinone nucleosides.
Kraszewska, Karina; Kaczyńska, Iwona; Jankowski, Stefan; Karolak-Wojciechowska, Janina; Sochacka, Elzbieta
2011-04-01
4-Pyrimidinone ribofuranoside (H(2)o(4)U) and 4-pyrimidinone 2'-deoxyribofuranoside (dH(2)o(4)U) were synthesized by the oxidative desulfurization of parent 2-thiouracil nucleosides with m-chloroperbenzoic acid. The crystal structures of H(2)o(4)U and dH(2)o(4)U and their conformations in solution were determined and compared with corresponding 2-thiouracil and uracil nucleosides. The absence of a large 2-thiocarbonyl/2-carbonyl group in the nucleobase moiety results in C2'-endo puckering of the ribofuranose ring (S conformer) in the crystal structure of H(2)o(4)U, which is not typical of RNA nucleosides. Interestingly, the hydrogen bonding network in the crystals of dH(2)o(4)U stabilizes the sugar moiety conformation in the C3'-endo form (N conformer), rarely found in DNA nucleosides. In aqueous solution, dH(2)o(4)U reveals a similar population of the C2'-endo conformation (65%) to that of 2'-deoxy-2-thiouridine (62%), while the 62% population of the S conformer for H(2)o(4)U is significantly different from that of the parent 2-thiouridine, for which the N conformer is dominant (71%). Such a difference may be of biological importance, as the desulfurization process of natural tRNA 2-thiouridines may occur under conditions of oxidative stress in the cell and may influence the decoding process. Copyright © 2011 Elsevier Ltd. All rights reserved.
Rigid supersymmetry from conformal supergravity in five dimensions
International Nuclear Information System (INIS)
Pini, Alessandro; Rodriguez-Gomez, Diego; Schmude, Johannes
2015-01-01
We study the rigid limit of 5d conformal supergravity with minimal supersymmetry on Riemannian manifolds. The necessary and sufficient condition for the existence of a solution is the existence of a conformal Killing vector. Whenever a certain SU(2) curvature becomes abelian the backgrounds define a transversally holomorphic foliation. Subsequently we turn to the question under which circumstances these backgrounds admit a kinetic Yang-Mills term in the action of a vector multiplet. Here we find that the conformal Killing vector has to be Killing. We supplement the discussion with various appendices.
Directory of Open Access Journals (Sweden)
Marija Luić
2016-06-01
Full Text Available It is generaly believed that enzymes retain most of their functionality in the crystal form due to the large solvent content of protein crystals. This is facilitated by the fact that their natural environment in solution is not too far from the one found in the crystal form. Nevertheless, if the nature of the enzyme is such to require conformational changes, overcoming of the crystal packing constraints may prove to be too difficult. Such conformational change is present in one class of enzymes (purine nucleoside phosphorylases, that is the subject of our scientific interest for many years. The influence of crystal symmetry and crystal packing on the conformation of the active sites in the case of homohexameric purine nucleoside phosphorylases is presented and analysed. This work is licensed under a Creative Commons Attribution 4.0 International License.
Norbornane-based nucleoside and nucleotide analogues locked in North conformation
Czech Academy of Sciences Publication Activity Database
Dejmek, Milan; Šála, Michal; Hřebabecký, Hubert; Dračínský, Martin; Procházková, Eliška; Chalupská, Dominika; Klíma, Martin; Plačková, Pavla; Hájek, Miroslav; Andrei, G.; Naesens, L.; Leyssen, P.; Neyts, J.; Balzarini, J.; Bouřa, Evžen; Nencka, Radim
2015-01-01
Roč. 23, č. 1 (2015), s. 184-191 ISSN 0968-0896 R&D Projects: GA ČR GPP207/12/P625; GA MŠk LO1302 Institutional support: RVO:61388963 Keywords : carbocyclic nucleosides * purines * norbornane * antiviral * PI4KIIalpha Subject RIV: CC - Organic Chemistry Impact factor: 2.923, year: 2015
Czech Academy of Sciences Publication Activity Database
Šimák, Ondřej; Pachl, Petr; Fábry, Milan; Buděšínský, Miloš; Jandušík, T.; Hnízda, Aleš; Skleničková, Radka; Petrová, Magdalena; Veverka, Václav; Řezáčová, Pavlína; Brynda, Jiří; Rosenberg, Ivan
2014-01-01
Roč. 12, č. 40 (2014), s. 7971-7982 ISSN 1477-0520 R&D Projects: GA ČR GA203/09/0820; GA ČR GA13-24880S; GA ČR GA13-26526S; GA MŠk(CZ) LK11205; GA AV ČR KAN200520801 Institutional support: RVO:61388963 ; RVO:68378050 Keywords : 5'(3')-nucleotidase * structure * inhibition * cdN * mdN * nucleoside * SAR * phosphonic acid Subject RIV: CC - Organic Chemistry Impact factor: 3.562, year: 2014
Choy, Meng S; Li, Yang; Machado, Luciana E S F; Kunze, Micha B A; Connors, Christopher R; Wei, Xingyu; Lindorff-Larsen, Kresten; Page, Rebecca; Peti, Wolfgang
2017-02-16
Protein function originates from a cooperation of structural rigidity, dynamics at different timescales, and allostery. However, how these three pillars of protein function are integrated is still only poorly understood. Here we show how these pillars are connected in Protein Tyrosine Phosphatase 1B (PTP1B), a drug target for diabetes and cancer that catalyzes the dephosphorylation of numerous substrates in essential signaling pathways. By combining new experimental and computational data on WT-PTP1B and ≥10 PTP1B variants in multiple states, we discovered a fundamental and evolutionarily conserved CH/π switch that is critical for positioning the catalytically important WPD loop. Furthermore, our data show that PTP1B uses conformational and dynamic allostery to regulate its activity. This shows that both conformational rigidity and dynamics are essential for controlling protein activity. This connection between rigidity and dynamics at different timescales is likely a hallmark of all enzyme function. Copyright © 2017 Elsevier Inc. All rights reserved.
Directory of Open Access Journals (Sweden)
Rohit S Bavi
2013-02-01
Full Text Available Modified nucleic acid bases are most commonly found in tRNA. These may contain modifications from simple methylation to addition of bulky groups. Methylation of the four canonical nucleotide bases at a wide variety of positions is particularly prominent among the known modification. Methylation of N2 group of guanine is a relatively common modification in tRNA and rRNA. N2-methylguanosine (m2G is the second most often encountered nucleoside in E. coli tRNAs. N2, N2-dimethylguanosine (m22G is found in the majority of eukaryotic tRNAs and involved in forming base pair interactions with adjacent bases. Hence, in order to understand the structural significance of these methylated nucleic acid bases we have carried out molecular dynamics simulation to see the salvation effect. The results obtained shows iso-energetic conformational behaviors for m2G and m22G. The simulation trajectory of m2G shows regular periodical fluctuations suggesting that m2G is equally stable as either s-cis or s-trans rotamers. The two rotamers of m2G may interact canonically or non-canonically with opposite base as s-trans m2G26:C/A/U44 and s-cis m2G26:A/U44. The free rotations around the C-N bond could be the possible reason for these iso-energetic conformations. Dimethylation of G has almost no influence on base pairing with either A or U. Thus, these results reveal that modified nucleosides m2G and m22G may play an important role to prevent tRNA from adopting the unusual mitochondrial like conformation.
Shustova, Natalia B; Cozzolino, Anthony F; Dincă, Mircea
2012-12-05
Minimization of the torsional barrier for phenyl ring flipping in a metal-organic framework (MOF) based on the new ethynyl-extended octacarboxylate ligand H(8)TDPEPE leads to a fluorescent material with a near-dark state. Immobilization of the ligand in the rigid structure also unexpectedly causes significant strain. We used DFT calculations to estimate the ligand strain energies in our and all other topologically related materials and correlated these with empirical structural descriptors to derive general rules for trapping molecules in high-energy conformations within MOFs. These studies portend possible applications of MOFs for studying fundamental concepts related to conformational locking and its effects on molecular reactivity and chromophore photophysics.
Conformational properties of rigid-chain amphiphilic macromolecules : The phase diagram
Markov, V. A.; Vasilevskaya, V. V.; Khalatur, P. G.; ten Brinke, G.; Khokhlov, A. R.
The coil-globule transition in rigid-chain amphiphilic macromolecules was studied by means of computer simulation, and the phase diagrams for such molecules in the solvent quality-persistence length coordinates were constructed. It was shown that the type of phase diagram depends to a substantial
Conformationally rigid histone deacetylase inhibitors correct DF508-CFTR protein function
DEFF Research Database (Denmark)
Vickers, Chris J.; Olsen, Christian Adam; Hutt, Darren M.
2011-01-01
and bacterial infection, therapy using HDAC inhibitors has the potential to treat and correct the underlying etiology associated with the disorder. Subsequently, we have synthesized conformationally well-defined cyclic tetrapeptide derivatives based on the natural product HDAC inhibitor Apicidin, in order...
Beginning with a known 3-oxabicyclo[3.1.0]-hexane scaffold, the relocation of the fused cyclopropane ring bond and the shifting of the oxygen atom to an alternative location engendered a new 2-oxabicyclo[3.1.0]hexane template that mimics more closely the tetrahydrofuran ring of conventional nucleosides. The synthesis of this new class of locked nucleosides involved a novel
Czech Academy of Sciences Publication Activity Database
Kóšiová, Ivana; Šimák, Ondřej; Panova, Natalya; Buděšínský, Miloš; Petrová, Magdalena; Rejman, Dominik; Liboska, Radek; Páv, Ondřej; Rosenberg, Ivan
2014-01-01
Roč. 74, Mar 3 (2014), s. 145-168 ISSN 0223-5234 R&D Projects: GA ČR GA203/09/0820; GA ČR GA202/09/0193; GA ČR GA13-24880S; GA ČR GA13-26526S Institutional support: RVO:61388963 Keywords : phosphonate * conformationally constrained nucleotide analog * human thymidine phosphorylase * PBMC * bi-substrate-like inhibitor * Michael addition Subject RIV: CC - Organic Chemistry Impact factor: 3.447, year: 2014
Yurenko, Yevgen P; Zhurakivsky, Roman O; Samijlenko, Svitlana P; Hovorun, Dmytro M
2011-08-01
The aim of this work is to cast some light on the H-bonds in double-stranded DNA in its AI and BI forms. For this purpose, we have performed the MP2 and DFT quantum chemical calculations of the canonical nucleoside conformers, relative to the AI and BI DNA forms, and their Watson-Crick pairs, which were regarded as the simplest models of the double-stranded DNA. Based on the atoms-in-molecules analysis (AIM), five types of the CH···O hydrogen bonds, involving bases and sugar, were detected numerically from 1 to 3 per a conformer: C2'H···O5', C1'H···O2, C6H···O5', C8H···O5', and C6H···O4'. The energy values of H-bonds occupy the range of 2.3-5.6 kcal/mol, surely exceeding the kT value (0.62 kcal/mol). The nucleoside CH···O hydrogen bonds appeared to "survive" turns of bases against the sugar, sometimes in rather large ranges of the angle values, pertinent to certain conformations, which points out to the source of the DNA lability, necessary for the conformational adaptation in processes of its functioning. The calculation of the interactions in the dA·T nucleoside pair gives evidence, that additionally to the N6H···O4 and N1···N3H canonical H-bonds, between the bases adenine and thymine the third one (C2H···O2) is formed, which, though being rather weak (about 1 kcal/mol), satisfies the AIM criteria of H-bonding and may be classified as a true H-bond. The total energy of all the CH···O nontraditional intramolecular H-bonds in DNA nucleoside pairs appeared to be commensurable with the energy of H-bonds between the bases in Watson-Crick pairs, which implies their possible important role in the DNA shaping.
Czech Academy of Sciences Publication Activity Database
Šimon, Petr; Baszczyňski, Ondřej; Šaman, David; Stepan, G.; Hu, E.; Lansdon, E. B.; Jansa, P.; Janeba, Zlatko
2016-01-01
Roč. 122, Oct 21 (2016), s. 185-195 ISSN 0223-5234 Institutional support: RVO:61388963 Keywords : diarylpyrimidine (DAPY) * etravirine * human immunodeficiency virus ( HIV ) * non-nucleoside reverse transcriptase inhibitors * NNRTIs * rilpivirine Subject RIV: CC - Organic Chemistry Impact factor: 4.519, year: 2016
International Nuclear Information System (INIS)
Liu Yuanhua; Li Najun; Xia Xuewei; Xu Qingfeng; Ge Jianfeng; Lu Jianmei
2010-01-01
A nonvolatile write-once-read-many-times (WORM) memory device based on poly((4-vinylbenzyl)-9H-carbazole) (PVCz) was fabricated by a simple and conventional process. The as-fabricated device was found to be at its OFF state and could be programmed irreversibly to the ON state with a low transition voltage of -1.7 V. The device exhibits a high ON/OFF current ratio of up to 10 6 , high stability in retention time up to 8 h and number of read cycles up to 10 8 under a read voltage of -1.0 V in both ON and OFF states. The results of X-ray diffraction (XRD) and fluorescence emission spectra in different states of PVCz indicate that the electrical bistable phenomenon is caused by the voltage-induced conformation change of the pendant carbazole groups. With high performance, low power consumption and low production cost, the device fabricated with PVCz has a potential application for nonvolatile memory.
DEFF Research Database (Denmark)
Babu, B. Ravindra; Prasad, Ashok K.; Trikha, Smriti
2002-01-01
. The phosphoramidite approach was used for automated incorporation of the LNA-type beta-configured C-aryl monomers 17a-17e into short DNA and 2'-OMe-RNA/LNA strands. It is shown that universal hybridization can be obtained with a conformationally restricted monomer as demonstrated most convincingly for the pyrene LNA...... monomer 17d, both in a DNA context and in an RNA-like context. Increased binding affinity of oligonucleotide probes for universal hybridization can be induced by combining the pyrene LNA monomer 17d with affinity-enhancing 2'-OMe-RNA/LNA monomers....
Marquez, Victor E; Hughes, Stephen H; Sei, Shizuko; Agbaria, Riad
2006-09-01
Conformationally locked (North)-methanocarbathymidine (N-MCT) and (South)-methanocarbathymidine (S-MCT) have been used to investigate the conformational preferences of kinases and polymerases. The herpes kinases show a distinct bias for S-MCT, while DNA polymerases almost exclusively incorporate the North 5'-triphosphate (N-MCT-TP). Only N-MCT demonstrated potent antiviral activity against herpes simplex viruses (HSV-1 and 2) and Kaposi's sarcoma-associated herpesvirus (KSHV). The activity of N-MCT depends on its metabolic transformation to N-MCT-TP by the herpes kinases (HSV-tk or KSHV-tk), which catalyze the mono and diphosphorylation steps; cellular kinases generate the triphosphate. N-MCT at a dose of 5.6 mg/kg was totally protective for mice inoculated intranasally with HSV-1. Tumor cells that are not responsive to antiviral therapy became sensitive to N-MCT if the cells expressed HSV-tk. N-MCT given twice daily (100 mg/kg) for 7 days completely inhibited the growth of MC38 tumors derived from cells that express HSV-tk in mice while exhibiting no effect on tumors derived from non-transduced cells. After i.p. administration, N-MCT was rapidly absorbed and distributed in all organs examined with slow penetration into brain and testes. N-MCT-TP was also a potent inhibitor of HIV replication in human osteosarcoma (HOS) cells expressing HSV-tk.
Nucleotides, Nucleosides, and Nucleobases
DEFF Research Database (Denmark)
Jensen, Kaj Frank; Dandanell, Gert; Hove-Jensen, Bjarne
2008-01-01
We review literature on the metabolism of ribo- and deoxyribonucleotides, nucleosides, and nucleobases in Escherichia coli and Salmonella,including biosynthesis, degradation, interconversion, and transport. Emphasis is placed on enzymology and regulation of the pathways, at both the level of gene...
Crespo-Hernandez, Carlos E; Close, David M; Gorb, Leonid; Leszczynski, Jerzy
2007-05-17
Redox potentials for the DNA nucleobases and nucleosides, various relevant nucleoside analogues, Watson-Crick base pairs, and seven organic dyes are presented based on DFT/B3LYP/6-31++G(d,p) and B3YLP/6-311+G(2df,p)//B3LYP/6-31+G* levels of calculations. The values are determined from an experimentally calibrated set of equations that correlate the vertical ionization (electron affinity) energy of 20 organic molecules with their experimental reversible oxidation (reduction) potential. Our results are in good agreement with those estimated experimentally for the DNA nucleosides in acetonitrile solutions (Seidel et al. J. Phys. Chem. 1996, 100, 5541). We have found that nucleosides with anti conformation exhibit lower oxidation potentials than the corresponding syn conformers. The lowering in the oxidation potential is due to the formation of an intramolecular hydrogen bonding interaction between the 5'-OH group of the sugar and the N3 of the purine bases or C2=O of the pyrimidine bases in the syn conformation. Pairing of adenine or guanine with its complementary pyrimidine base decreases its oxidation potential by 0.15 or 0.28 V, respectively. The calculated energy difference between the oxidation potential for the G.C base pair and that of the guanine base is in good agreement with the experimental value estimated recently (0.34 V: Caruso, T.; et al. J. Am. Chem. Soc. 2005, 127, 15040). The complete and consistent set of reversible redox values determined in this work for the DNA constituents is expected to be of considerable value to those studying charge and electronic energy transfer in DNA.
Nucleoside Inhibitors of Zika Virus
Czech Academy of Sciences Publication Activity Database
Eyer, L.; Nencka, Radim; Huvarová, I.; Palus, Martin; Alves, M. J.; Gould, E. A.; De Clercq, E.; Růžek, Daniel
2016-01-01
Roč. 214, č. 5 (2016), s. 707-711 ISSN 0022-1899 Institutional support: RVO:61388963 ; RVO:60077344 Keywords : Zika virus * flavivirus * nucleoside analogue * antiviral * therapy Subject RIV: CC - Organic Chemistry; EE - Microbiology, Virology (BC-A) Impact factor: 6.273, year: 2016
HIV-1 Non-Nucleoside Reverse Transcriptase Inhibitors
DEFF Research Database (Denmark)
Vanangamudi, Murugesan; Poongavanam, Vasanthanathan; Namasivayam, Vigneshwaran
2017-01-01
BACKGROUND: Design of inhibitors for HIV-1 reverse transcriptase inhibition (HIV-1 RT) is one of the successful chemotherapies for the treatment of HIV infection. Among the inhibitors available for HIV-1 RT, non-nucleoside reverse transcriptase inhibitors (NNRTIs) have shown to be very promising......: The conformation dependent-alignment based (CoMFA and CoMSIA) methods have been proven very successful ligand based strategy in the drug design. Here, CoMFA and CoMSIA studies reported for structurally distinct NNRTIs including thiazolobenzimidazole, dipyridodiazepinone, 1,1,3-trioxo [1,2,4]-thiadiazine...
Nucleoside analog toxicity and nucleoside kinase deficiency : Effects on mitochondrial DNA
Bjerke, Mia
2008-01-01
Nucleoside analogs are modified nucleosides used in treatment of cancer and viral infections. They are dependent on intracellular phosphorylation to be pharmacologically active. Deoxyribonucleoside kinases catalyze the rate-limiting step in the phosphorylation of many clinically used nucleoside analogs. Human cells contain four distinct deoxyribonucleoside kinases that have partially overlapping substrate specificities for both naturally occurring deoxyribonucleosides as wel...
Marine Nucleosides: Structure, Bioactivity, Synthesis and Biosynthesis
Directory of Open Access Journals (Sweden)
Ri-Ming Huang
2014-12-01
Full Text Available Nucleosides are glycosylamines that structurally form part of nucleotide molecules, the building block of DNA and RNA. Both nucleosides and nucleotides are vital components of all living cells and involved in several key biological processes. Some of these nucleosides have been obtained from a variety of marine resources. Because of the biological importance of these compounds, this review covers 68 marine originated nucleosides and their synthetic analogs published up to June 2014. The review will focus on the structures, bioactivities, synthesis and biosynthetic processes of these compounds.
Pentose phosphates in nucleoside interconversion and catabolism.
Tozzi, Maria G; Camici, Marcella; Mascia, Laura; Sgarrella, Francesco; Ipata, Piero L
2006-03-01
Ribose phosphates are either synthesized through the oxidative branch of the pentose phosphate pathway, or are supplied by nucleoside phosphorylases. The two main pentose phosphates, ribose-5-phosphate and ribose-1-phosphate, are readily interconverted by the action of phosphopentomutase. Ribose-5-phosphate is the direct precursor of 5-phosphoribosyl-1-pyrophosphate, for both de novo and 'salvage' synthesis of nucleotides. Phosphorolysis of deoxyribonucleosides is the main source of deoxyribose phosphates, which are interconvertible, through the action of phosphopentomutase. The pentose moiety of all nucleosides can serve as a carbon and energy source. During the past decade, extensive advances have been made in elucidating the pathways by which the pentose phosphates, arising from nucleoside phosphorolysis, are either recycled, without opening of their furanosidic ring, or catabolized as a carbon and energy source. We review herein the experimental knowledge on the molecular mechanisms by which (a) ribose-1-phosphate, produced by purine nucleoside phosphorylase acting catabolically, is either anabolized for pyrimidine salvage and 5-fluorouracil activation, with uridine phosphorylase acting anabolically, or recycled for nucleoside and base interconversion; (b) the nucleosides can be regarded, both in bacteria and in eukaryotic cells, as carriers of sugars, that are made available though the action of nucleoside phosphorylases. In bacteria, catabolism of nucleosides, when suitable carbon and energy sources are not available, is accomplished by a battery of nucleoside transporters and of inducible catabolic enzymes for purine and pyrimidine nucleosides and for pentose phosphates. In eukaryotic cells, the modulation of pentose phosphate production by nucleoside catabolism seems to be affected by developmental and physiological factors on enzyme levels.
Nucleoside antibiotics: biosynthesis, regulation, and biotechnology.
Niu, Guoqing; Tan, Huarong
2015-02-01
The alarming rise in antibiotic-resistant pathogens has coincided with a decline in the supply of new antibiotics. It is therefore of great importance to find and create new antibiotics. Nucleoside antibiotics are a large family of natural products with diverse biological functions. Their biosynthesis is a complex process through multistep enzymatic reactions and is subject to hierarchical regulation. Genetic and biochemical studies of the biosynthetic machinery have provided the basis for pathway engineering and combinatorial biosynthesis to create new or hybrid nucleoside antibiotics. Dissection of regulatory mechanisms is leading to strategies to increase the titer of bioactive nucleoside antibiotics. Copyright © 2014. Published by Elsevier Ltd.
Visualizing multistep elevator-like transitions of a nucleoside transporter.
Hirschi, Marscha; Johnson, Zachary Lee; Lee, Seok-Yong
2017-05-04
Membrane transporters move substrates across the membrane by alternating access of their binding sites between the opposite sides of the membrane. An emerging model of this process is the elevator mechanism, in which a substrate-binding transport domain moves a large distance across the membrane. This mechanism has been characterized by a transition between two states, but the conformational path that leads to the transition is not yet known, largely because the available structural information has been limited to the two end states. Here we present crystal structures of the inward-facing, intermediate, and outward-facing states of a concentrative nucleoside transporter from Neisseria wadsworthii. Notably, we determined the structures of multiple intermediate conformations, in which the transport domain is captured halfway through its elevator motion. Our structures present a trajectory of the conformational transition in the elevator model, revealing multiple intermediate steps and state-dependent conformational changes within the transport domain that are associated with the elevator-like motion.
International Nuclear Information System (INIS)
Kulikowski, T.; Bretner, M.; Felczak, K.; Drabikowska, A.; Shugar, D.
1998-01-01
Full text. Pyrimidine nucleoside analogues are an important class of compounds with antimetabolic (antitumor, antiparasitic and antiviral) properties. The synthesis of thiated nucleoside and nucleotide analogues, determination of structures, conformation and dissociation constans, their potential chemotherapeutic activities, and their substrate/inhibitor properties in various enzyme systems, with emphasis on enzymes related to chemotherapeutic activities, were investigated. In the series of thionated inhibitors of thymidylate synthase (TS), potential antitumor agents, regioselective syntheses were elaborated for 2- and 4-thio, and 2,4-dithio derivatives of 2'-deoxyuridine (dUrd), 5-fluoro-2'-deoxyuridine (FdUrd), and several other 5-fluoro-, 5-bromo- and 5-trifluoromethyl congeners, and the 2-thio derivatives of FdUrd and its α-anomer, which proved to be selective agents with high cytotoxicities correlated with the inhibitory activities vs TS of their corresponding 5'-monophosphates. Regioslective syntheses were also elaborated for 2'-deoxycytidin e and 5-fluoro-2'-deoxycitidine derivatives. Solution conformation of these nucleosides were deduced from high-resolution (500 MHz) 1 H NMR spectra. Substrate/inhibitor properties of 2-thio-2'-deoxycitidine (S 2 dCyd) and 5-fluoro-2-thio-2'-deoxycitidine ( S 2 FdCyd) with respect to human leukemic spleen deoxycytidine kinase have been examined. Both are substrates, and also good inhibitors, of phosphorylation of 2'-deoxycitidine and 2'-deoxyadenosine. Particular attention was directed to the specificity of t he NTP phosphate donor for several nucleoside kinases, and procedures have been developed for distinguishing between ATP and other NTP donors, a problem of importance in chemotherapy with nucleoside analogues. Biological properties of the newly synthetize d thiated pyrimidine 2',3'-dideoxy-3'-fluoronucleosides, S 2 ,3'-FddUrd and S 2 ,3'-FddThd, were also investigated. Thiated 3'-fluoronucleosides were moderate
Thermostability in rubredoxin and its relationship to mechanical rigidity
Rader, A. J.
2010-03-01
The source of increased stability in proteins from organisms that thrive in extreme thermal environments is not well understood. Previous experimental and theoretical studies have suggested many different features possibly responsible for such thermostability. Many of these thermostabilizing mechanisms can be accounted for in terms of structural rigidity. Thus a plausible hypothesis accounting for this remarkable stability in thermophilic enzymes states that these enzymes have enhanced conformational rigidity at temperatures below their native, functioning temperature. Experimental evidence exists to both support and contradict this supposition. We computationally investigate the relationship between thermostability and rigidity using rubredoxin as a case study. The mechanical rigidity is calculated using atomic models of homologous rubredoxin structures from the hyperthermophile Pyrococcus furiosus and mesophile Clostridium pasteurianum using the FIRST software. A global increase in structural rigidity (equivalently a decrease in flexibility) corresponds to an increase in thermostability. Locally, rigidity differences (between mesophilic and thermophilic structures) agree with differences in protection factors.
Thermostability in rubredoxin and its relationship to mechanical rigidity
International Nuclear Information System (INIS)
Rader, A J
2010-01-01
The source of increased stability in proteins from organisms that thrive in extreme thermal environments is not well understood. Previous experimental and theoretical studies have suggested many different features possibly responsible for such thermostability. Many of these thermostabilizing mechanisms can be accounted for in terms of structural rigidity. Thus a plausible hypothesis accounting for this remarkable stability in thermophilic enzymes states that these enzymes have enhanced conformational rigidity at temperatures below their native, functioning temperature. Experimental evidence exists to both support and contradict this supposition. We computationally investigate the relationship between thermostability and rigidity using rubredoxin as a case study. The mechanical rigidity is calculated using atomic models of homologous rubredoxin structures from the hyperthermophile Pyrococcus furiosus and mesophile Clostridium pasteurianum using the FIRST software. A global increase in structural rigidity (equivalently a decrease in flexibility) corresponds to an increase in thermostability. Locally, rigidity differences (between mesophilic and thermophilic structures) agree with differences in protection factors
Genetics Home Reference: purine nucleoside phosphorylase deficiency
... the expand/collapse boxes. Description Purine nucleoside phosphorylase deficiency is one of several disorders that damage the immune system and cause severe combined immunodeficiency (SCID). People with SCID lack virtually all immune protection from foreign invaders such as bacteria, viruses, and ...
Conformal Nets II: Conformal Blocks
Bartels, Arthur; Douglas, Christopher L.; Henriques, André
2017-08-01
Conformal nets provide a mathematical formalism for conformal field theory. Associated to a conformal net with finite index, we give a construction of the `bundle of conformal blocks', a representation of the mapping class groupoid of closed topological surfaces into the category of finite-dimensional projective Hilbert spaces. We also construct infinite-dimensional spaces of conformal blocks for topological surfaces with smooth boundary. We prove that the conformal blocks satisfy a factorization formula for gluing surfaces along circles, and an analogous formula for gluing surfaces along intervals. We use this interval factorization property to give a new proof of the modularity of the category of representations of a conformal net.
Conformal invariance in harmonic superspace
International Nuclear Information System (INIS)
Galperin, A.; Ivanov, E.; Ogievetsky, V.; Sokatchev, E.
1987-01-01
In the present paper we show how the N = 2 superconformal group is realised in harmonic superspace and examine conformal invariance of N = 2 off-shell theories. We believe that the example of N = O self-dual Yang-Mills equations can serve as an instructive introduction to the subject of harmonic superspace and this is examined. The rigid N = 2 conformal supersymmetry and its local version, i.e. N = 2 conformal supergravity is also discussed. The paper is a contribution to the book commemorating the sixtieth birthday of E.S. Fradkin. (author)
Weiss, Asia; Whiteley, Walter
2014-01-01
This book contains recent contributions to the fields of rigidity and symmetry with two primary focuses: to present the mathematically rigorous treatment of rigidity of structures, and to explore the interaction of geometry, algebra, and combinatorics. Overall, the book shows how researchers from diverse backgrounds explore connections among the various discrete structures with symmetry as the unifying theme. Contributions present recent trends and advances in discrete geometry, particularly in the theory of polytopes. The rapid development of abstract polytope theory has resulted in a rich theory featuring an attractive interplay of methods and tools from discrete geometry, group theory, classical geometry, hyperbolic geometry and topology. The volume will also be a valuable source as an introduction to the ideas of both combinatorial and geometric rigidity theory and its applications, incorporating the surprising impact of symmetry. It will appeal to students at both the advanced undergraduate and gradu...
Pukhlikov, Aleksandr
2013-01-01
Birational rigidity is a striking and mysterious phenomenon in higher-dimensional algebraic geometry. It turns out that certain natural families of algebraic varieties (for example, three-dimensional quartics) belong to the same classification type as the projective space but have radically different birational geometric properties. In particular, they admit no non-trivial birational self-maps and cannot be fibred into rational varieties by a rational map. The origins of the theory of birational rigidity are in the work of Max Noether and Fano; however, it was only in 1970 that Iskovskikh and Manin proved birational superrigidity of quartic three-folds. This book gives a systematic exposition of, and a comprehensive introduction to, the theory of birational rigidity, presenting in a uniform way, ideas, techniques, and results that so far could only be found in journal papers. The recent rapid progress in birational geometry and the widening interaction with the neighboring areas generate the growing interest ...
Tetrofuranose nucleoside phosphonic acids: Synthesis and properties
Czech Academy of Sciences Publication Activity Database
Poláková, Ivana; Buděšínský, Miloš; Točík, Zdeněk; Rosenberg, Ivan
2011-01-01
Roč. 76, č. 5 (2011), s. 503-536 ISSN 0010-0765 R&D Projects: GA AV ČR KAN200520801; GA ČR GA203/09/0820; GA MŠk(CZ) LC06061; GA MŠk(CZ) LC06077 Institutional research plan: CEZ:AV0Z40550506 Keywords : tetrofuranosyl phosphonate * nucleotide analogues * phosphonomethoxy nucleosides * sugar hydroxyphosphonates Subject RIV: CC - Organic Chemistry Impact factor: 1.283, year: 2011
DEFF Research Database (Denmark)
Ryttov, Thomas Aaby; Sannino, Francesco
2010-01-01
fixed point. As a consistency check we recover the previously investigated bounds of the conformal windows when restricting to a single matter representation. The earlier conformal windows can be imagined to be part now of the new conformal house. We predict the nonperturbative anomalous dimensions...... at the infrared fixed points. We further investigate the effects of adding mass terms to the condensates on the conformal house chiral dynamics and construct the simplest instanton induced effective Lagrangian terms...
Tănase, Constantin I; Drăghici, Constantin; Căproiu, Miron Teodor; Shova, Sergiu; Mathe, Christophe; Cocu, Florea G; Enache, Cristian; Maganu, Maria
2014-01-01
An amine group was synthesized starting from an optically active bicyclo[2.2.1]heptane compound, which was then used to build the 5 atoms ring of a key 6-chloropurine intermediate. This was then reacted with ammonia and selected amines obtaining new adenine- and 6-substituted adenine conformationally constrained carbocyclic nucleoside analogues with a bicyclo[2.2.1]heptane skeleton in the sugar moiety. X-ray crystallography confirmed an exo-coupling of base to the ring and a L configuration of the nucleoside analogues. The compounds were tested for anticancer activity. Copyright © 2013 Elsevier Ltd. All rights reserved.
Rigid supersymmetry with boundaries
Energy Technology Data Exchange (ETDEWEB)
Belyaev, D.V. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Van Nieuwenhuizen, P. [State Univ. of New York, Stony Brook, NY (United States). C.N. Yang Inst. for Theoretical Physics
2008-01-15
We construct rigidly supersymmetric bulk-plus-boundary actions, both in x-space and in superspace. For each standard supersymmetric bulk action a minimal supersymmetric bulk-plus-boundary action follows from an extended F- or D-term formula. Additional separately supersymmetric boundary actions can be systematically constructed using co-dimension one multiplets (boundary superfields). We also discuss the orbit of boundary conditions which follow from the Euler-Lagrange variational principle. (orig.)
This section provides information on: current laws, regulations and guidance, policy and technical guidance, project-level conformity, general information, contacts and training, adequacy review of SIP submissions
A monoclonal antibody that specifically recognizes m6A nucleoside
Espuny, Ruth; Castro, Ana; Codony, Carles; Eritja Casadellà, Ramón; Bach-Elias, Montse
1998-01-01
A hybridoma against the nucleoside m6A has been obtained from mouse spleen. This hybridoma was named H65 and it secretes monoclonal antibodies anti-m6A. The competition assays showed that the monoclonal antibody was highly specific for m6A nucleoside.
Two nucleoside transporters in Lactococcus lactis with different substrate specificities
DEFF Research Database (Denmark)
Martinussen, Jan; Sørensen, Claus; Jendresen, Christian Bille
2010-01-01
, and the utilization of nucleotides is dependent on exogenous phosphatases. The composition of transporters with specificity for purine and pyrimidine nucleosides and nucleobases is subject to variation. The ability of Lactococcus lactis to transport different nucleosides across the cell membrane was characterized...
Bag, Subhendu Sekhar; Talukdar, Sangita; Kundu, Rajen; Saito, Isao; Jana, Subhashis
2014-01-25
Dual door entry to exciplex formation was established in a chimeric DNA duplex wherein a fluorescent non-nucleosidic base surrogate () is paired against a fluorescent nucleosidic base surrogate (). Packing of the nucleobases via intercalative stacking interactions led to an exciplex emission either via FRET from the donor or direct excitation of the FRET acceptor .
Directory of Open Access Journals (Sweden)
Nikolay Ivantchev
2013-10-01
Full Text Available Conformism was studied among 46 workers with different kinds of occupations by means of two modified scales measuring conformity by Santor, Messervey, and Kusumakar (2000 – scale for perceived peer pressure and scale for conformism in antisocial situations. The hypothesis of the study that workers’ conformism is expressed in a medium degree was confirmed partly. More than a half of the workers conform in a medium degree for taking risk, and for the use of alcohol and drugs, and for sexual relationships. More than a half of the respondents conform in a small degree for anti-social activities (like a theft. The workers were more inclined to conform for risk taking (10.9%, then – for the use of alcohol, drugs and for sexual relationships (8.7%, and in the lowest degree – for anti-social activities (6.5%. The workers who were inclined for the use of alcohol and drugs tended also to conform for anti-social activities.
Directory of Open Access Journals (Sweden)
Roger Stromberg
2013-10-01
Full Text Available An efficient and facile strategy has been developed for bromination of nucleosides using sodium monobromoisocyanurate (SMBI. Our methodology demonstrates bromination at the C-5 position of pyrimidine nucleosides and the C-8 position of purine nucleosides. Unprotected and also several protected nucleosides were brominated in moderate to high yields following this procedure.
Directory of Open Access Journals (Sweden)
Priscila O de Giuseppe
Full Text Available The hexameric purine nucleoside phosphorylase from Bacillus subtilis (BsPNP233 displays great potential to produce nucleoside analogues in industry and can be exploited in the development of new anti-tumor gene therapies. In order to provide structural basis for enzyme and substrates rational optimization, aiming at those applications, the present work shows a thorough and detailed structural description of the binding mode of substrates and nucleoside analogues to the active site of the hexameric BsPNP233. Here we report the crystal structure of BsPNP233 in the apo form and in complex with 11 ligands, including clinically relevant compounds. The crystal structure of six ligands (adenine, 2'deoxyguanosine, aciclovir, ganciclovir, 8-bromoguanosine, 6-chloroguanosine in complex with a hexameric PNP are presented for the first time. Our data showed that free bases adopt alternative conformations in the BsPNP233 active site and indicated that binding of the co-substrate (2'deoxyribose 1-phosphate might contribute for stabilizing the bases in a favorable orientation for catalysis. The BsPNP233-adenosine complex revealed that a hydrogen bond between the 5' hydroxyl group of adenosine and Arg(43* side chain contributes for the ribosyl radical to adopt an unusual C3'-endo conformation. The structures with 6-chloroguanosine and 8-bromoguanosine pointed out that the Cl(6 and Br(8 substrate modifications seem to be detrimental for catalysis and can be explored in the design of inhibitors for hexameric PNPs from pathogens. Our data also corroborated the competitive inhibition mechanism of hexameric PNPs by tubercidin and suggested that the acyclic nucleoside ganciclovir is a better inhibitor for hexameric PNPs than aciclovir. Furthermore, comparative structural analyses indicated that the replacement of Ser(90 by a threonine in the B. cereus hexameric adenosine phosphorylase (Thr(91 is responsible for the lack of negative cooperativity of phosphate binding
Wilhelm, M; Fishman, J A; Pontikis, R; Aubertin, A M; Wilhelm, F X
2002-12-01
Transplantation of organs, tissues or cells from pigs to humans could be a potential solution to the shortage of human organs for transplantation. Porcine endogenous retroviruses (PERVs) remain a major safety concern for porcine xenotransplantation. Thus, finding drugs that could be used as virological prophylaxis (or therapy) against PERV replication would be desirable. One of the most effective ways to block retroviral multiplication is to inhibit the enzyme reverse transcriptase (RT) which catalyzes the reverse transcription of viral RNA to proviral double-stranded DNA. We report here the cloning and expression of PERV RT and its susceptibility to several inhibitors. Our data demonstrate PERV susceptibility in vitro to the triphosphorylated nucleoside analog of zidovudine (AZT) and to ddGTP and to a lesser extent to ddTTP but almost no susceptibility to the non-nucleoside RT inhibitors tested.
Directory of Open Access Journals (Sweden)
Richard Daifuku
2018-02-01
Full Text Available Vitamin E phosphate (VEP nucleoside prodrugs are designed to bypass two mechanisms of tumor resistance to therapeutic nucleosides: nucleoside transport and kinase downregulation. Certain isoforms of vitamin E (VE have shown activity against solid and hematologic tumors and result in chemosensitization. Because gemcitabine is one of the most common chemotherapeutics for the treatment of cancer, it was used to demonstrate the constructs utility. Four different VE isoforms were conjugated with gemcitabine at the 5′ position. Two of these were δ-tocopherol-monophosphate (MP gemcitabine (NUC050 and δ-tocotrienol-MP gemcitabine (NUC052. NUC050 was shown to be able to deliver gemcitabine-MP intracellularly by a nucleoside transport independent mechanism. Its half-life administered IV in mice was 3.9 h. In a mouse xenograft model of non-small cell lung cancer (NSCLC NCI-H460, NUC050 at a dose of 40 mg/kg IV qwk × 4 resulted in significant inhibition to tumor growth on days 11–31 (p < 0.05 compared to saline control (SC. Median survival was 33 days (NUC050 vs. 25.5 days (SC ((hazard ratio HR = 0.24, p = 0.017. Further, NUC050 significantly inhibited tumor growth compared to historic data with gemcitabine at 135 mg/kg IV q5d × 3 on days 14–41 (p < 0.05. NUC052 was administered at a dose of 40 mg/kg IV qwk × 2 followed by 50 mg/kg qwk × 2. NUC052 resulted in inhibition to tumor growth on days 14–27 (p < 0.05 and median survival was 34 days (HR = 0.27, p = 0.033. NUC050 and NUC052 have been shown to be safe and effective in a mouse xenograft of NSCLC.
Directory of Open Access Journals (Sweden)
Frauendiener Jörg
2000-08-01
Full Text Available The notion of conformal infinity has a long history within the research in Einstein's theory of gravity. Today, ``conformal infinity'' is related with almost all other branches of research in general relativity, from quantisation procedures to abstract mathematical issues to numerical applications. This review article attempts to show how this concept gradually and inevitably evolved out of physical issues, namely the need to understand gravitational radiation and isolated systems within the theory of gravitation and how it lends itself very naturally to solve radiation problems in numerical relativity. The fundamental concept of null-infinity is introduced. Friedrich's regular conformal field equations are presented and various initial value problems for them are discussed. Finally, it is shown that the conformal field equations provide a very powerful method within numerical relativity to study global problems such as gravitational wave propagation and detection.
Frauendiener, Jörg
2004-01-01
The notion of conformal infinity has a long history within the research in Einstein's theory of gravity. Today, "conformal infinity" is related to almost all other branches of research in general relativity, from quantisation procedures to abstract mathematical issues to numerical applications. This review article attempts to show how this concept gradually and inevitably evolved from physical issues, namely the need to understand gravitational radiation and isolated systems within the theory of gravitation, and how it lends itself very naturally to the solution of radiation problems in numerical relativity. The fundamental concept of null-infinity is introduced. Friedrich's regular conformal field equations are presented and various initial value problems for them are discussed. Finally, it is shown that the conformal field equations provide a very powerful method within numerical relativity to study global problems such as gravitational wave propagation and detection.
Directory of Open Access Journals (Sweden)
Frauendiener Jörg
2004-01-01
Full Text Available The notion of conformal infinity has a long history within the research in Einstein's theory of gravity. Today, 'conformal infinity' is related to almost all other branches of research in general relativity, from quantisation procedures to abstract mathematical issues to numerical applications. This review article attempts to show how this concept gradually and inevitably evolved from physical issues, namely the need to understand gravitational radiation and isolated systems within the theory of gravitation, and how it lends itself very naturally to the solution of radiation problems in numerical relativity. The fundamental concept of null-infinity is introduced. Friedrich's regular conformal field equations are presented and various initial value problems for them are discussed. Finally, it is shown that the conformal field equations provide a very powerful method within numerical relativity to study global problems such as gravitational wave propagation and detection.
The General Conformity requirements ensure that the actions taken by federal agencies in nonattainment and maintenance areas do not interfere with a state’s plans to meet national standards for air quality.
Frauendiener, J?rg
2000-01-01
The notion of conformal infinity has a long history within the research in Einstein's theory of gravity. Today, 'conformal infinity' is related to almost all other branches of research in general relativity, from quantisation procedures to abstract mathematical issues to numerical applications. This review article attempts to show how this concept gradually and inevitably evolved from physical issues, namely the need to understand gravitational radiation and isolated systems within the theory...
Conformation radiotherapy and conformal radiotherapy
International Nuclear Information System (INIS)
Morita, Kozo
1999-01-01
In order to coincide the high dose region to the target volume, the 'Conformation Radiotherapy Technique' using the multileaf collimator and the device for 'hollow-out technique' was developed by Prof. S. Takahashi in 1960. This technique can be classified a type of 2D-dynamic conformal RT techniques. By the clinical application of this technique, the late complications of the lens, the intestine and the urinary bladder after radiotherapy for the maxillary cancer and the cervical cancer decreased. Since 1980's the exact position and shape of the tumor and the surrounding normal tissues can be easily obtained by the tremendous development of the CT/MRI imaging technique. As a result, various kinds of new conformal techniques such as the 3D-CRT, the dose intensity modulation, the tomotherapy have been developed since the beginning of 1990'. Several 'dose escalation study with 2D-/3D conformal RT' is now under way to improve the treatment results. (author)
Meteorite-catalyzed synthesis of nucleosides and other prebiotic compounds
Czech Academy of Sciences Publication Activity Database
Ferus, Martin; Knížek, Antonín; Civiš, Svatopluk
2015-01-01
Roč. 112, č. 23 (2015), s. 7109-7110 ISSN 0027-8424 Institutional support: RVO:61388955 Keywords : meteorite-catalzzed synthesis * nucleosides * prebiotic compounds Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 9.423, year: 2015
International Nuclear Information System (INIS)
Hooft, G.
2012-01-01
The dynamical degree of freedom for the gravitational force is the metric tensor, having 10 locally independent degrees of freedom (of which 4 can be used to fix the coordinate choice). In conformal gravity, we split this field into an overall scalar factor and a nine-component remainder. All unrenormalizable infinities are in this remainder, while the scalar component can be handled like any other scalar field such as the Higgs field. In this formalism, conformal symmetry is spontaneously broken. An imperative demand on any healthy quantum gravity theory is that black holes should be described as quantum systems with micro-states as dictated by the Hawking-Bekenstein theory. This requires conformal symmetry that may be broken spontaneously but not explicitly, and this means that all conformal anomalies must cancel out. Cancellation of conformal anomalies yields constraints on the matter sector as described by some universal field theory. Thus black hole physics may eventually be of help in the construction of unified field theories. (author)
Torsional Rigidity of Minimal Submanifolds
DEFF Research Database (Denmark)
Markvorsen, Steen; Palmer, Vicente
2006-01-01
We prove explicit upper bounds for the torsional rigidity of extrinsic domains of minimal submanifolds $P^m$ in ambient Riemannian manifolds $N^n$ with a pole $p$. The upper bounds are given in terms of the torsional rigidities of corresponding Schwarz symmetrizations of the domains in warped...
Quantum charged rigid membrane
Energy Technology Data Exchange (ETDEWEB)
Cordero, Ruben [Departamento de Fisica, Escuela Superior de Fisica y Matematicas del I.P.N., Unidad Adolfo Lopez Mateos, Edificio 9, 07738 Mexico, D.F. (Mexico); Molgado, Alberto [Unidad Academica de Fisica, Universidad Autonoma de Zacatecas, Zacatecas Zac. (Mexico); Rojas, Efrain, E-mail: cordero@esfm.ipn.mx, E-mail: amolgado@fisica.uaz.edu.mx, E-mail: efrojas@uv.mx [Departamento de Fisica, Facultad de Fisica e Inteligencia Artificial, Universidad Veracruzana, 91000 Xalapa, Veracruz (Mexico)
2011-03-21
The early Dirac proposal to model the electron as a charged membrane is reviewed. A rigidity term, instead of the natural membrane tension, involving linearly the extrinsic curvature of the worldvolume swept out by the membrane is considered in the action modeling the bubble in the presence of an electromagnetic field. We set up this model as a genuine second-order derivative theory by considering a non-trivial boundary term which plays a relevant part in our formulation. The Lagrangian in question is linear in the bubble acceleration and by means of the Ostrogradski-Hamiltonian approach, we observed that the theory comprises the management of both first- and second-class constraints. We thus show that our second-order approach is robust allowing for a proper quantization. We found an effective quantum potential which permits us to compute bounded states for the system. We comment on the possibility of describing brane world universes by invoking this kind of second-order correction terms.
Quantum charged rigid membrane
International Nuclear Information System (INIS)
Cordero, Ruben; Molgado, Alberto; Rojas, Efrain
2011-01-01
The early Dirac proposal to model the electron as a charged membrane is reviewed. A rigidity term, instead of the natural membrane tension, involving linearly the extrinsic curvature of the worldvolume swept out by the membrane is considered in the action modeling the bubble in the presence of an electromagnetic field. We set up this model as a genuine second-order derivative theory by considering a non-trivial boundary term which plays a relevant part in our formulation. The Lagrangian in question is linear in the bubble acceleration and by means of the Ostrogradski-Hamiltonian approach, we observed that the theory comprises the management of both first- and second-class constraints. We thus show that our second-order approach is robust allowing for a proper quantization. We found an effective quantum potential which permits us to compute bounded states for the system. We comment on the possibility of describing brane world universes by invoking this kind of second-order correction terms.
Synthesis of coumarin or ferrocene labeled nucleosides via Staudinger ligation
Directory of Open Access Journals (Sweden)
Kois Pavol
2006-11-01
Full Text Available Abstract Background Reaction of azides with triaryl phosphines under mild conditions gives iminophosphoranes which can react with almost any kind of electrophilic reagent, e.g. aldehydes/ketones to form imines or esters to form amides. This so-called Staudinger ligation has been employed in a wide range of applications as a general tool for bioconjugation including specific labeling of nucleic acids. Results A new approach for the preparation of labeled nucleosides via intermolecular Staudinger ligation is described. Reaction of azidonucleosides with triphenylphosphine lead to iminophosphorane intermediates, which react subsequently with derivatives of coumarin or ferrocene to form coumarin or ferrocene labeled nucleosides. Fluorescent properties of coumarin labeled nucleosides are determined. Conclusion New coumarin and ferrocene labeled nucleosides were prepared via intermolecular Staudinger ligation. This reaction joins the fluorescent coumarin and biospecific nucleoside to the new molecule with promising fluorescent and electrochemical properties. The isolated yields of products depend on the structure of azidonucleoside and carboxylic acids. A detailed study of the kinetics of the Staudinger ligation with nucleoside substrates is in progress.
Alcolea Palafox, M.; Kattan, D.; Afseth, N. K.
2018-04-01
A theoretical and experimental vibrational study of the anti-HIV d4T (stavudine or Zerit) nucleoside analogue was carried out. The predicted spectra in the three most stable conformers in the biological active anti-form of the isolated state were compared. Comparison of the conformers with those of the natural nucleoside thymidine was carried out. The calculated spectra were scaled by using different scaling procedures and three DFT methods. The TLSE procedure leads to the lowest error and is thus recommended for scaling. With the population of these conformers the IR gas-phase spectra were predicted. The crystal unit cell of the different polymorphism forms of d4T were simulated through dimer forms by using DFT methods. The scaled spectra of these dimer forms were compared. The FT-IR spectrum was recorded in the solid state in the 400-4000 cm-1 range. The respective vibrational bands were analyzed and assigned to different normal modes of vibration by comparison with the scaled vibrational values of the different dimer forms. Through this comparison, the polymorphous form of the solid state sample was identified. The study indicates that d4T exist only in the ketonic form in the solid state. The results obtained were in agreement with those determined in related anti-HIV nucleoside analogues.
Design, Conformation, and Crystallography of 2-Naphthyl Phenyl Ethers as Potent Anti-HIV Agents
Energy Technology Data Exchange (ETDEWEB)
Lee, Won-Gil; Chan, Albert H.; Spasov, Krasimir A.; Anderson, Karen S.; Jorgensen, William L.
2016-12-08
Catechol diethers that incorporate a 7-cyano-2-naphthyl substituent are reported as non-nucleoside inhibitors of HIV-1 reverse transcriptase (NNRTIs). Many of the compounds have 1–10 nM potencies toward wild-type HIV-1. An interesting conformational effect allows two unique conformers for the naphthyl group in complexes with HIV-RT. X-ray crystal structures for 4a and 4f illustrate the alternatives.
Calculating ensemble averaged descriptions of protein rigidity without sampling.
Directory of Open Access Journals (Sweden)
Luis C González
Full Text Available Previous works have demonstrated that protein rigidity is related to thermodynamic stability, especially under conditions that favor formation of native structure. Mechanical network rigidity properties of a single conformation are efficiently calculated using the integer body-bar Pebble Game (PG algorithm. However, thermodynamic properties require averaging over many samples from the ensemble of accessible conformations to accurately account for fluctuations in network topology. We have developed a mean field Virtual Pebble Game (VPG that represents the ensemble of networks by a single effective network. That is, all possible number of distance constraints (or bars that can form between a pair of rigid bodies is replaced by the average number. The resulting effective network is viewed as having weighted edges, where the weight of an edge quantifies its capacity to absorb degrees of freedom. The VPG is interpreted as a flow problem on this effective network, which eliminates the need to sample. Across a nonredundant dataset of 272 protein structures, we apply the VPG to proteins for the first time. Our results show numerically and visually that the rigidity characterizations of the VPG accurately reflect the ensemble averaged [Formula: see text] properties. This result positions the VPG as an efficient alternative to understand the mechanical role that chemical interactions play in maintaining protein stability.
Calculating ensemble averaged descriptions of protein rigidity without sampling.
González, Luis C; Wang, Hui; Livesay, Dennis R; Jacobs, Donald J
2012-01-01
Previous works have demonstrated that protein rigidity is related to thermodynamic stability, especially under conditions that favor formation of native structure. Mechanical network rigidity properties of a single conformation are efficiently calculated using the integer body-bar Pebble Game (PG) algorithm. However, thermodynamic properties require averaging over many samples from the ensemble of accessible conformations to accurately account for fluctuations in network topology. We have developed a mean field Virtual Pebble Game (VPG) that represents the ensemble of networks by a single effective network. That is, all possible number of distance constraints (or bars) that can form between a pair of rigid bodies is replaced by the average number. The resulting effective network is viewed as having weighted edges, where the weight of an edge quantifies its capacity to absorb degrees of freedom. The VPG is interpreted as a flow problem on this effective network, which eliminates the need to sample. Across a nonredundant dataset of 272 protein structures, we apply the VPG to proteins for the first time. Our results show numerically and visually that the rigidity characterizations of the VPG accurately reflect the ensemble averaged [Formula: see text] properties. This result positions the VPG as an efficient alternative to understand the mechanical role that chemical interactions play in maintaining protein stability.
DEFF Research Database (Denmark)
Rijkhoff, Jan
2010-01-01
classes. Finally this article wants to claim that the distinction between rigid and flexible noun categories (a) adds a new dimension to current classifications of parts of speech systems, (b) correlates with certain grammatical phenomena (e.g. so-called number discord), and (c) helps to explain the parts......This article argues that in addition to the major flexible lexical categories in Hengeveld’s classification of parts of speech systems (Contentive, Non-Verb, Modifier), there are also flexible word classes within the rigid lexical category Noun (Set Noun, Sort Noun, General Noun). Members...... by the flexible item in the external world. I will then argue that flexible word classes constitute a proper category (i.e. they are not the result of a merger of some rigid word classes) in that members of flexible word categories display the same properties regarding category membership as members of rigid word...
International Nuclear Information System (INIS)
Kaplan, David B.; Lee, Jong-Wan; Son, Dam T.; Stephanov, Mikhail A.
2009-01-01
We consider zero-temperature transitions from conformal to nonconformal phases in quantum theories. We argue that there are three generic mechanisms for the loss of conformality in any number of dimensions: (i) fixed point goes to zero coupling, (ii) fixed point runs off to infinite coupling, or (iii) an IR fixed point annihilates with a UV fixed point and they both disappear into the complex plane. We give both relativistic and nonrelativistic examples of the last case in various dimensions and show that the critical behavior of the mass gap behaves similarly to the correlation length in the finite temperature Berezinskii-Kosterlitz-Thouless (BKT) phase transition in two dimensions, ξ∼exp(c/|T-T c | 1/2 ). We speculate that the chiral phase transition in QCD at large number of fermion flavors belongs to this universality class, and attempt to identify the UV fixed point that annihilates with the Banks-Zaks fixed point at the lower end of the conformal window.
Evaluation for rigidity of box construction of nuclear reactor building
International Nuclear Information System (INIS)
Yamakawa, Tetsuo
1979-01-01
A huge box-shaped structure (hereafter, called box construction) of reinforced concrete is presently utilized as the reactor building structure in nuclear power plants. Evaluation of the rigidity of the huge box construction is required for making a vibration analysis model of nuclear reactor buildings. It is necessary to handle the box construction as the plates to which the force in plane is applied. This paper describes that the bending theory in elementary beam theory is equivalent to a peculiar, orthogonally anisotropic plate, the shearing rigidity and film rigidity in y direction of which are put to infinity and the Poisson's ratio is put to zero, viewed from the two-dimensional theory of elasticity. The form factor of 1.2 for shearing deformation in rectangular cross section was calculated from the parabolic distribution of shearing stress intensity, and it is the maximum value. The factor is equal to 1.2 for slender beams, but smaller than 1.2 for short and thick beams, having tendency to converge to 1.0. The non-conformity of boundary conditions regarding the shearing force at the both ends of cantilevers does not affect very seriously the evaluation of shearing rigidity. From the above results, it was found that the application of the theory to the box construction was able to give the rigidity evaluation with sufficient engineering accuracy. The theory can also be applied to the evaluation of tube type ultrahigh buildings. (Wakatsuki, Y.)
New insights into the synergism of nucleoside analogs with radiotherapy
International Nuclear Information System (INIS)
Lee, Michael W; Parker, William B; Xu, Bo
2013-01-01
Nucleoside analogs have been frequently used in combination with radiotherapy in the clinical setting, as it has long been understood that inhibition of DNA repair pathways is an important means by which many nucleoside analogs synergize. Recent advances in our understanding of the structure and function of deoxycytidine kinase (dCK), a critical enzyme required for the anti-tumor activity for many nucleoside analogs, have clarified the mechanistic role this kinase plays in chemo- and radio-sensitization. A heretofore unrecognized role of dCK in the DNA damage response and cell cycle machinery has helped explain the synergistic effect of these agents with radiotherapy. Since most currently employed nucleoside analogs are primarily activated by dCK, these findings lend fresh impetus to efforts focused on profiling and modulating dCK expression and activity in tumors. In this review we will briefly review the pharmacology and biochemistry of the major nucleoside analogs in clinical use that are activated by dCK. This will be followed by discussions of recent advances in our understanding of dCK activation via post-translational modifications in response to radiation and current strategies aimed at enhancing this activity in cancer cells
Synthesis and Antiviral Activity of 3-Aminoindole Nucleosides of 2-Acetamido-2-deoxy-D-glucose
Energy Technology Data Exchange (ETDEWEB)
Abdelrahman, Adel A. H.; Elessawy, Farag A.; Barakat, Yousif A. [Menoufia Univ., Shebin El-Koam (Egypt); Ellatif, Mona M. Abd [The British Univ. in Egypt, Cairo (Egypt)
2012-10-15
A new method for the construction of 3-aminoindole nucleosides of 2-acetamido-2-deoxy-D-glucose based is presented. Nitration and acetylation of the indole nucleosides by acetic anhydride-nitric acid mixture followed by reduction using silver catalyst (SNSM) impregnated on silica gel, afforded the corresponding amino indole nucleosides. The nucleosides were tested for antiviral activity against hepatitis B virus (HBV) to show different degrees of antiviral activities or inhibitory actions.
Directory of Open Access Journals (Sweden)
Hanadi Sinokrot
2017-10-01
Full Text Available Background: Poor pharmacokinetic profiles and resistance are the main two drawbacks from which currently used antiviral agents suffer, thus make them excellent targets for research, especially in the presence of viral pandemics such as HIV and hepatitis C. Methods: The strategies employed in the studies covered in this review were sorted by the type of drug synthesized into ester prodrugs, targeted delivery prodrugs, macromolecular prodrugs, other nucleoside conjugates, and non-nucleoside drugs. Results: Utilizing the ester prodrug approach a novel isopropyl ester prodrug was found to be potent HIV integrase inhibitor. Further, employing the targeted delivery prodrug zanamivir and valine ester prodrug was made and shown a sole delivery of zanamivir. Additionally, VivaGel, a dendrimer macromolecular prodrug, was found to be very efficient and is now undergoing clinical trials. Conclusions: Of all the strategies employed (ester, targeted delivery, macromolecular, protides and nucleoside analogues, and non-nucleoside analogues prodrugs, the most promising are nucleoside analogues and macromolecular prodrugs. The macromolecular prodrug VivaGel works by two mechanisms: envelope mediated and receptor mediated disruption. Nucleotide analogues have witnessed productive era in the recent past few years. The era of non-interferon based treatment of hepatitis (through direct inhibitors of NS5A has dawned.
Deoxyribonucleoside kinases activate nucleoside antibiotics in severely pathogenic bacteria
DEFF Research Database (Denmark)
Sandrini, Michael; Shannon, O.; Clausen, A.R.
2007-01-01
Common bacterial pathogens are becoming progressively more resistant to traditional antibiotics, representing a major public-health crisis. Therefore, there is a need for a variety of antibiotics with alternative modes of action. In our study, several nucleoside analogs were tested against pathog...... alternative for combating pathogenic bacteria.......Common bacterial pathogens are becoming progressively more resistant to traditional antibiotics, representing a major public-health crisis. Therefore, there is a need for a variety of antibiotics with alternative modes of action. In our study, several nucleoside analogs were tested against...... pathogenic staphylococci and streptococci. We show that pyrimidine-based nucleoside analogs, like 3'-azido-3'-deoxythymidine (AZT) and 2',2'-difluoro-2'deoxycytidine (gemcitabine), are specifically activated by the endogenous bacterial deoxyribonucleoside kinases, leading to cell death. Deoxyribonucleoside...
Synthesis of O-Amino Sugars and Nucleosides
Directory of Open Access Journals (Sweden)
Na Chen
2018-03-01
Full Text Available Nucleic acids and carbohydrates are essential biomolecules involved in numerous biological and pathological processes. Development of multifunctional building blocks based on nucleosides and sugars is in high demand for the generation of novel oligonucleotide mimics and glycoconjugates for biomedical applications. Recently, aminooxyl-functionalized compounds have attracted increasing research interest because of their easy derivatization through oxime ligation or N-oxyamide formation reactions. Various biological applications have been reported for O-amino carbohydrate- and nucleoside-derived compounds. Here, we report our efforts in the design and synthesis of glyco-, glycosyl, nucleoside- and nucleo-aminooxy acid derivatives from readily available sugars and amino acids, and their use for the generation of N-oxyamide-linked oligosaccharides, glycopeptides, glycolipids, oligonucleosides and nucleopeptides as novel glycoconjugates or oligonucleotide mimics. Delicate and key points in the synthesis will be emphasized.
Rigid multibody system dynamics with uncertain rigid bodies
Energy Technology Data Exchange (ETDEWEB)
Batou, A., E-mail: anas.batou@univ-paris-est.fr; Soize, C., E-mail: christian.soize@univ-paris-est.fr [Universite Paris-Est, Laboratoire Modelisation et Simulation Multi Echelle, MSME UMR 8208 CNRS (France)
2012-03-15
This paper is devoted to the construction of a probabilistic model of uncertain rigid bodies for multibody system dynamics. We first construct a stochastic model of an uncertain rigid body by replacing the mass, the center of mass, and the tensor of inertia by random variables. The prior probability distributions of the stochastic model are constructed using the maximum entropy principle under the constraints defined by the available information. The generators of independent realizations corresponding to the prior probability distribution of these random quantities are further developed. Then several uncertain rigid bodies can be linked to each other in order to calculate the random response of a multibody dynamical system. An application is proposed to illustrate the theoretical development.
Conformational change of adenosine deaminase during ligand-exchange in a crystal.
Kinoshita, Takayoshi; Tada, Toshiji; Nakanishi, Isao
2008-08-15
Adenosine deaminase (ADA) perpetuates chronic inflammation by degrading extracellular adenosine which is toxic for lymphocytes. ADA has two distinct conformations: open form and closed form. From the crystal structures with various ligands, the non-nucleoside type inhibitors bind to the active site occupying the critical water-binding-position and sustain the open form of apo-ADA. In contrast, substrate mimics do not occupy the critical position, and induce the large conformational change to the closed form. However, it is difficult to predict the binding of (+)-erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA), as it possesses characteristic parts of both the substrate and the non-nucleoside inhibitors. The crystal structure shows that EHNA binds to the open form through a novel recognition of the adenine base accompanying conformational change from the closed form of the PR-ADA complex in crystalline state.
Conformal FDTD modeling wake fields
Energy Technology Data Exchange (ETDEWEB)
Jurgens, T.; Harfoush, F.
1991-05-01
Many computer codes have been written to model wake fields. Here we describe the use of the Conformal Finite Difference Time Domain (CFDTD) method to model the wake fields generated by a rigid beam traveling through various accelerating structures. The non- cylindrical symmetry of some of the problems considered here requires the use of a three dimensional code. In traditional FDTD codes, curved surfaces are approximated by rectangular steps. The errors introduced in wake field calculations by such an approximation can be reduced by increasing the mesh size, therefore increasing the cost of computing. Another approach, validated here, deforms Ampere and Faraday contours near a media interface so as to conform to the interface. These improvements of the FDTD method result in better accuracy of the fields at asymptotically no computational cost. This method is also capable of modeling thin wires as found in beam profile monitors, and slots and cracks as found in resistive wall motions. 4 refs., 5 figs.
DEFF Research Database (Denmark)
Sandrini, Michael; Clausen, Anders; On, Stephen L. W.
2007-01-01
To investigate the bactericidal activity of antiviral and anticancer nucleoside analogues against a variety of pathogenic bacteria and characterize the activating enzymes, deoxyribonucleoside kinases (dNKs). Several FDA-approved nucleoside analogue drugs were screened for their potential bacteric......-specific manner. Therefore, nucleoside analogues have a potential to be employed as antibiotics in the fight against emerging multiresistant bacteria....
Kovács, Zsolt; Juhász, Gábor; Palkovits, Miklós; Dobolyi, Arpád; Kékesi, Katalin A
2011-01-01
Nucleosides, such as uridine, inosine, guanosine and adenosine, may participate in the regulation of sleep, cognition, memory and nociception, the suppression of seizures, and have also been suggested to play a role in the pathophysiology of some neurodegenerative and neuropsychiatric diseases. Under pathological conditions, levels of nucleosides change extremely in the brain, indicating their participation in the pathophysiology of disorders like Alzheimer's disease, Parkinson's disease and schizophrenia. These findings have resulted in an increasing attention to the roles of nucleosides in the central nervous system. The specific effects of nucleosides depend on the expression of their receptors and transporters in neuronal and glial cells, as well as their extracellular concentrations in the brain. A complex interlinked metabolic network and transporters of nucleosides may balance nucleoside levels in the brain tissue under normal conditions and enable the fine modulation of neuronal and glial processes via nucleoside receptor signaling mechanisms. Brain levels of nucleosides were found to vary when measured in a variety of different brain regions. In addition, nucleoside levels also depend on age and gender. Furthermore, distributions of nucleoside transporters and receptors as well as nucleoside metabolic enzyme activities demonstrate the area, age and gender dependence of the nucleoside system, suggesting different roles of nucleosides in functionally different brain areas. The aim of this review article is to summarize our present knowledge of the area-, age- and gender-dependent distribution of nucleoside levels, nucleoside metabolic enzyme activity, nucleoside receptors and nucleoside transporters in the brain.
Rigidity of Glasses and Macromolecules
Thorpe, M. F.
1998-03-01
The simple yet powerful ideas of percolation theory have found their way into many different areas of research. In this talk we show how RIGIDITY PERCOLATION can be studied at a similar level of sophistication, using a powerful new program THE PEBBLE GAME (D. J. Jacobs and M. F. Thorpe, Phys. Rev. E) 53, 3682 (1996). that uses an integer algorithm. This program can analyse the rigidity of two and three dimensional networks containing more than one million bars and joints. We find the total number of floppy modes, and find the critical behavior as the network goes from floppy to rigid as more bars are added. We discuss the relevance of this work to network glasses, and how it relates to experiments that involve the mechanical properties like hardness and elasticity of covalent glassy networks like Ge_xAs_ySe_1-x-y and dicuss recent experiments that suggest that the rigidity transition may be first order (Xingwei Feng, W. J.Bresser and P. Boolchand, Phys. Rev. Lett 78), 4422 (1997).. This approach is also useful in macromolecules and proteins, where detailed information about the rigid domain structure can be obtained.
Rigidly foldable origami gadgets and tessellations
Evans, Thomas A.; Lang, Robert J.; Magleby, Spencer P.; Howell, Larry L.
2015-01-01
Rigidly foldable origami allows for motion where all deflection occurs at the crease lines and facilitates the application of origami in materials other than paper. In this paper, we use a recently discovered method for determining rigid foldability to identify existing flat-foldable rigidly foldable tessellations, which are also categorized. We introduce rigidly foldable origami gadgets which may be used to modify existing tessellations or to create new tessellations. Several modified and new rigidly foldable tessellations are presented. PMID:26473037
Fang, X; Parkinson, F E; Mowles, D A; Young, J D; Cass, C E
1996-01-01
We have demonstrated that monkey kidney (COS-1) cells have a single type of nucleoside transport process, which, because it was equilibrative, sodium-independent and could be inhibited by nitrobenzylthioinosine (NBMPR), was identified as the 'equilibrative sensitive' or 'es' transporter. Using NBMPR or dilazep to inhibit the endogenous nucleoside transport activity, we have transiently expressed a cDNA that encodes an inhibitor-insensitive, concentrative nucleoside transporter protein (cNT1ra...
Synthesis of (Purin-6-yl)methylphosphonate Bases and Nucleosides
Czech Academy of Sciences Publication Activity Database
Hasník, Zbyněk; Pohl, Radek; Hocek, Michal
2010-01-01
Roč. 51, č. 18 (2010), s. 2464-2466 ISSN 0040-4039 R&D Projects: GA MŠk 1M0508 Institutional research plan: CEZ:AV0Z40550506 Keywords : purines * nucleosides * phosphonates * cross-coupling Subject RIV: CC - Organic Chemistry Impact factor: 2.618, year: 2010
Amino Acid Ester Prodrugs of Nucleoside and Nucleotide Antivirals
Czech Academy of Sciences Publication Activity Database
Krečmerová, Marcela
2017-01-01
Roč. 17, č. 10 (2017), s. 818-833 ISSN 1389-5575 Grant - others:AV ČR(CZ) M200551201 Institutional support: RVO:61388963 Keywords : acyclic nucleoside analogues * antiherpetics * antiretrovirals * cidofovir * peptidomimetics * prodrugs Subject RIV: CC - Organic Chemistry OBOR OECD: Organic chemistry Impact factor: 2.661, year: 2016
Antiviral acyclic nucleoside phosphonates: New structures and prodrugs
Czech Academy of Sciences Publication Activity Database
Krečmerová, Marcela; Tichý, Tomáš; Pomeisl, Karel; Andrei, G.; Balzarini, J.; Snoeck, R.
2016-01-01
Roč. 1, č. 2 (2016), s. 37 [PharmaMed-2016. International Conference on Medicinal and Pharmaceutical Chemistry . 05.12.2016-07.12.2016, Dubai] R&D Projects: GA ČR(CZ) GA14-00522S Institutional support: RVO:61388963 Keywords : acyclic nucleoside phosphonates * prodrugs * antivirals * 5-azacytosine Subject RIV: CC - Organic Chemistry
Two convergent approaches toward novel carbocyclic C-nucleosides
Czech Academy of Sciences Publication Activity Database
Nencka, Radim; Šála, Michal; Dejmek, Milan; Dračínský, Martin; Holý, Antonín; Hřebabecký, Hubert
-, č. 23 (2010), s. 4119-4130 ISSN 0039-7881 R&D Projects: GA MŠk 1M0508 Institutional research plan: CEZ:AV0Z40550506 Keywords : carbocyclic C-nucleosides * convergent approach * uracil * pyrimidines Subject RIV: CC - Organic Chemistry Impact factor: 2.260, year: 2010
Rigidity-tuning conductive elastomer
Shan, Wanliang; Diller, Stuart; Tutcuoglu, Abbas; Majidi, Carmel
2015-06-01
We introduce a conductive propylene-based elastomer (cPBE) that rapidly and reversibly changes its mechanical rigidity when powered with electrical current. The elastomer is rigid in its natural state, with an elastic (Young’s) modulus of 175.5 MPa, and softens when electrically activated. By embedding the cPBE in an electrically insulating sheet of polydimethylsiloxane (PDMS), we create a cPBE-PDMS composite that can reversibly change its tensile modulus between 37 and 1.5 MPa. The rigidity change takes ˜6 s and is initiated when a 100 V voltage drop is applied across the two ends of the cPBE film. This magnitude of change in elastic rigidity is similar to that observed in natural skeletal muscle and catch connective tissue. We characterize the tunable load-bearing capability of the cPBE-PDMS composite with a motorized tensile test and deadweight experiment. Lastly, we demonstrate the ability to control the routing of internal forces by embedding several cPBE-PDMS ‘active tendons’ into a soft robotic pneumatic bending actuator. Selectively activating the artificial tendons controls the neutral axis and direction of bending during inflation.
Rigidity-tuning conductive elastomer
International Nuclear Information System (INIS)
Shan, Wanliang; Diller, Stuart; Tutcuoglu, Abbas; Majidi, Carmel
2015-01-01
We introduce a conductive propylene-based elastomer (cPBE) that rapidly and reversibly changes its mechanical rigidity when powered with electrical current. The elastomer is rigid in its natural state, with an elastic (Young’s) modulus of 175.5 MPa, and softens when electrically activated. By embedding the cPBE in an electrically insulating sheet of polydimethylsiloxane (PDMS), we create a cPBE–PDMS composite that can reversibly change its tensile modulus between 37 and 1.5 MPa. The rigidity change takes ∼6 s and is initiated when a 100 V voltage drop is applied across the two ends of the cPBE film. This magnitude of change in elastic rigidity is similar to that observed in natural skeletal muscle and catch connective tissue. We characterize the tunable load-bearing capability of the cPBE–PDMS composite with a motorized tensile test and deadweight experiment. Lastly, we demonstrate the ability to control the routing of internal forces by embedding several cPBE–PDMS ‘active tendons’ into a soft robotic pneumatic bending actuator. Selectively activating the artificial tendons controls the neutral axis and direction of bending during inflation. (paper)
Energy Technology Data Exchange (ETDEWEB)
Giuseppe, P.O.; Meza, A.N.; Martins, N.H.; Santos, C.R.; Murakami, M.T. [Laboratorio Nacional de Luz Sincrotron (LNLS), Campinas, SP (Brazil)
2012-07-01
Full text: Purine nucleoside phosphorylases (PNPs) play a key role in the purine-salvage pathway in both prokaryotes and eukaryotes. Its ribosyltransferase activity is of great biotechnological interest due to potential application in the synthesis of nucleoside analogues used in the treatment of antiviral infections and in anticancer chemotherapy. Trimeric PNPs are found mainly in vertebrates and are specific for 6-oxo-purines whereas hexameric PNPs are prevalent in prokaryotes and exhibit a broad range of substrates including 6-oxo and 6-amino purines. BsPNP233, the hexameric PNP from B. subtilis, is able to catalyze the bioconversion of ribavirin, an anti-viral drug, and is relatively thermostable, being a good target for industrial use. Here we report the crystal structures of BsPNP233 in the apo form and in complex with adenosine solved at 2.65 and 1.91 resolution, respectively. The apo and ligand-bound BsPNP233 subunits superposed with an overall r.m.s. deviation of 0.31 for all C{alpha} atoms, which suggests that no major conformational changes occur upon substrate binding. Based on the crystal structure of BsPNP233 in complex with adenosine we have defined the active site residues implicated in binding the ribose (H4{sup *}, R43{sup *}, M64, R87, E178, M179, E180) and the nitrogenous base (S90, C91, G92, S202, V177, F159). These residues are highly conserved among the bacterial hexameric PNPs, suggesting they share the same mode of interaction with the substrates. This work will probably contribute to a better understanding of the molecular basis for the broad substrate specificity of hexameric PNPs and to projects aiming the rational design of PNPs for industrial purposes. (author)
Czech Academy of Sciences Publication Activity Database
Jansa, Petr; Kolman, Viktor; Kostinová, Alexandra; Dračínský, Martin; Mertlíková-Kaiserová, Helena; Janeba, Zlatko
2011-01-01
Roč. 76, č. 10 (2011), s. 1187-1198 ISSN 0010-0765 R&D Projects: GA MV VG20102015046 Institutional research plan: CEZ:AV0Z40550506 Keywords : nucleosides * nucleotides * phosphorus * fluorine * biological activity * antibiotics Subject RIV: CC - Organic Chemistry Impact factor: 1.283, year: 2011
Tomaschitz, R
2000-01-01
We study tachyons conformally coupled to the background geometry of a Milne universe. The causality of superluminal signal transfer is scrutinized in this context. The cosmic time of the comoving frame determines a distinguished time order for events connected by superluminal signals. An observer can relate his rest frame to the galaxy frame, and compare so the time order of events in his proper time to the cosmic time order. All observers can in this way arrive at identical conclusions on the causality of events connected by superluminal signals. An unambiguous energy concept for tachyonic rays is defined by means of the cosmic time of the comoving reference frame, without resorting to an antiparticle interpretation. On that basis we give an explicit proof that no signals can be sent into the past of observers. Causality violating signals are energetically forbidden, as they would have negative energy in the rest frame of the emitting observer. If an observer emits a superluminal signal, the tachyonic respon...
Czech Academy of Sciences Publication Activity Database
Dejmek, Milan; Hřebabecký, Hubert; Dračínský, Martin; Neyts, J.; Leyssen, P.; Mertlíková-Kaiserová, Helena; Nencka, Radim
2011-01-01
Roč. 76, č. 12 (2011), s. 1549-1566 ISSN 0010-0765 R&D Projects: GA MŠk 1M0508 Institutional research plan: CEZ:AV0Z40550506 Keywords : 1'-homonucleosides * Diels - Alder reaction * antiviral agents Subject RIV: CC - Organic Chemistry Impact factor: 1.283, year: 2011
Czech Academy of Sciences Publication Activity Database
Vaněk, Václav; Buděšínský, Miloš; Rinnová, Markéta; Rosenberg, Ivan
2009-01-01
Roč. 65, č. 4 (2009), s. 862-876 ISSN 0040-4020 R&D Projects: GA ČR GA203/05/0827; GA MŠk(CZ) LC06077; GA MŠk LC512; GA MŠk(CZ) LC06061 Institutional research plan: CEZ:AV0Z40550506 Keywords : nucleotide analogues * phosphonates * prolinol derivatives * N- alkylation Subject RIV: CC - Organic Chemistry Impact factor: 3.219, year: 2009
Conformal field theory in conformal space
International Nuclear Information System (INIS)
Preitschopf, C.R.; Vasiliev, M.A.
1999-01-01
We present a new framework for a Lagrangian description of conformal field theories in various dimensions based on a local version of d + 2-dimensional conformal space. The results include a true gauge theory of conformal gravity in d = (1, 3) and any standard matter coupled to it. An important feature is the automatic derivation of the conformal gravity constraints, which are necessary for the analysis of the matter systems
DEFF Research Database (Denmark)
Rijkhoff, Jan
2008-01-01
Studies in Language 32-3 (2008), 727-752. Special issue: Parts of Speech: Descriptive tools, theoretical constructs Jan Rijkhoff - On flexible and rigid nouns This article argues that in addition to the flexible lexical categories in Hengeveld’s classification of parts-of-speech systems (Contentive......, Non-Verb, Modifier), there are also flexible word classes within the rigid lexical category Noun (Set Noun, Sort Noun, General Noun). Members of flexible word classes are characterized by their vague semantics, which in the case of nouns means that values for the semantic features Shape...... and Homogeneity are either left undetermined or they are specified in such a way that they do not quite match the properties of the kind of entity denoted by the flexible item in the external world. I will then argue that flexible word classes constitute a proper category (i.e. they are not the result of a merger...
Elasticity of Relativistic Rigid Bodies?
Smarandache, Florentin
2013-10-01
In the classical Twin Paradox, according to the Special Theory of Relativity, when the traveling twin blasts off from the Earth to a relative velocity v =√{/3 } 2 c with respect to the Earth, his measuring stick and other physical objects in the direction of relative motion shrink to half their lengths. How is that possible in the real physical world to have let's say a rigid rocket shrinking to half and then later elongated back to normal as an elastic material when it stops? What is the explanation for the traveler's measuring stick and other physical objects, in effect, return to the same length to their original length in the Stay-At-Home, but there is no record of their having shrunk? If it's a rigid (not elastic) object, how can it shrink and then elongate back to normal? It might get broken in such situation.
Functionally rigid bistable [2]rotaxanes
DEFF Research Database (Denmark)
Nygaard, Sune; Leung, Ken C-F; Aprahamian, Ivan
2007-01-01
defines an unambiguous distance of 1.5 nm over which the ring moves between the MPTTF and NP units. The degenerate NP/NP [2]rotaxane was used to investigate the shuttling barrier by dynamic 1H NMR spectroscopy for the movement of the CBPQT4+ ring across the new rigid spacer. It is evident from...... better control over the position of the ring component in the ground state but also for control over the location of the CBPQT4+ ring during solution-state switching experiments, triggered either chemically (1H NMR) or electrochemically (cyclic voltammetry). In this instance, the use of the rigid spacer......Two-station [2]rotaxanes in the shape of a degenerate naphthalene (NP) shuttle and a nondegenerate monopyrrolotetrathiafulvalene (MPTTF)/NP redox-controllable switch have been synthesized and characterized in solution. Their dumbbell-shaped components are composed of polyether chains interrupted...
Rigid body dynamics of mechanisms
Hahn, Hubert
2003-01-01
The second volume of Rigid Body Dynamics of Mechanisms covers applications via a systematic method for deriving model equations of planar and spatial mechanisms. The necessary theoretical foundations have been laid in the first volume that introduces the theoretical mechanical aspects of mechatronic systems. Here the focus is on the application of the modeling methodology to various examples of rigid-body mechanisms, simple planar ones as well as more challenging spatial problems. A rich variety of joint models, active constraints, plus active and passive force elements is treated. The book is intended for self-study by working engineers and students concerned with the control of mechanical systems, i.e. robotics, mechatronics, vehicles, and machine tools. The examples included are a likely source from which to choose models for university lectures.
Associative memory through rigid origami
Murugan, Arvind; Brenner, Michael
2015-03-01
Mechanisms such as Miura Ori have proven useful in diverse contexts since they have only one degree of freedom that is easily controlled. We combine the theory of rigid origami and associative memory in frustrated neural networks to create structures that can ``learn'' multiple generic folding mechanisms and yet can be robustly controlled. We show that such rigid origami structures can ``recall'' a specific learned mechanism when induced by a physical impulse that only need resemble the desired mechanism (i.e. robust recall through association). Such associative memory in matter, seen before in self-assembly, arises due to a balance between local promiscuity (i.e., many local degrees of freedom) and global frustration which minimizes interference between different learned behaviors. Origami with associative memory can lead to a new class of deployable structures and kinetic architectures with multiple context-dependent behaviors.
Rigidity spectrum of Forbush decrease
International Nuclear Information System (INIS)
Sakakibara, S.; Munakata, K.; Nagashima, K.
1985-01-01
Using data from neutron monitors and muon telescopes at surface and underground stations, the average rigidity spectrum of Forbush decreases (Fds) during the period of 1978-1982 were obtained. Thirty eight Ed-events are classified into two groups, Hard Fd and Soft FD according to size of Fd at the Sakashita station. It is found that a spectral form of a fractional-power type (P to the-gamma sub 1 (P+P sub c) to the -gamma sub2) is more suitable than that of a power-exponential type or of a power type with an upper limiting rigidity. The best fitted spectrum of the fractional-power type is expressed by gamma sub1 = 0.37, gamma sub2 = 0.89 and P subc = 10 GV for Hard Fd and gamma sub1 = 0.77, gamma sub2 = 1.02 and P sub c - 14GV for Soft Fd
Signature of Thermal Rigidity Percolation
International Nuclear Information System (INIS)
Huerta, Adrián
2013-01-01
To explore the role that temperature and percolation of rigidity play in determining the macroscopic properties, we propose a model that adds translational degrees of freedom to the spins of the well known Ising hamiltonian. In particular, the Ising model illustrate the longstanding idea that the growth of correlations on approach to a critical point could be describable in terms of the percolation of some sort of p hysical cluster . For certain parameters of this model we observe two well defined peaks of C V , that suggest the existence of two kinds of p hysical percolation , namely connectivity and rigidity percolation. Thermal fluctuations give rise to two different kinds of elementary excitations, i.e. droplets and configuron, as suggested by Angell in the framework of a bond lattice model approach. The later is reflected in the fluctuations of redundant constraints that gives stability to the structure and correlate with the order parameter
Reconstructing rotations and rigid body motions from exact point correspondences through reflections
Fontijne, D.; Dorst, L.; Dorst, L.; Lasenby, J.
2011-01-01
We describe a new algorithm to reconstruct a rigid body motion from point correspondences. The algorithm works by constructing a series of reflections which align the points with their correspondences one by one. This is naturally and efficiently implemented in the conformal model of geometric
Torsional rigidity, isospectrality and quantum graphs
International Nuclear Information System (INIS)
Colladay, Don; McDonald, Patrick; Kaganovskiy, Leon
2017-01-01
We study torsional rigidity for graph and quantum graph analogs of well-known pairs of isospectral non-isometric planar domains. We prove that such isospectral pairs are distinguished by torsional rigidity. (paper)
Rigidity of monodromies for Appell's hypergeometric functions
Directory of Open Access Journals (Sweden)
Yoshishige Haraoka
2015-01-01
Full Text Available For monodromy representations of holonomic systems, the rigidity can be defined. We examine the rigidity of the monodromy representations for Appell's hypergeometric functions, and get the representations explicitly. The results show how the topology of the singular locus and the spectral types of the local monodromies work for the study of the rigidity.
Synthesis of tritium labelled nucleoside triphosphates by enzymatic phosphorylation
International Nuclear Information System (INIS)
Shen Decun; Ji Linzhen; Liao Sha
1986-01-01
[5- 3 H]UMP, [5- 3 H]CMP, [8- 3 H]AMP and [8- 3 H]GMP were prepared from 5BrUMP 5BrCMP 8BrAMP and 8BrGMP by catalytic halogentritium replacement at the same time. [5- 3 H]UTP, [5- 3 H]CTP, [8- 3 H]ATP and [8- 3 H]GTP were subsequently synthesized from [5- 3 H]UMP, [5- 3 H]CMP, [8- 3 H]AMP and [8- 3 H]GMP by enzymatic phosphorylation with the crude enzyme prepared from brewer's yeasts and purified by paper chromatography simultaneously. In addition, four kinds of tritium labelled nucleoside monophosphates and four kinds of tritium labelled nucleoside diphosphates were obtained as the by-products. The specific activity of these products is between 14-19 Ci/mmol and the radiochemical purity is more than 98%
C-Nucleosides: Synthetic Strategies and Biological Applications
Czech Academy of Sciences Publication Activity Database
Štambaský, J.; Hocek, Michal; Kočovský, P.
2009-01-01
Roč. 109, č. 12 (2009), s. 6729-6764 ISSN 0009-2665 R&D Projects: GA MŠk LC512; GA AV ČR IAA400550902 Grant - others:NIH(US) 1R03TW007372-01 Institutional research plan: CEZ:AV0Z40550506 Keywords : nucleosides * nucleobases * biological activity * extension of genetic alphabet Subject RIV: CC - Organic Chemistry Impact factor: 35.957, year: 2009
Nucleoside-Lipid-Based Nanocarriers for Sorafenib Delivery
Benizri, Sebastien; Ferey, Ludivine; Alies, Bruno; Mebarek, Naila; Vacher, Gaelle; Appavoo, Ananda; Staedel, Cathy; Gaudin, Karen; Barthélémy, Philippe
2018-01-01
Although the application of sorafenib, a small inhibitor of tyrosine protein kinases, to cancer treatments remains a worldwide option in chemotherapy, novel strategies are needed to address the low water solubility (drug. In this context, the use of nanocarriers is currently investigated in order to overcome these drawbacks. In this contribution, we report a new type of sorafenib-based nanoparticles stabilized by hybrid nucleoside-lipids. The solid lipid nanoparticles (SLNs) showed negative or positive zeta potential values depending on the nucleoside-lipid charge. Transmission electron microscopy of sorafenib-loaded SLNs revealed parallelepiped nanoparticles of about 200 nm. Biological studies achieved on four different cell lines, including liver and breast cancers, revealed enhanced anticancer activities of Sorafenib-based SLNs compared to the free drug. Importantly, contrast phase microscopy images recorded after incubation of cancer cells in the presence of SLNs at high concentration in sorafenib (> 80 μM) revealed a total cancer cell death in all cases. These results highlight the potential of nucleoside-lipid-based SLNs as drug delivery systems.
Bjerke, Mia; Solaroli, Nicola; Lesko, Nicole; Balzarini, Jan; Johansson, Magnus; Karlsson, Anna
2010-01-01
Thymidine kinase 2 (TK2) is a mitochondrial deoxyribonucleoside kinase that phosphorylates several nucleoside analogs used in anti-viral and anti-cancer therapy. A fibroblast cell line with decreased TK2 activity was investigated in order to obtain insights in the effects of TK2 deficiency on nucleotide metabolism. The role of TK2 for the sensitivity against cytotoxic nucleoside analogs was also investigated. The TK2 deficient cells retained their sensitivity against all pyrimidine nucleoside...
Czech Academy of Sciences Publication Activity Database
Xavier, N.M.; Goncalves-Pereira, R.; Jorda, Radek; Řezníčková, Eva; Kryštof, Vladimír; Oliveira, M.C.
2017-01-01
Roč. 89, č. 9 (2017), s. 1267-1281 ISSN 0033-4545 R&D Projects: GA MŠk(CZ) LO1204 Institutional support: RVO:61389030 Keywords : anticancer activity * azido nucleosides * bioactive molecules * ics-28 * N-glycosylation * nucleoside phosphoramidates * nucleoside/nucleotide analogs * Staudinger-phosphite reaction Subject RIV: EB - Genetics ; Molecular Biology OBOR OECD: Organic chemistry Impact factor: 2.626, year: 2016
Geometry, rigidity, and group actions
Farb, Benson; Zimmer, Robert J
2011-01-01
The study of group actions is more than a hundred years old but remains to this day a vibrant and widely studied topic in a variety of mathematic fields. A central development in the last fifty years is the phenomenon of rigidity, whereby one can classify actions of certain groups, such as lattices in semi-simple Lie groups. This provides a way to classify all possible symmetries of important spaces and all spaces admitting given symmetries. Paradigmatic results can be found in the seminal work of George Mostow, Gergory Margulis, and Robert J. Zimmer, among others.The p
Bjerke, Mia; Solaroli, Nicola; Lesko, Nicole; Balzarini, Jan; Johansson, Magnus; Karlsson, Anna
2010-01-01
Thymidine kinase 2 (TK2) is a mitochondrial deoxyribonucleoside kinase that phosphorylates several nucleoside analogs used in anti-viral and anti-cancer therapy. A fibroblast cell line with decreased TK2 activity was investigated in order to obtain insights in the effects of TK2 deficiency on nucleotide metabolism. The role of TK2 for the sensitivity against cytotoxic nucleoside analogs was also investigated. The TK2 deficient cells retained their sensitivity against all pyrimidine nucleoside analogs tested. This study suggests that nucleoside analog phosphorylation mediated by TK2 may be less important, compared to other deoxyribonucleoside kinases, for the cytotoxic effects of these compounds.
DEFF Research Database (Denmark)
Hrdlicka, Patrick J; Andersen, Nicolai K; Jepsen, Jan S
2005-01-01
The synthesis of branched and conformationally restricted analogs of the anticancer nucleosides 3'-C-ethynyluridine (EUrd) and 3'-C-ethynylcytidine (ECyd) is presented. Molecular modeling and (1)H NMR coupling constant analysis revealed that the furanose rings of all analogs except the LNA analog...
Rigid Body Energy Minimization on Manifolds for Molecular Docking.
Mirzaei, Hanieh; Beglov, Dmitri; Paschalidis, Ioannis Ch; Vajda, Sandor; Vakili, Pirooz; Kozakov, Dima
2012-11-13
Virtually all docking methods include some local continuous minimization of an energy/scoring function in order to remove steric clashes and obtain more reliable energy values. In this paper, we describe an efficient rigid-body optimization algorithm that, compared to the most widely used algorithms, converges approximately an order of magnitude faster to conformations with equal or slightly lower energy. The space of rigid body transformations is a nonlinear manifold, namely, a space which locally resembles a Euclidean space. We use a canonical parametrization of the manifold, called the exponential parametrization, to map the Euclidean tangent space of the manifold onto the manifold itself. Thus, we locally transform the rigid body optimization to an optimization over a Euclidean space where basic optimization algorithms are applicable. Compared to commonly used methods, this formulation substantially reduces the dimension of the search space. As a result, it requires far fewer costly function and gradient evaluations and leads to a more efficient algorithm. We have selected the LBFGS quasi-Newton method for local optimization since it uses only gradient information to obtain second order information about the energy function and avoids the far more costly direct Hessian evaluations. Two applications, one in protein-protein docking, and the other in protein-small molecular interactions, as part of macromolecular docking protocols are presented. The code is available to the community under open source license, and with minimal effort can be incorporated into any molecular modeling package.
3D QSAR Studies of DAMNI Analogs as Possible Non-nucleoside Reverse Transcriptase Inhibitors
Directory of Open Access Journals (Sweden)
S. Ganguly
2008-01-01
Full Text Available The non-nucleoside inhibitors of HIV-1-reverse transcriptase (NNRTIs are an important class of drugs employed in antiviral therapy. Recently, a novel family of NNRTIs commonly referred to as 1-[2-diarylmethoxy] ethyl 2-methyl-5-nitroimidazoles (DAMNI derivatives have been discovered. The 3D-QSAR studies on DAMNI derivatives as NNRTIs was performed by comparative molecular field analysis (CoMFA and comparative molecular similarity indices analysis (CoMSIA methods to determine the factors required for the activity of these compounds. The global minimum energy conformer of the template molecule 15, the most active molecule of the series, was obtained by simulated annealing method and used to build the structures of the molecules in the dataset. The combination of steric and electrostatic fields in CoMSIA gave the best results with cross-validated and conventional correlation coefficients of 0.654 and 0.928 respectively. The predictive ability of CoMFA and CoMSIA were determined using a test set of ten DAMNI derivatives giving predictive correlation coefficients of 0.92 and 0.98 respectively indicating good predictive power. Further, the robustness of the models was verified by bootstrapping analysis. The information obtained from CoMFA and CoMSIA 3D contour maps may be of utility in the design of more potent DAMNI analogs as NNRTIs in future.
Segal, Meirav; Fischer, Bilha
2012-02-28
Uridine cannot be utilized as fluorescent probe due to its extremely low quantum yield. For improving the uracil fluorescence characteristics we extended the natural chromophore at the C5 position by coupling substituted aromatic rings directly or via an alkenyl or alkynyl linker to create fluorophores. Extension of the uracil base was achieved by treating 5-I-uridine with the appropriate boronic acid under the Suzuki coupling conditions. Analogues containing an alkynyl linker were obtained from 5-I-uridine and the suitable boronic acid in a Sonogashira coupling reaction. The uracil fluorescent analogues proposed here were designed to satisfy the following requirements: a minimal chemical modification at a position not involved in base-pairing, resulting in relatively long absorption and emission wavelengths and high quantum yield. 5-((4-Methoxy-phenyl)-trans-vinyl)-2'-deoxy-uridine, 6b, was found to be a promising fluorescent probe. Probe 6b exhibits a quantum yield that is 3000-fold larger than that of the natural chromophore (Φ 0.12), maximum emission (478 nm) which is 170 nm red shifted as compared to uridine, and a Stokes shift of 143 nm. In addition, since probe 6b adopts the anti conformation and S sugar puckering favored by B-DNA, it makes a promising nucleoside analogue to be incorporated in an oligonucleotide probe for detection of genetic material.
DEFF Research Database (Denmark)
Jensen, Kaj Frank
1978-01-01
Two purine nucleoside phosphorylases (purine-nucleoside:orthophosphate ribosyltransferase, EC 2.4.2.1) were purified from vegetative Bacillus subtilis cells. One enzyme, inosine-guanosine phosphorylase, showed great similarity to the homologous enzyme of Bacillus cereus. It appeared...
An enzymatic glycosylation of nucleoside analogues using beta-galactosidase from Escherichia coli
Czech Academy of Sciences Publication Activity Database
Blažek, Jiří; Jansa, Petr; Baszczyňski, Ondřej; Kaiser, Martin Maxmilian; Otmar, Miroslav; Krečmerová, Marcela; Dračínský, Martin; Holý, Antonín; Králová, B.
2012-01-01
Roč. 20, č. 9 (2012), s. 3111-3118 ISSN 0968-0896 R&D Projects: GA MŠk 1M0508 Institutional research plan: CEZ:AV0Z40550506 Keywords : glycosylation * galactosylation * beta-galactosidase * enzymatic synthesis * nucleoside * acyclic nucleoside analogues Subject RIV: CC - Organic Chemistry Impact factor: 2.903, year: 2012
Origin, Utilization, and Recycling of Nucleosides in the Central Nervous System
Ipata, Piero Luigi
2011-01-01
The brain relies on the salvage of preformed purine and pyrimidine rings, mainly in the form of nucleosides, to maintain its nucleotide pool in the proper qualitative and quantitative balance. The transport of nucleosides from blood into neurons and glia is considered to be an essential prerequisite to enter their metabolic utilization in the…
Cytosine arabinoside influx and nucleoside transport sites in acute leukemia.
Wiley, J S; Jones, S P; Sawyer, W H; Paterson, A R
1982-02-01
Although cytosine arabinoside (araC) can induce a remission in a majority of patients presenting with acute myeloblastic leukemia (AML), a minority fail to respond and moreover the drug has less effect in acute lymphoblastic leukemia (ALL). The carrier-mediated influx of araC into purified blasts from patients with AML, ALL, and acute undifferentiated leukemia (AUL) has been compared to that of normal lymphocytes and polymorphs. Blasts showed a larger mediated influx of araC than mature cells, since mean influxes for myeloblasts and lymphoblasts were 6- and 2.3-fold greater than polymorphs and lymphocytes, respectively. Also, the mean influx for myeloblasts was fourfold greater than the mean for lymphoblasts. The number of nucleoside transport sites was estimated for each cell type by measuring the equilibrium binding of [(3)H]nitrobenzylthioinosine (NBMPR), which inhibits nucleoside fluxes by binding with high affinity to specific sites on the transport mechanism. The mean binding site numbers for myeloblasts and lymphoblasts were 5- and 2.8-fold greater, respectively, than for the mature cells of the same maturation series. The mean number of NBMPR binding sites for myeloblasts was fourfold greater than for lymphoblasts. Patients with AUL were heterogeneous since blasts from some gave values within the myeloblastic range and others within the lymphoblastic range. The araC influx correlated closely with the number of NBMPR binding sites measured in the same cells on the same day. Transport parameters were measured on blasts from 15 patients with AML or AUL who were then treated with standard induction therapy containing araC. Eight patients entered complete remission, while seven failed therapy, among whom were the three patients with the lowest araC influx (myeloblasts have both higher araC transport rates and more nucleoside transport sites than lymphoblasts and this factor may contribute to the greater sensitivity of AML to this drug. AraC transport varied >10
Addressing the selectivity and toxicity of antiviral nucleosides.
Feng, Joy Y
2018-01-01
Nucleoside and nucleotide analogs have played significant roles in antiviral therapies and are valued for their impressive potency and high barrier to resistance. They have been approved for treatment of herpes simplex virus-1, HIV, HBV, HCV, and influenza, and new drugs are being developed for the treatment of RSV, Ebola, coronavirus MERS, and other emerging viruses. However, this class of compounds has also experienced a high attrition rate in clinical trials due to toxicity. In this review, we discuss the utility of different biochemical and cell-based assays and provide recommendations for assessing toxicity liability before entering animal toxicity studies.
Purine nucleoside phosphorylase deficiency in two unrelated Saudi patients
International Nuclear Information System (INIS)
Alangari, Abdullah; AlHarbi, Abdullah; AlGhonaium Abdulaziz; Santisteban, Ines; Hershfield, Michael
2009-01-01
Purine nucleoside phosphorylase (PNP) deficiency is a rare autosomal recessive metabolic disorder that results in combined immunodeficiency, neurologic dysfunction and autoimmunity. PNP deficiency has never been reported from Saudi Arabia or in patients with an Arabic ethnic background. We report on two Saudi girls with PNP deficiency. Both showed severe lymphopenia and neurological involvement. Sequencing of the PNP gene of one girl revealed a novel missense mutation Pro146>Leu in exon 4 due to a change in the codon from CCT>CTT. Expression of PNP (146L) cDNA in E coli indicated that the mutation greatly reduced, but did not completely eliminate PNP activity. (author)
Supersymmetric Yang-Mills theory on conformal supergravity backgrounds in ten dimensions
Energy Technology Data Exchange (ETDEWEB)
Medeiros, Paul de; Figueroa-O’Farrill, José [Maxwell Institute and School of Mathematics, The University of Edinburgh,James Clerk Maxwell Building, Peter Guthrie Tait Road, Edinburgh EH9 3FD (United Kingdom)
2016-03-14
We consider bosonic supersymmetric backgrounds of ten-dimensional conformal supergravity. Up to local conformal isometry, we classify the maximally supersymmetric backgrounds, determine their conformal symmetry superalgebras and show how they arise as near-horizon geometries of certain half-BPS backgrounds or as a plane-wave limit thereof. We then show how to define Yang-Mills theory with rigid supersymmetry on any supersymmetric conformal supergravity background and, in particular, on the maximally supersymmetric backgrounds. We conclude by commenting on a striking resemblance between the supersymmetric backgrounds of ten-dimensional conformal supergravity and those of eleven-dimensional Poincaré supergravity.
Versatile synthesis and biological evaluation of novel 3’-fluorinated purine nucleosides
Directory of Open Access Journals (Sweden)
Hang Ren
2015-12-01
Full Text Available A unified synthetic strategy accessing novel 3'-fluorinated purine nucleoside derivatives and their biological evaluation were achieved. Novel 3’-fluorinated analogues were constructed from a common 3’-deoxy-3’-fluororibofuranose intermediate. Employing Suzuki and Stille cross-coupling reactions, fifteen 3’-fluororibose purine nucleosides 1–15 and eight 3’-fluororibose 2-chloro/2-aminopurine nucleosides 16–23 with various substituents at position 6 of the purine ring were efficiently synthesized. Furthermore, 3’-fluorine analogs of natural products nebularine and 6-methylpurine riboside were constructed via our convergent synthetic strategy. Synthesized nucleosides were tested against HT116 (colon cancer and 143B (osteosarcoma cancer tumor cell lines. We have demonstrated 3’-fluorine purine nucleoside analogues display potent tumor cell growth inhibition activity at sub- or low micromolar concentration.
Mondal, Santanu; Manna, Debasish; Mugesh, Govindasamy
2015-08-03
Halogenated nucleosides can be incorporated into the newly synthesized DNA of replicating cells and therefore are commonly used in the detection of proliferating cells in living tissues. Dehalogenation of these modified nucleosides is one of the key pathways involved in DNA repair mediated by the uracil-DNA glycosylase. Herein, we report the first example of a selenium-mediated dehalogenation of halogenated nucleosides. We also show that the mechanism for the debromination is remarkably different from that of deiodination and that the presence of a ribose or deoxyribose moiety in the nucleosides facilitates the deiodination. The results described herein should help in understanding the metabolism of halogenated nucleosides in DNA and RNA. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Viscous conformal gauge theories
DEFF Research Database (Denmark)
Toniato, Arianna; Sannino, Francesco; Rischke, Dirk H.
2017-01-01
We present the conformal behavior of the shear viscosity-to-entropy density ratio and the fermion-number diffusion coefficient within the perturbative regime of the conformal window for gauge-fermion theories.......We present the conformal behavior of the shear viscosity-to-entropy density ratio and the fermion-number diffusion coefficient within the perturbative regime of the conformal window for gauge-fermion theories....
International Nuclear Information System (INIS)
Kozameh, C.N.; Newman, E.T.; Tod, K.P.
1985-01-01
Conformal transformations in four-dimensional. In particular, a new set of two necessary and sufficient conditions for a space to be conformal to an Einstein space is presented. The first condition defines the class of spaces conformal to C spaces, whereas the last one (the vanishing of the Bach tensor) gives the particular subclass of C spaces which are conformally related to Einstein spaces. (author)
Superspace conformal field theory
Energy Technology Data Exchange (ETDEWEB)
Quella, Thomas [Koeln Univ. (Germany). Inst. fuer Theoretische Physik; Schomerus, Volker [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2013-07-15
Conformal sigma models and WZW models on coset superspaces provide important examples of logarithmic conformal field theories. They possess many applications to problems in string and condensed matter theory. We review recent results and developments, including the general construction of WZW models on type I supergroups, the classification of conformal sigma models and their embedding into string theory.
Superspace conformal field theory
International Nuclear Information System (INIS)
Quella, Thomas
2013-07-01
Conformal sigma models and WZW models on coset superspaces provide important examples of logarithmic conformal field theories. They possess many applications to problems in string and condensed matter theory. We review recent results and developments, including the general construction of WZW models on type I supergroups, the classification of conformal sigma models and their embedding into string theory.
Czech Academy of Sciences Publication Activity Database
Macíčková-Cahová, Hana; Pohl, Radek; Horáková Brázdilová, Petra; Havran, Luděk; Špaček, Jan; Fojta, Miroslav; Hocek, Michal
2011-01-01
Roč. 17, č. 21 (2011), s. 5833-5841 ISSN 0947-6539 R&D Projects: GA MŠk(CZ) LC06035; GA MŠk LC512; GA ČR GA203/09/0317; GA AV ČR(CZ) IAA400040901 Institutional research plan: CEZ:AV0Z40550506; CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : DNA polymerases * electrochemistry * nucleosides * nucleotides * organosulfur compounds Subject RIV: CC - Organic Chemistry Impact factor: 5.925, year: 2011
Do non-nucleoside reverse transcriptase inhibitors contribute to lipodystrophy?
Nolan, David
2005-01-01
Lipodystrophy complications, including lipoatrophy (pathological fat loss) and metabolic complications, have emerged as important long-term toxicities associated with antiretroviral therapy in the current era. The wealth of data that has accumulated over the past 6 years has now clarified the contribution of specific antiretroviral drugs to the risk of these clinical endpoints, with evidence that lipoatrophy is strongly associated with the choice of nucleoside reverse transcriptase inhibitor therapy (specifically, stavudine and to a lesser extent zidovudine). The aetiological basis of metabolic complications of antiretroviral therapy has proven to be complex, in that the risk appears to be modulated by a number of lifestyle factors that have made the metabolic syndrome highly prevalent in the general population, with additional contributions from HIV disease status itself, as well as from individual drugs within the HIV protease inhibitor class. The currently licensed non-nucleoside reverse transcriptase inhibitor (NNRTI) drugs, efavirenz and nevirapine, have been proven to have a favourable safety profile in terms of lipodystrophy complications. However, it must be noted that NNRTI drugs also have individual toxicity profiles that must be accounted for when considering and/or monitoring their use in the treatment of HIV infection.
Pu, Fang; Ren, Jinsong; Qu, Xiaogang
2018-02-21
The incorporation of biomolecules into nanomaterials generates functional nanosystems with novel and advanced properties, presenting great potential for applications in various fields. Nucleobases, nucleosides and nucleotides, as building blocks of nucleic acids and biological coenzymes, constitute necessary components of the foundation of life. In recent years, as versatile biomolecules for the construction or regulation of functional nanomaterials, they have stimulated interest in researchers, due to their unique properties such as structural diversity, multiplex binding sites, self-assembly ability, stability, biocompatibility, and chirality. In this review, strategies for the synthesis of nanomaterials and the regulation of their morphologies and functions using nucleobases, nucleosides, and nucleotides as building blocks, templates or modulators are summarized alongside selected applications. The diverse applications range from sensing, bioimaging, and drug delivery to mimicking light-harvesting antenna, the construction of logic gates, and beyond. Furthermore, some perspectives and challenges in this emerging field are proposed. This review is directed toward the broader scientific community interested in biomolecule-based functional nanomaterials.
Topological orders in rigid states
International Nuclear Information System (INIS)
Wen, X.G.
1990-01-01
The authors study a new kind of ordering topological order in rigid states (the states with no local gapless excitations). This paper concentrates on characterization of the different topological orders. As an example the authors discuss in detail chiral spin states of 2+1 dimensional spin systems. Chiral spin states are described by the topological Chern-Simons theories in the continuum limit. The authors show that the topological orders can be characterized by a non-Abelian gauge structure over the moduli space which parametrizes a family of the model Hamiltonians supporting topologically ordered ground states. In 2 + 1 dimensions, the non-Abelian gauge structure determines possible fractional statistics of the quasi-particle excitations over the topologically ordered ground states. The dynamics of the low lying global excitations is shown to be independent of random spatial dependent perturbations. The ground state degeneracy and the non-Abelian gauge structures discussed in this paper are very robust, even against those perturbations that break translation symmetry. The authors also discuss the symmetry properties of the degenerate ground states of chiral spin states. The authors find that some degenerate ground states of chiral spin states on torus carry non-trivial quantum numbers of the 90 degrees rotation
Non-conformable, partial and conformable transposition
DEFF Research Database (Denmark)
König, Thomas; Mäder, Lars Kai
2013-01-01
and the Commission regarding a directive’s outcome, play a much more strategic role than has to date acknowledged in the transposition literature. Whereas disagreement of a member state delays conformable transposition, it speeds up non-conformable transposition. Disagreement of the Commission only prolongs...... the transposition process. We therefore conclude that a stronger focus on an effective sanctioning mechanism is warranted for safeguarding compliance with directives....
Energy Technology Data Exchange (ETDEWEB)
Cadet, J; Ducolomb, R [CEA Centre d' Etudes Nucleaires de Grenoble, 38 (France). Lab. de Radiobiologie; Hruska, F E [Manitoba Univ., Winnipeg (Canada). Dept. of Chemistry
1979-06-20
The conformational properties of ten 6-hydroxylated dihydrothymidine derivatives including the various diastereoisomers of 5,6-dihydroxy-5,6-dihydrothymidine, 6-hydroxy-5,6-dihydrothymidine and 5-bromo-6-hydroxy-5,6-dihydrothymidine have been studied by 250 MHz proton magnetic resonance in aqueous solutions. A close correlation has been established between the carbon-6 configuration and the osidic conformation. The increase in the amplitude of the puckering within the furanose ring compared to that of thymidine or 2'-deoxyuridine is more pronounced for the levortatory (6S) nucleosides than for the dextrorotatory (6R) diastereoisomers. The importance of the 2'endo conformer population decreases in the following order: (-)> (+)>thymidine. The absence of destabilizing effects on the g/sup +/ rotameric population about the C(4')-C(5') bond denotes the lack of any interaction between exocyclic hydroxymethyl group and the 6-hydroxyl function or the 2-keto group. The 5,6-saturated nucleosides adopt a preferential anti conformation. The comparison has been extended to syn nucleosides which show opposite trends in the sugar conformation and g/sup +/ distribution.
Xia, Yi; Qu, Fanqi; Peng, Ling
2010-08-01
Synthetic nucleoside mimics are important candidates in the searing for antiviral and anticancer drugs. Ribavirin, the first antiviral nucleoside drug, is unique in its antiviral activity with mutilple modes of action, which are mainly due to its special triazole heterocycle as nucleobase. Additionally, introducing aromatic functionalities to the nucleobase is able to confer novel mechanisms of action for nucleoside mimics. With the aim to combine the special characteristics of unnatural triazole heterocycles with those of the appended aromatic groups on the nucleobases, novel 1,2,4-triazole nucleoside analogs bearing aromatic moieties were designed and developed. The present short review summarizes the molecular design, chemical synthesis and biological activity of these triazole nucleoside analogs. Indeed, the discovery of antiviral and anticancer activities shown by these triazole nucleosides as well as the new mechanism underlying the biological activity by one of the anticancer leads has validated the rationale for molecular design and impacted us to further explore the concept with the aim of developing structurally novel nucleoside drug candidates with new modes of action.
Enhancement of Nucleoside Production in Hirsutella sinensis Based on Biosynthetic Pathway Analysis
Liu, Zhi-Qiang; Zhang, Bo; Lin, Shan; Baker, Peter James; Chen, Mao-Sheng; Xue, Ya-Ping; Wu, Hui; Xu, Feng; Yuan, Shui-Jin; Teng, Yi; Wu, Ling-Fang
2017-01-01
To enhance nucleoside production in Hirsutella sinensis, the biosynthetic pathways of purine and pyrimidine nucleosides were constructed and verified. The differential expression analysis showed that purine nucleoside phosphorylase, inosine monophosphate dehydrogenase, and guanosine monophosphate synthase genes involved in purine nucleotide biosynthesis were significantly upregulated 16.56-fold, 8-fold, and 5.43-fold, respectively. Moreover, dihydroorotate dehydrogenase, uridine nucleosidase, uridine/cytidine monophosphate kinase, and inosine triphosphate pyrophosphatase genes participating in pyrimidine nucleoside biosynthesis were upregulated 4.53-fold, 10.63-fold, 4.26-fold, and 5.98-fold, respectively. To enhance the nucleoside production, precursors for synthesis of nucleosides were added based on the analysis of biosynthetic pathways. Uridine and cytidine contents, respectively, reached 5.04 mg/g and 3.54 mg/g when adding 2 mg/mL of ribose, resulting in an increase of 28.6% and 296% compared with the control, respectively. Meanwhile, uridine and cytidine contents, respectively, reached 10.83 mg/g 2.12 mg/g when adding 0.3 mg/mL of uracil, leading to an increase of 176.3% and 137.1%, respectively. This report indicated that fermentation regulation was an effective way to enhance the nucleoside production in H. sinensis based on biosynthetic pathway analysis. PMID:29333435
Aqueous microwaves assisted cross-coupling reactions applied to unprotected nucleosides.
Directory of Open Access Journals (Sweden)
CHRISTOPHE eLEN
2015-02-01
Full Text Available Nucleoside analogues have attracted much attention due to their potential biological activities. Amongst all synthetic nucleosides, C5-modified pyrimidines and C7- or C8-modified purines have mostly been prepared using palladium cross-coupling reactions and then studied as antitumoral and antiviral agents. Our objective is to focus this review on the Suzuki-Miyaura and on the Heck cross-couplings of nucleosides using microwave irradiations which are an alternative technology compatible with green chemistry and sustainable development.
The synthesis of nucleoside bases with 14 C
International Nuclear Information System (INIS)
Matloubi, H.; Mehrdad, M.
1997-01-01
Labelled organic compounds have been widely and diligently applied to research problems in life science and chemistry. In many laboratories they have lost their novelty and have been become conventional research tools since long time ago. these applications frequently require organic compounds substituted (or labelled) with isotopes, but the isotopes are (with certain exception) extracted in first place in simple inorganic forms. The conversion of these simple form into the more or less complex labelled compounds called for by research workers has become in effect a new branch of practical organic chemistry. The preparation of labelled compounds, carbon-14 is probably more extensively and variously used than any other isotope. It emits only beta-particles. In this project, two kinds of nucleoside bases under the name uracil-2- 14 C and thymine (methyl- 14 C) were prepared.(author). 14 refs., 3 figs., 2 tabs
Directory of Open Access Journals (Sweden)
Meytal Galilee
2018-01-01
Full Text Available Reverse transcriptase (RT is the target for the majority of anti-HIV-1 drugs. As with all anti-AIDS treatments, continued success of RT inhibitors is persistently disrupted by the occurrence of resistance mutations. To explore latent resistance mechanisms potentially accessible to therapeutically challenged HIV-1 viruses, we examined RT from the related feline immunodeficiency virus (FIV. FIV closely parallels HIV-1 in its replication and pathogenicity, however, is resistant to all non-nucleoside inhibitors (NNRTI. The intrinsic resistance of FIV RT is particularly interesting since FIV harbors the Y181 and Y188 sensitivity residues absent in both HIV-2 and SIV. Unlike RT from HIV-2 or SIV, previous efforts have failed to make FIV RT susceptible to NNRTIs concluding that the structure or flexibility of the feline enzyme must be profoundly different. We report the first crystal structure of FIV RT and, being the first structure of an RT from a non-primate lentivirus, enrich the structural and species repertoires available for RT. The structure demonstrates that while the NNRTI binding pocket is conserved, minor subtleties at the entryway can render the FIV RT pocket more restricted and unfavorable for effective NNRTI binding. Measuring NNRTI binding affinity to FIV RT shows that the "closed" pocket configuration inhibits NNRTI binding. Mutating the loop residues rimming the entryway of FIV RT pocket allows for NNRTI binding, however, it does not confer sensitivity to these inhibitors. This reveals a further layer of resistance caused by inherent FIV RT variances that could have enhanced the dissociation of bound inhibitors, or, perhaps, modulated protein plasticity to overcome inhibitory effects of bound NNRTIs. The more "closed" conformation of FIV RT pocket can provide a template for the development of innovative drugs that could unlock the constrained pocket, and the resilient mutant version of the enzyme can offer a fresh model for the study
Analysis of Switched-Rigid Floating Oscillator
Directory of Open Access Journals (Sweden)
Prabhakar R. Marur
2009-01-01
Full Text Available In explicit finite element simulations, a technique called deformable-to-rigid (D2R switching is used routinely to reduce the computation time. Using the D2R option, the deformable parts in the model can be switched to rigid and reverted back to deformable when needed during the analysis. The time of activation of D2R however influences the overall dynamics of the system being analyzed. In this paper, a theoretical basis for the selection of time of rigid switching based on system energy is established. A floating oscillator problem is investigated for this purpose and closed-form analytical expressions are derived for different phases in rigid switching. The analytical expressions are validated by comparing the theoretical results with numerical computations.
Rigid pricing and rationally inattentive consumer
Czech Academy of Sciences Publication Activity Database
Matějka, Filip
158 B, July (2015), s. 656-678 ISSN 0022-0531 Institutional support: PRVOUK-P23 Keywords : rational inattention * imperfect information * nominal rigidity Subject RIV: AH - Economics Impact factor: 1.097, year: 2015
Rigid pricing and rationally inattentive consumer
Czech Academy of Sciences Publication Activity Database
Matějka, Filip
158 B, July (2015), s. 656-678 ISSN 0022-0531 Institutional support: RVO:67985998 Keywords : rational inattention * imperfect information * nominal rigidity Subject RIV: AH - Economics Impact factor: 1.097, year: 2015
Soft soils reinforced by rigid vertical inclusions
Directory of Open Access Journals (Sweden)
Iulia-Victoria NEAGOE
2013-12-01
Full Text Available Reinforcement of soft soils by rigid vertical inclusions is an increasingly used technique over the last few years. The system consists of rigid or semi-rigid vertical inclusions and a granular platform for the loads transfer from the structure to the inclusions. This technique aims to reduce the differential settlements both at ground level as below the structure. Reinforcement by rigid inclusions is mainly used for foundation works for large commercial and industrial platforms, storage tanks, wastewater treatment plants, wind farms, bridges, roads, railway embankments. The subject is one of interest as it proves the recently concerns at international level in research and design; however, most studies deal more with the static behavior and less with the dynamic one.
Flexible and rigid cystoscopy in women.
Gee, Jason R; Waterman, Bradley J; Jarrard, David F; Hedican, Sean P; Bruskewitz, Reginald C; Nakada, Stephen Y
2009-01-01
Previous studies have evaluated the tolerability of rigid versus flexible cystoscopy in men. Similar studies, however, have not been performed in women. We sought to determine whether office-based flexible cystoscopy was better tolerated than rigid cystoscopy in women. Following full IRB approval, women were prospectively randomized in a single-blind manner. Patients were randomized to flexible or rigid cystoscopy and draped in the lithotomy position to maintain blinding of the study. Questionnaires evaluated discomfort before, during, and after cystoscopy. Thirty-six women were randomized to flexible (18) or rigid (18) cystoscopy. Indications were surveillance (16), hematuria (15), recurrent UTIs (2), voiding dysfunction (1), and other (2). All questionnaires were returned by 31/36 women. Using a 10-point visual analog scale (VAS), median discomfort during the procedure for flexible and rigid cystoscopy were 1.4 and 1.8, respectively, in patients perceiving pain. Median recalled pain 1 week later was similar at 0.8 and 1.15, respectively. None of these differences were statistically significant. Flexible and rigid cystoscopy are well tolerated in women. Discomfort during and after the procedure is minimal in both groups. Urologists should perform either procedure in women based on their preference and skill level.
A DNA Origami Mechanical Device for the Regulation of Microcosmic Structural Rigidity.
Wan, Neng; Hong, Zhouping; Wang, Huading; Fu, Xin; Zhang, Ziyue; Li, Chao; Xia, Han; Fang, Yan; Li, Maoteng; Zhan, Yi; Yang, Xiangliang
2017-11-01
DNA origami makes it feasible to fabricate a tremendous number of DNA nanostructures with various geometries, dimensions, and functionalities. Moreover, an increasing amount of research on DNA nanostructures is focused on biological and biomedical applications. Here, the reversible regulation of microcosmic structural rigidity is accomplished using a DNA origami device in vitro. The designed DNA origami monomer is composed of an internal central axis and an external sliding tube. Due to the external tube sliding, the device transforms between flexible and rigid states. By transporting the device into the liposome, the conformational change of the origami device induces a structural change in the liposome. The results obtained demonstrate that the programmed DNA origami device can be applied to regulate the microcosmic structural rigidity of liposomes. Because microcosmic structural rigidity is important to cell proliferation and function, the results obtained potentially provide a foundation for the regulation of cell microcosmic structural rigidity using DNA nanostructures. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Modification of Purine and Pyrimidine Nucleosides by Direct C-H Bond Activation
Directory of Open Access Journals (Sweden)
Yong Liang
2015-03-01
Full Text Available Transition metal-catalyzed modifications of the activated heterocyclic bases of nucleosides as well as DNA or RNA fragments employing traditional cross-coupling methods have been well-established in nucleic acid chemistry. This review covers advances in the area of cross-coupling reactions in which nucleosides are functionalized via direct activation of the C8-H bond in purine and the C5-H or C6-H bond in uracil bases. The review focuses on Pd/Cu-catalyzed couplings between unactivated nucleoside bases with aryl halides. It also discusses cross-dehydrogenative arylations and alkenylations as well as other reactions used for modification of nucleoside bases that avoid the use of organometallic precursors and involve direct C-H bond activation in at least one substrate. The scope and efficiency of these coupling reactions along with some mechanistic considerations are discussed.
Silverman, B D; Pitman, M C; Platt, D E
1999-06-01
Molecular moment descriptors of the shape and charge distributions of twenty five nucleoside structures have been examined. The structures include thymidine as well as the difluorotoluene nucleoside analog which has been found to pair efficiently with adenine by polymerase catalysis. The remaining twenty three structures have been chosen to be as structurally similar to thymidine and to the difluorotoluene nucleoside analog as possible. The moment descriptors which include a description of the relationship of molecular charge to shape show the difluorotoluene nucleoside to be one of the most proximate molecules to thymidine in the space of the molecular moments. The calculations, therefore, suggest that polymerase specificity might be not only a consequence of molecular steric features alone but also of the molecular electrostatic environment and its registration with molecular shape.
Efficient method of enzymatic synthesis of nucleosides labelled with 14C and 3H
International Nuclear Information System (INIS)
Nejedly, Z.; Filip, J.
1988-01-01
The method is presented of enzymatic synthesis of nucleosides labelled with 14 C or 3 H either uniformly or specifically in the base or the deoxyribosyl or ribosyl moiety. The method is based on the ribosylation or deoxyribosylation of the nucleic acid bases (non-labelled or labelled with 14 C or 3 H) by the catalytic effect of enzymes occurring in the supernatant fractions of non-purified homogenates of Escherichia coli B. bacteria. The non-labelled and labelled nucleosides are used as donors of ribosyl or deoxyribosyl groups. The HPLC method is used for separating labelled nucleosides. The radiochemical purity of the labelled nucleosides is higher than 98%, molar activity ranges from 9.2 to 18.5 GBq.mmol -1 ( 14 C-labelled compounds) and from 0.6 to 1.9 TBq.mmol -1 (3H-labelled compounds). (author). 4 figs., 8 refs
Theoretical conformational analysis of the bovine adrenal medulla 12 residue peptide molecule
Akhmedov, N. A.; Tagiyev, Z. H.; Hasanov, E. M.; Akverdieva, G. A.
2003-02-01
The spatial structure and conformational properties of the bovine adrenal medulla 12 residue peptide Tyr1-Gly2-Gly3-Phe4-Met5-Arg6-Arg7-Val8-Gly9-Arg10-Pro11-Glu12 (BAM-12P) molecule were studied by theoretical conformational analysis. It is revealed that this molecule can exist in several stable states. The energy and geometrical parameters for the low-energy conformations are obtained. The conformationally rigid and labile segments of this molecule were revealed.
Aberrant Apoptotic Response of Colorectal Cancer Cells to Novel Nucleoside Analogues.
Directory of Open Access Journals (Sweden)
Leonie Harmse
Full Text Available Despite the increased understanding of colorectal cancer and the introduction of targeted drug therapy, the metastatic phase of the disease remains refractory to treatment. Since the deregulation of normal apoptosis contributes to the pathogenesis of colorectal cancer, novel nucleoside analogues were synthesized here and evaluated for their ability to induce apoptosis and cause cell death in two colorectal adeno-carcinoma cell lines, Caco-2 and HT-29. Three novel nucleoside analogues assessed here showed cytotoxic activity, as measured by the MTT assay against both cell lines: the IC50 values ranged between 3 and 37 μM, with Caco-2 cells being more sensitive than HT-29 cells. Compared to camptothecin, the positive control, the nucleoside analogues were significantly less toxic to normal unstimulated leukocytes (p>0.05. Moreover, the nucleosides were able to induce apoptosis as measured by an increase in caspase 8 and caspase 3 activity above that of the control. This was additionally supported by data derived from Annexin V-FITC assays. Despite marginal changes to the mitochondrial membrane potential, all three nucleosides caused a significant increase in cytosolic cytochrome c (p>0.05, with a corresponding decrease in mitochondrial cytochrome c. Morphological analysis of both cell lines showed the rapid appearance of vacuoles following exposure to two of the nucleosides, while a third caused cellular detachment, delayed cytoplasmic vacuolisation and nuclear abnormalities. Preliminary investigations, using the autophagic indicator monodansylcadaverine and chloroquine as positive control, showed that two of the nucleosides induced the formation of autophagic vacuoles. In summary, the novel nucleoside analogues showed selective cytotoxicity towards both cancer cell lines and are effective initiators of an unusual apoptotic response, demonstrating their potential to serve as structural scaffolds for more potent analogues.
Aberrant Apoptotic Response of Colorectal Cancer Cells to Novel Nucleoside Analogues.
Harmse, Leonie; Dahan-Farkas, Nurit; Panayides, Jenny-Lee; van Otterlo, Willem; Penny, Clement
2015-01-01
Despite the increased understanding of colorectal cancer and the introduction of targeted drug therapy, the metastatic phase of the disease remains refractory to treatment. Since the deregulation of normal apoptosis contributes to the pathogenesis of colorectal cancer, novel nucleoside analogues were synthesized here and evaluated for their ability to induce apoptosis and cause cell death in two colorectal adeno-carcinoma cell lines, Caco-2 and HT-29. Three novel nucleoside analogues assessed here showed cytotoxic activity, as measured by the MTT assay against both cell lines: the IC50 values ranged between 3 and 37 μM, with Caco-2 cells being more sensitive than HT-29 cells. Compared to camptothecin, the positive control, the nucleoside analogues were significantly less toxic to normal unstimulated leukocytes (p>0.05). Moreover, the nucleosides were able to induce apoptosis as measured by an increase in caspase 8 and caspase 3 activity above that of the control. This was additionally supported by data derived from Annexin V-FITC assays. Despite marginal changes to the mitochondrial membrane potential, all three nucleosides caused a significant increase in cytosolic cytochrome c (p>0.05), with a corresponding decrease in mitochondrial cytochrome c. Morphological analysis of both cell lines showed the rapid appearance of vacuoles following exposure to two of the nucleosides, while a third caused cellular detachment, delayed cytoplasmic vacuolisation and nuclear abnormalities. Preliminary investigations, using the autophagic indicator monodansylcadaverine and chloroquine as positive control, showed that two of the nucleosides induced the formation of autophagic vacuoles. In summary, the novel nucleoside analogues showed selective cytotoxicity towards both cancer cell lines and are effective initiators of an unusual apoptotic response, demonstrating their potential to serve as structural scaffolds for more potent analogues.
Inhibition by nucleosides of glucose-transport activity in human erythrocytes.
Jarvis, S M
1988-01-01
The interaction of nucleosides with the glucose carrier of human erythrocytes was examined by studying the effect of nucleosides on reversible cytochalasin B-binding activity and glucose transport. Adenosine, inosine and thymidine were more potent inhibitors of cytochalasin B binding to human erythrocyte membranes than was D-glucose [IC50 (concentration causing 50% inhibition) values of 10, 24, 28 and 38 mM respectively]. Moreover, low concentrations of thymidine and adenosine inhibited D-glu...
Induced quantum conformal gravity
International Nuclear Information System (INIS)
Novozhilov, Y.V.; Vassilevich, D.V.
1988-11-01
Quantum gravity is considered as induced by matter degrees of freedom and related to the symmetry breakdown in the low energy region of a non-Abelian gauge theory of fundamental fields. An effective action for quantum conformal gravity is derived where both the gravitational constant and conformal kinetic term are positive. Relation with induced classical gravity is established. (author). 15 refs
Thickenings and conformal gravity
Lebrun, Claude
1991-07-01
A twistor correspondence is given for complex conformal space-times with vanishing Bach and Eastwood-Dighton tensors; when the Weyl curvature is algebraically general, these equations are precisely the conformal version of Einstein's vacuum equations with cosmological constant. This gives a fully curved version of the linearized correspondence of Baston and Mason [B-M].
Thickenings and conformal gravity
Energy Technology Data Exchange (ETDEWEB)
LeBrun, C. (State Univ. of New York, Stony Brook, NY (USA). Dept. of Mathematics)
1991-07-01
A twistor correspondence is given for complex conformal space-times with vanishing Bach and Eastwood-Dighton tensors; when the Weyl curvature is algebraically general, these equations are precisely the conformal version of Einstein's vacuum equations with cosmological constant. This gives a fully curved version of the linearized correspondence of Baston and Mason (B-M). (orig.).
Thickenings and conformal gravity
International Nuclear Information System (INIS)
LeBrun, C.
1991-01-01
A twistor correspondence is given for complex conformal space-times with vanishing Bach and Eastwood-Dighton tensors; when the Weyl curvature is algebraically general, these equations are precisely the conformal version of Einstein's vacuum equations with cosmological constant. This gives a fully curved version of the linearized correspondence of Baston and Mason [B-M]. (orig.)
Conformal transformations in superspace
International Nuclear Information System (INIS)
Dao Vong Duc
1977-01-01
The spinor extension of the conformal algebra is investigated. The transformation law of superfields under the conformal coordinate inversion R defined in the superspace is derived. Using R-technique, the superconformally covariant two-point and three-point correlation functions are found
Conformational stability of calreticulin
DEFF Research Database (Denmark)
Jørgensen, C.S.; Trandum, C.; Larsen, N.
2005-01-01
The conformational stability of calreticulin was investigated. Apparent unfolding temperatures (T-m) increased from 31 degrees C at pH 5 to 51 degrees C at pH 9, but electrophoretic analysis revealed that calreticulin oligomerized instead of unfolding. Structural analyses showed that the single C......-terminal a-helix was of major importance to the conformational stability of calreticulin....
Rigid Body Sampling and Individual Time Stepping for Rigid-Fluid Coupling of Fluid Simulation
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Xiaokun Wang
2017-01-01
Full Text Available In this paper, we propose an efficient and simple rigid-fluid coupling scheme with scientific programming algorithms for particle-based fluid simulation and three-dimensional visualization. Our approach samples the surface of rigid bodies with boundary particles that interact with fluids. It contains two procedures, that is, surface sampling and sampling relaxation, which insures uniform distribution of particles with less iterations. Furthermore, we present a rigid-fluid coupling scheme integrating individual time stepping to rigid-fluid coupling, which gains an obvious speedup compared to previous method. The experimental results demonstrate the effectiveness of our approach.
International Nuclear Information System (INIS)
Feuvret, Loic; Noel, Georges; Mazeron, Jean-Jacques; Bey, Pierre
2006-01-01
We present a critical analysis of the conformity indices described in the literature and an evaluation of their field of application. Three-dimensional conformal radiotherapy, with or without intensity modulation, is based on medical imaging techniques, three-dimensional dosimetry software, compression accessories, and verification procedures. It consists of delineating target volumes and critical healthy tissues to select the best combination of beams. This approach allows better adaptation of the isodose to the tumor volume, while limiting irradiation of healthy tissues. Tools must be developed to evaluate the quality of proposed treatment plans. Dosimetry software provides the dose distribution in each CT section and dose-volume histograms without really indicating the degree of conformity. The conformity index is a complementary tool that attributes a score to a treatment plan or that can compare several treatment plans for the same patient. The future of conformal index in everyday practice therefore remains unclear
Lipases in green chemistry: acylation and alcoholysis on steroids and nucleosides.
Baldessari, Alicia; Iglesias, Luis E
2012-01-01
In this article, we describe the application of lipases in acylation and alcoholysis reactions on steroids and nucleosides. In the field of steroids, a variety of acetyl and fatty acid derivatives of androstanes, pregnanes, and cholestanes have been prepared through lipase-catalyzed acylation and alcoholysis reactions taking advantage of the high regio- and stereoselectivity of these enzymes. The substrates as well as the products show a high degree of biological activity as neurosteroids, hormones, and glucocorticoids. The regioselective preparation of diacylated nucleosides by means of an enzymatic alcoholysis allowed the synthesis of nucleosides prodrugs or modified nucleosides. The quantitative full deacylation and dealkoxycarbonylation of nucleosides and steroids is a mild synthetic method for the deprotection of these labile compounds. Some of the reported steroid and nucleoside products are novel, and it is not possible to obtain them satisfactorily by following traditional synthetic procedures. The advantages presented by this methodology, such as selectivity, mild reaction conditions, and low environmental impact, make the lipases an important tool in the application of the principles of Green Chemistry, offering a convenient way to prepare derivatives of natural compounds with a great potential in the pharmaceutical industry.
Conformal invariance in supergravity
International Nuclear Information System (INIS)
Bergshoeff, E.A.
1983-01-01
In this thesis the author explains the role of conformal invariance in supergravity. He presents the complete structure of extended conformal supergravity for N <= 4. The outline of this work is as follows. In chapter 2 he briefly summarizes the essential properties of supersymmetry and supergravity and indicates the use of conformal invariance in supergravity. The idea that the introduction of additional symmetry transformations can make clear the structure of a field theory is not reserved to supergravity only. By means of some simple examples it is shown in chapter 3 how one can always introduce additional gauge transformations in a theory of massive vector fields. Moreover it is shown how the gauge invariant formulation sometimes explains the quantum mechanical properties of the theory. In chapter 4 the author defines the conformal transformations and summarizes their main properties. He explains how these conformal transformations can be used to analyse the structure of gravity. The supersymmetric extension of these results is discussed in chapter 5. Here he describes as an example how N=1 supergravity can be reformulated in a conformally-invariant way. He also shows that beyond N=1 the gauge fields of the superconformal symmetries do not constitute an off-shell field representation of extended conformal supergravity. Therefore, in chapter 6, a systematic method to construct the off-shell formulation of all extended conformal supergravity theories with N <= 4 is developed. As an example he uses this method to construct N=1 conformal supergravity. Finally, in chapter 7 N=4 conformal supergravity is discussed. (Auth.)
Conformal Ablative Thermal Protection Systems (CA-TPS) for Venus and Saturn Backshells
Beck, R.; Gasch, M.; Stackpoole, M.; Wilder, M.; Boghozian, T.; Chavez-Garcia, J.; Prabhu, Dinesh; Kazemba, Cole D.; Venkatapathy, E.
2016-01-01
This poster provides an overview of the work performed to date on the Conformal Ablative TPS (CA-TPS) element of the TPSM project out of GCDP. Under this element, NASA is developing improved ablative TPS materials based on flexible felt for reinforcement rather than rigid reinforcements. By replacing the reinforcements with felt, the resulting materials have much higher strain-to-failure and are much lower in thermal conductivity than their rigid counterparts. These characteristics should allow for larger tile sizes, direct bonding to aeroshells and even lower weight TPS. The conformal phenolic impregnated carbon felt (C-PICA) is a candidate for backshell TPS for both Venus and Saturn entry vehicles.
Conformal expansions and renormalons
Energy Technology Data Exchange (ETDEWEB)
Rathsman, J.
2000-02-07
The coefficients in perturbative expansions in gauge theories are factorially increasing, predominantly due to renormalons. This type of factorial increase is not expected in conformal theories. In QCD conformal relations between observables can be defined in the presence of a perturbative infrared fixed-point. Using the Banks-Zaks expansion the authors study the effect of the large-order behavior of the perturbative series on the conformal coefficients. The authors find that in general these coefficients become factorially increasing. However, when the factorial behavior genuinely originates in a renormalon integral, as implied by a postulated skeleton expansion, it does not affect the conformal coefficients. As a consequence, the conformal coefficients will indeed be free of renormalon divergence, in accordance with previous observations concerning the smallness of these coefficients for specific observables. The authors further show that the correspondence of the BLM method with the skeleton expansion implies a unique scale-setting procedure. The BLM coefficients can be interpreted as the conformal coefficients in the series relating the fixed-point value of the observable with that of the skeleton effective charge. Through the skeleton expansion the relevance of renormalon-free conformal coefficients extends to real-world QCD.
Identifying Floppy and Rigid Regions in Proteins
Jacobs, D. J.; Thorpe, M. F.; Kuhn, L. A.
1998-03-01
In proteins it is possible to separate hard covalent forces involving bond lengths and bond angles from other weak forces. We model the microstructure of the protein as a generic bar-joint truss framework, where the hard covalent forces and strong hydrogen bonds are regarded as rigid bar constraints. We study the mechanical stability of proteins using FIRST (Floppy Inclusions and Rigid Substructure Topography) based on a recently developed combinatorial constraint counting algorithm (the 3D Pebble Game), which is a generalization of the 2D pebble game (D. J. Jacobs and M. F. Thorpe, ``Generic Rigidity: The Pebble Game'', Phys. Rev. Lett.) 75, 4051-4054 (1995) for the special class of bond-bending networks (D. J. Jacobs, "Generic Rigidity in Three Dimensional Bond-bending Networks", Preprint Aug (1997)). This approach is useful in identifying rigid motifs and flexible linkages in proteins, and thereby determines the essential degrees of freedom. We will show some preliminary results from the FIRST analysis on the myohemerythrin and lyozyme proteins.
International Nuclear Information System (INIS)
Ma Jianhua; Lin Weizhen; Wang Wenfeng; Han Zhenhui; Yao Side; Lin Nianyun
1999-01-01
The interaction of triplet state of sodium salt of anthraquinone-2-sulfonic acid (AQS) with nucleosides has been investigated in CH 3 CN using KrF(248 nm) laser flash photolysis. The transient absorption spectra and kinetics obtained from the interaction of triplet AQS and nucleoside demonstrated that the primary ionic radical pair, radical cation of nucleosides and radical anion of AQS has been detected simultaneously for the first time
Conformal sequestering simplified
International Nuclear Information System (INIS)
Schmaltz, Martin; Sundrum, Raman
2006-01-01
Sequestering is important for obtaining flavor-universal soft masses in models where supersymmetry breaking is mediated at high scales. We construct a simple and robust class of hidden sector models which sequester themselves from the visible sector due to strong and conformally invariant hidden dynamics. Masses for hidden matter eventually break the conformal symmetry and lead to supersymmetry breaking by the mechanism recently discovered by Intriligator, Seiberg and Shih. We give a unified treatment of subtleties due to global symmetries of the CFT. There is enough review for the paper to constitute a self-contained account of conformal sequestering
Conformally connected universes
International Nuclear Information System (INIS)
Cantor, M.; Piran, T.
1983-01-01
A well-known difficulty associated with the conformal method for the solution of the general relativistic Hamiltonian constraint is the appearance of an aphysical ''bag of gold'' singularity at the nodal surface of the conformal factor. This happens whenever the background Ricci scalar is too large. Using a simple model, it is demonstrated that some of these singular solutions do have a physical meaning, and that these can be considered as initial data for Universe containing black holes, which are connected, in a conformally nonsingular way with each other. The relation between the ADM mass and the horizon area in this solution supports the cosmic censorship conjecture. (author)
Quantum mechanics of a generalised rigid body
International Nuclear Information System (INIS)
Gripaios, Ben; Sutherland, Dave
2016-01-01
We consider the quantum version of Arnold’s generalisation of a rigid body in classical mechanics. Thus, we quantise the motion on an arbitrary Lie group manifold of a particle whose classical trajectories correspond to the geodesics of any one-sided-invariant metric. We show how the derivation of the spectrum of energy eigenstates can be simplified by making use of automorphisms of the Lie algebra and (for groups of type I) by methods of harmonic analysis. We show how the method can be extended to cosets, generalising the linear rigid rotor. As examples, we consider all connected and simply connected Lie groups up to dimension 3. This includes the universal cover of the archetypical rigid body, along with a number of new exactly solvable models. We also discuss a possible application to the topical problem of quantising a perfect fluid. (paper)
Durable bistable auxetics made of rigid solids
Shang, Xiao; Liu, Lu; Rafsanjani, Ahmad; Pasini, Damiano
2018-02-01
Bistable Auxetic Metamaterials (BAMs) are a class of monolithic perforated periodic structures with negative Poisson's ratio. Under tension, a BAM can expand and reach a second state of equilibrium through a globally large shape transformation that is ensured by the flexibility of its elastomeric base material. However, if made from a rigid polymer, or metal, BAM ceases to function due to the inevitable rupture of its ligaments. The goal of this work is to extend the unique functionality of the original kirigami architecture of BAM to a rigid solid base material. We use experiments and numerical simulations to assess performance, bistability and durability of rigid BAMs at 10,000 cycles. Geometric maps are presented to elucidate the role of the main descriptors of BAM architecture. The proposed design enables the realization of BAM from a large palette of materials, including elastic-perfectly plastic materials and potentially brittle materials.
Laboureur, Laurent; Guérineau, Vincent; Auxilien, Sylvie; Yoshizawa, Satoko; Touboul, David
2018-02-16
A method based on supercritical fluid chromatography coupled to high resolution mass spectrometry for the profiling of canonical and modified nucleosides was optimized, and compared to classical reverse-phase liquid chromatography in terms of separation, number of detected modified nucleosides and sensitivity. Limits of detection and quantification were measured using statistical method and quantifications of twelve nucleosides of a tRNA digest from E. coli are in good agreement with previously reported data. Results highlight the complementarity of both separation techniques to cover the largest view of nucleoside modifications for forthcoming epigenetic studies. Copyright © 2017 Elsevier B.V. All rights reserved.
Rilpivirine: a new non-nucleoside reverse transcriptase inhibitor.
Sharma, Mamta; Saravolatz, Louis D
2013-02-01
Rilpivirine is a new non-nucleoside reverse transcriptase inhibitor (NNRTI) that is approved for HIV-1 treatment-naive adult patients in combination with other antiretroviral agents. The recommended dose is a 25 mg tablet once daily taken orally with a meal. Due to cytochrome P450 3A4 enzyme induction or gastric pH increase, rilpivirine cannot be coadministered with a number of other drugs (anticonvulsants, rifabutin, rifampicin, rifapentine, proton pump inhibitors, systemic dexamethasone and St John's wort). Rilpivirine should be used with caution when coadministered with a drug with a known risk for torsade de pointes. Rilpivirine has a better tolerability than a comparative NNRTI, efavirenz, in clinical trials, with fewer central nervous system adverse effects, rashes, lipid abnormalities and discontinuation rates. Virological failure occurs more commonly with higher baseline viral loads (>100,000 copies/mL) and lower baseline CD4 counts (<50 cells/mm(3)). Seventeen NNRTI mutations have been associated with decreased susceptibility to rilpivirine: K101E/P, E138A/G/K/Q/R, V179L, Y181C/I/V, H221Y, F227C, M230I/L, Y188L and the combination L100I + K103N. Resistance to rilpivirine largely excludes future use of the NNRTI class.
Oxidation of pyrimidine nucleosides and nucleotides by osmium tetroxide.
Burton, K
1967-08-01
1. Pyrimidine nucleosides such as thymidine, uridine or cytidine are oxidized readily at 0 degrees by osmium tetroxide in ammonium chloride buffer. There is virtually no oxidation in bicarbonate buffer of similar pH. Oxidation of 1-methyluracil yields 5,6-dihydro-4,5,6-trihydroxy-1-methyl-2-pyrimidone. 2. Osmium tetroxide and ammonia react reversibly in aqueous solution to form a yellow 1:1 complex, probably OsO(3)NH. A second molecule of ammonia must be involved in the oxidation of UMP since the rate of this reaction is approximately proportional to the square of the concentration of unprotonated ammonia. 3. 4-Thiouridine reacts with osmium tetroxide much more rapidly than does uridine. The changes of absorption spectra are different in sodium bicarbonate buffer and in ammonium chloride buffer. They occur faster in the latter buffer and, under suitable conditions, cytidine is a major product. 4. Polyuridylic acid is oxidized readily by ammoniacal osmium tetroxide, but its oxidation is inhibited by polyadenylic acid. Pyrimidines of yeast amino acid-transfer RNA are oxidized more slowly than the corresponding mononucleosides, especially the thymine residues. Appreciable oxidation can occur without change of sedimentation coefficient.
Directory of Open Access Journals (Sweden)
Oleg Golubev
2014-10-01
Full Text Available Formation of mixed-ligand Pd2+ complexes between canonical nucleoside 5'-monophosphates and five metal-ion-binding nucleoside analogs has been studied by 1H-NMR spectroscopy to test the ability of these nucleoside surrogates to discriminate between unmodified nucleobases by Pd2+-mediated base pairing. The nucleoside analogs studied included 2,6-bis(3,5-dimethylpyrazol-1-yl-, 2,6-bis(1-methylhydrazinyl- and 6-(3,5-dimethylpyrazol-1-yl-substituted 9-(β-d-ribofuranosylpurines 1–3, and 2,4-bis(3,5-dimethylpyrazol-1-yl- and 2,4-bis(1-methylhydrazinyl-substituted 5-(β-d-ribofuranosyl-pyrimidines 4–5. Among these, the purine derivatives 1-3 bound Pd2+ much more tightly than the pyrimidine derivatives 4, 5 despite apparently similar structures of the potential coordination sites. Compounds 1 and 2 formed markedly stable mixed-ligand Pd2+ complexes with UMP and GMP, UMP binding favored by 1 and GMP by 2. With 3, formation of mixed-ligand complexes was retarded by binding of two molecules of 3 to Pd2+.
Effect of rigid inclusions on sintering
International Nuclear Information System (INIS)
Rahaman, M.N.; De Jonghe, L.C.
1988-01-01
The predictions of recent theoretical studies on the effect of inert, rigid inclusions on the sintering of ceramic powder matrices are examined and compared with experimental data. The densification of glass matrix composites with inclusion volume fractions of ≤0.15 can be adequately explained by Scherer's theory for viscous sintering with rigid inclusions. Inclusions cause a vast reduction in the densification rates of polycrystalline matrix composites even at low inclusion volume fractions. Models put forward to explain the sintering of polycrystalline matrix composites are discussed
Type number and rigidity of fibred surfaces
International Nuclear Information System (INIS)
Markov, P E
2001-01-01
Infinitesimal l-th order bendings, 1≤l≤∞, of higher-dimensional surfaces are considered in higher-dimensional flat spaces (for l=∞ an infinitesimal bending is assumed to be an analytic bending). In terms of the Allendoerfer type number, criteria are established for the (r,l)-rigidity (in the terminology of Sabitov) of such surfaces. In particular, an (r,l)-infinitesimal analogue is proved of the classical theorem of Allendoerfer on the unbendability of surfaces with type number ≥3 and the class of (r,l)-rigid fibred surfaces is distinguished
Rigid origami vertices: conditions and forcing sets
Directory of Open Access Journals (Sweden)
Zachary Abel
2016-04-01
Full Text Available We develop an intrinsic necessary and sufficient condition for single-vertex origami crease patterns to be able to fold rigidly. We classify such patterns in the case where the creases are pre-assigned to be mountains and valleys as well as in the unassigned case. We also illustrate the utility of this result by applying it to the new concept of minimal forcing sets for rigid origami models, which are the smallest collection of creases that, when folded, will force all the other creases to fold in a prescribed way.
Evaluating a method for automated rigid registration
DEFF Research Database (Denmark)
Darkner, Sune; Vester-Christensen, Martin; Larsen, Rasmus
2007-01-01
to point distance. T-test for common mean are used to determine the performance of the two methods (supported by a Wilcoxon signed rank test). The performance influence of sampling density, sampling quantity, and norms is analyzed using a similar method.......We evaluate a novel method for fully automated rigid registration of 2D manifolds in 3D space based on distance maps, the Gibbs sampler and Iterated Conditional Modes (ICM). The method is tested against the ICP considered as the gold standard for automated rigid registration. Furthermore...
Liu, Xiaofeng; Bai, Fang; Ouyang, Sisheng; Wang, Xicheng; Li, Honglin; Jiang, Hualiang
2009-03-31
Conformation generation is a ubiquitous problem in molecule modelling. Many applications require sampling the broad molecular conformational space or perceiving the bioactive conformers to ensure success. Numerous in silico methods have been proposed in an attempt to resolve the problem, ranging from deterministic to non-deterministic and systemic to stochastic ones. In this work, we described an efficient conformation sampling method named Cyndi, which is based on multi-objective evolution algorithm. The conformational perturbation is subjected to evolutionary operation on the genome encoded with dihedral torsions. Various objectives are designated to render the generated Pareto optimal conformers to be energy-favoured as well as evenly scattered across the conformational space. An optional objective concerning the degree of molecular extension is added to achieve geometrically extended or compact conformations which have been observed to impact the molecular bioactivity (J Comput -Aided Mol Des 2002, 16: 105-112). Testing the performance of Cyndi against a test set consisting of 329 small molecules reveals an average minimum RMSD of 0.864 A to corresponding bioactive conformations, indicating Cyndi is highly competitive against other conformation generation methods. Meanwhile, the high-speed performance (0.49 +/- 0.18 seconds per molecule) renders Cyndi to be a practical toolkit for conformational database preparation and facilitates subsequent pharmacophore mapping or rigid docking. The copy of precompiled executable of Cyndi and the test set molecules in mol2 format are accessible in Additional file 1. On the basis of MOEA algorithm, we present a new, highly efficient conformation generation method, Cyndi, and report the results of validation and performance studies comparing with other four methods. The results reveal that Cyndi is capable of generating geometrically diverse conformers and outperforms other four multiple conformer generators in the case of
Directory of Open Access Journals (Sweden)
Li Honglin
2009-03-01
Full Text Available Abstract Background Conformation generation is a ubiquitous problem in molecule modelling. Many applications require sampling the broad molecular conformational space or perceiving the bioactive conformers to ensure success. Numerous in silico methods have been proposed in an attempt to resolve the problem, ranging from deterministic to non-deterministic and systemic to stochastic ones. In this work, we described an efficient conformation sampling method named Cyndi, which is based on multi-objective evolution algorithm. Results The conformational perturbation is subjected to evolutionary operation on the genome encoded with dihedral torsions. Various objectives are designated to render the generated Pareto optimal conformers to be energy-favoured as well as evenly scattered across the conformational space. An optional objective concerning the degree of molecular extension is added to achieve geometrically extended or compact conformations which have been observed to impact the molecular bioactivity (J Comput -Aided Mol Des 2002, 16: 105–112. Testing the performance of Cyndi against a test set consisting of 329 small molecules reveals an average minimum RMSD of 0.864 Å to corresponding bioactive conformations, indicating Cyndi is highly competitive against other conformation generation methods. Meanwhile, the high-speed performance (0.49 ± 0.18 seconds per molecule renders Cyndi to be a practical toolkit for conformational database preparation and facilitates subsequent pharmacophore mapping or rigid docking. The copy of precompiled executable of Cyndi and the test set molecules in mol2 format are accessible in Additional file 1. Conclusion On the basis of MOEA algorithm, we present a new, highly efficient conformation generation method, Cyndi, and report the results of validation and performance studies comparing with other four methods. The results reveal that Cyndi is capable of generating geometrically diverse conformers and outperforms
Conformable variational iteration method
Directory of Open Access Journals (Sweden)
Omer Acan
2017-02-01
Full Text Available In this study, we introduce the conformable variational iteration method based on new defined fractional derivative called conformable fractional derivative. This new method is applied two fractional order ordinary differential equations. To see how the solutions of this method, linear homogeneous and non-linear non-homogeneous fractional ordinary differential equations are selected. Obtained results are compared the exact solutions and their graphics are plotted to demonstrate efficiency and accuracy of the method.
Delineating the conformal window
DEFF Research Database (Denmark)
Frandsen, Mads Toudal; Pickup, Thomas; Teper, Michael
2011-01-01
We identify and characterise the conformal window in gauge theories relevant for beyond the standard model building, e.g. Technicolour, using the criteria of metric confinement and causal analytic couplings, which are known to be consistent with the phase diagram of supersymmetric QCD from Seiberg...... duality. Using these criteria we find perturbation theory to be consistent throughout the predicted conformal window for several of these gauge theories and we discuss recent lattice results in the light of our findings....
Kim, Do-Nyun; Altschuler, Josiah; Strong, Campbell; McGill, Gaël; Bathe, Mark
2011-01-01
The conformational dynamics data bank (CDDB, http://www.cdyn.org) is a database that aims to provide comprehensive results on the conformational dynamics of high molecular weight proteins and protein assemblies. Analysis is performed using a recently introduced coarse-grained computational approach that is applied to the majority of structures present in the electron microscopy data bank (EMDB). Results include equilibrium thermal fluctuations and elastic strain energy distributions that identify rigid versus flexible protein domains generally, as well as those associated with specific functional transitions, and correlations in molecular motions that identify molecular regions that are highly coupled dynamically, with implications for allosteric mechanisms. A practical web-based search interface enables users to easily collect conformational dynamics data in various formats. The data bank is maintained and updated automatically to include conformational dynamics results for new structural entries as they become available in the EMDB. The CDDB complements static structural information to facilitate the investigation and interpretation of the biological function of proteins and protein assemblies essential to cell function.
Soft lubrication: The elastohydrodynamics of nonconforming and conforming contacts
Skotheim, J. M.; Mahadevan, L.
2005-09-01
We study the lubrication of fluid-immersed soft interfaces and show that elastic deformation couples tangential and normal forces and thus generates lift. We consider materials that deform easily, due to either geometry (e.g., a shell) or constitutive properties (e.g., a gel or a rubber), so that the effects of pressure and temperature on the fluid properties may be neglected. Four different system geometries are considered: a rigid cylinder moving parallel to a soft layer coating a rigid substrate; a soft cylinder moving parallel to a rigid substrate; a cylindrical shell moving parallel to a rigid substrate; and finally a cylindrical conforming journal bearing coated with a thin soft layer. In addition, for the particular case of a soft layer coating a rigid substrate, we consider both elastic and poroelastic material responses. For all these cases, we find the same generic behavior: there is an optimal combination of geometric and material parameters that maximizes the dimensionless normal force as a function of the softness parameter η =hydrodynamicpressure/elasticstiffness=surfacedeflection/gapthickness, which characterizes the fluid-induced deformation of the interface. The corresponding cases for a spherical slider are treated using scaling concepts.
Geometric integrators for stochastic rigid body dynamics
Tretyakov, Mikhail
2016-01-05
Geometric integrators play an important role in simulating dynamical systems on long time intervals with high accuracy. We will illustrate geometric integration ideas within the stochastic context, mostly on examples of stochastic thermostats for rigid body dynamics. The talk will be mainly based on joint recent work with Rusland Davidchak and Tom Ouldridge.
Combinatorial and Algorithmic Rigidity: Beyond Two Dimensions
2012-12-01
44]. Theorems of Maxwell- Laman type were ob- tained in [9, 15, 43]. 2 3. Counting and Enumeration. As anticipated in the project, we relied on methods...decompositions. Graphs and Combinatorics, 25:219–238, 2009. [43] I. Streinu and L. Theran. Slider-pinning rigidity: a Maxwell- Laman -type theorem. Discrete and
Birationally rigid varieties. I. Fano varieties
International Nuclear Information System (INIS)
Pukhlikov, A V
2007-01-01
The theory of birational rigidity of rationally connected varieties generalises the classical rationality problem. This paper gives a survey of the current state of this theory and traces its history from Noether's theorem and the Lueroth problem to the latest results on the birational superrigidity of higher-dimensional Fano varieties. The main components of the method of maximal singularities are considered.
Rigid polyurethane and kenaf core composite foams
Rigid polyurethane foams are valuable in many construction applications. Kenaf is a bast fiber plant where the surface stem skin provides bast fibers whose strength-to-weight ratio competes with glass fiber. The higher volume product of the kenaf core is an under-investigated area in composite appli...
Geometric integrators for stochastic rigid body dynamics
Tretyakov, Mikhail
2016-01-01
Geometric integrators play an important role in simulating dynamical systems on long time intervals with high accuracy. We will illustrate geometric integration ideas within the stochastic context, mostly on examples of stochastic thermostats for rigid body dynamics. The talk will be mainly based on joint recent work with Rusland Davidchak and Tom Ouldridge.
Rigidity Sensing Explained by Active Matter Theory
Marcq, Philippe; Yoshinaga, Natsuhiko; Prost, Jacques
2011-01-01
The magnitude of traction forces exerted by living animal cells on their environment is a monotonically increasing and approximately sigmoidal function of the stiffness of the external medium. We rationalize this observation using active matter theory, and propose that adaptation to substrate rigidity results from an interplay between passive elasticity and active contractility.
About deformation and rigidity in relativity
International Nuclear Information System (INIS)
Coll, Bartolome
2007-01-01
The notion of deformation involves that of rigidity. In relativity, starting from Born's early definition of rigidity, some other ones have been proposed, offering more or less interesting aspects but also accompanied of undesired or even pathological properties. In order to clarify the origin of these difficulties presented by the notion of rigidity in relativity, we analyze with some detail significant aspects of the unambiguous classical, Newtonian, notion. In particular, the relative character of its kinetic definition is pointed out, allowing to predict and to understand the limitations imposed by Herglotz-Noether theorem. Also, its equivalent dynamic definition is obtained and, in contrast, its absolute character is shown. But in spite of this absolute character, the dynamic definition is shown to be not extensible to relativity. The metric deformation of Minkowski space by the presence of a gravitational field is interpreted as a universal deformation, and it is shown that, under natural conditions, only a simple deformation law is possible, relating locally, but in an one-to-one way, gravitational fields and gauge classes of two-forms. We argue that fields of unit vectors associated to the internal gauge class of two-forms of every space-time (and, in particular, of Minkowski space-time) are the relativistic analogues of the classical accelerated observers, i.e. of the classical rigid motions. Some other consequences of the universal law of gravitational deformation are commented
Rigid pricing and rationally inattentive consumer
Czech Academy of Sciences Publication Activity Database
Matějka, Filip
2010-01-01
Roč. 20, č. 2 (2010), s. 1-40 ISSN 1211-3298 R&D Projects: GA MŠk LC542 Institutional research plan: CEZ:AV0Z70850503 Keywords : rational inattention * nominal rigidity Subject RIV: AH - Economics http://www.cerge-ei.cz/pdf/wp/Wp409.pdf
Cracking of open traffic rigid pavement
Directory of Open Access Journals (Sweden)
Niken Chatarina
2017-01-01
Full Text Available The research is done by observing the growth of real structure cracking in Natar, Lampung, Indonesia compared to C. Niken’s et al research and literature study. The rigid pavement was done with open traffic system. There are two main crack types on Natar rigid pavement: cracks cross the road, and cracks spreads on rigid pavement surface. The observation of cracks was analyzed by analyzing material, casting, curing, loading and shrinkage mechanism. The relationship between these analysis and shrinkage mechanism was studied in concrete micro structure. Open traffic make hydration process occur under vibration; therefore, fresh concrete was compressed and tensioned alternately since beginning. High temperature together with compression, cement dissociation, the growth of Ca2+ at very early age leads abnormal swelling. No prevention from outside water movement leads hydration process occur with limited water which caused spreads fine cracks. Limited water improves shrinkage and plastic phase becomes shorter; therefore, rigid pavement can’t accommodate the abnormal swelling and shrinking alternately and creates the spread of cracks. Discontinuing casting the concrete makes both mix under different condition, the first is shrink and the second is swell and creates weak line on the border; so, the cracks appear as cracks across the road.
Rigid Spine Syndrome among Children in Oman
Directory of Open Access Journals (Sweden)
Roshan Koul
2015-08-01
Full Text Available Objectives: Rigidity of the spine is common in adults but is rarely observed in children. The aim of this study was to report on rigid spine syndrome (RSS among children in Oman. Methods: Data on children diagnosed with RSS were collected consecutively at presentation between 1996 and 2014 at the Sultan Qaboos University Hospital (SQUH in Muscat, Oman. A diagnosis of RSS was based on the patient’s history, clinical examination, biochemical investigations, electrophysiological findings, neuro-imaging and muscle biopsy. Atrophy of the paraspinal muscles, particularly the erector spinae, was the diagnostic feature; this was noted using magnetic resonance imaging of the spine. Children with disease onset in the paraspinal muscles were labelled as having primary RSS or rigid spinal muscular dystrophy. Secondary RSS was classified as RSS due to the late involvement of other muscle diseases. Results: Over the 18-year period, 12 children were included in the study, with a maleto- female ratio of 9:3. A total of 10 children were found to have primary RSS or rigid spinal muscular dystrophy syndrome while two had secondary RSS. Onset of the disease ranged from birth to 18 months of age. A family history was noted, with two siblings from one family and three siblings from another (n = 5. On examination, children with primary RSS had typical features of severe spine rigidity at onset, with the rest of the neurological examination being normal. Conclusion: RSS is a rare disease with only 12 reported cases found at SQUH during the study period. Cases of primary RSS should be differentiated from the secondary type.
Role of active site rigidity in activity: MD simulation and fluorescence study on a lipase mutant.
Directory of Open Access Journals (Sweden)
Md Zahid Kamal
Full Text Available Relationship between stability and activity of enzymes is maintained by underlying conformational flexibility. In thermophilic enzymes, a decrease in flexibility causes low enzyme activity while in less stable proteins such as mesophiles and psychrophiles, an increase in flexibility is associated with enhanced enzyme activity. Recently, we identified a mutant of a lipase whose stability and activity were enhanced simultaneously. In this work, we probed the conformational dynamics of the mutant and the wild type lipase, particularly flexibility of their active site using molecular dynamic simulations and time-resolved fluorescence techniques. In contrast to the earlier observations, our data show that active site of the mutant is more rigid than wild type enzyme. Further investigation suggests that this lipase needs minimal reorganization/flexibility of active site residues during its catalytic cycle. Molecular dynamic simulations suggest that catalytically competent active site geometry of the mutant is relatively more preserved than wild type lipase, which might have led to its higher enzyme activity. Our study implies that widely accepted positive correlation between conformation flexibility and enzyme activity need not be stringent and draws attention to the possibility that high enzyme activity can still be accomplished in a rigid active site and stable protein structures. This finding has a significant implication towards better understanding of involvement of dynamic motions in enzyme catalysis and enzyme engineering through mutations in active site.
Spacelike conformal Killing vectors and spacelike congruences
International Nuclear Information System (INIS)
Mason, D.P.; Tsamparlis, M.
1985-01-01
Necessary and sufficient conditions are derived for space-time to admit a spacelike conformal motion with symmetry vector parallel to a unit spacelike vector field n/sup a/. These conditions are expressed in terms of the shear and expansion of the spacelike congruence generated by n/sup a/ and in terms of the four-velocity of the observer employed at any given point of the congruence. It is shown that either the expansion or the rotation of this spacelike congruence must vanish if Dn/sup a//dp = 0, where p denotes arc length measured along the integral curves of n/sup a/, and also that there exist no proper spacelike homothetic motions with constant expansion. Propagation equations for the projection tensor and the rotation tensor are derived and it is proved that every isometric spacelike congruence is rigid. Fluid space-times are studied in detail. A relation is established between spacelike conformal motions and material curves in the fluid: if a fluid space-time admits a spacelike conformal Killing vector parallel to n/sup a/ and n/sub a/u/sup a/ = 0, where u/sup a/ is the fluid four-velocity, then the integral curves of n/sup a/ are material curves in an irrotational fluid, while if the fluid vorticity is nonzero, then the integral curves of n/sup a/ are material curves if and only if they are vortex lines. An alternative derivation, based on the theory of spacelike congruences, of some of the results of Collins [J. Math. Phys. 25, 995 (1984)] on conformal Killing vectors parallel to the local vorticity vector in shear-free perfect fluids with zero magnetic Weyl tensor is given
Conformity and statistical tolerancing
Leblond, Laurent; Pillet, Maurice
2018-02-01
Statistical tolerancing was first proposed by Shewhart (Economic Control of Quality of Manufactured Product, (1931) reprinted 1980 by ASQC), in spite of this long history, its use remains moderate. One of the probable reasons for this low utilization is undoubtedly the difficulty for designers to anticipate the risks of this approach. The arithmetic tolerance (worst case) allows a simple interpretation: conformity is defined by the presence of the characteristic in an interval. Statistical tolerancing is more complex in its definition. An interval is not sufficient to define the conformance. To justify the statistical tolerancing formula used by designers, a tolerance interval should be interpreted as the interval where most of the parts produced should probably be located. This tolerance is justified by considering a conformity criterion of the parts guaranteeing low offsets on the latter characteristics. Unlike traditional arithmetic tolerancing, statistical tolerancing requires a sustained exchange of information between design and manufacture to be used safely. This paper proposes a formal definition of the conformity, which we apply successively to the quadratic and arithmetic tolerancing. We introduce a concept of concavity, which helps us to demonstrate the link between tolerancing approach and conformity. We use this concept to demonstrate the various acceptable propositions of statistical tolerancing (in the space decentring, dispersion).
Axiomatic conformal field theory
International Nuclear Information System (INIS)
Gaberdiel, M.R.; Goddard, P.
2000-01-01
A new rigourous approach to conformal field theory is presented. The basic objects are families of complex-valued amplitudes, which define a meromorphic conformal field theory (or chiral algebra) and which lead naturally to the definition of topological vector spaces, between which vertex operators act as continuous operators. In fact, in order to develop the theory, Moebius invariance rather than full conformal invariance is required but it is shown that every Moebius theory can be extended to a conformal theory by the construction of a Virasoro field. In this approach, a representation of a conformal field theory is naturally defined in terms of a family of amplitudes with appropriate analytic properties. It is shown that these amplitudes can also be derived from a suitable collection of states in the meromorphic theory. Zhu's algebra then appears naturally as the algebra of conditions which states defining highest weight representations must satisfy. The relationship of the representations of Zhu's algebra to the classification of highest weight representations is explained. (orig.)
The two-body problem of a pseudo-rigid body and a rigid sphere
DEFF Research Database (Denmark)
Kristiansen, Kristian Uldall; Vereshchagin, M.; Gózdziewski, K.
2012-01-01
n this paper we consider the two-body problem of a spherical pseudo-rigid body and a rigid sphere. Due to the rotational and "re-labelling" symmetries, the system is shown to possess conservation of angular momentum and circulation. We follow a reduction procedure similar to that undertaken...... in the study of the two-body problem of a rigid body and a sphere so that the computed reduced non-canonical Hamiltonian takes a similar form. We then consider relative equilibria and show that the notions of locally central and planar equilibria coincide. Finally, we show that Riemann's theorem on pseudo......-rigid bodies has an extension to this system for planar relative equilibria....
Polyoxin (POL) is an unusual nucleoside antibiotic, in which peptidyl moiety and nucleoside skeleton are linked by an amide bond. However, their biosynthesis remains poorly understood. Here, we report the deciphering of PolG as an ATP-dependent ligase responsible for the assembly of POL. A polG muta...
Gao, Wen-Li; Li, Ning; Zong, Min-Hua
2011-11-01
Regioselective undecylenoylation of purine nucleosides as potential dual prodrugs was achieved by Candida antarctica lipase B using adenosine as a model reactant. The optimum organic solvent, molar ratio of vinyl ester to nucleoside, enzyme dosage, reaction temperature and molecular sieve amount were anhydrous THF, 5:1, 20 U/ml, 45°C and 75 mg/ml, respectively. Under the optimum conditions, the initial reaction rate, yield and 5'-regioselectivity were 1.1 mM/h, 90% and >99%, respectively. The enzymatic acylation of various nucleosides furnished the desired 5'-ester derivatives with the yields of 60-95% and 5'-regioselectivities of >99%. In addition, the lipase displayed excellent operational stability in THF, and retained 96% of its initial activity after reused for five batches.
Characterization of nucleosides and nucleobases in fruits of Ziziphus jujuba by UPLC-DAD-MS.
Guo, Sheng; Duan, Jin-Ao; Tang, Yu-Ping; Zhu, Zhen-Hua; Qian, Ye-Fei; Yang, Nian-Yun; Shang, Er-Xin; Qian, Da-Wei
2010-10-13
The fruit of Ziziphus jujuba , named dazao in Chinese, has been utilized as food as well as crude drugs in China for thousands of years. To explore the profiles of the nucleosides and nucleobases in this fruit, an ultraperformance liquid chromatograph coupled with a photodiode array detector and electrospray ionization-mass spectrometer method (UPLC-DAD-MS) has been established and validated in this paper. The validated method was successfully applied for the simultaneous characterization and quantitation of 9 nucleosides and nucleobases in 49 dazao samples, which comprised 43 cultivars from 26 cultivation regions. Furthermore, principal component analysis (PCA) was performed to classify the samples on the basis of the contents of the nine analyzed compounds. The results showed that almost all of these dazao samples were rich in nucleosides and nucleobases, although their contents were obviously various, and the proposed method could serve as a prerequisite for quality control of jujube products.
International Nuclear Information System (INIS)
Goddard, Peter
1990-01-01
The algebra of the group of conformal transformations in two dimensions consists of two commuting copies of the Virasoro algebra. In many mathematical and physical contexts, the representations of ν which are relevant satisfy two conditions: they are unitary and they have the ''positive energy'' property that L o is bounded below. In an irreducible unitary representation the central element c takes a fixed real value. In physical contexts, the value of c is a characteristic of a theory. If c < 1, it turns out that the conformal algebra is sufficient to ''solve'' the theory, in the sense of relating the calculation of the infinite set of physically interesting quantities to a finite subset which can be handled in principle. For c ≥ 1, this is no longer the case for the algebra alone and one needs some sort of extended conformal algebra, such as the superconformal algebra. It is these algebras that this paper aims at addressing. (author)
Algebraic conformal field theory
International Nuclear Information System (INIS)
Fuchs, J.; Nationaal Inst. voor Kernfysica en Hoge-Energiefysica
1991-11-01
Many conformal field theory features are special versions of structures which are present in arbitrary 2-dimensional quantum field theories. So it makes sense to describe 2-dimensional conformal field theories in context of algebraic theory of superselection sectors. While most of the results of the algebraic theory are rather abstract, conformal field theories offer the possibility to work out many formulae explicitly. In particular, one can construct the full algebra A-bar of global observables and the endomorphisms of A-bar which represent the superselection sectors. Some explicit results are presented for the level 1 so(N) WZW theories; the algebra A-bar is found to be the enveloping algebra of a Lie algebra L-bar which is an extension of the chiral symmetry algebra of the WZW theory. (author). 21 refs., 6 figs
Marco Guerrazzi; Nicola Meccheri
2009-01-01
This paper offers a critical discussion of the concept of labour market rigidity relevant to explaining unemployment. Starting from Keynes’s own view, we discuss how the concept of labour market flexibility has changed over time, involving nominal or real wage flexibility, contract flexibility or labour market institution flexibility. We also provide a critical assessment of the factors that lead the search framework highlighting labour market rigidities (frictions) to challenge the more wide...
Killing tensors and conformal Killing tensors from conformal Killing vectors
International Nuclear Information System (INIS)
Rani, Raffaele; Edgar, S Brian; Barnes, Alan
2003-01-01
Koutras has proposed some methods to construct reducible proper conformal Killing tensors and Killing tensors (which are, in general, irreducible) when a pair of orthogonal conformal Killing vectors exist in a given space. We give the completely general result demonstrating that this severe restriction of orthogonality is unnecessary. In addition, we correct and extend some results concerning Killing tensors constructed from a single conformal Killing vector. A number of examples demonstrate that it is possible to construct a much larger class of reducible proper conformal Killing tensors and Killing tensors than permitted by the Koutras algorithms. In particular, by showing that all conformal Killing tensors are reducible in conformally flat spaces, we have a method of constructing all conformal Killing tensors, and hence all the Killing tensors (which will in general be irreducible) of conformally flat spaces using their conformal Killing vectors
Synthesis and antiviral activity of 3'-deoxy-3'-C-hydroxymethyl nucleosides.
Bamford, M J; Coe, P L; Walker, R T
1990-09-01
A series of 3'-branched-chain sugar nucleosides, in particular 3'-deoxy-3'-C-hydroxmethyl nucleosides, have been synthesized and evaluated as antiviral agents. Reaction of 1-(2,3-epoxy-5-O-trityl-beta-D-lyxo-pentofuranosyl) derivatives 12 and 13, of uracil and thymine, respectively, with 5,6-dihydro-2-lithio-5-methyl-1,3,5-dithiazine 14 afforded the corresponding 3'-functionalized nucleosides 15 and 16, respectively. Replacement of the trityl group with tertbutyldiphenylsilyl allowed high yielding hydrolysis of the 3'-function to give the 3'-deoxy-3'-C-formyl-beta-D-arabino-pentofuranosyl nucleosides 21 and 22. Desilylation afforded the 1-(3-deoxy-3-C-formyl-beta- D-lyxo-pentofuranosyl) 3',5'-O-hemiacetal nucleosides 33 and 34, respectively. Reduction of the formyl group of 21 and 22, followed by desilylation, yielded the 3'-deoxy-3'-C-(hydroxymethyl)-beta-D-arabino- pentofuranosyl) analogues 7 and 8, respectively. The uracil base moiety of 7 was converted to 5-iodouracil and then to (E)-5-(2-bromovinyl)uracil to furnish an analogue 10 of BVaraU. The 1-(3-deoxy-3-C-(hydroxymethyl)-beta-D-lyxo-pentofuranosyl) and 1-(2,3-dideoxy-3-C-(hydroxymethyl)-beta-D-erythro-pentofuranosyl) derivatives of uracil (31 and 6, respectively) and 5-iodouracil (32 and 9, respectively) were also obtained. All novel, fully deprotected nucleoside analogues were evaluated for antiviral activity against human immunodeficiency virus type-1, herpes simplex virus types-1 and -2, varicella zoster virus, human cytomegalovirus and influenza A. Of the compounds tested only (E)-5-(2-bromovinyl)-1-[3-deoxy- 3-C-(hydroxymethyl)-beta-D-arabino-pentofuranosyl]uracil (10) inhibited VZV (alone), but did so at concentrations well below the cytotoxicity threshold.
Directory of Open Access Journals (Sweden)
Qiang Yu
2008-12-01
Full Text Available Enantioselective syntheses from dimethyl tartrate of 1,3,5-triazine homo-N-nucleoside analogs, containing a 1,4-dioxane moiety replacing the sugar unit in natural nucleosides, were accomplished. The triazine heterocycle in the nucleoside analogs was further substituted with combinations of NH2, OH and Cl in the 2,4-triazine positions.
Hakobyan, Astghik; Galindo, Inmaculada; Nañez, Almudena; Arabyan, Erik; Karalyan, Zaven; Chistov, Alexey A; Streshnev, Philipp P; Korshun, Vladimir A; Alonso, Covadonga; Zakaryan, Hovakim
2018-01-01
Rigid amphipathic fusion inhibitors (RAFIs) are a family of nucleoside derivatives that inhibit the infectivity of several enveloped viruses by interacting with virion envelope lipids and inhibiting fusion between viral and cellular membranes. Here we tested the antiviral activity of two RAFIs, 5-(Perylen-3-ylethynyl)-arabino-uridine (aUY11) and 5-(Perylen-3-ylethynyl)uracil-1-acetic acid (cm1UY11) against African swine fever virus (ASFV), for which no effective vaccine is available. Both compounds displayed a potent, dose-dependent inhibitory effect on ASFV infection in Vero cells. The major antiviral effect was observed when aUY11 and cm1UY11 were added at early stages of infection and maintained during the complete viral cycle. Furthermore, virucidal assay revealed a significant extracellular anti-ASFV activity for both compounds. We also found decrease in the synthesis of early and late viral proteins in Vero cells treated with cm1UY11. Finally, the inhibitory effect of aUY11 and cm1UY11 on ASFV infection in porcine alveolar macrophages was confirmed. Overall, our study has identified novel anti-ASFV compounds with potential for future therapeutic developments.
Versatile synthesis of amino acid functionalized nucleosides via a domino carboxamidation reaction
Directory of Open Access Journals (Sweden)
Vicky Gheerardijn
2014-11-01
Full Text Available Functionalized oligonucleotides have recently gained increased attention for incorporation in modified nucleic acid structures both for the design of aptamers with enhanced binding properties as well as the construction of catalytic DNA and RNA. As a shortcut alternative to the incorporation of multiple modified residues, each bearing one extra functional group, we present here a straightforward method for direct linking of functionalized amino acids to the nucleoside base, thus equipping the nucleoside with two extra functionalities at once. As a proof of principle, we have introduced three amino acids with functional groups frequently used as key-intermediates in DNA- and RNAzymes via an efficient and straightforward domino carboxamidation reaction.
Use of nucleoside (tide) analogues in patients with hepatitis B-related acute liver failure
DEFF Research Database (Denmark)
Dao, Doan Y; Seremba, Emmanuel; Ajmera, Veeral
2012-01-01
The efficacy of nucleoside(tide) analogues (NA) in the treatment of acute liver failure due to hepatitis B virus (HBV-ALF) remains controversial. We determined retrospectively the impact of NAs in a large cohort of patients with HBV-ALF.......The efficacy of nucleoside(tide) analogues (NA) in the treatment of acute liver failure due to hepatitis B virus (HBV-ALF) remains controversial. We determined retrospectively the impact of NAs in a large cohort of patients with HBV-ALF....
Mutagenicity of irradiated solutions of nuclei acid bases and nucleosides in Salmonella typhimurium
International Nuclear Information System (INIS)
Wilmer, J.; Schubert, J.
1981-01-01
Solutions of nucleic acid bases, nucleosides and a nucleotide, saturated with either N 2 , N 2 O or O 2 , were irradiated and tested for mutagenicity towards Salmonella typhimurium, with and without pre-incubation. Irradiated solutions of the nuclei acid bases were all non-mutagenic. Irradiated solutions of the nucleosides showed mutagenicity in S. typhimurium TA100 (pre-incubation assay). Generally, the mutagenicity followed the order: N 2 O > N 2 > O 2 . The results show that the formation of mutagenic radiolytic products is initiated by attack of mainly solutions of the nucleotide thymidine-5'-monophosphate, no mutagenicity could be detected. (orig.)
Financial Constraints and Nominal Price Rigidities
DEFF Research Database (Denmark)
Menno, Dominik Francesco; Balleer, Almut; Hristov, Nikolay
This paper investigates how financial market imperfections and the frequency of price adjustment interact. Based on new firm-level evidence for Germany, we document that financially constrained firms adjust prices more often than their unconstrained counterparts, both upwards and downwards. We show...... that these empirical patterns are consistent with a partial equilibrium menu-cost model with a working capital constraint. We then use the model to show how the presence of financial frictions changes profits and the price distribution of firms compared to a model without financial frictions. Our results suggest...... that tighter financial constraints are associated with higher nominal rigidities, higher prices and lower output. Moreover, in response to aggregate shocks, aggregate price rigidity moves substantially, the response of inflation is dampened, while output reacts more in the presence of financial frictions...
Rigidity of the magic pentagram game
Kalev, Amir; Miller, Carl A.
2018-01-01
A game is rigid if a near-optimal score guarantees, under the sole assumption of the validity of quantum mechanics, that the players are using an approximately unique quantum strategy. Rigidity has a vital role in quantum cryptography as it permits a strictly classical user to trust behavior in the quantum realm. This property can be traced back as far as 1998 (Mayers and Yao) and has been proved for multiple classes of games. In this paper we prove ridigity for the magic pentagram game, a simple binary constraint satisfaction game involving two players, five clauses and ten variables. We show that all near-optimal strategies for the pentagram game are approximately equivalent to a unique strategy involving real Pauli measurements on three maximally-entangled qubit pairs.
Rigidity of the magic pentagram game.
Kalev, Amir; Miller, Carl A
2018-01-01
A game is rigid if a near-optimal score guarantees, under the sole assumption of the validity of quantum mechanics, that the players are using an approximately unique quantum strategy. Rigidity has a vital role in quantum cryptography as it permits a strictly classical user to trust behavior in the quantum realm. This property can be traced back as far as 1998 (Mayers and Yao) and has been proved for multiple classes of games. In this paper we prove ridigity for the magic pentagram game, a simple binary constraint satisfaction game involving two players, five clauses and ten variables. We show that all near-optimal strategies for the pentagram game are approximately equivalent to a unique strategy involving real Pauli measurements on three maximally-entangled qubit pairs.
Rigid cohomology over Laurent series fields
Lazda, Christopher
2016-01-01
In this monograph, the authors develop a new theory of p-adic cohomology for varieties over Laurent series fields in positive characteristic, based on Berthelot's theory of rigid cohomology. Many major fundamental properties of these cohomology groups are proven, such as finite dimensionality and cohomological descent, as well as interpretations in terms of Monsky-Washnitzer cohomology and Le Stum's overconvergent site. Applications of this new theory to arithmetic questions, such as l-independence and the weight monodromy conjecture, are also discussed. The construction of these cohomology groups, analogous to the Galois representations associated to varieties over local fields in mixed characteristic, fills a major gap in the study of arithmetic cohomology theories over function fields. By extending the scope of existing methods, the results presented here also serve as a first step towards a more general theory of p-adic cohomology over non-perfect ground fields. Rigid Cohomology over Laurent Series Fields...
Collective Excitations in Protein as a Measure of Balance Between its Softness and Rigidity
International Nuclear Information System (INIS)
Shrestha, Utsab R.; Bhowmik, Debsindhu; Van Delinder, Kurt W.; Mamontov, Eugene; O’Neill, Hugh
2017-01-01
Here, we elucidate the protein activity from the perspective of protein softness and flexibility by studying the collective phonon-like excitations in a globular protein, human serum albumin (HSA), and taking advantage of the state-of-the-art inelastic X-ray scattering (IXS) technique. Such excitations demonstrate that the protein becomes softer upon thermal denaturation due to disruption of weak noncovalent bonds. On the other hand, no significant change in the local excitations is detected in ligand- (drugs) bound HSA compared to the ligand-free HSA. These results clearly suggest that the protein conformational flexibility and rigidity are balanced by the native protein structure for biological activity.
Collective Excitations in Protein as a Measure of Balance Between its Softness and Rigidity
Energy Technology Data Exchange (ETDEWEB)
Shrestha, Utsab R. [Wayne State Univ., Detroit, MI (United States). Dept. of Physics and Astronomy; Bhowmik, Debsindhu [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Computational Science and Engineering Division; Van Delinder, Kurt W. [Wayne State Univ., Detroit, MI (United States). Dept. of Physics and Astronomy; Mamontov, Eugene [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical and Engineering Materials Division; O’Neill, Hugh [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Biology and Soft Matter Division; Zhang, Qiu [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Biology and Soft Matter Division; Alatas, Ahmet [Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source; Chu, Xiang-Qiang [Wayne State Univ., Detroit, MI (United States). Dept. of Physics and Astronomy
2017-01-12
Here, we elucidate the protein activity from the perspective of protein softness and flexibility by studying the collective phonon-like excitations in a globular protein, human serum albumin (HSA), and taking advantage of the state-of-the-art inelastic X-ray scattering (IXS) technique. Such excitations demonstrate that the protein becomes softer upon thermal denaturation due to disruption of weak noncovalent bonds. On the other hand, no significant change in the local excitations is detected in ligand- (drugs) bound HSA compared to the ligand-free HSA. These results clearly suggest that the protein conformational flexibility and rigidity are balanced by the native protein structure for biological activity.
Modeling the Flexural Rigidity of Rod Photoreceptors
Haeri, Mohammad; Knox, Barry E.; Ahmadi, Aphrodite
2013-01-01
In vertebrate eyes, the rod photoreceptor has a modified cilium with an extended cylindrical structure specialized for phototransduction called the outer segment (OS). The OS has numerous stacked membrane disks and can bend or break when subjected to mechanical forces. The OS exhibits axial structural variation, with extended bands composed of a few hundred membrane disks whose thickness is diurnally modulated. Using high-resolution confocal microscopy, we have observed OS flexing and disruption in live transgenic Xenopus rods. Based on the experimental observations, we introduce a coarse-grained model of OS mechanical rigidity using elasticity theory, representing the axial OS banding explicitly via a spring-bead model. We calculate a bending stiffness of ∼105 nN⋅μm2, which is seven orders-of-magnitude larger than that of typical cilia and flagella. This bending stiffness has a quadratic relation to OS radius, so that thinner OS have lower fragility. Furthermore, we find that increasing the spatial frequency of axial OS banding decreases OS rigidity, reducing its fragility. Moreover, the model predicts a tendency for OS to break in bands with higher spring number density, analogous to the experimental observation that transgenic rods tended to break preferentially in bands of high fluorescence. We discuss how pathological alterations of disk membrane properties by mutant proteins may lead to increased OS rigidity and thus increased breakage, ultimately contributing to retinal degeneration. PMID:23442852
Blast wave interaction with a rigid surface
International Nuclear Information System (INIS)
Josey, T.; Whitehouse, D.R.; Ripley, R.C.; Dionne, J.P.
2004-01-01
A simple model used to investigate blast wave interactions with a rigid surface is presented. The model uses a constant volume energy source analogue to predict pressure histories at gauges located directly above the charge. A series of two-dimensional axi-symmetric CFD calculations were performed, varying the height of the charge relative to the ground. Pressure histories, along with isopycnic plots are presented to evaluate the effects of placing a charge in close proximity to a rigid surface. When a charge is placed near a solid surface the pressure histories experienced at gauges above the charge indicate the presence of two distinct pressure peaks. The first peak is caused by the primary shock and the second peak is a result of the wave reflections from the rigid surface. As the distance from the charge to the wall is increased the magnitude of the second pressure peak is reduced, provided that the distance between the charge and the gauge is maintained constant. The simple model presented is able to capture significant, predictable flow features. (author)
Lateral rigidity of cracked concrete structures
International Nuclear Information System (INIS)
Castellani, A.; Chesi, C.
1979-01-01
Numerical results are discussed on the lateral rigidity of reinforced concrete structures with a given crack distribution. They have been favourably checked with experimental results for cylindrical shells under the effect of a thermal gradient producing vertical cracking or vertical plus horizontal cracking. The main effects characterizing the concrete behaviour are: (1) The shear transfer across a crack; (2) The shear transfer degradation after cyclic loading; (3) The tension stiffening provided by the concrete between crack and crack, in the normal stress transfer; (4) The temperature effect on the elastic moduli of concrete, when cracks are of thermal origin. Only the 1st effect is discussed on an experimental basis. Two broad cathegories of reinforced concrete structures have been investigated in this respect: shear walls of buildings and cylindrical containment structures. The main conclusions so far reached are: (1) Vertical cracks are unlikely to decrease the lateral rigidity to less than 80% of the original one, and to less than 90% when they do not involve the entire thickness of the wall; (2) The appearence of horizontal cracks can reduce the lateral rigidity by some 30% or more; (3) A noticeable but not yet evaluated influence is shown by cyclic loading. (orig.)
Stresses in Circular Plates with Rigid Elements
Velikanov, N. L.; Koryagin, S. I.; Sharkov, O. V.
2018-05-01
Calculations of residual stress fields are carried out by numerical and static methods, using the flat cross-section hypothesis. The failure of metal when exposed to residual stresses is, in most cases, brittle. The presence in the engineering structures of rigid elements often leads to the crack initiation and structure failure. This is due to the fact that rigid elements under the influence of external stresses are stress concentrators. In addition, if these elements are fixed by welding, the residual welding stresses can lead to an increase in stress concentration and, ultimately, to failure. The development of design schemes for such structures is a very urgent task for complex technical systems. To determine the stresses in a circular plate with a welded circular rigid insert under the influence of an external load, one can use the solution of the plane stress problem for annular plates in polar coordinates. The polar coordinates of the points are the polar radius and the polar angle, and the stress state is determined by normal radial stresses, tangential and shearing stresses. The use of the above mentioned design schemes, formulas, will allow more accurate determination of residual stresses in annular welded structures. This will help to establish the most likely directions of failure and take measures at the stages of designing, manufacturing and repairing engineering structures to prevent these failures. However, it must be taken into account that the external load, the presence of insulation can lead to a change in the residual stress field.
International Nuclear Information System (INIS)
Faria, F. F.
2014-01-01
We construct a massive theory of gravity that is invariant under conformal transformations. The massive action of the theory depends on the metric tensor and a scalar field, which are considered the only field variables. We find the vacuum field equations of the theory and analyze its weak-field approximation and Newtonian limit.
International Nuclear Information System (INIS)
Moore, G.; Seiberg, N.
1989-01-01
All known rational conformal field theories may be obtained from (2+1)-dimensional Chern-Simons gauge theories by appropriate choice of gauge group. We conjecture that all rational field theories are classified by groups via (2+1)-dimensional Chern-Simons gauge theories. (orig.)
International Nuclear Information System (INIS)
Maia, M.D.
2006-01-01
It is shown that the information loss/recovery theorem based on the ADS/CFT correspondence is not consistent with the stability of the Schwarzschild or Reissner-Nordstrom black holes. Nonetheless, the conformal invariance of Yang-Mills theory points to new relativity principle compatible with quantum unitarity near those black holes
Animal culture: chimpanzee conformity?
van Schaik, Carel P
2012-05-22
Culture-like phenomena in wild animals have received much attention, but how good is the evidence and how similar are they to human culture? New data on chimpanzees suggest their culture may even have an element of conformity. Copyright © 2012 Elsevier Ltd. All rights reserved.
Parafermionic conformal field theory
International Nuclear Information System (INIS)
Kurak, V.
1989-09-01
Conformal parafermionic field theories are reviewed with emphasis on the computation of their OPE estructure constants. It is presented a simple computational of these for the Z(N) parafermions, unveilling their Lie algebra content. (A.C.A.S.) [pt
Quantifying polypeptide conformational space: sensitivity to conformation and ensemble definition.
Sullivan, David C; Lim, Carmay
2006-08-24
Quantifying the density of conformations over phase space (the conformational distribution) is needed to model important macromolecular processes such as protein folding. In this work, we quantify the conformational distribution for a simple polypeptide (N-mer polyalanine) using the cumulative distribution function (CDF), which gives the probability that two randomly selected conformations are separated by less than a "conformational" distance and whose inverse gives conformation counts as a function of conformational radius. An important finding is that the conformation counts obtained by the CDF inverse depend critically on the assignment of a conformation's distance span and the ensemble (e.g., unfolded state model): varying ensemble and conformation definition (1 --> 2 A) varies the CDF-based conformation counts for Ala(50) from 10(11) to 10(69). In particular, relatively short molecular dynamics (MD) relaxation of Ala(50)'s random-walk ensemble reduces the number of conformers from 10(55) to 10(14) (using a 1 A root-mean-square-deviation radius conformation definition) pointing to potential disconnections in comparing the results from simplified models of unfolded proteins with those from all-atom MD simulations. Explicit waters are found to roughen the landscape considerably. Under some common conformation definitions, the results herein provide (i) an upper limit to the number of accessible conformations that compose unfolded states of proteins, (ii) the optimal clustering radius/conformation radius for counting conformations for a given energy and solvent model, (iii) a means of comparing various studies, and (iv) an assessment of the applicability of random search in protein folding.
Anopheles gambiae Purine Nucleoside Phosphorylase: Catalysis, Structure, and Inhibition
Energy Technology Data Exchange (ETDEWEB)
Taylor,E.; Rinaldo-Matthis, A.; Li, L.; Ghanem, M.; Hazleton, K.; Cassera, M.; Almo, S.; Schramm, V.
2007-01-01
The purine salvage pathway of Anopheles gambiae, a mosquito that transmits malaria, has been identified in genome searches on the basis of sequence homology with characterized enzymes. Purine nucleoside phosphorylase (PNP) is a target for the development of therapeutic agents in humans and purine auxotrophs, including malarial parasites. The PNP from Anopheles gambiae (AgPNP) was expressed in Escherichia coli and compared to the PNPs from Homo sapiens (HsPNP) and Plasmodium falciparum (PfPNP). AgPNP has kcat values of 54 and 41 s-1 for 2'-deoxyinosine and inosine, its preferred substrates, and 1.0 s-1 for guanosine. However, the chemical step is fast for AgPNP at 226 s-1 for guanosine in pre-steady-state studies. 5'-Deaza-1'-aza-2'-deoxy-1'-(9-methylene)-Immucillin-H (DADMe-ImmH) is a transition-state mimic for a 2'-deoxyinosine ribocation with a fully dissociated N-ribosidic bond and is a slow-onset, tight-binding inhibitor with a dissociation constant of 3.5 pM. This is the tightest-binding inhibitor known for any PNP, with a remarkable Km/Ki* of 5.4 x 107, and is consistent with enzymatic transition state predictions of enhanced transition-state analogue binding in enzymes with enhanced catalytic efficiency. Deoxyguanosine is a weaker substrate than deoxyinosine, and DADMe-Immucillin-G is less tightly bound than DADMe-ImmH, with a dissociation constant of 23 pM for AgPNP as compared to 7 pM for HsPNP. The crystal structure of AgPNP was determined in complex with DADMe-ImmH and phosphate to a resolution of 2.2 Angstroms to reveal the differences in substrate and inhibitor specificity. The distance from the N1' cation to the phosphate O4 anion is shorter in the AgPNP{center_dot}DADMe-ImmH{center_dot}PO4 complex than in HsPNP{center_dot}DADMe-ImmH{center_dot}SO4, offering one explanation for the stronger inhibitory effect of DADMe-ImmH for AgPNP.
Effective lethal mutagenesis of influenza virus by three nucleoside analogs.
Pauly, Matthew D; Lauring, Adam S
2015-04-01
Lethal mutagenesis is a broad-spectrum antiviral strategy that exploits the high mutation rate and low mutational tolerance of many RNA viruses. This approach uses mutagenic drugs to increase viral mutation rates and burden viral populations with mutations that reduce the number of infectious progeny. We investigated the effectiveness of lethal mutagenesis as a strategy against influenza virus using three nucleoside analogs, ribavirin, 5-azacytidine, and 5-fluorouracil. All three drugs were active against a panel of seasonal H3N2 and laboratory-adapted H1N1 strains. We found that each drug increased the frequency of mutations in influenza virus populations and decreased the virus' specific infectivity, indicating a mutagenic mode of action. We were able to drive viral populations to extinction by passaging influenza virus in the presence of each drug, indicating that complete lethal mutagenesis of influenza virus populations can be achieved when a sufficient mutational burden is applied. Population-wide resistance to these mutagenic agents did not arise after serial passage of influenza virus populations in sublethal concentrations of drug. Sequencing of these drug-passaged viral populations revealed genome-wide accumulation of mutations at low frequency. The replicative capacity of drug-passaged populations was reduced at higher multiplicities of infection, suggesting the presence of defective interfering particles and a possible barrier to the evolution of resistance. Together, our data suggest that lethal mutagenesis may be a particularly effective therapeutic approach with a high genetic barrier to resistance for influenza virus. Influenza virus is an RNA virus that causes significant morbidity and mortality during annual epidemics. Novel therapies for RNA viruses are needed due to the ease with which these viruses evolve resistance to existing therapeutics. Lethal mutagenesis is a broad-spectrum strategy that exploits the high mutation rate and the low
49 CFR 587.18 - Dimensions of fixed rigid barrier.
2010-10-01
... TRAFFIC SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) DEFORMABLE BARRIERS Offset Deformable Barrier § 587.18 Dimensions of fixed rigid barrier. (a) The fixed rigid barrier has a mass of not... 49 Transportation 7 2010-10-01 2010-10-01 false Dimensions of fixed rigid barrier. 587.18 Section...
Conformal cosmological model and SNe Ia data
International Nuclear Information System (INIS)
Zakharov, A. F.; Pervushin, V. N.
2012-01-01
Now there is a huge scientific activity in astrophysical studies and cosmological ones in particular. Cosmology transforms from a pure theoretical branch of science into an observational one. All the cosmological models have to pass observational tests. The supernovae type Ia (SNe Ia) test is among the most important ones. If one applies the test to determine parameters of the standard Friedmann-Robertson-Walker cosmological model one can conclude that observations lead to the discovery of the dominance of the Λ term and as a result to an acceleration of the Universe. However, there are big mysteries connected with an origin and an essence of dark matter (DM) and the Λ term or dark energy (DE). Alternative theories of gravitation are treated as a possible solution of DM and DE puzzles. The conformal cosmological approach is one of possible alternatives to the standard ΛCDM model. As it was noted several years ago, in the framework of the conformal cosmological approach an introduction of a rigid matter can explain observational data without Λ term (or dark energy). We confirm the claim with much larger set of observational data.
Free Energy Landscapes of Alanine Oligopeptides in Rigid-Body and Hybrid Water Models.
Nayar, Divya; Chakravarty, Charusita
2015-08-27
Replica exchange molecular dynamics is used to study the effect of different rigid-body (mTIP3P, TIP4P, SPC/E) and hybrid (H1.56, H3.00) water models on the conformational free energy landscape of the alanine oligopeptides (acAnme and acA5nme), in conjunction with the CHARMM22 force field. The free energy landscape is mapped out as a function of the Ramachandran angles. In addition, various secondary structure metrics, solvation shell properties, and the number of peptide-solvent hydrogen bonds are monitored. Alanine dipeptide is found to have similar free energy landscapes in different solvent models, an insensitivity which may be due to the absence of possibilities for forming i-(i + 4) or i-(i + 3) intrapeptide hydrogen bonds. The pentapeptide, acA5nme, where there are three intrapeptide backbone hydrogen bonds, shows a conformational free energy landscape with a much greater degree of sensitivity to the choice of solvent model, though the three rigid-body water models differ only quantitatively. The pentapeptide prefers nonhelical, non-native PPII and β-sheet populations as the solvent is changed from SPC/E to the less tetrahedral liquid (H1.56) to an LJ-like liquid (H3.00). The pentapeptide conformational order metrics indicate a preference for open, solvent-exposed, non-native structures in hybrid solvent models at all temperatures of study. The possible correlations between the properties of solvent models and secondary structure preferences of alanine oligopeptides are discussed, and the competition between intrapeptide, peptide-solvent, and solvent-solvent hydrogen bonding is shown to be crucial in the relative free energies of different conformers.
International Nuclear Information System (INIS)
Stancanello, J.; Loeckx, D.; Francescon, P.; Calvedon, C.; Avanzo, M.; Cora, S.; Scalchi, P.; Cerveri, P.; Ferrigno, G.
2004-01-01
This work aims at comparing rigid, affine and Local Non Rigid (LNR) CT-3D Rotational Angiography (CT-3DRA) registrations based on mutual information. 10 cranial and 1 spinal cases have been registered by rigid and affine transformations; while LNR has been applied to the cases where residual deformation must be corrected. An example of CT-3DRA registration without regularization term and an example of LNR using the similarity criterion and the regularization term as well as 3D superposition of the 3DRA before and after the registration without the regularization term are presented. All the registrations performed by rigid transformation converged to an acceptable solution. The results about the robustness test in axial direction are reported. Conclusions: For cranial cases, affine transformation endowed with threshold-segmentation pre-processing can be considered the most favourable solution for almost all registrations; for some cases, LNR provides more accurate results. For the spinal case rigid transformation is the most suitable when immobilizing patient during examinations; in this case the increase of accuracy by using LNR registrations seems to be not significant
Czech Academy of Sciences Publication Activity Database
Hocková, Dana; Rosenbergová, Šárka; Ménová, Petra; Páv, Ondřej; Pohl, Radek; Novák, Pavel; Rosenberg, Ivan
2015-01-01
Roč. 13, č. 15 (2015), s. 4449-4458 ISSN 1477-0520 R&D Projects: GA ČR GAP207/11/0108; GA ČR GA13-26526S Institutional support: RVO:61388963 Keywords : acyclic nucleoside phosphonates * oligonucleotides * solid phase synthesis Subject RIV: CC - Organic Chemistry Impact factor: 3.559, year: 2015
Girke, Christopher; Arutyunova, Elena; Syed, Maria; Traub, Michaela; Möhlmann, Torsten; Lemieux, M Joanne
2015-09-01
Equilibrative nucleoside transporters (ENTs) facilitate the import of nucleosides and their analogs into cells in a bidirectional, non-concentrative manner. However, in contrast to their name, most characterized plant ENTs act in a concentrative manner. A direct characterization of any ENT protein has been hindered due to difficulties in overexpression and obtaining pure recombinant protein. The equilibrative nucleoside transporter 7 from Arabidopsis thaliana (AtENT7) was expressed in Xenopus laevis oocytes to assess mechanism of substrate uptake. Recombinant protein fused to enhanced green fluorescent protein (eGFP) was expressed in Pichia pastoris to characterize its oligomeric state by gel filtration and substrate binding by microscale thermophoresis (MST). AtENT7 expressed in X. laevis oocytes works as a classic equilibrative transporter. The expression of AtENT7-eGFP in the P. pastoris system yielded milligram amounts of pure protein that exists as stable homodimers. The concentration dependent binding of purine and pyrimidine nucleosides to the purified recombinant protein, assessed by MST, confirmed that AtENT7-eGFP is properly folded. For the first time the binding of nucleobases was observed for AtENT7. The availability of pure recombinant AtENT7 will permit detailed kinetic and structural studies of this unique member of the ENT family and, given the functional similarity to mammalian ENTs, will serve as a good model for understanding the structural basis of translocation mechanism for the family. Copyright © 2015 Elsevier B.V. All rights reserved.
Czech Academy of Sciences Publication Activity Database
Potměšil, Petr; Holý, Antonín; Kmoníčková, Eva; Křížková, Jana; Zídek, Zdeněk
2007-01-01
Roč. 14, č. 1 (2007), s. 59-66 ISSN 1021-7770 R&D Projects: GA MŠk 1M0508 Institutional research plan: CEZ:AV0Z50390512; CEZ:AV0Z40550506 Keywords : Acyclic nucleoside phosponate * HIV * Monocyte chemotactic protein Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.024, year: 2007
Qu, C. (Changbo); L. Xu (Lei); Y. Yin (Yuebang); M.P. Peppelenbosch (Maikel); Q. Pan (Qiuwei); W. Wang (Wenshi)
2017-01-01
textabstractHepatitis E virus (HEV) infection has emerged as a global health issue, but no approved medication is available. The nucleoside analogue 2’-C-methylcytidine (2CMC), a viral polymerase inhibitor, has been shown to inhibit infection with a variety of viruses, including hepatitis C virus
Phosphorylation of nm23/nucleoside diphosphate kinase by casein kinase 2 in vitro
DEFF Research Database (Denmark)
Engel, M; Issinger, O G; Lascu, I
1994-01-01
We have investigated phosphorylation of human nucleoside diphosphate kinase (NDPK) and of homologous NDPK from different species by human casein kinase 2 (CK-2). The human NDPK isotypes A and B were phosphorylated by CK-2 in vitro both when the purified proteins and total lysate of HL-60 leukemia...
Czech Academy of Sciences Publication Activity Database
Keough, D. T.; Hocková, Dana; Rejman, Dominik; Špaček, Petr; Vrbková, Silvie; Krečmerová, Marcela; Eng, W. S.; Jans, H.; West, N. P.; Naesens, L. M. J.; de Jersey, J.; Guddat, L. W.
2013-01-01
Roč. 56, č. 17 (2013), s. 6967-6984 ISSN 0022-2623 R&D Projects: GA ČR GAP207/11/0108 Institutional support: RVO:61388963 Keywords : nucleoside phosphonates * antibacterial agents * hypoxanthine-guanine phosphoribosyltransferase * state analog inhibitor * antimalarial chemotherapy Subject RIV: CC - Organic Chemistry Impact factor: 5.480, year: 2013
Czech Academy of Sciences Publication Activity Database
Keough, D. T.; Hocková, Dana; Holý, Antonín; Naesens, L.; Skinner-Adams, T. S.; de Jersey, J.; Guddat, L. W.
2009-01-01
Roč. 52, č. 14 (2009), s. 4391-4399 ISSN 0022-2623 R&D Projects: GA MŠk 1M0508; GA AV ČR 1QS400550501 Institutional research plan: CEZ:AV0Z40550506 Keywords : acyclic nucleoside phosphonates * phosphoribosyltransferase * enzyme inhibitors * Plasmodium falciparum Subject RIV: CC - Organic Chemistry Impact factor: 4.802, year: 2009
Antiretrovirus activity of a novel class of acyclic pyrimidine nucleoside phosphonates
Czech Academy of Sciences Publication Activity Database
Balzarini, J.; Pannecouque, C.; De Clercq, E.; Aquaro, S.; Perno, C. F.; Egberink, H.; Holý, Antonín
2002-01-01
Roč. 46, č. 7 (2002), s. 2185-2193 ISSN 0066-4804 R&D Projects: GA ČR GV203/96/K001 Institutional research plan: CEZ:AV0Z4055905 Keywords : nucleoside phosphonates Subject RIV: CC - Organic Chemistry Impact factor: 4.215, year: 2002
Czech Academy of Sciences Publication Activity Database
Břehová, Petra; Šmídková, Markéta; Skácel, Jan; Dračínský, Martin; Mertlíková-Kaiserová, Helena; Velasquez, M. P. S.; Watts, V. J.; Janeba, Zlatko
2016-01-01
Roč. 11, č. 22 (2016), s. 2534-2546 ISSN 1860-7179 R&D Projects: GA MV VG20102015046; GA MŠk LO1302 Institutional support: RVO:61388963 Keywords : adenylate cyclase toxin * acyclic nucleoside phosphonates * anthranilic acid Subject RIV: CC - Organic Chemistry Impact factor: 3.225, year: 2016
Czech Academy of Sciences Publication Activity Database
Kalachová, Lubica; Pohl, Radek; Hocek, Michal
-, č. 1 (2009), s. 105-112 ISSN 0039-7881 R&D Projects: GA MŠk LC512 Institutional research plan: CEZ:AV0Z40550506 Keywords : nucleosides * pyrimidines * cross-coupling * bipyridine s Subject RIV: CC - Organic Chemistry Impact factor: 2.572, year: 2009
Secretion of antiretroviral chemokines by human cells cultured with acyclic nucleoside phosphonates
Czech Academy of Sciences Publication Activity Database
Zídek, Zdeněk; Kmoníčková, Eva; Holý, Antonín
2007-01-01
Roč. 574, - (2007), s. 77-84 ISSN 0014-2999 R&D Projects: GA MŠk 1M0508 Institutional research plan: CEZ:AV0Z50390512; CEZ:AV0Z40550506 Keywords : Acyclic nucleoside phosphonate * Chemokine * Cytokine Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.376, year: 2007
Czech Academy of Sciences Publication Activity Database
Wielgus-Kutrowska, B.; Frank, J.; Holý, Antonín; Koellner, G.; Bzowska, A.
2003-01-01
Roč. 22, 5/8 (2003), s. 1695-1698 ISSN 1525-7770 Grant - others:PCSR(PL) 6 P04A04416; PCSR(PL) 3 P04A03524 Institutional research plan: CEZ:AV0Z4055905 Keywords : purine nucleoside phosphorylase * fluorescence Subject RIV: CC - Organic Chemistry Impact factor: 0.813, year: 2003
ACTIVATION OF G-PROTEINS BY RECEPTOR-STIMULATED NUCLEOSIDE DIPHOSPHATE KINASE IN DICTYOSTELIUM
Bominaar, Anthony A.; Molijn, Anco C.; Pestel, Martine; Veron, Michel; Haastert, Peter J.M. van
Recently, interest in the enzyme nucleoside diphosphate kinase (EC 2.7.4.6) has increased as a result of its possible involvement in cell proliferation and development. Since NDP kinase is one of the major sources of GTP in cells, it has been suggested that the effects of an altered NDP kinase
Maiti, Munmun; Maiti, Mohitosh; Rozenski, Jef; De Jonghe, Steven; Herdewijn, Piet
2015-05-14
In view of a persistent threat to mankind, the development of nucleotide-based prodrugs against hepatitis C virus (HCV) is considered as a constant effort in many medicinal chemistry groups. In an attempt to identify novel nucleoside phosphoramidate analogues for improving the anti-HCV activity, we have explored, for the first time, aspartic acid (Asp) and iminodiacetic acid (IDA) esters as amidate counterparts by considering three 2'-C-methyl containing nucleosides, 2'-C-Me-cytidine, 2'-C-Me-uridine and 2'-C-Me-2'-fluoro-uridine. Synthesis of these analogues required protection for the vicinal diol functionality of the sugar moiety and the amino group of the cytidine nucleoside to regioselectively perform phosphorylation reaction at the 5'-hydroxyl group. Anti-HCV data demonstrate that the Asp-based phosphoramidates are ∼550 fold more potent than the parent nucleosides. The inhibitory activity of the Asp-ProTides was higher than the Ala-ProTides, suggesting that Asp would be a potential amino acid candidate to be considered for developing novel antiviral prodrugs.
Pd0-Catalyzed Methyl Transfer on Nucleosides and Oligonucleotides, Envisaged as a PET Tracer
Directory of Open Access Journals (Sweden)
Eric Fouquet
2013-11-01
Full Text Available The methyl transfer reaction from activated monomethyltin, via a modified Stille coupling reaction, was studied under “ligandless” conditions on fully deprotected 5'-modified nucleosides and one dinucleotide. The reaction was optimized to proceed in a few minutes and quantitative yield, even under dilute conditions, thus affording a rapid and efficient new method for oligonucleotide labelling with carbon-11.
beta-1,2,3-Triazolyl-Nucleosides as Nicotinamide Riboside Mimics
Czech Academy of Sciences Publication Activity Database
Amigues, E.J.; Armstrong, E.; Dvořáková, Marcela; Migaud, M.E.; Huang, M.
2009-01-01
Roč. 28, č. 3 (2009), s. 238-259 ISSN 1525-7770 Institutional research plan: CEZ:AV0Z50380511 Keywords : Nucleoside * nucleotide * sirtuin Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 0.768, year: 2009
Synthesis and NMR spectral studies if some nucleosides and their analoges
International Nuclear Information System (INIS)
Ansari, F.L.; Awan, H.S.; Kazmi, N.A.
1995-01-01
Massive efforts have been extended towards the analysis of nucleosides due mainly to their applications in the field of medicine. Present work describes two methods for the synthesis of nucleosides and their analogues. The first method involves the use of phase transfer catalysis for the glycosidation of benzimidazoles. The reaction of 2,3,5-tri-o-benzoyl-beta -d-arabinofuranosyl chloride with benzimidazole and 2 (alpha-hydroxyethyl) benzimidazole in the presence of tetrabutylammoniumhydroensulfide led to the synthesis of nucleosides respectively. Likewise the coupling of 1,2:4, 6-di-O-isopropylidene-3-chloro-alpha-D-fructofurano side with benzimidazole led to the desired product. The second method involves a triflate mediated coupling of benzyl-2,3-anhydro-4-O-triflyl-beta-L-ribopyranoside with benzimidazole which led to the facile displacement of the triflyl group with benzimidazole resulting in the synthesis of nucleoside. However, an attempt towards the coupling of 1,2:5,6-di-O-isopropylidene-3-O-triflyl-alpha-D-glucofuranoside with benzimidazole does not led to the desired coupling, instead an unusual conversion of the triflate ester to mesitylate ester of the sugar appears to have been taken place. (author)
DEFF Research Database (Denmark)
Mikkelsen, Niels Egil; Munch-Petersen, Birgitte; Eklund, Hans
2008-01-01
-drug that eventually may kill the cell. To be able to optimize the function of dNK, it is vital to have structural information of dNK complexes. Here we present crystal structures of dNK complexed with four different nucleoside analogs floxuridine (5FdU), brivudine (BVDU), zidovudine (AZT) and zalcitabine (ddC...
Detergent inhibited, heat labile nucleoside triphosphatase in cores of avian myeloblastosis virus
DEFF Research Database (Denmark)
Jensen, Kaj Frank
1978-01-01
Endogenous DNA synthesis was studied in isolated core particles of avian myeloblastosis virus. It was found that cores contained an enzymatic activity which rapidly converted the added nucleoside triphosphates to diphosphates (but not further) at 0 degrees C, thus inhibiting DNA synthesis...
Rigid body essential X-ray crystallography
DEFF Research Database (Denmark)
Bjerrum, Esben Jannik; Biggin, Philip C
2008-01-01
The ligand-binding domain (LBD) from the ionotropic glutamate receptor subtype 2 (GluR2) has been shown to adopt a range of ligand-dependent conformational states. These states have been described in terms of the rotation required to fit subdomain (lobe) 2 following superposition of subdomain (lo...
Transportation Conformity Training and Presentations
EPA's OTAQ has provided multiple conformity training sessions in the past to assist state and local governments in implementing conformity requirements. As training information is prepared for other venues, it will be posted on this page.
Influence of flock coating on bending rigidity of woven fabrics
Ozdemir, O.; Kesimci, M. O.
2017-10-01
This work presents the preliminary results of our efforts that focused on the effect of the flock coating on the bending rigidity of woven fabrics. For this objective, a laboratory scale flocking unit is designed and flocked samples of controlled flock density are produced. Bending rigidity of the samples with different flock densities are measured on both flocked and unflocked sides. It is shown that the bending rigidity depends on both flock density and whether the side to be measured is flocked or not. Adhesive layer thickness on the bending rigidity is shown to be dramatic. And at higher basis weights, flock density gets less effective on bending rigidity.
DEFF Research Database (Denmark)
Mojaza, Matin; Pica, Claudio; Sannino, Francesco
2010-01-01
of flavors. Surprisingly this number, if computed to the order g^2, agrees with previous predictions for the lower boundary of the conformal window for nonsupersymmetric gauge theories. The higher order results tend to predict a higher number of critical flavors. These are universal properties, i......We compute the nonzero temperature free energy up to the order g^6 \\ln(1/g) in the coupling constant for vector like SU(N) gauge theories featuring matter transforming according to different representations of the underlying gauge group. The number of matter fields, i.e. flavors, is arranged...... in such a way that the theory develops a perturbative stable infrared fixed point at zero temperature. Due to large distance conformality we trade the coupling constant with its fixed point value and define a reduced free energy which depends only on the number of flavors, colors and matter representation. We...
Conformational flexibility of aspartame.
Toniolo, Claudio; Temussi, Pierandrea
2016-05-01
L-Aspartyl-L-phenylalanine methyl ester, better known as aspartame, is not only one of the most used artificial sweeteners, but also a very interesting molecule with respect to the correlation between molecular structure and taste. The extreme conformational flexibility of this dipeptide posed a huge difficulty when researchers tried to use it as a lead compound to design new sweeteners. In particular, it was difficult to take advantage of its molecular model as a mold to infer the shape of the, then unknown, active site of the sweet taste receptor. Here, we follow the story of the 3D structural aspects of aspartame from early conformational studies to recent docking into homology models of the receptor. © 2016 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 376-384, 2016. © 2016 Wiley Periodicals, Inc.
Semiflexible polymer conformation, distribution and migration in microcapillary flows
International Nuclear Information System (INIS)
Chelakkot, Raghunath; Gompper, Gerhard; Winkler, Roland G
2011-01-01
The flow behavior of a semiflexible polymer in microchannels is studied using multiparticle collision dynamics, a particle-based hydrodynamic simulation technique. Conformations, distributions, and radial cross-streamline migration are investigated for various bending rigidities, with persistence lengths L p in the range 0.5 ≤ L p /L r ≤ 30. The flow behavior is governed by the competition between a hydrodynamic lift force and steric repulsion from the wall, which lead to migration away from the wall, and a locally varying flow induced orientation, which drives the polymer away from the channel center and towards the wall. The different dependences of these effects on the polymer bending rigidity and the flow velocity results in a complex dynamical behavior. However, a generic effect is the appearance of a maximum in the monomer and the center-of-mass distributions, which occurs at the channel center for small flow velocities, but moves off-center at higher velocities.
Rigidity of the polypeptide backbone in the triple-stranded collagen molecule.
Nemethy, G
1981-02-01
Conformational energy computations were carried out on collagen-like triple-stranded conformations of several polytripeptides with the structure CH3CO(GXY)3NHCH3, where X and Y can be Pro, Ala, or Gly. The computed minimum-energy conformations for various sequences are compared with that computed earlier for poly(Gly-Pro-Pro). Usually, substitution of Ala or Gly residues for Pro does not cause any strain or distortion of the conformation of the triple-stranded complex. Thus, the structure is a very stable and essentially rigid one. Unfavorable interactions were found only in the case of CH3CO(Gly-Ala-Pro)NHCH3. These interactions are a consequence of differences between the residue geometry of Ala and Pro. They result in small changes of some backbone dihedral angles and in an increase of intra- and interchain energies. The presence of a single Gly-Ala-Pro tripeptide within a sequence of Gly-Pro-Pro tripeptides is not sufficient, however, to cause even a small distoration of the triple strand. No deviation of the peptide groups from planarity is required to stabilize the triple-stranded structure.
Understanding geological processes: Visualization of rigid and non-rigid transformations
Shipley, T. F.; Atit, K.; Manduca, C. A.; Ormand, C. J.; Resnick, I.; Tikoff, B.
2012-12-01
Visualizations are used in the geological sciences to support reasoning about structures and events. Research in cognitive sciences offers insights into the range of skills of different users, and ultimately how visualizations might support different users. To understand the range of skills needed to reason about earth processes we have developed a program of research that is grounded in the geosciences' careful description of the spatial and spatiotemporal patterns associated with earth processes. In particular, we are pursuing a research program that identifies specific spatial skills and investigates whether and how they are related to each other. For this study, we focus on a specific question: Is there an important distinction in the geosciences between rigid and non-rigid deformation? To study a general spatial thinking skill we employed displays with non-geological objects that had been altered by rigid change (rotation), and two types of non-rigid change ("brittle" (or discontinuous) and "ductile" (or continuous) deformation). Disciplinary scientists (geosciences and chemistry faculty), and novices (non-science faculty and undergraduate psychology students) answered questions that required them to visualize the appearance of the object before the change. In one study, geologists and chemists were found to be superior to non-science faculty in reasoning about rigid rotations (e.g., what an object would look like from a different perspective). Geologists were superior to chemists in reasoning about brittle deformations (e.g., what an object looked like before it was broken - here the object was a word cut into many fragments displaced in different directions). This finding is consistent with two hypotheses: 1) Experts are good at visualizing the types of changes required for their domain; and 2) Visualization of rigid and non-rigid changes are not the same skill. An additional important finding is that there was a broad range of skill in both rigid and non-rigid
Prediction of flexible/rigid regions from protein sequences using k-spaced amino acid pairs
Directory of Open Access Journals (Sweden)
Ruan Jishou
2007-04-01
Full Text Available Abstract Background Traditionally, it is believed that the native structure of a protein corresponds to a global minimum of its free energy. However, with the growing number of known tertiary (3D protein structures, researchers have discovered that some proteins can alter their structures in response to a change in their surroundings or with the help of other proteins or ligands. Such structural shifts play a crucial role with respect to the protein function. To this end, we propose a machine learning method for the prediction of the flexible/rigid regions of proteins (referred to as FlexRP; the method is based on a novel sequence representation and feature selection. Knowledge of the flexible/rigid regions may provide insights into the protein folding process and the 3D structure prediction. Results The flexible/rigid regions were defined based on a dataset, which includes protein sequences that have multiple experimental structures, and which was previously used to study the structural conservation of proteins. Sequences drawn from this dataset were represented based on feature sets that were proposed in prior research, such as PSI-BLAST profiles, composition vector and binary sequence encoding, and a newly proposed representation based on frequencies of k-spaced amino acid pairs. These representations were processed by feature selection to reduce the dimensionality. Several machine learning methods for the prediction of flexible/rigid regions and two recently proposed methods for the prediction of conformational changes and unstructured regions were compared with the proposed method. The FlexRP method, which applies Logistic Regression and collocation-based representation with 95 features, obtained 79.5% accuracy. The two runner-up methods, which apply the same sequence representation and Support Vector Machines (SVM and Naïve Bayes classifiers, obtained 79.2% and 78.4% accuracy, respectively. The remaining considered methods are
Conformal description of spinning particles
International Nuclear Information System (INIS)
Todorov, I.T.
1986-01-01
This book is an introduction to the application of the conformal group to quantum field theory of particles with spin. After an introduction to the twistor representations of the conformal group of a conformally flat space-time and twistor flag manifolds with Su(2,2) orbits the classical phase space of conformal spinning particles is described. Thereafter the twistor description of classical zero mass fields is considered together with the quantization. (HSI)
Conformal boundaries of warped products
DEFF Research Database (Denmark)
Kokkendorff, Simon Lyngby
2006-01-01
In this note we prove a result on how to determine the conformal boundary of a type of warped product of two length spaces in terms of the individual conformal boundaries. In the situation, that we treat, the warping and conformal distortion functions are functions of distance to a base point....... The result is applied to produce examples of CAT(0)-spaces, where the conformal and ideal boundaries differ in interesting ways....
Conformal radiotherapy: a glossary
International Nuclear Information System (INIS)
Dubray, B.; Giraud, P.; Beaudre, A.
1999-01-01
Most of the concepts and terms related to conformal radiotherapy were produced by English-speaking authors and eventually validated by international groups of experts, whose working language was also English. Therefore, a significant part of this literature is poorly accessible to the French-speaking radiation oncology community. The present paper gathers the 'official' definitions already published in French, along with propositions for the remaining terms which should be submitted to a more formal and representative validation process. (author)
Structural and thermodynamic analysis of modified nucleosides in self-assembled DNA cross-tiles.
Hakker, Lauren; Marchi, Alexandria N; Harris, Kimberly A; LaBean, Thomas H; Agris, Paul F
2014-01-01
DNA Holliday junctions are important natural strand-exchange structures that form during homologous recombination. Immobile four-arm junctions, analogs to Holliday junctions, have been designed to self-assemble into cross-tile structures by maximizing Watson-Crick base pairing and fixed crossover points. The cross-tiles, self-assembled from base pair recognition between designed single-stranded DNAs, form higher order lattice structures through cohesion of self-associating sticky ends. These cross-tiles have 16 unpaired nucleosides in the central loop at the junction of the four duplex stems. The importance of the centralized unpaired nucleosides to the structure's thermodynamic stability and self-assembly is unknown. Cross-tile DNA nanostructures were designed and constructed from nine single-stranded DNAs with four shell strands, four arms, and a central loop containing 16 unpaired bases. The 16 unpaired bases were either 2'-deoxyribothymidines, 2'-O-methylribouridines, or abasic 1',2'-dideoxyribonucleosides. Thermodynamic profiles and structural base-stacking contributions were assessed using UV absorption spectroscopy during thermal denaturation and circular dichroism spectroscopy, respectively, and the resulting structures were observed by atomic force microscopy. There were surprisingly significant changes in the thermodynamic and structural properties of lattice formation as a result of altering only the 16 unpaired, centralized nucleosides. The 16 unpaired 2'-O-methyluridines were stabilizing and produced uniform tubular structures. In contrast, the abasic nucleosides were destabilizing producing a mixture of structures. These results strongly indicate the importance of a small number of centrally located unpaired nucleosides within the structures. Since minor modifications lead to palpable changes in lattice formation, DNA cross-tiles present an easily manipulated structure convenient for applications in biomedical and biosensing devices.
Assessment of nucleosides as putative tumor biomarkers in prostate cancer screening by CE-UV.
Buzatto, Adriana Zardini; de Oliveira Silva, Mariana; Poppi, Ronei Jesus; Simionato, Ana Valéria Colnaghi
2017-05-01
Cancer is responsible for millions of deaths worldwide, but most base diseases may be cured if detected early. Screening tests may be used to identify early-stage malignant neoplasms. However, the major screening tool for prostate cancer, the prostate-specific antigen test, has unsuitable sensitivity. Since cancer cells may affect the pattern of consumption and excretion of nucleosides, such biomolecules are putative biomarkers that can be used for diagnosis and treatment evaluation. Using a previously validated method for the analysis of nucleosides in blood serum by capillary electrophoresis with UV-vis spectroscopy detection, we investigated 60 samples from healthy individuals and 42 samples from prostate cancer patients. The concentrations of nucleosides in both groups were compared and a multivariate partial least squares-discriminant analysis classification model was optimized for prediction of prostate cancer. The validation of the model with an independent sample set resulted in the correct classification of 82.4% of the samples, with sensitivity of 90.5% and specificity of 76.7%. A significant downregulation of 5-methyluridine and inosine was observed, which can be indicative of the carcinogenic process. Therefore, such analytes are potential candidates for prostate cancer screening. Graphical Abstract Separation of the studied nucleosides and the internal standard 8-Bromoguanosine by CE-UV (a); classification of the external validation samples (30 from healthy volunteers and 21 from prostate cancer patients) by the developed Partial Least Square - Discriminant Analysis (PLS-DA) model with accuracy of 82.4% (b); Receiver Operating Characteristics (ROC) curve (c); and Variable Importance in the Projection (VIP) values for the studied nucleosides (d). A significant down-regulation of 5- methyluridine (5mU) and inosine (I) was observed, which can be indicative of the presence of prostate tumors.
A rigid porous filter and filtration method
Energy Technology Data Exchange (ETDEWEB)
Chiang, Ta-Kuan; Straub, Douglas, Straub L.; Dennis, Richard A.
1998-12-01
The present invention involves a porous rigid filter comprising a plurality of concentric filtration elements having internal flow passages and forming external flow passages there between. The present invention also involves a pressure vessel containing the filter for the removal of particulate from high pressure particulate containing gases, and further involves a method for using the filter to remove such particulate. The present filter has the advantage of requiring fewer filter elements due to the high surface area- to-volume ratio provided by the filter, requires a reduced pressure vessel size, and exhibits enhanced mechanical design properties, improved cleaning properties, configuration options, modularity and ease of fabrication.
Mechanical Characterization of Rigid Polyurethane Foams
Energy Technology Data Exchange (ETDEWEB)
Lu, Wei-Yang [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Mechanics of Materials
2014-12-01
Foam materials are used to protect sensitive components from impact loading. In order to predict and simulate the foam performance under various loading conditions, a validated foam model is needed and the mechanical properties of foams need to be characterized. Uniaxial compression and tension tests were conducted for different densities of foams under various temperatures and loading rates. Crush stress, tensile strength, and elastic modulus were obtained. A newly developed confined compression experiment provided data for investigating the foam flow direction. A biaxial tension experiment was also developed to explore the damage surface of a rigid polyurethane foam.
Rigidity of complete generic shrinking Ricci solitons
Chu, Yawei; Zhou, Jundong; Wang, Xue
2018-01-01
Let (Mn , g , X) be a complete generic shrinking Ricci soliton of dimension n ≥ 3. In this paper, by employing curvature inequalities, the formula of X-Laplacian for the norm square of the trace-free curvature tensor, the weak maximum principle and the estimate of the scalar curvature of (Mn , g) , we prove some rigidity results for (Mn , g , X) . In particular, it is showed that (Mn , g , X) is isometric to Rn or a finite quotient of Sn under a pointwise pinching condition. Moreover, we establish several optimal inequalities and classify those shrinking solitons for equalities.
Felipe, A; Valdes, R; Santo, B; Lloberas, J; Casado, J; Pastor-Anglada, M
1998-01-01
Hepatocytes show a Na+-dependent nucleoside transport activity that is kinetically heterogeneous and consistent with the expression of at least two independent concentrative Na+-coupled nucleoside transport systems (Mercader et al. Biochem. J. 317, 835-842, 1996). So far, only a single nucleoside carrier-related cDNA (SPNT) has been isolated from liver cells (Che et al. J. Biol. Chem. 270, 13596-13599, 1995). This cDNA presumably encodes a plasma membrane protein responsible for Na+-dependent...
International Nuclear Information System (INIS)
Bush, C.A.; Rao, B.N.N.
1986-01-01
The 1 H NMR spectra of AFGP's ranging in molecular weight from 2600 to 30,000 Daltons isolated from several different species of polar fish have been measured. The spectrum of AFGP 1-4 from Pagothenia borchgrevinki with an average of 30 repeating subunits has a single resonance for each proton of the glycotripeptide repeating unit, (ala-[gal-(β-1→3) galNAc-(α--O-]thr-ala)/sub n/. Its 1 H NMR spectrum including resonances of the amide protons has been completely assigned. Coupling constants and nuclear Overhauser enhancements (n.O.e.) between protons on distant residues imply conformational order. The 2600 dalton molecular weight glycopeptides (AFGP-8) have pro in place of ala at certain specific points in the sequence and AFGP-8R of Eleginus gracilis has arg in place of one thr. The resonances of pro and arg were assigned by decoupling. The resonances of the carboxy and amino terminals have distinct chemical shifts and were assigned in AFGP-8 of Boreogadus saida by titration. n.O.e. between α--protons and amide protons of the adjacent residue (sequential n.O.e.) were used in assignments of additional resonances and to assign the distinctive resonances of thr followed by pro. Conformational energy calculations on the repeating glycotripeptide subunit of AFGP show that the α--glucosidic linkage has a fixed conformation while the β--linkage is less rigid. A conformational model for AFGP 1-4, which is based on the calculations has the peptide in an extended left-handed helix with three residues per turn similar to polyproline II. The model is consistent with CD data, amide proton coupling constants, temperature dependence of amide proton chemical shifts
Fast, clash-free RNA conformational morphing using molecular junctions.
Héliou, Amélie; Budday, Dominik; Fonseca, Rasmus; van den Bedem, Henry
2017-07-15
Non-coding ribonucleic acids (ncRNA) are functional RNA molecules that are not translated into protein. They are extremely dynamic, adopting diverse conformational substates, which enables them to modulate their interaction with a large number of other molecules. The flexibility of ncRNA provides a challenge for probing their complex 3D conformational landscape, both experimentally and computationally. Despite their conformational diversity, ncRNAs mostly preserve their secondary structure throughout the dynamic ensemble. Here we present a kinematics-based procedure to morph an RNA molecule between conformational substates, while avoiding inter-atomic clashes. We represent an RNA as a kinematic linkage, with fixed groups of atoms as rigid bodies and rotatable bonds as degrees of freedom. Our procedure maintains RNA secondary structure by treating hydrogen bonds between base pairs as constraints. The constraints define a lower-dimensional, secondary-structure constraint manifold in conformation space, where motions are largely governed by molecular junctions of unpaired nucleotides. On a large benchmark set, we show that our morphing procedure compares favorably to peer algorithms, and can approach goal conformations to within a low all-atom RMSD by directing fewer than 1% of its atoms. Our results suggest that molecular junctions can modulate 3D structural rearrangements, while secondary structure elements guide large parts of the molecule along the transition to the correct final conformation. The source code, binaries and data are available at https://simtk.org/home/kgs . amelie.heliou@polytechnique.edu or vdbedem@stanford.edu. Supplementary data are available at Bioinformatics online. © The Author (2017). Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com
Directory of Open Access Journals (Sweden)
Anna I Sulatskaya
Full Text Available In this work, the fluorescence of thioflavin T (ThT was studied in a wide range of viscosity and temperature. It was shown that ThT fluorescence quantum yield varies from 0.0001 in water at room temperature to 0.28 in rigid isotropic solution (T/η→0. The deviation of the fluorescence quantum yield from unity in rigid isotropic solution suggests that fluorescence quantum yield depends not only on the ultra-fast oscillation of ThT fragments relative to each other in an excited state as was suggested earlier, but also depends on the molecular configuration in the ground state. This means that the fluorescence quantum yield of the dye incorporated into amyloid fibrils must depend on its conformation, which, in turn, depends on the ThT environment. Therefore, the fluorescence quantum yield of ThT incorporated into amyloid fibrils can differ from that in the rigid isotropic solution. In particular, the fluorescence quantum yield of ThT incorporated into insulin fibrils was determined to be 0.43. Consequently, the ThT fluorescence quantum yield could be used to characterize the peculiarities of the fibrillar structure, which opens some new possibilities in the ThT use for structural characterization of the amyloid fibrils.
Public policies targeting labour market rigidities
Directory of Open Access Journals (Sweden)
Andreea Claudia ŞERBAN
2013-02-01
Full Text Available Labour market rigidity becomes an issue of increasing importance under conditions of shocks associated with the economic crisis due to the need to increase the adaptability and responsiveness to them. Thus, labour market policies must be directed towards mitigating rigidities caused by institutional or demographic factors or certain mismatch between demand and supply of education qualifications. This paper highlights the major role of the active labour market policies targeting the increase of labour flexibility, stressing the importance and impact on the ability to adapt quickly and effectively to macroeconomic shocks. Located on a declining trend in the years preceding the crisis, spending on labour market policies increased in 2009 in all the Member States of the European Union. Spending differences are significant between countries, Romania being at the lowest end of the European Union. This requires special attention because the increased adaptability of workers through training, as active measure, is of major importance considering the increased speed of changes in the labour market.
Vertebral Column Resection for Rigid Spinal Deformity.
Saifi, Comron; Laratta, Joseph L; Petridis, Petros; Shillingford, Jamal N; Lehman, Ronald A; Lenke, Lawrence G
2017-05-01
Broad narrative review. To review the evolution, operative technique, outcomes, and complications associated with posterior vertebral column resection. A literature review of posterior vertebral column resection was performed. The authors' surgical technique is outlined in detail. The authors' experience and the literature regarding vertebral column resection are discussed at length. Treatment of severe, rigid coronal and/or sagittal malalignment with posterior vertebral column resection results in approximately 50-70% correction depending on the type of deformity. Surgical site infection rates range from 2.9% to 9.7%. Transient and permanent neurologic injury rates range from 0% to 13.8% and 0% to 6.3%, respectively. Although there are significant variations in EBL throughout the literature, it can be minimized by utilizing tranexamic acid intraoperatively. The ability to correct a rigid deformity in the spine relies on osteotomies. Each osteotomy is associated with a particular magnitude of correction at a single level. Posterior vertebral column resection is the most powerful posterior osteotomy method providing a successful correction of fixed complex deformities. Despite meticulous surgical technique and precision, this robust osteotomy technique can be associated with significant morbidity even in the most experienced hands.
Optimized imaging using non-rigid registration
International Nuclear Information System (INIS)
Berkels, Benjamin; Binev, Peter; Blom, Douglas A.; Dahmen, Wolfgang; Sharpley, Robert C.; Vogt, Thomas
2014-01-01
The extraordinary improvements of modern imaging devices offer access to data with unprecedented information content. However, widely used image processing methodologies fall far short of exploiting the full breadth of information offered by numerous types of scanning probe, optical, and electron microscopies. In many applications, it is necessary to keep measurement intensities below a desired threshold. We propose a methodology for extracting an increased level of information by processing a series of data sets suffering, in particular, from high degree of spatial uncertainty caused by complex multiscale motion during the acquisition process. An important role is played by a non-rigid pixel-wise registration method that can cope with low signal-to-noise ratios. This is accompanied by formulating objective quality measures which replace human intervention and visual inspection in the processing chain. Scanning transmission electron microscopy of siliceous zeolite material exhibits the above-mentioned obstructions and therefore serves as orientation and a test of our procedures. - Highlights: • Developed a new process for extracting more information from a series of STEM images. • An objective non-rigid registration process copes with distortions. • Images of zeolite Y show retrieval of all information available from the data set. • Quantitative measures of registration quality were implemented. • Applicable to any serially acquired data, e.g. STM, AFM, STXM, etc
Conformational analysis by intersection: CONAN.
Smellie, Andrew; Stanton, Robert; Henne, Randy; Teig, Steve
2003-01-15
As high throughput techniques in chemical synthesis and screening improve, more demands are placed on computer assisted design and virtual screening. Many of these computational methods require one or more three-dimensional conformations for molecules, creating a demand for a conformational analysis tool that can rapidly and robustly cover the low-energy conformational spaces of small molecules. A new algorithm of intersection is presented here, which quickly generates (on average heuristics are applied after intersection to generate a small representative collection of conformations that span the conformational space. In a study of approximately 97,000 randomly selected molecules from the MDDR, results are presented that explore these conformations and their ability to cover low-energy conformational space. Copyright 2002 Wiley Periodicals, Inc. J Comput Chem 24: 10-20, 2003
Conformal superalgebras via tractor calculus
Lischewski, Andree
2015-01-01
We use the manifestly conformally invariant description of a Lorentzian conformal structure in terms of a parabolic Cartan geometry in order to introduce a superalgebra structure on the space of twistor spinors and normal conformal vector fields formulated in purely algebraic terms on parallel sections in tractor bundles. Via a fixed metric in the conformal class, one reproduces a conformal superalgebra structure that has been considered in the literature before. The tractor approach, however, makes clear that the failure of this object to be a Lie superalgebra in certain cases is due to purely algebraic identities on the spinor module and to special properties of the conformal holonomy representation. Moreover, it naturally generalizes to higher signatures. This yields new formulas for constructing new twistor spinors and higher order normal conformal Killing forms out of existing ones, generalizing the well-known spinorial Lie derivative. Moreover, we derive restrictions on the possible dimension of the space of twistor spinors in any metric signature.
Classical extended conformal symmetries
International Nuclear Information System (INIS)
Viswanathan, R.
1990-02-01
Extensions of the Virasoro algebra are constructed as Poisson brackets of higher spin fields which appear as coefficient fields in certain covariant derivative operators of order N. These differential operators are constructed so as to be covariant under reparametrizations on fields of definite conformal dimension. Factorization of such an N-th order operator in terms of first order operators, together with the inclusion of a spin one U(1) current, is shown to lead to a two-parameter W-algebra. One of these parameters plays the role of interpolating between W-algebras based on different Lie algebras of the same rank. (author). 11 refs
Radiation reaction of a classical quasi-rigid extended particle
International Nuclear Information System (INIS)
Medina, Rodrigo
2006-01-01
The problem of the self-interaction of a quasi-rigid classical particle with an arbitrary spherically symmetric charge distribution is completely solved up to the first order in the acceleration. No ad hoc assumptions are made. The relativistic equations of conservation of energy and momentum in a continuous medium are used. The electromagnetic fields are calculated in the reference frame of instantaneous rest using the Coulomb gauge; in this way the troublesome power expansion is avoided. Most of the puzzles that this problem has aroused are due to the inertia of the negative pressure that equilibrates the electrostatic repulsion inside the particle. The effective mass of this pressure is -U e /(3c 2 ), where U e is the electrostatic energy. When the pressure mass is taken into account the dressed mass m turns out to be the bare mass plus the electrostatic mass m = m 0 + U e /c 2 . It is shown that a proper mechanical behaviour requires that m 0 > U e /3c 2 . This condition poses a lower bound on the radius that a particle of a given bare mass and charge may have. The violation of this condition is the reason why the Lorentz-Abraham-Dirac formula for the radiation reaction of a point charge predicts unphysical motions that run away or violate causality. Provided the mass condition is met the solutions of the exact equation of motion never run away and conform to causality and conservation of energy and momentum. When the radius is much smaller than the wavelength of the radiated fields, but the mass condition is still met, the exact expression reduces to the formula that Rohrlich (2002 Phys. Lett. A 303 307) has advocated for the radiation reaction of a quasi-point charge
International Nuclear Information System (INIS)
Stein, R.L.
1978-01-01
Theoretical equilibrium α-deuterium isotope effects were calculated for systems modeling nucleoside and glycoside hydrolyses using a computer program (Burton, G.W., Sims, L.B., Wilson, J.C., and Fry, A.J., J. Amer. Chem. Soc., 99, 3374(1977)) which computes isotope effects directly from the expression of Biegeleisen and Mayer (Biegeleisen, J. and Mayer, M.G., J. Chem. Phys., 17, 675(1949)). For nucleoside hydrolysis proceeding through an oxocarbonium ion intermediate, KH/KD = 1.21 to 1.25; while for nucleoside hydrolysis proceeding through an oxocarbonium ion intermediate KH/KD = 1.15 to 1.19. The models used in the calculations were generated systematically and involved a minimum of subjectivity in the selection of molecular parameters. The isotope effects calculated formed the basis for the interpretation of experimental kinetic α-deuterium isotope effects for nucleoside and glycoside hydrolysis
Conformally symmetric traversable wormholes
International Nuclear Information System (INIS)
Boehmer, Christian G.; Harko, Tiberiu; Lobo, Francisco S. N.
2007-01-01
Exact solutions of traversable wormholes are found under the assumption of spherical symmetry and the existence of a nonstatic conformal symmetry, which presents a more systematic approach in searching for exact wormhole solutions. In this work, a wide variety of solutions are deduced by considering choices for the form function, a specific linear equation of state relating the energy density and the pressure anisotropy, and various phantom wormhole geometries are explored. A large class of solutions impose that the spatial distribution of the exotic matter is restricted to the throat neighborhood, with a cutoff of the stress-energy tensor at a finite junction interface, although asymptotically flat exact solutions are also found. Using the 'volume integral quantifier', it is found that the conformally symmetric phantom wormhole geometries may, in principle, be constructed by infinitesimally small amounts of averaged null energy condition violating matter. Considering the tidal acceleration traversability conditions for the phantom wormhole geometry, specific wormhole dimensions and the traversal velocity are also deduced
Supergravitational conformal Galileons
Deen, Rehan; Ovrut, Burt
2017-08-01
The worldvolume actions of 3+1 dimensional bosonic branes embedded in a five-dimensional bulk space can lead to important effective field theories, such as the DBI conformal Galileons, and may, when the Null Energy Condition is violated, play an essential role in cosmological theories of the early universe. These include Galileon Genesis and "bouncing" cosmology, where a pre-Big Bang contracting phase bounces smoothly to the presently observed expanding universe. Perhaps the most natural arena for such branes to arise is within the context of superstring and M -theory vacua. Here, not only are branes required for the consistency of the theory, but, in many cases, the exact spectrum of particle physics occurs at low energy. However, such theories have the additional constraint that they must be N = 1 supersymmetric. This motivates us to compute the worldvolume actions of N = 1 supersymmetric three-branes, first in flat superspace and then to generalize them to N = 1 supergravitation. In this paper, for simplicity, we begin the process, not within the context of a superstring vacuum but, rather, for the conformal Galileons arising on a co-dimension one brane embedded in a maximally symmetric AdS 5 bulk space. We proceed to N = 1 supersymmetrize the associated worldvolume theory and then generalize the results to N = 1 supergravity, opening the door to possible new cosmological scenarios
Vasudevan, Gayatri; Ullman, Buddy; Landfear, Scott M.
2001-01-01
Leishmania parasites lack a purine biosynthetic pathway and depend on surface nucleoside and nucleobase transporters to provide them with host purines. Leishmania donovani possess two closely related genes that encode high affinity adenosine-pyrimidine nucleoside transporters LdNT1.1 and LdNT1.2 and that transport the toxic adenosine analog tubercidin in addition to the natural substrates. In this study, we have characterized a drug-resistant clonal mutant of L. do...
Coherent distributions for the rigid rotator
Energy Technology Data Exchange (ETDEWEB)
Grigorescu, Marius [CP 15-645, Bucharest 014700 (Romania)
2016-06-15
Coherent solutions of the classical Liouville equation for the rigid rotator are presented as positive phase-space distributions localized on the Lagrangian submanifolds of Hamilton-Jacobi theory. These solutions become Wigner-type quasiprobability distributions by a formal discretization of the left-invariant vector fields from their Fourier transform in angular momentum. The results are consistent with the usual quantization of the anisotropic rotator, but the expected value of the Hamiltonian contains a finite “zero point” energy term. It is shown that during the time when a quasiprobability distribution evolves according to the Liouville equation, the related quantum wave function should satisfy the time-dependent Schrödinger equation.
Static friction between rigid fractal surfaces.
Alonso-Marroquin, Fernando; Huang, Pengyu; Hanaor, Dorian A H; Flores-Johnson, E A; Proust, Gwénaëlle; Gan, Yixiang; Shen, Luming
2015-09-01
Using spheropolygon-based simulations and contact slope analysis, we investigate the effects of surface topography and atomic scale friction on the macroscopically observed friction between rigid blocks with fractal surface structures. From our mathematical derivation, the angle of macroscopic friction is the result of the sum of the angle of atomic friction and the slope angle between the contact surfaces. The latter is obtained from the determination of all possible contact slopes between the two surface profiles through an alternative signature function. Our theory is validated through numerical simulations of spheropolygons with fractal Koch surfaces and is applied to the description of frictional properties of Weierstrass-Mandelbrot surfaces. The agreement between simulations and theory suggests that for interpreting macroscopic frictional behavior, the descriptors of surface morphology should be defined from the signature function rather than from the slopes of the contacting surfaces.
Observational properties of rigidly rotating dust configurations
Energy Technology Data Exchange (ETDEWEB)
Ilyas, Batyr; Malafarina, Daniele [Nazarbayev University, Department of Physics, Astana (Kazakhstan); Yang, Jinye [Fudan University, Center for Field Theory and Particle Physics and Department of Physics, Shanghai (China); Bambi, Cosimo [Fudan University, Center for Field Theory and Particle Physics and Department of Physics, Shanghai (China); Eberhard-Karls Universitaet Tuebingen, Theoretical Astrophysics, Tuebingen (Germany)
2017-07-15
We study the observational properties of a class of exact solutions of Einstein's field equations describing stationary, axially symmetric, rigidly rotating dust (i.e. non-interacting particles). We ask the question whether such solutions can describe astrophysical rotating dark matter clouds near the center of galaxies and we probe the possibility that they may constitute an alternative to supermassive black holes at the center of galaxies. We show that light emission from accretion disks made of ordinary baryonic matter in this space-time has several differences with respect to the emission of light from similar accretion disks around black holes. The shape of the iron Kα line in the reflection spectrum of accretion disks can potentially distinguish this class of solutions from the Kerr metric, but this may not be possible with current X-ray missions. (orig.)
On real structures on rigid surfaces
International Nuclear Information System (INIS)
Kulikov, Vik S; Kharlamov, V M
2002-01-01
We construct examples of rigid surfaces (that is, surfaces whose deformation class consists of a unique surface) with a particular behaviour with respect to real structures. In one example the surface has no real structure. In another it has a unique real structure, which is not maximal with respect to the Smith-Thom inequality. These examples give negative answers to the following problems: the existence of real surfaces in each deformation class of complex surfaces, and the existence of maximal real surfaces in every complex deformation class that contains real surfaces. Moreover, we prove that there are no real surfaces among surfaces of general type with p g =q=0 and K 2 =9. These surfaces also provide new counterexamples to the 'Dif = Def' problem
On real structures on rigid surfaces
Energy Technology Data Exchange (ETDEWEB)
Kulikov, Vik S [Steklov Mathematical Institute, Russian Academy of Sciences (Russian Federation); Kharlamov, V M [Institut de Recherche Matematique Avanee Universite Louis Pasteur et CNRS 7 rue Rene Descartes (France)
2002-02-28
We construct examples of rigid surfaces (that is, surfaces whose deformation class consists of a unique surface) with a particular behaviour with respect to real structures. In one example the surface has no real structure. In another it has a unique real structure, which is not maximal with respect to the Smith-Thom inequality. These examples give negative answers to the following problems: the existence of real surfaces in each deformation class of complex surfaces, and the existence of maximal real surfaces in every complex deformation class that contains real surfaces. Moreover, we prove that there are no real surfaces among surfaces of general type with p{sub g}=q=0 and K{sup 2}=9. These surfaces also provide new counterexamples to the 'Dif = Def' problem.
Management of rigid post-traumatic kyphosis.
Wu, S S; Hwa, S Y; Lin, L C; Pai, W M; Chen, P Q; Au, M K
1996-10-01
Rigid post-traumatic kyphosis after fracture of the thoracolumbar and lumbar spine represents a failure of initial management of the injury. Kyphosis moves the center of gravity anterior. The kyphosis and instability may result in pain, deformity, and increased neurologic deficits. Management for symptomatic post-traumatic kyphosis always has presented a challenge to orthopedic surgeons. To evaluate the surgical results of one stage posterior correction for rigid symptomatic post-traumatic kyphosis of the thoracolumbar and lumbar spine. The management for post-traumatic kyphosis remains controversial. Anterior, posterior, or combined anterior and posterior procedures have been advocated by different authors and show various degrees of success. One vertebra immediately above and below the level of the deformity was instrumented posteriorly by a transpedicular system (internal fixator AO). Posterior decompression was performed by excision of the spinal process and bilateral laminectomy. With the deformed vertebra through the pedicle, the vertebral body carefully is removed around the pedicle level, approximating a wedge shape. The extent to which the deformed vertebral body should be removed is determined by the attempted correction. Correction of the deformity is achieved by manipulation of the operating table and compression of the adjacent Schanz screws above and below the lesion. Thirteen patients with post-traumatic kyphosis with symptoms of fatigue and pain caused by slow progression of kyphotic deformities received posterior decompression, correction, and stabilization as a definitive treatment. The precorrection kyphosis ranged from 30-60 degrees, with a mean of 40 degrees +/- 10.8 degrees. After correction, kyphosis was reduced to an average of 1.5 degrees +/- 3.8 degrees, with a range from -5 degrees to 5 degrees. The average angle of correction was 38.8 degrees +/- 10.4 degrees, with a range from 25 degrees to 60 degrees. Significant difference was found
Dual Quaternion Variational Integrator for Rigid Body Dynamic Simulation
Xu, Jiafeng; Halse, Karl Henning
2016-01-01
In rigid body dynamic simulations, often the algorithm is required to deal with general situations where both reference point and inertia matrix are arbitrarily de- fined. We introduce a novel Lie group variational integrator using dual quaternion for simulating rigid body dynamics in all six degrees of freedom. Dual quaternion is used to represent rigid body kinematics and one-step Lie group method is used to derive dynamic equations. The combination of these two becomes the first Lie group ...
Tang, Danming; Lam, Cynthia; Louie, Salina; Hoi, Kam Hon; Shaw, David; Yim, Mandy; Snedecor, Brad; Misaghi, Shahram
2018-01-01
In the process of generating stable monoclonal antibody (mAb) producing cell lines, reagents such as methotrexate (MTX) or methionine sulfoximine (MSX) are often used. However, using such selection reagent(s) increases the possibility of having higher occurrence of sequence variants in the expressed antibody molecules due to the effects of MTX or MSX on de novo nucleotide synthesis. Since MSX inhibits glutamine synthase (GS) and results in both amino acid and nucleoside starvation, it is questioned whether supplementing nucleosides into the media could lower sequence variant levels without affecting titer. The results show that the supplementation of nucleosides to the media during MSX selection decreased genomic DNA mutagenesis rates in the selected cells, probably by reducing nucleotide mis-incorporation into the DNA. Furthermore, addition of nucleosides enhance clone recovery post selection and does not affect antibody expression. It is further observed that nucleoside supplements lowered DNA mutagenesis rates only at the initial stage of the clone selection and do not have any effect on DNA mutagenesis rates after stable cell lines are established. Therefore, the data suggests that addition of nucleosides during early stages of MSX selection can lower sequence variant levels without affecting titer or clone stability in antibody expression. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Tile-based rigidization surface parametric design study
Giner Munoz, Laura; Luntz, Jonathan; Brei, Diann; Kim, Wonhee
2018-03-01
Inflatable technologies have proven useful in consumer goods as well as in more recent applications including civil structures, aerospace, medical, and robotics. However, inflatable technologies are typically lacking in their ability to provide rigid structural support. Particle jamming improves upon this by providing structures which are normally flexible and moldable but become rigid when air is removed. Because these are based on an airtight bladder filled with loose particles, they always occupy the full volume of its rigid state, even when not rigidized. More recent developments in layer jamming have created thin, compact rigidizing surfaces replacing the loose volume of particles with thinly layered surface materials. Work in this area has been applied to several specific applications with positive results but have not generally provided the broader understanding of the rigidization performance as a function of design parameters required for directly adapting layer rigidization technology to other applications. This paper presents a parametric design study of a new layer jamming vacuum rigidization architecture: tile-based vacuum rigidization. This form of rigidization is based on layers of tiles contained within a thin vacuum bladder which can be bent, rolled, or otherwise compactly stowed, but when deployed flat, can be vacuumed and form a large, flat, rigid plate capable of supporting large forces both localized and distributed over the surface. The general architecture and operation detailing rigidization and compliance mechanisms is introduced. To quantitatively characterize the rigidization behavior, prototypes rigidization surfaces are fabricated and an experimental technique is developed based on a 3-point bending test. Performance evaluation metrics are developed to describe the stiffness, load-bearing capacity, and internal slippage of tested prototypes. A set of experimental parametric studies are performed to better understand the impact of
Three-dimensional structure of E. Coli purine nucleoside phosphorylase at 0.99 Å resolution
Energy Technology Data Exchange (ETDEWEB)
Timofeev, V. I., E-mail: tostars@mail.ru [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation); Abramchik, Yu. A., E-mail: ugama@yandex.ru [Russian Academy of Sciences, Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry (Russian Federation); Zhukhlistova, N. E., E-mail: inna@ns.crys.ras.ru [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation); Muravieva, T. I.; Esipov, R. S. [Russian Academy of Sciences, Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry (Russian Federation); Kuranova, I. P. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)
2016-03-15
Purine nucleoside phosphorylases (PNPs) catalyze the reversible phosphorolysis of nucleosides and are key enzymes involved in nucleotide metabolism. They are essential for normal cell function and can catalyze the transglycosylation. Crystals of E. coli PNP were grown in microgravity by the capillary counterdiffusion method through a gel layer. The three-dimensional structure of the enzyme was determined by the molecular-replacement method at 0.99 Å resolution. The structural features are considered, and the structure of E. coli PNP is compared with the structures of the free enzyme and its complexes with purine base derivatives established earlier. A comparison of the environment of the purine base in the complex of PNP with formycin A and of the pyrimidine base in the complex of uridine phosphorylase with thymidine revealed the main structural features of the base-binding sites. Coordinates of the atomic model determined with high accuracy were deposited in the Protein Data Bank (PDB-ID: 4RJ2).
Ward identities for conformal models
International Nuclear Information System (INIS)
Lazzarini, S.; Stora, R.
1988-01-01
Ward identities which express the symmetry of conformal models are treated. Diffeomorphism invariance or locally holomorphic coordinate transformations are used. Diffeomorphism invariance is then understood in terms of Riemannian geometry. Two different sets of Ward identities expressing diffeomorphism invariance in a conformally invariant way are found for the free bosonic string. Using a geometrical argument, the correct invariance for a large class of conformal models is given
Conformational analysis of lignin models
International Nuclear Information System (INIS)
Santos, Helio F. dos
2001-01-01
The conformational equilibrium for two 5,5' biphenyl lignin models have been analyzed using a quantum mechanical semiempirical method. The gas phase and solution structures are discussed based on the NMR and X-ray experimental data. The results obtained showed that the observed conformations are solvent-dependent, being the geometries and the thermodynamic properties correlated with the experimental information. This study shows how a systematic theoretical conformational analysis can help to understand chemical processes at a molecular level. (author)
On the linear conformal gravitation
International Nuclear Information System (INIS)
Pal'chik, M.Ya.; Fradkin, E.S.
1984-01-01
Conformal gravitation is analyzed under the assumption that its solution possesses the property of conformal symmetry. This assumption has sense in the case of small distances and only for definite types of matter fields, namely: at special choice of matter fields and their interactions, providing a lack of conformal anomalies; or at definite magnitudes of binding constants, coinciding with the zeroes of the Gell-Mann-Low function. The field equations, of the group-theoretical natura are obtained
Fermion-scalar conformal blocks
Energy Technology Data Exchange (ETDEWEB)
Iliesiu, Luca [Joseph Henry Laboratories, Princeton University,Washington Road, Princeton, NJ 08544 (United States); Kos, Filip [Department of Physics, Yale University,217 Prospect Street, New Haven, CT 06520 (United States); Poland, David [Department of Physics, Yale University,217 Prospect Street, New Haven, CT 06520 (United States); School of Natural Sciences, Institute for Advanced Study,1 Einstein Dr, Princeton, New Jersey 08540 (United States); Pufu, Silviu S. [Joseph Henry Laboratories, Princeton University,Washington Road, Princeton, NJ 08544 (United States); Simmons-Duffin, David [School of Natural Sciences, Institute for Advanced Study,1 Einstein Dr, Princeton, New Jersey 08540 (United States); Yacoby, Ran [Joseph Henry Laboratories, Princeton University,Washington Road, Princeton, NJ 08544 (United States)
2016-04-13
We compute the conformal blocks associated with scalar-scalar-fermion-fermion 4-point functions in 3D CFTs. Together with the known scalar conformal blocks, our result completes the task of determining the so-called ‘seed blocks’ in three dimensions. Conformal blocks associated with 4-point functions of operators with arbitrary spins can now be determined from these seed blocks by using known differential operators.
N3 and O2 Protonated Conformers of the Cytosine Mononucleotides Coexist in the Gas Phase
Wu, R. R.; Hamlow, L. A.; He, C. C.; Nei, Y.-w.; Berden, G.; Oomens, J.; Rodgers, M. T.
2017-08-01
The gas-phase conformations of the protonated forms of the DNA and RNA cytosine mononucleotides, [pdCyd+H]+ and [pCyd+H]+, are examined by infrared multiple photon dissociation (IRMPD) action spectroscopy over the IR fingerprint and hydrogen-stretching regions complemented by electronic structure calculations. The low-energy conformations of [pdCyd+H]+ and [pCyd+H]+ and their relative stabilities are computed at the B3LYP/6-311+G(2d,2p)//B3LYP/6-311+G(d,p) and MP2(full)/6-311+G(2d,2p)//B3LYP/6-311+G(d,p) levels of theory. Comparisons of the measured IRMPD action spectra and B3LYP/6-311+G(d,p) linear IR spectra computed for the low-energy conformers allow the conformers present in the experiments to be determined. Similar to that found in previous IRMPD action spectroscopy studies of the protonated forms of the cytosine nucleosides, [dCyd+H]+ and [Cyd+H]+, both N3 and O2 protonated cytosine mononucleotides exhibiting an anti orientation of cytosine are found to coexist in the experimental population. The 2'-hydroxyl substituent does not significantly influence the most stable conformations of [pCyd+H]+ versus those of [pdCyd+H]+, as the IRMPD spectral profiles of [pdCyd+H]+ and [pCyd+H]+ are similar. However, the presence of the 2'-hydroxyl substituent does influence the relative intensities of the measured IRMPD bands. Comparisons to IRMPD spectroscopy studies of the deprotonated forms of the cytosine mononucleotides, [pdCyd-H]- and [pCyd-H]-, provide insight into the effects of protonation versus deprotonation on the conformational features of the nucleobase and sugar moieties. Likewise, comparisons to results of IRMPD spectroscopy studies of the protonated cytosine nucleosides provide insight into the influence of the phosphate moiety on structure. Comparison with previous ion mobility results shows the superiority of IRMPD spectroscopy for distinguishing various protonation sites.
Mechanisms by Which Human DNA Primase Chooses To Polymerize a Nucleoside Triphosphate
Czech Academy of Sciences Publication Activity Database
Urban, M.; Joubert, Nicolas; Purse, B. W.; Hocek, Michal; Kuchta, R. D.
2010-01-01
Roč. 49, č. 4 (2010), s. 727-735 ISSN 0006-2960 R&D Projects: GA MŠk LC512; GA AV ČR IAA400550902 Grant - others:NIH(US) GM54194 Institutional research plan: CEZ:AV0Z40550506 Keywords : C-nucleosides * DNA polymerase * primase * mechanism Subject RIV: CC - Organic Chemistry Impact factor: 3.226, year: 2010
Novel modified purine bases and nucleosides: new methodologies of synthesis and biological activity
Czech Academy of Sciences Publication Activity Database
Hocek, Michal
-, č. 49 (2005), s. 29-30 ISSN 0261-3166. [International Symposium on Nucleic Acids Chemistry /4./. Fukuoka, 20.09.2005-22.09.2005] R&D Projects: GA ČR(CZ) GA203/03/0035; GA MŠk(CZ) 1M0508 Institutional research plan: CEZ:AV0Z40550506 Keywords : purines * nucleosides * synthesis Subject RIV: CC - Organic Chemistry
Czech Academy of Sciences Publication Activity Database
Vávrová, K.; Kovaříková, P.; Školová, B.; Líbalová, M.; Roh, J.; Čáp, R.; Holý, Antonín; Hrabálek, A.
2011-01-01
Roč. 28, č. 12 (2011), s. 3105-3115 ISSN 0724-8741 R&D Projects: GA MŠk 1M0508 Grant - others:GA ČR(CZ) GAP207/11/0365 Institutional research plan: CEZ:AV0Z40550506 Keywords : acyclic nucleoside phosphonates * antivirals * antineoplastics * permeation enhancer * topical skin application * transdermal delivery Subject RIV: CC - Organic Chemistry Impact factor: 4.093, year: 2011
Mechanism of action and selective toxicity of ascamycin, a nucleoside antibiotic.
Osada, H; Isono, K
1985-01-01
An unidentified Streptomyces sp. produces two nucleoside antibiotics, ascamycin and its dealanyl derivative. In contrast to the broad antibacterial activity of dealanylascamycin against various gram-negative and gram-positive bacteria, ascamycin showed selective toxicity against Xanthomonas citri and X. oryzae. Both ascamycin and dealanylascamycin inhibited the protein synthesis of X. citri, but only dealanylascamycin inhibited that of Escherichia coli. In cell-free systems from E. coli and X...
Czech Academy of Sciences Publication Activity Database
Frydrych, Jan; Skácel, Jan; Šmídková, Markéta; Mertlíková-Kaiserová, Helena; Dračínský, Martin; Gnanasekaran, Ramachandran; Lepšík, Martin; Soto-Velasquez, M.; Watts, V. J.; Janeba, Zlatko
2018-01-01
Roč. 13, č. 2 (2018), s. 199-206 ISSN 1860-7179 R&D Projects: GA MV VG20102015046; GA ČR(CZ) GBP208/12/G016; GA MŠk LO1302 Institutional support: RVO:61388963 Keywords : acyclic nucleoside phosphonates * adenylate cyclase toxin * bisamidates * Bordetella pertussis * prodrugs Subject RIV: CC - Organic Chemistry OBOR OECD: Organic chemistry Impact factor: 3.225, year: 2016
Czech Academy of Sciences Publication Activity Database
Eyer, L.; Šmídková, Markéta; Nencka, Radim; Neča, J.; Kastl, T.; Palus, Martin; De Clercq, E.; Růžek, Daniel
2016-01-01
Roč. 133, Sep (2016), s. 119-129 ISSN 0166-3542 R&D Projects: GA MZd(CZ) NV16-34238A; GA ČR(CZ) GA16-20054S Institutional support: RVO:61388963 ; RVO:60077344 Keywords : structure-activity relationship * tick-borne encephalitis * nucleoside inhibitor * antiviral activity * cytotoxicity Subject RIV: CC - Organic Chemistry; EE - Microbiology, Virology (BC-A) Impact factor: 4.271, year: 2016
New prodrugs of two pyrimidine acyclic nucleoside phosphonates: Synthesis and antiviral activity
Czech Academy of Sciences Publication Activity Database
Krečmerová, Marcela; Dračínský, Martin; Snoeck, R.; Balzarini, J.; Pomeisl, Karel; Andrei, G.
2017-01-01
Roč. 25, č. 17 (2017), s. 4637-4648 ISSN 0968-0896 R&D Projects: GA ČR(CZ) GA14-00522S Institutional support: RVO:61388963 Keywords : acyclic nucleoside phosphonates * open-ring * PMEO-DAPy * 5-azacytosine * PME-azaC * HPMP-5-azaC Subject RIV: CC - Organic Chemistry OBOR OECD: Organic chemistry Impact factor: 2.930, year: 2016
Instantons in conformal gravity
International Nuclear Information System (INIS)
Strominger, A.; Horowitz, G.T.; Perry, M.J.
1984-01-01
Fe study extrema of the general conformally invariant action: Ssub(c)=∫1/sub(α) 2 Csup(abcd)Csub(abcd)+γRsup(abcd*)Rsup(*)sub(abcd)+iTHETARsup(abcd)*Rsub(abcd). We find the first examples in four dimensions of asymptotically euclidean gravitational instantons. These have arbitrary Euler number and Hirzebruch signature. Some of these instantons represent tunneling between zero-curvature vacua that are not related by small gauge transformations. Others represent tunneling between flat space and topologically non-trivial zero-energy initial data. A general formula for the one-loop determinant is derived in terms of the renormalization group invariant masses, the volume of space-time, the Euler number and the Hirzebruch signature. (orig.)
DEFF Research Database (Denmark)
Gjerdrum Pedersen, Esben Rahbek; Neergaard, Peter; Thusgaard Pedersen, Janni
2013-01-01
This paper analyses how large Danish companies are responding to new governmental regulation which requires them to report on corporate social responsibility (CSR). The paper is based on an analysis of 142 company annual reports required by the new Danish regulation regarding CSR reporting, plus 10...... interviews with first-time reporting companies and six interviews with companies that failed to comply with the new law. It is concluded that coercive pressures from government have an impact on CSR reporting practices. Further, the analysis finds traces of mimetic isomorphism which inspires a homogenisation...... in CSR reporting practices. Finally, it is argued that non-conformance with the new regulatory requirements is not solely about conscious resistance but may also be caused by, for example, lack of awareness, resource limitations, misinterpretations, and practical difficulties....
Reflections on Conformal Spectra
CERN. Geneva
2015-01-01
We use modular invariance and crossing symmetry of conformal field theory to reveal approximate reflection symmetries in the spectral decompositions of the partition function in two dimensions in the limit of large central charge and of the four-point function in any dimension in the limit of large scaling dimensions Δ0 of external operators. We use these symmetries to motivate universal upper bounds on the spectrum and the operator product expansion coefficients, which we then derive by independent techniques. Some of the bounds for four-point functions are valid for finite Δ0 as well as for large Δ0. We discuss a similar symmetry in a large spacetime dimension limit. Finally, we comment on the analogue of the Cardy formula and sparse light spectrum condition for the four-point function. (based on 1510.08772 with Kim & Ooguri). This seminar will be given via videolink
Dekker, Frank J; de Mol, Nico J; Bultinck, Patrick; Kemmink, Johan; Hilbers, Hans W; Liskamp, Rob M J; Dekker, Frank
2003-01-01
A general approach in drug design is making ligands more rigid in order to avoid loss in conformational entropy (deltaS(conf)) upon receptor binding. We hypothesized that in the high affinity binding of pYEEI peptide ligands to the p56(lck) SH2 domain this loss in deltaS(conf) might be diminished
Conformal boundary loop models
International Nuclear Information System (INIS)
Jacobsen, Jesper Lykke; Saleur, Hubert
2008-01-01
We study a model of densely packed self-avoiding loops on the annulus, related to the Temperley-Lieb algebra with an extra idempotent boundary generator. Four different weights are given to the loops, depending on their homotopy class and whether they touch the outer rim of the annulus. When the weight of a contractible bulk loop x≡q+q -1 element of (-2,2], this model is conformally invariant for any real weight of the remaining three parameters. We classify the conformal boundary conditions and give exact expressions for the corresponding boundary scaling dimensions. The amplitudes with which the sectors with any prescribed number and types of non-contractible loops appear in the full partition function Z are computed rigorously. Based on this, we write a number of identities involving Z which hold true for any finite size. When the weight of a contractible boundary loop y takes certain discrete values, y r ≡([r+1] q )/([r] q ) with r integer, other identities involving the standard characters K r,s of the Virasoro algebra are established. The connection with Dirichlet and Neumann boundary conditions in the O(n) model is discussed in detail, and new scaling dimensions are derived. When q is a root of unity and y=y r , exact connections with the A m type RSOS model are made. These involve precise relations between the spectra of the loop and RSOS model transfer matrices, valid in finite size. Finally, the results where y=y r are related to the theory of Temperley-Lieb cabling
Energy Technology Data Exchange (ETDEWEB)
Brodsky, S
2003-11-19
Theoretical and phenomenological evidence is now accumulating that the QCD coupling becomes constant at small virtuality; i.e., {alpha}{sub s}(Q{sup 2}) develops an infrared fixed point in contradiction to the usual assumption of singular growth in the infrared. For example, the hadronic decays of the {tau} lepton can be used to determine the effective charge {alpha}{sub {tau}}(m{sub {tau}{prime}}{sup 2}) for a hypothetical {tau}-lepton with mass in the range 0 < m{sub {tau}{prime}} < m{sub {tau}}. The {tau} decay data at low mass scales indicates that the effective charge freezes at a value of s = m{sub {tau}{prime}}{sup 2} of order 1 GeV{sup 2} with a magnitude {alpha}{sub {tau}} {approx} 0.9 {+-} 0.1. The near-constant behavior of effective couplings suggests that QCD can be approximated as a conformal theory even at relatively small momentum transfer and why there are no significant running coupling corrections to quark counting rules for exclusive processes. The AdS/CFT correspondence of large N{sub c} supergravity theory in higher-dimensional anti-de Sitter space with supersymmetric QCD in 4-dimensional space-time also has interesting implications for hadron phenomenology in the conformal limit, including an all-orders demonstration of counting rules for exclusive processes and light-front wavefunctions. The utility of light-front quantization and light-front Fock wavefunctions for analyzing nonperturbative QCD and representing the dynamics of QCD bound states is also discussed.
Study of conformation and dynamic of surfactant molecules in graphite oxide via NMR
Energy Technology Data Exchange (ETDEWEB)
Ai, X.Q. [Jiangsu Second Normal University, College of Physics and Electronic Engineering, Nanjing (China); Ma, L.G. [Nanjing Xiaozhuang University, School of Electronic Engineering, Nanjing (China)
2016-08-15
The conformation and dynamic of surfactant in graphite oxide (GO) was investigated by solid-state {sup 13}C magic-angle-spinning NMR and {sup 1}H-{sup 13}C cross-polarization/magic-angle-spinning NMR spectra. The conformation ordering of the alkyl chains in the confined system shows strong dependence on its orientation. While the alkyl chains parallel to the GO layer in lateral monolayer arrangement are in gauche conformation in addition to a small amount of all-trans conformation, those with orientation radiating away from the GO in paraffin bilayer arrangement is in all-trans conformation in addition to some gauche conformation even though high-order diffraction peaks appears. NMR results suggest that the least mobile segment is located at the GO-surfactant interface corresponding to the N-methylene group. Further from it, the mobility of the alkyl chain increases. The terminal methyl and N-methyl carbon groups have the highest mobile. The chains in all-trans conformational state are characterized as more rigid than chains with gauche conformation; each segment of the confined alkyl chains with the lateral monolayer arrangement exhibits less mobility as compared to that with the paraffin bilayer arrangement. (orig.)
International Nuclear Information System (INIS)
Hou, Qiao-Ming; Liu, Xiang; Brostromer, Erik; Li, Lan-Fen; Su, Xiao-Dong
2009-01-01
Purine nucleoside phosphorylase (PNP), which is a pivotal enzyme in the nucleotide-salvage pathway, has been expressed in Escherichia coli strain BL21 (DE3) in a soluble form at a high level. After purification of the PNP enzyme, the protein was crystallized using the sitting-drop vapour-diffusion technique. The punA gene of the cariogenic pathogen Streptococcus mutans encodes purine nucleoside phosphorylase (PNP), which is a pivotal enzyme in the nucleotide-salvage pathway, catalyzing the phosphorolysis of purine nucleosides to generate purine bases and α-ribose 1-phosphate. In the present work, the PNP protein was expressed in Escherichia coli strain BL21 (DE3) in a soluble form at a high level. After purification of the PNP enzyme, the protein was crystallized using the sitting-drop vapour-diffusion technique; the crystals diffracted to 1.6 Å resolution at best. The crystals belonged to space group H3, with unit-cell parameters a = b = 113.0, c = 60.1 Å
In Silico Investigation of Flavonoids as Potential Trypanosomal Nucleoside Hydrolase Inhibitors
Directory of Open Access Journals (Sweden)
Christina Hung Hung Ha
2015-01-01
Full Text Available Human African Trypanosomiasis is endemic to 37 countries of sub-Saharan Africa. It is caused by two related species of Trypanosoma brucei. Current therapies suffer from resistance and public accessibility of expensive medicines. Finding safer and effective therapies of natural origin is being extensively explored worldwide. Pentamidine is the only available therapy for inhibiting the P2 adenosine transporter involved in the purine salvage pathway of the trypanosomatids. The objective of the present study is to use computational studies for the investigation of the probable trypanocidal mechanism of flavonoids. Docking experiments were carried out on eight flavonoids of varying level of hydroxylation, namely, flavone, 5-hydroxyflavone, 7-hydroxyflavone, chrysin, apigenin, kaempferol, fisetin, and quercetin. Using AutoDock 4.2, these compounds were tested for their affinity towards inosine-adenosine-guanosine nucleoside hydrolase and the inosine-guanosine nucleoside hydrolase, the major enzymes of the purine salvage pathway. Our results showed that all of the eight tested flavonoids showed high affinities for both hydrolases (lowest free binding energy ranging from −10.23 to −7.14 kcal/mol. These compounds, especially the hydroxylated derivatives, could be further studied as potential inhibitors of the nucleoside hydrolases.
Zan, Ke; Huang, Li-Li; Guo, Li-Nong; Liu, Jie; Zheng, Jian; Ma, Shuang-Cheng; Qian, Zheng-Ming; Li, Wen-Jia
2017-10-01
This study is to establish the HPLC specific chromatogram and determine four main nucleosides of wild and cultivated Cordyceps sinensis. Uridine, inosine, guanosine and adenosine were selected as reference substance. HPLC analysis was performed on a Waters XSelect HSS T3 C₁₈ (4.6 mm×250 mm, 5 μm), with a mobile phase consisting of water(A)-acetonitrile (B) at a flow rate of 0.6 mL•min⁻¹ (0-5 min,0% B;5-15 min,0%-10% B, 15-30 min,10%-20% B, 30-33 min, 20%-50% B, 33-35 min, 50%-0% B, 35-40 min, 0% B). The detection wavelength was 260 nm and the column temperature was controlled at 30 ℃, and the injection volume was 5 μL. HPLC specific chromatogram of wild and cultivated C. sinensis was established and four main nucleosides were simultaneously determined by the above method. Specific chromatograms and contents of four main nucleosides showed no significant differences between cultivated and wild C. sinensis. These results can provide scientific evidences for further development and utilization of cultivated C. sinensis. Copyright© by the Chinese Pharmaceutical Association.
Logarithmic conformal field theory through nilpotent conformal dimensions
International Nuclear Information System (INIS)
Moghimi-Araghi, S.; Rouhani, S.; Saadat, M.
2001-01-01
We study logarithmic conformal field theories (LCFTs) through the introduction of nilpotent conformal weights. Using this device, we derive the properties of LCFTs such as the transformation laws, singular vectors and the structure of correlation functions. We discuss the emergence of an extra energy momentum tensor, which is the logarithmic partner of the energy momentum tensor
Replacement between conformity and counter-conformity in consumption decisions.
Chou, Ting-Jui; Chang, En-Chung; Dai, Qi; Wong, Veronica
2013-02-01
This study assessed, in a Chinese context, how self-esteem interacts with perceived similarity and uniqueness to yield cognitive dissonance, and whether the dissonance leads to self-reported conformity or counter-conformity behavior. Participants were 408 respondents from 4 major Chinese cities (M age = 33.0 yr., SD = 4.3; 48% men). Self-perceptions of uniqueness, similarity, cognitive dissonance, self-esteem and need to behave in conformity or counter-conformity were measured. A theoretical model was assessed in four situations, relating the ratings of self-esteem and perceived similarity/uniqueness to the way other people at a wedding were dressed, and the resultant cognitive dissonance and conformity/ counter-conformity behavior. Regardless of high or low self-esteem, all participants reported cognitive dissonance when they were told that they were dressed extremely similarly to or extremely differently from the other people attending the wedding. However, the conforming/counter-conforming strategies used by participants to resolve the cognitive dissonance differed. When encountering dissonance induced by the perceived extreme uniqueness of dress, participants with low self-esteem tended to say they would dress next time so as to conform with the way others were dressed, while those with high self-esteem indicated they would continue their counter-conformity in attire. When encountering dissonance induced by the perceived extreme similarity to others, both those with high and low self-esteem tended to say they would dress in an unorthodox manner to surprise other people in the future.
On Associative Conformal Algebras of Linear Growth
Retakh, Alexander
2000-01-01
Lie conformal algebras appear in the theory of vertex algebras. Their relation is similar to that of Lie algebras and their universal enveloping algebras. Associative conformal algebras play a role in conformal representation theory. We introduce the notions of conformal identity and unital associative conformal algebras and classify finitely generated simple unital associative conformal algebras of linear growth. These are precisely the complete algebras of conformal endomorphisms of finite ...
Energy Technology Data Exchange (ETDEWEB)
Kim, Seyeon; Hong, Joon Hee [Chosun University, Gwangju (Korea, Republic of)
2016-04-15
The first synthesis of novel 5',5'-difluoro-30-hydroxy apiose nucleoside cyclomonophosphonic acid analogs was performed as potent anti-retroviral agents. Phosphonation was performed by direct displacement of a triflate intermediate with diethyl(lithiodifluoromethyl) phosphonate to give the corresponding(α, α-difluoroalkyl) phosphonate. Condensation successfully proceeded from a glycosyl donor with persilylated bases to yield the nucleoside phosphonate analogs. Deprotection of diethyl phosphonates provided the target nucleoside cyclomonophosphonic acid analogs. The synthesized nucleoside analogs were subjected to anti-viral screening against the human immunodeficiency virus-1 (HIV-1). Cytosine analogs show significant anti-HIV activity.
Algebraic Methods for Counting Euclidean Embeddings of Rigid Graphs
I.Z. Emiris; E.P. Tsigaridas; A. Varvitsiotis (Antonios); E.R. Gasner
2009-01-01
textabstract The study of (minimally) rigid graphs is motivated by numerous applications, mostly in robotics and bioinformatics. A major open problem concerns the number of embeddings of such graphs, up to rigid motions, in Euclidean space. We capture embeddability by polynomial systems
Recent advancements in conformal gravity
International Nuclear Information System (INIS)
O’Brien, James G.; Chaykov, Spasen S.; Moss, Robert J.; Dentico, Jeremy; Stulge, Modestas; Stefanski, Brian
2017-01-01
In recent years, due to the lack of direct observed evidence of cold dark matter, coupled with the shrinking parameter space to search for new dark matter particles, there has been increased interest in Alternative Gravitational theories. This paper, addresses three recent advances in conformal gravity, a fourth order renormalizable metric theory of gravitation originally formulated by Weyl, and later advanced by Mannheim and Kazanas. The first section of the paper applies conformal gravity to the rotation curves of the LITTLE THINGS survey, extending the total number of rotation curves successfully fit by conformal gravity to well over 200 individual data sets without the need for additional dark matter. Further, in this rotation curve study, we show how MOND and conformal gravity compare for each galaxy in the sample. Second, we look at the original Zwicky problem of applying the virial theorem to the Coma cluster in order to get an estimate for the cluster mass. However, instead of using the standard Newtonian potential, here we use the weak field approximation of conformal gravity. We show that in the conformal case we can get a much smaller mass estimate and thus there is no apparent need to include dark matter. We then show that this calculation is in agreement with the observational data from other well studied clusters. Last, we explore the calculation of the deflection of starlight through conformal gravity, as a first step towards applying conformal gravity to gravitaitonal lensing. (paper)
Conformal invariance in harmonic superspace
International Nuclear Information System (INIS)
Galperin, A.; Ivanov, E.; Ogievetsky, V.; Sokatchev, E.
1985-01-01
N=2 conformal supersymmetry is realized in harmonic superspace, its peculiarities are analyzed. The coordinate group and analytical prepotentials for N=2 conformal supergravity are found. A new version of the N=2 Einstein supergravity with infinite number of auxiliary fields is suggested. A hypermultiplet without central charges and constraints is used as a compensator
Counselor Identity: Conformity or Distinction?
McLaughlin, Jerry E.; Boettcher, Kathryn
2009-01-01
The authors explore 3 debates in other disciplines similar to counseling's identity debate in order to learn about common themes and outcomes. Conformity, distinction, and cohesion emerged as common themes. They conclude that counselors should retain their distinctive, humanistic approach rather than conforming to the dominant, medical approach.
THE RIGIDITY OF THE EARTH'S INNER CORE
Directory of Open Access Journals (Sweden)
K. E. BULLEN
1953-06-01
Full Text Available The purpose of this paper is to examine and assess, in the
light of recent evidence, the theory lliat the Earth's inner core has
a significant rigidity.
The presenee of an inner core in the Earth is revealed from
observations of the seismie pliase PKP in the « sliadow zone » for
which the epicentral distance A lies in the range 105" < A < 143".
Miss I. Lehmann (r in 1936, followed by Gutenberg and Richter (2
in 1938, atlrihuted these observations to tlie presence of an inner
core; and Jeffreys (3 in 1939 applied Airy's theory of diffraetion
near a caustic to sliow that the alternative theory of diffraetion
round the outer boundary of the centrai core was not capable of
explaining tlie observations in the shadow zone. The existence of the
inner core has been fairly generallv accepted sinee tliis ealculation
of Jeffreys.
The theory of pseudo-rigid bodies
Cohen, Harley
1988-01-01
This monograph concerns the development, analysis, and application of the theory of pseudo-rigid bodies. It collects together our work on that subject over the last five years. While some results have appeared else where, much of the work is new. Our objective in writing this mono graph has been to present a new theory of the deformation of bodies, one that has not only a firm theoretical basis, but also the simplicity to serve as an effective tool in practical problems. Consequently, the main body of the treatise is a multifaceted development of the theory, from foundations to explicit solutions to linearizations to methods of approximation. The fact that this variety of aspects, each examined in considerable detail, can be collected together in a single, unified treat ment gives this theory an elegance that we feel sets it apart from many others. While our goal has always been to give a complete treatment of the theory as it now stands, the work here is not meant to be definitive. Theories are not ent...
Almost Poisson integration of rigid body systems
International Nuclear Information System (INIS)
Austin, M.A.; Krishnaprasad, P.S.; Li-Sheng Wang
1993-01-01
In this paper we discuss the numerical integration of Lie-Poisson systems using the mid-point rule. Since such systems result from the reduction of hamiltonian systems with symmetry by lie group actions, we also present examples of reconstruction rules for the full dynamics. A primary motivation is to preserve in the integration process, various conserved quantities of the original dynamics. A main result of this paper is an O(h 3 ) error estimate for the Lie-Poisson structure, where h is the integration step-size. We note that Lie-Poisson systems appear naturally in many areas of physical science and engineering, including theoretical mechanics of fluids and plasmas, satellite dynamics, and polarization dynamics. In the present paper we consider a series of progressively complicated examples related to rigid body systems. We also consider a dissipative example associated to a Lie-Poisson system. The behavior of the mid-point rule and an associated reconstruction rule is numerically explored. 24 refs., 9 figs
Rigid multipodal platforms for metal surfaces
Directory of Open Access Journals (Sweden)
Michal Valášek
2016-03-01
Full Text Available In this review the recent progress in molecular platforms that form rigid and well-defined contact to a metal surface are discussed. Most of the presented examples have at least three anchoring units in order to control the spatial arrangement of the protruding molecular subunit. Another interesting feature is the lateral orientation of these foot structures which, depending on the particular application, is equally important as the spatial arrangement of the molecules. The numerous approaches towards assembling and organizing functional molecules into specific architectures on metal substrates are reviewed here. Particular attention is paid to variations of both, the core structures and the anchoring groups. Furthermore, the analytical methods enabling the investigation of individual molecules as well as monomolecular layers of ordered platform structures are summarized. The presented multipodal platforms bearing several anchoring groups form considerably more stable molecule–metal contacts than corresponding monopodal analogues and exhibit an enlarged separation of the functional molecules due to the increased footprint, as well as restrict tilting of the functional termini with respect to the metal surface. These platforms are thus ideally suited to tune important properties of the molecule–metal interface. On a single-molecule level, several of these platforms enable the control over the arrangement of the protruding rod-type molecular structures (e.g., molecular wires, switches, rotors, sensors with respect to the surface of the substrate.
Inflatable Tubular Structures Rigidized with Foams
Tinker, Michael L.; Schnell, Andrew R.
2010-01-01
Inflatable tubular structures that have annular cross sections rigidized with foams, and the means of erecting such structures in the field, are undergoing development. Although the development effort has focused on lightweight structural booms to be transported in compact form and deployed in outer space, the principles of design and fabrication are also potentially applicable to terrestrial structures, including components of ultralightweight aircraft, lightweight storage buildings and shelters, lightweight insulation, and sales displays. The use of foams to deploy and harden inflatable structures was first proposed as early as the 1960s, and has been investigated in recent years by NASA, the U.S. Air Force Research Laboratory, industry, and academia. In cases of deployable booms, most of the investigation in recent years has focused on solid cross sections, because they can be constructed relatively easily. However, solid-section foam-filled booms can be much too heavy for some applications. In contrast, booms with annular cross sections according to the present innovation can be tailored to obtain desired combinations of stiffness and weight through choice of diameters, wall thicknesses, and foam densities. By far the most compelling advantage afforded by this innovation is the possibility of drastically reducing weights while retaining or increasing the stiffnesses, relative to comparable booms that have solid foamfilled cross sections. A typical boom according to this innovation includes inner and outer polyimide film sleeves to contain foam that is injected between them during deployment.
Spontaneous droplet trampolining on rigid superhydrophobic surfaces
Schutzius, Thomas M.; Jung, Stefan; Maitra, Tanmoy; Graeber, Gustav; Köhme, Moritz; Poulikakos, Dimos
2015-11-01
Spontaneous removal of condensed matter from surfaces is exploited in nature and in a broad range of technologies to achieve self-cleaning, anti-icing and condensation control. But despite much progress, our understanding of the phenomena leading to such behaviour remains incomplete, which makes it challenging to rationally design surfaces that benefit from its manifestation. Here we show that water droplets resting on superhydrophobic textured surfaces in a low-pressure environment can self-remove through sudden spontaneous levitation and subsequent trampoline-like bouncing behaviour, in which sequential collisions with the surface accelerate the droplets. These collisions have restitution coefficients (ratios of relative speeds after and before collision) greater than unity despite complete rigidity of the surface, and thus seemingly violate the second law of thermodynamics. However, these restitution coefficients result from an overpressure beneath the droplet produced by fast droplet vaporization while substrate adhesion and surface texture restrict vapour flow. We also show that the high vaporization rates experienced by the droplets and the associated cooling can result in freezing from a supercooled state that triggers a sudden increase in vaporization, which in turn boosts the levitation process. This effect can spontaneously remove surface icing by lifting away icy drops the moment they freeze. Although these observations are relevant only to systems in a low-pressure environment, they show how surface texturing can produce droplet-surface interactions that prohibit liquid and freezing water-droplet retention on surfaces.
Recursion Relations for Conformal Blocks
Penedones, João; Yamazaki, Masahito
2016-09-12
In the context of conformal field theories in general space-time dimension, we find all the possible singularities of the conformal blocks as functions of the scaling dimension $\\Delta$ of the exchanged operator. In particular, we argue, using representation theory of parabolic Verma modules, that in odd spacetime dimension the singularities are only simple poles. We discuss how to use this information to write recursion relations that determine the conformal blocks. We first recover the recursion relation introduced in 1307.6856 for conformal blocks of external scalar operators. We then generalize this recursion relation for the conformal blocks associated to the four point function of three scalar and one vector operator. Finally we specialize to the case in which the vector operator is a conserved current.
Conformal algebra of Riemann surfaces
International Nuclear Information System (INIS)
Vafa, C.
1988-01-01
It has become clear over the last few years that 2-dimensional conformal field theories are a crucial ingredient of string theory. Conformal field theories correspond to vacuum solutions of strings; or more precisely we know how to compute string spectrum and scattering amplitudes by starting from a formal theory (with a proper value of central charge of the Virasoro algebra). Certain non-linear sigma models do give rise to conformal theories. A lot of progress has been made in the understanding of conformal theories. The author discusses a different view of conformal theories which was motivated by the development of operator formalism on Riemann surfaces. The author discusses an interesting recent work from this point of view
The logarithmic conformal field theories
International Nuclear Information System (INIS)
Rahimi Tabar, M.R.; Aghamohammadi, A.; Khorrami, M.
1997-01-01
We study the correlation functions of logarithmic conformal field theories. First, assuming conformal invariance, we explicitly calculate two- and three-point functions. This calculation is done for the general case of more than one logarithmic field in a block, and more than one set of logarithmic fields. Then we show that one can regard the logarithmic field as a formal derivative of the ordinary field with respect to its conformal weight. This enables one to calculate any n-point function containing the logarithmic field in terms of ordinary n-point functions. Finally, we calculate the operator product expansion (OPE) coefficients of a logarithmic conformal field theory, and show that these can be obtained from the corresponding coefficients of ordinary conformal theory by a simple derivation. (orig.)
Molecular Origin of Model Membrane Bending Rigidity
International Nuclear Information System (INIS)
Kurtisovski, Erol; Taulier, Nicolas; Waks, Marcel; Ober, Raymond; Urbach, Wladimir
2007-01-01
The behavior of the bending modulus κ of bilayers in lamellar phases was studied by Small Angle X-ray Scattering technique for various nonionic C i E j surfactants. The bilayers are either unswollen and dispersed in water or swollen by water and dispersed in dodecane. For unswollen bilayers, the values of κ decrease with both an increase in the area per surfactant molecule and in the polar head length. They increase when the aliphatic chain length increases at constant area per surfactant molecule. Whereas for water-swollen membranes, the values of κ decrease as the content of water increases converging to the value of the single monolayer bending modulus. Such a behavior results from the decoupling of the fluctuations of the two surfactant membrane monolayers. Our results emphasize the determinant contribution of the surfactant conformation to κ
Pyrimidine homoribonucleosides: synthesis, solution conformation, and some biological properties.
Lassota, P; Kuśmierek, J T; Stolarski, R; Shugar, D
1987-05-01
Conversion of uridine and cytidine to their 5'-O-tosyl derivatives, followed by cyanation with tetraethylammonium cyanide, reduction and deamination, led to isolation of the hitherto unknown homouridine (1-(5'-deoxy-beta-D-allofuranosyl)uracil) and homocytidine (1-(5'-deoxy-beta-D-allofuranosyl)cytosine), analogues of uridine and cytidine in which the exocyclic 5'-CH2OH chain is extended by one carbon to CH2CH2OH. Homocytidine was also phosphorylated to its 6'-phosphate and 6'-pyrophosphate analogues. In addition, it was converted, via its 2,2'-anhydro derivative, to arahomocytidine, an analogue of the chemotherapeutically active araC. The structures of all the foregoing were established by various criteria, including 1H and 13C NMR spectroscopy, both of which were also applied to analyses of the solution conformations of the various compounds, particularly as regards the conformations of the exocyclic chains. The behaviour of the homo analogues was examined in several enzymatic systems. Homocytidine was a feeble substrate, without inhibitory properties, of E. coli cytidine deaminase. Homocytidine was an excellent substrate for wheat shoot nucleoside phosphotransferase; while homouridine was a good substrate for E. coli uridine phosphorylase. Although homoCMP was neither a substrate, nor an inhibitor, of snake venom 5'-nucleotidase, homoCDP was a potent inhibitor of this enzyme (Ki approximately 6 microM). HomoCDP was not a substrate for M. luteus polynucleotide phosphorylase. None of the compounds exhibited significant activity vs herpes simplex virus type 1, or cytotoxic activity in several mammalian cell lines.
Conformal solids and holography
Esposito, A.; Garcia-Saenz, S.; Nicolis, A.; Penco, R.
2017-12-01
We argue that a SO( d) magnetic monopole in an asymptotically AdS space-time is dual to a d-dimensional strongly coupled system in a solid state. In light of this, it would be remiss of us not to dub such a field configuration solidon. In the presence of mixed boundary conditions, a solidon spontaneously breaks translations (among many other symmetries) and gives rise to Goldstone excitations on the boundary — the phonons of the solid. We derive the quadratic action for the boundary phonons in the probe limit and show that, when the mixed boundary conditions preserve conformal symmetry, the longitudinal and transverse sound speeds are related to each other as expected from effective field theory arguments. We then include backreaction and calculate the free energy of the solidon for a particular choice of mixed boundary conditions, corresponding to a relevant multi-trace deformation of the boundary theory. We find such free energy to be lower than that of thermal AdS. This suggests that our solidon undergoes a solid-to-liquid first order phase transition by melting into a Schwarzschild-AdS black hole as the temperature is raised.
Intensity modulated conformal radiotherapy
International Nuclear Information System (INIS)
Noel, Georges; Moty-Monnereau, Celine; Meyer, Aurelia; David, Pauline; Pages, Frederique; Muller, Felix; Lee-Robin, Sun Hae; David, Denis Jean
2006-12-01
This publication reports the assessment of intensity-modulated conformal radiotherapy (IMCR). This assessment is based on a literature survey which focussed on indications, efficiency and safety on the short term, on the risk of radio-induced cancer on the long term, on the role in the therapeutic strategy, on the conditions of execution, on the impact on morbidity-mortality and life quality, on the impact on the health system and on public health policies and program. This assessment is also based on the opinion of a group of experts regarding the technical benefit of IMCR, its indications depending on the cancer type, safety in terms of radio-induced cancers, and conditions of execution. Before this assessment, the report thus indicates indications for which the use of IMCR can be considered as sufficient or not determined. It also proposes a technical description of IMCR and helical tomo-therapy, discusses the use of this technique for various pathologies or tumours, analyses the present situation of care in France, and comments the identification of this technique in foreign classifications
International Nuclear Information System (INIS)
Zotto, Michele Del; Heckman, Jonathan J.; Tomasiello, Alessandro; Vafa, Cumrun
2015-01-01
A single M5-brane probing G, an ADE-type singularity, leads to a system which has G×G global symmetry and can be viewed as “bifundamental” (G,G) matter. For the A N series, this leads to the usual notion of bifundamental matter. For the other cases it corresponds to a strongly interacting (1,0) superconformal system in six dimensions. Similarly, an ADE singularity intersecting the Hořava-Witten wall leads to a superconformal matter system with E 8 ×G global symmetry. Using the F-theory realization of these theories, we elucidate the Coulomb/tensor branch of (G,G ′ ) conformal matter. This leads to the notion of fractionalization of an M5-brane on an ADE singularity as well as fractionalization of the intersection point of the ADE singularity with the Hořava-Witten wall. Partial Higgsing of these theories leads to new 6d SCFTs in the infrared, which we also characterize. This generalizes the class of (1,0) theories which can be perturbatively realized by suspended branes in IIA string theory. By reducing on a circle, we arrive at novel duals for 5d affine quiver theories. Introducing many M5-branes leads to large N gravity duals.
BUTCHER, PR; KALVERBOER, A; MINDERAA, RB; VANDOORMAAL, EF; TENWOLDE, Y
1993-01-01
The associations between a mother's rigidity, her sensitivity in early (3 month) interaction and the quality of her premature infant's attachment at 13 months were investigated. Rigidity as a personality characteristic was not found to be significantly associated with sensitivity or quality of
Towards conformal loop quantum gravity
International Nuclear Information System (INIS)
Wang, Charles H-T
2006-01-01
A discussion is given of recent developments in canonical gravity that assimilates the conformal analysis of gravitational degrees of freedom. The work is motivated by the problem of time in quantum gravity and is carried out at the metric and the triad levels. At the metric level, it is shown that by extending the Arnowitt-Deser-Misner (ADM) phase space of general relativity (GR), a conformal form of geometrodynamics can be constructed. In addition to the Hamiltonian and Diffeomorphism constraints, an extra first class constraint is introduced to generate conformal transformations. This phase space consists of York's mean extrinsic curvature time, conformal three-metric and their momenta. At the triad level, the phase space of GR is further enlarged by incorporating spin-gauge as well as conformal symmetries. This leads to a canonical formulation of GR using a new set of real spin connection variables. The resulting gravitational constraints are first class, consisting of the Hamiltonian constraint and the canonical generators for spin-gauge and conformorphism transformations. The formulation has a remarkable feature of being parameter-free. Indeed, it is shown that a conformal parameter of the Barbero-Immirzi type can be absorbed by the conformal symmetry of the extended phase space. This gives rise to an alternative approach to loop quantum gravity that addresses both the conceptual problem of time and the technical problem of functional calculus in quantum gravity
Benchmarking Commercial Conformer Ensemble Generators.
Friedrich, Nils-Ole; de Bruyn Kops, Christina; Flachsenberg, Florian; Sommer, Kai; Rarey, Matthias; Kirchmair, Johannes
2017-11-27
We assess and compare the performance of eight commercial conformer ensemble generators (ConfGen, ConfGenX, cxcalc, iCon, MOE LowModeMD, MOE Stochastic, MOE Conformation Import, and OMEGA) and one leading free algorithm, the distance geometry algorithm implemented in RDKit. The comparative study is based on a new version of the Platinum Diverse Dataset, a high-quality benchmarking dataset of 2859 protein-bound ligand conformations extracted from the PDB. Differences in the performance of commercial algorithms are much smaller than those observed for free algorithms in our previous study (J. Chem. Inf. 2017, 57, 529-539). For commercial algorithms, the median minimum root-mean-square deviations measured between protein-bound ligand conformations and ensembles of a maximum of 250 conformers are between 0.46 and 0.61 Å. Commercial conformer ensemble generators are characterized by their high robustness, with at least 99% of all input molecules successfully processed and few or even no substantial geometrical errors detectable in their output conformations. The RDKit distance geometry algorithm (with minimization enabled) appears to be a good free alternative since its performance is comparable to that of the midranked commercial algorithms. Based on a statistical analysis, we elaborate on which algorithms to use and how to parametrize them for best performance in different application scenarios.
Two dimensional infinite conformal symmetry
International Nuclear Information System (INIS)
Mohanta, N.N.; Tripathy, K.C.
1993-01-01
The invariant discontinuous (discrete) conformal transformation groups, namely the Kleinian and Fuchsian groups Gamma (with an arbitrary signature) of H (the Poincare upper half-plane l) and the unit disc Delta are explicitly constructed from the fundamental domain D. The Riemann surface with signatures of Gamma and conformally invariant automorphic forms (functions) with Peterson scalar product are discussed. The functor, where the category of complex Hilbert spaces spanned by the space of cusp forms constitutes the two dimensional conformal field theory. (Author) 7 refs
Harmony of spinning conformal blocks
Energy Technology Data Exchange (ETDEWEB)
Schomerus, Volker [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Theory Group; Sobko, Evgeny [Stockholm Univ. (Sweden); Nordita, Stockholm (Sweden); Isachenkov, Mikhail [Weizmann Institute of Science, Rehovoth (Israel). Dept. of Particle Physics and Astrophysics
2016-12-07
Conformal blocks for correlation functions of tensor operators play an increasingly important role for the conformal bootstrap programme. We develop a universal approach to such spinning blocks through the harmonic analysis of certain bundles over a coset of the conformal group. The resulting Casimir equations are given by a matrix version of the Calogero-Sutherland Hamiltonian that describes the scattering of interacting spinning particles in a 1-dimensional external potential. The approach is illustrated in several examples including fermionic seed blocks in 3D CFT where they take a very simple form.
Harmony of spinning conformal blocks
Energy Technology Data Exchange (ETDEWEB)
Schomerus, Volker [DESY Hamburg, Theory Group,Notkestraße 85, 22607 Hamburg (Germany); Sobko, Evgeny [Nordita and Stockholm University,Roslagstullsbacken 23, SE-106 91 Stockholm (Sweden); Isachenkov, Mikhail [Department of Particle Physics and Astrophysics, Weizmann Institute of Science,Rehovot 7610001 (Israel)
2017-03-15
Conformal blocks for correlation functions of tensor operators play an increasingly important role for the conformal bootstrap programme. We develop a universal approach to such spinning blocks through the harmonic analysis of certain bundles over a coset of the conformal group. The resulting Casimir equations are given by a matrix version of the Calogero-Sutherland Hamiltonian that describes the scattering of interacting spinning particles in a 1-dimensional external potential. The approach is illustrated in several examples including fermionic seed blocks in 3D CFT where they take a very simple form.
Mass generation within conformal invariant theories
International Nuclear Information System (INIS)
Flato, M.; Guenin, M.
1981-01-01
The massless Yang-Mills theory is strongly conformally invariant and renormalizable; however, when masses are introduced the theory becomes nonrenormalizable and weakly conformally invariant. Conditions which recover strong conformal invariance are discussed in the letter. (author)
Reversible Rigidity Control Using Low Melting Temperature Alloys
Shan, Wanliang; Lu, Tong; Majidi, Carmel
2013-03-01
Inspired by nature, materials able to achieve rapid rigidity changes have important applications for human body protection in military and many other areas. This talk presents the fabrication and design of soft-matter technologies that exhibit rapid reversible rigidity control. Fabricated with a masked deposition technique, the soft-matter composite contains liquid-phase and phase-changing metal alloys embedded in a soft and highly stretchable elastomer. The composite material can reversibly change its rigidity by three orders of magnitude and sustain large deformation.
The Almost Periodic Rigidity of Crystallographic Bar-Joint Frameworks
Directory of Open Access Journals (Sweden)
Ghada Badri
2014-04-01
Full Text Available A crystallographic bar-joint framework, C in Rd, is shown to be almost periodically infinitesimally rigid if and only if it is strictly periodically infinitesimally rigid and the rigid unit mode (RUM spectrum, Ω (C, is a singleton. Moreover, the almost periodic infinitesimal flexes of C are characterised in terms of a matrix-valued function, ΦC(z, on the d-torus, Td, determined by a full rank translation symmetry group and an associated motif of joints and bars.
APPLICATION OF RIGID LINKS IN STRUCTURAL DESIGN MODELS
Directory of Open Access Journals (Sweden)
Sergey Yu. Fialko
2017-09-01
Full Text Available A special finite element modelling rigid links is proposed for the linear static and buckling analysis. Unlike the classical approach based on the theorems of rigid body kinematics, the proposed approach preserves the similarity between the adjacency graph for a sparse matrix and the adjacency graph for nodes of the finite element model, which allows applying sparse direct solvers more effectively. Besides, the proposed approach allows significantly reducing the number of nonzero entries in the factored stiffness matrix in comparison with the classical one, which greatly reduces the duration of the solution. For buckling problems of structures containing rigid bodies, this approach gives correct results. Several examples demonstrate its efficiency.
Unciuleac, Mihaela-Carmen; Smith, Paul C; Shuman, Stewart
2016-05-15
AAA proteins (ATPases associated with various cellular activities) use the energy of ATP hydrolysis to drive conformational changes in diverse macromolecular targets. Here, we report the biochemical characterization and 2.5-Å crystal structure of a Mycobacterium smegmatis AAA protein Msm0858, the ortholog of Mycobacterium tuberculosis Rv0435c. Msm0858 is a magnesium-dependent ATPase and is active with all nucleoside triphosphates (NTPs) and deoxynucleoside triphosphates (dNTPs) as substrates. The Msm0858 structure comprises (i) an N-terminal domain (amino acids [aa] 17 to 201) composed of two β-barrel modules and (ii) two AAA domains, D1 (aa 212 to 473) and D2 (aa 476 to 744), each of which has ADP in the active site. Msm0858-ADP is a monomer in solution and in crystallized form. Msm0858 domains are structurally homologous to the corresponding modules of mammalian p97. However, the position of the N-domain modules relative to the AAA domains in the Msm0858-ADP tertiary structure is different and would impede the formation of a p97-like hexameric quaternary structure. Mutational analysis of the A-box and B-box motifs indicated that the D1 and D2 AAA domains are both capable of ATP hydrolysis. Simultaneous mutations of the D1 and D2 active-site motifs were required to abolish ATPase activity. ATPase activity was effaced by mutation of the putative D2 arginine finger, suggesting that Msm0858 might oligomerize during the ATPase reaction cycle. A truncated variant Msm0858 (aa 212 to 745) that lacks the N domain was characterized as a catalytically active homodimer. Recent studies have underscored the importance of AAA proteins (ATPases associated with various cellular activities) in the physiology of mycobacteria. This study reports the ATPase activity and crystal structure of a previously uncharacterized mycobacterial AAA protein, Msm0858. Msm0858 consists of an N-terminal β-barrel domain and two AAA domains, each with ADP bound in the active site. Msm0858 is a
Conformal FDTD modeling of 3-D wake fields
International Nuclear Information System (INIS)
Jurgens, T.G.; Harfoush, F.A.
1991-01-01
Many computer codes have been written to model wake fields. Here the authors describe the use of the Conformal Finite Difference Time Domain (CFDTD) method to model the wake fields generated by a rigid beam traveling through various accelerating structures. The non-cylindrical symmetry of some of the problems considered here requires the use of a three dimensional code. In traditional FDTD codes, curved surfaces are approximated by rectangular steps. The errors introduced in wake field calculations by such an approximation can be reduced by increasing the mesh size, therefore increasing the cost of computing. Another approach, validated here, deforms Ampere and Faraday contours near a media interface so as to conform to the interface. These improvements so as to conform to the interface. These improvements to the FDTD method result in better accuracy of the fields at asymptotically no computational cost. This method is also capable of modeling thin wires as found in beam profile monitors, and slots and cracks as found in resistive wall monitors
Saliba, Jason; Zabriskie, Ryan; Ghosh, Rajarshi; Powell, Bradford C; Hicks, Stephanie; Kimmel, Marek; Meng, Qingchang; Ritter, Deborah I; Wheeler, David A; Gibbs, Richard A; Tsai, Francis T F; Plon, Sharon E
2016-01-01
Background Mutations or alteration in expression of the 5’ nucleotidase gene family can confer altered responses to treatment with nucleoside analogs. While investigating leukemia susceptibility genes, we discovered a very rare p.L254P NT5C1A missense variant in the substrate recognition motif. Given the paucity of cellular drug response data from NT5C1A germline variation, we characterized p.L254P and eight rare variants of NT5C1A from genomic databases. Methods Through lentiviral infection, we created HEK293 cell lines that stably overexpress wildtype NT5C1A, p.L254P, or eight NT5C1A variants reported in the NHLBI Exome Variant server (one truncating and seven missense). IC50 values were determined by cytotoxicity assays after exposure to chemotherapeutic nucleoside analogs (Cladribine, Gemcitabine, 5-Fluorouracil). In addition, we used structure-based homology modeling to generate a 3D model for the C-terminal region of NT5C1A. Results The p.R180X (truncating), p.A214T, and p.L254P missense changes were the only variants that significantly impaired protein function across all nucleotide analogs tested (>5-fold difference versus WT; p<.05). Several of the remaining variants individually displayed differential effects (both more and less resistant) across the analogs tested. The homology model provided a structural framework to understand the impact of NT5C1A mutants on catalysis and drug processing. The model predicted active site residues within NT5C1A motif III and we experimentally confirmed that p.K314 (not p.K320) is required for NT5C1A activity. Conclusion We characterized germline variation and predicted protein structures of NT5C1A. Individual missense changes showed substantial variation in response to the different nucleoside analogs tested, which may impact patients’ responses to treatment. PMID:26906009
Energy Technology Data Exchange (ETDEWEB)
Weiler, Monica [Department of Medicine III and Transfusion Medicine, University Hospital Grosshadern, Ludwig-Maximilians-University, Munich (Germany); Schmetzer, Helga [Helmholtz Center Munich (Germany); German Research Center for Environmental Health, Munich (Germany); Braeu, Marion; Buhmann, Raymund [Helmholtz Center Munich (Germany); German Research Center for Environmental Health, Munich (Germany); Department of Medicine III and Transfusion Medicine, University Hospital Grosshadern, Ludwig-Maximilians-University, Munich (Germany)
2016-11-15
The release of nucleic acids and derivatives after tissue-injury may affect cellular immune-response. We studied the impact of extracellular ribo-, desoxyribonucleotides and nucleosides on T-cell immunity. Peripheral-blood-mononuclear-cells (PBMCs) or isolated CD3{sup +}T-cells obtained from 6 healthy donors were stimulated via CD3/CD28 Dynabeads or dendritic cells (DCs) in the presence or absence of pyrimidine-, purine-nucleotides and -nucleosides (range 2–200 µM). Addition of deoxy-, guanosine-triphosphate (dGTP, GTP) and guanosine resulted concentration dependent in a complete, adenosine-triphosphate (ATP) in a partial inhibition of the induced T-cell-proliferation. Deoxyadenosine-triphosphate (dATP), adenosine and the pyrimidine-ribo- and -deoxyribonucleotides displayed no inhibitory capacity. Inhibitory effects of dGTP and GTP, but not of guanosine and ATP were culture-media-dependent and could be almost abrogated by use of the serum-free lymphocyte-culture-media X-Vivo15 instead of RPMI1640 with standard-supplementation. In contrast to RPMI1640, X-Vivo15 resulted in a significant down-regulation of the cell-surface-located ectonucleotidases CD39 (Ecto-Apyrase) and CD73 (Ecto-5′-Nucleotidase), critical for the extracellular nucleotides-hydrolysis to nucleosides, explaining the loss of inhibition mediated by dGTP and GTP, but not Guanosine. In line with previous findings ATP was found to exert immunosuppressive effects on T-cell-proliferation. Purine-nucleotides, dGTP and GTP displayed a higher inhibitory capacity, but seem to be strictly dependent on the microenvironmental conditions modulating the responsiveness of the respective T-lymphocytes. Further evaluation of experimental and respective clinical settings should anticipate these findings.
International Nuclear Information System (INIS)
Weiler, Monica; Schmetzer, Helga; Braeu, Marion; Buhmann, Raymund
2016-01-01
The release of nucleic acids and derivatives after tissue-injury may affect cellular immune-response. We studied the impact of extracellular ribo-, desoxyribonucleotides and nucleosides on T-cell immunity. Peripheral-blood-mononuclear-cells (PBMCs) or isolated CD3 + T-cells obtained from 6 healthy donors were stimulated via CD3/CD28 Dynabeads or dendritic cells (DCs) in the presence or absence of pyrimidine-, purine-nucleotides and -nucleosides (range 2–200 µM). Addition of deoxy-, guanosine-triphosphate (dGTP, GTP) and guanosine resulted concentration dependent in a complete, adenosine-triphosphate (ATP) in a partial inhibition of the induced T-cell-proliferation. Deoxyadenosine-triphosphate (dATP), adenosine and the pyrimidine-ribo- and -deoxyribonucleotides displayed no inhibitory capacity. Inhibitory effects of dGTP and GTP, but not of guanosine and ATP were culture-media-dependent and could be almost abrogated by use of the serum-free lymphocyte-culture-media X-Vivo15 instead of RPMI1640 with standard-supplementation. In contrast to RPMI1640, X-Vivo15 resulted in a significant down-regulation of the cell-surface-located ectonucleotidases CD39 (Ecto-Apyrase) and CD73 (Ecto-5′-Nucleotidase), critical for the extracellular nucleotides-hydrolysis to nucleosides, explaining the loss of inhibition mediated by dGTP and GTP, but not Guanosine. In line with previous findings ATP was found to exert immunosuppressive effects on T-cell-proliferation. Purine-nucleotides, dGTP and GTP displayed a higher inhibitory capacity, but seem to be strictly dependent on the microenvironmental conditions modulating the responsiveness of the respective T-lymphocytes. Further evaluation of experimental and respective clinical settings should anticipate these findings.
Analysis of the Main Nucleosides in Cordyceps Sinensis by LC/ESI-MS
Directory of Open Access Journals (Sweden)
Yun-Biao He
2010-01-01
Full Text Available A sensitive, selective and reliable liquid chromatography-mass spectrometry coupled with electrospray ionization interface method for simultaneous separation and determination of thymine, adenine, adenosine and cordycepin in Cordyceps sinensis has been established. The optimum separation for these analytes was achieved using a gradient elution system and a 2.0 × 150 mm Shimadzu VP-ODS column. 2-Chloroadenosine was used as internal standard for this assay. [M+H]+ions at m/z 127, 136, 268, 252 and 302 were chosen and selective ion monitoring (SIM mode was used for quantitative analysis of the four main nucleosides. The regression equations were linear in the range of 1.0–117.5 μg·mL-1 for thymine, 1.8-127.0 μg·mL-1 for adenine, 0.6-114.0 μg·mL-1 for adenosine and 0.5-107.5 μg·mL-1 for cordycepin. The limits of quantitation (LOQ and detection (LOD were 1.0 and 0.2 μg·mL-1 for thymine, 1.8 and 0.6 μg·mL-1 for adenine, 0.6 and 0.1 μg·mL-1 for adenosine and 0.5 and 0.1 μg·mL-1 for cordycepin, respectively. The recoveries of the four nucleosides ranged from 98.47 to 99.32%. The developed method was successfully used to determine nucleosides in Cordyceps sinensis from different sources.
Energy Technology Data Exchange (ETDEWEB)
Tran, Timothy H.; Christoffersen, S.; Allan, Paula W.; Parker, William B.; Piskur, Jure; Serra, I.; Terreni, M.; Ealick, Steven E. (Cornell); (Pavia); (Lund); (Southern Research)
2011-09-20
Uridine phosphorylase (UP), a key enzyme in the pyrimidine salvage pathway, catalyzes the reversible phosphorolysis of uridine or 2'-deoxyuridine to uracil and ribose 1-phosphate or 2'-deoxyribose 1-phosphate. This enzyme belongs to the nucleoside phosphorylase I superfamily whose members show diverse specificity for nucleoside substrates. Phylogenetic analysis shows Streptococcus pyogenes uridine phosphorylase (SpUP) is found in a distinct branch of the pyrimidine subfamily of nucleoside phosphorylases. To further characterize SpUP, we determined the crystal structure in complex with the products, ribose 1-phosphate and uracil, at 1.8 {angstrom} resolution. Like Escherichia coli UP (EcUP), the biological unit of SpUP is a hexamer with an ?/? monomeric fold. A novel feature of the active site is the presence of His169, which structurally aligns with Arg168 of the EcUP structure. A second active site residue, Lys162, is not present in previously determined UP structures and interacts with O2 of uracil. Biochemical studies of wild-type SpUP showed that its substrate specificity is similar to that of EcUP, while EcUP is {approx}7-fold more efficient than SpUP. Biochemical studies of SpUP mutants showed that mutations of His169 reduced activity, while mutation of Lys162 abolished all activity, suggesting that the negative charge in the transition state resides mostly on uracil O2. This is in contrast to EcUP for which transition state stabilization occurs mostly at O4.
Absence of a Universal Mechanism of Mitochondrial Toxicity by Nucleoside Analogs▿
Lund, Kaleb C.; Peterson, LaRae L.; Wallace, Kendall B.
2007-01-01
Nucleoside analogs are associated with various mitochondrial toxicities, and it is becoming increasingly difficult to accommodate these differences solely in the context of DNA polymerase gamma inhibition. Therefore, we examined the toxicities of zidovudine (AZT) (10 and 50 μM; 2.7 and 13.4 μg/ml), didanosine (ddI) (10 and 50 μM; 2.4 and 11.8 μg/ml), and zalcitabine (ddC) (1 and 5 μM; 0.21 and 1.1 μg/ml) in HepG2 and H9c2 cells without the presumption of mitochondrial DNA (mtDNA) depletion. Ethidium bromide (EtBr) (0.5 μg/ml; 1.3 μM) was used as a positive control. AZT treatment resulted in metabolic disruption (increased lactate and superoxide) and increased cell mortality with decreased proliferation, while mtDNA remained unchanged or increased (HepG2 cells; 50 μM AZT). ddC caused pronounced mtDNA depletion in HepG2 cells but not in H9c2 cells and increased mortality in HepG2 cells, but no significant metabolic disruption in either cell type. ddI caused a moderate depletion of mtDNA in both cell types but showed no other effects. EtBr exposure resulted in metabolic disruption, increased cell mortality with decreased cell proliferation, and mtDNA depletion in both cell types. We conclude that nucleoside analogs display unique toxicities within and between culture models, and therefore, care should be taken when generalizing about the mechanisms of nucleoside reverse transcriptase inhibitor toxicity. Additionally, mtDNA abundance does not necessarily correlate with metabolic disruption, especially in cell culture; careful discernment is recommended in this regard. PMID:17470651
Absence of a universal mechanism of mitochondrial toxicity by nucleoside analogs.
Lund, Kaleb C; Peterson, LaRae L; Wallace, Kendall B
2007-07-01
Nucleoside analogs are associated with various mitochondrial toxicities, and it is becoming increasingly difficult to accommodate these differences solely in the context of DNA polymerase gamma inhibition. Therefore, we examined the toxicities of zidovudine (AZT) (10 and 50 microM; 2.7 and 13.4 microg/ml), didanosine (ddI) (10 and 50 microM; 2.4 and 11.8 microg/ml), and zalcitabine (ddC) (1 and 5 microM; 0.21 and 1.1 microg/ml) in HepG2 and H9c2 cells without the presumption of mitochondrial DNA (mtDNA) depletion. Ethidium bromide (EtBr) (0.5 microg/ml; 1.3 microM) was used as a positive control. AZT treatment resulted in metabolic disruption (increased lactate and superoxide) and increased cell mortality with decreased proliferation, while mtDNA remained unchanged or increased (HepG2 cells; 50 microM AZT). ddC caused pronounced mtDNA depletion in HepG2 cells but not in H9c2 cells and increased mortality in HepG2 cells, but no significant metabolic disruption in either cell type. ddI caused a moderate depletion of mtDNA in both cell types but showed no other effects. EtBr exposure resulted in metabolic disruption, increased cell mortality with decreased cell proliferation, and mtDNA depletion in both cell types. We conclude that nucleoside analogs display unique toxicities within and between culture models, and therefore, care should be taken when generalizing about the mechanisms of nucleoside reverse transcriptase inhibitor toxicity. Additionally, mtDNA abundance does not necessarily correlate with metabolic disruption, especially in cell culture; careful discernment is recommended in this regard.
Logarithmic conformal field theory
Gainutdinov, Azat; Ridout, David; Runkel, Ingo
2013-12-01
Conformal field theory (CFT) has proven to be one of the richest and deepest subjects of modern theoretical and mathematical physics research, especially as regards statistical mechanics and string theory. It has also stimulated an enormous amount of activity in mathematics, shaping and building bridges between seemingly disparate fields through the study of vertex operator algebras, a (partial) axiomatisation of a chiral CFT. One can add to this that the successes of CFT, particularly when applied to statistical lattice models, have also served as an inspiration for mathematicians to develop entirely new fields: the Schramm-Loewner evolution and Smirnov's discrete complex analysis being notable examples. When the energy operator fails to be diagonalisable on the quantum state space, the CFT is said to be logarithmic. Consequently, a logarithmic CFT is one whose quantum space of states is constructed from a collection of representations which includes reducible but indecomposable ones. This qualifier arises because of the consequence that certain correlation functions will possess logarithmic singularities, something that contrasts with the familiar case of power law singularities. While such logarithmic singularities and reducible representations were noted by Rozansky and Saleur in their study of the U (1|1) Wess-Zumino-Witten model in 1992, the link between the non-diagonalisability of the energy operator and logarithmic singularities in correlators is usually ascribed to Gurarie's 1993 article (his paper also contains the first usage of the term 'logarithmic conformal field theory'). The class of CFTs that were under control at this time was quite small. In particular, an enormous amount of work from the statistical mechanics and string theory communities had produced a fairly detailed understanding of the (so-called) rational CFTs. However, physicists from both camps were well aware that applications from many diverse fields required significantly more
Higher-derivative generalization of conformal mechanics
Baranovsky, Oleg
2017-08-01
Higher-derivative analogs of multidimensional conformal particle and many-body conformal mechanics are constructed. Their Newton-Hooke counterparts are derived by applying appropriate coordinate transformations.
Naturality in conformal field theory
International Nuclear Information System (INIS)
Moore, G.; Seiberg, N.
1989-01-01
We discuss constraints on the operator product coefficients in diagonal and nondiagonal rational conformal field theories. Nondiagonal modular invariants always arise from automorphisms of the fusion rule algebra or from extensions of the chiral algebra. Moreover, when the chiral algebra has been maximally extended a strong form of the naturality principle of field theory can be proven for rational conformal field theory: operator product coefficients vanish if and only if the corresponding fusion rules vanish; that is, if and only if the vanishing can be understood in terms of a symmetry. We illustrate these ideas with several examples. We also generalize our ideas about rational conformal field theories to a larger class of theories: 'quasi-rational conformal field theories' and we explore some of their properties. (orig.)
Steady states in conformal theories
CERN. Geneva
2015-01-01
A novel conjecture regarding the steady state behavior of conformal field theories placed between two heat baths will be presented. Some verification of the conjecture will be provided in the context of fluid dynamics and holography.
National Automated Conformity Inspection Process -
Department of Transportation — The National Automated Conformity Inspection Process (NACIP) Application is intended to expedite the workflow process as it pertains to the FAA Form 81 0-10 Request...
Aspect of the conformal invariance
International Nuclear Information System (INIS)
Bauer, M.
1990-11-01
This thesis is about the study of several physical and mathematical aspects of critical phenomena at two dimensions. These phenomena have remarkable symmetry properties in the coordonnates changes keeping the angles. They are named conformal theories
Some Progress in Conformal Geometry
Directory of Open Access Journals (Sweden)
Sun-Yung A. Chang
2007-12-01
Full Text Available This is a survey paper of our current research on the theory of partial differential equations in conformal geometry. Our intention is to describe some of our current works in a rather brief and expository fashion. We are not giving a comprehensive survey on the subject and references cited here are not intended to be complete. We introduce a bubble tree structure to study the degeneration of a class of Yamabe metrics on Bach flat manifolds satisfying some global conformal bounds on compact manifolds of dimension 4. As applications, we establish a gap theorem, a finiteness theorem for diffeomorphism type for this class, and diameter bound of the $sigma_2$-metrics in a class of conformal 4-manifolds. For conformally compact Einstein metrics we introduce an eigenfunction compactification. As a consequence we obtain some topological constraints in terms of renormalized volumes.
Conformity Adequacy Review: Region 5
Resources are for air quality and transportation government and community leaders. Information on the conformity SIP adequacy/inadequacy of state implementation plans (SIPs) in EPA Region 5 (IL, IN, MI, OH, WI) is provided here.
Inverse bootstrapping conformal field theories
Li, Wenliang
2018-01-01
We propose a novel approach to study conformal field theories (CFTs) in general dimensions. In the conformal bootstrap program, one usually searches for consistent CFT data that satisfy crossing symmetry. In the new method, we reverse the logic and interpret manifestly crossing-symmetric functions as generating functions of conformal data. Physical CFTs can be obtained by scanning the space of crossing-symmetric functions. By truncating the fusion rules, we are able to concentrate on the low-lying operators and derive some approximate relations for their conformal data. It turns out that the free scalar theory, the 2d minimal model CFTs, the ϕ 4 Wilson-Fisher CFT, the Lee-Yang CFTs and the Ising CFTs are consistent with the universal relations from the minimal fusion rule ϕ 1 × ϕ 1 = I + ϕ 2 + T , where ϕ 1 , ϕ 2 are scalar operators, I is the identity operator and T is the stress tensor.
International Nuclear Information System (INIS)
Arnfors, Linda; Hansen, Thomas; Meining, Winfried; Schönheit, Peter; Ladenstein, Rudolf
2005-01-01
Nucleoside kinase from the hyperthermophilic archaeon M. jannaschii is a member of the PFK-B family which belongs to the ribokinase superfamily. Here, its expression, purification, crystallization and preliminary X-ray analysis are described. Methanocaldococcus jannaschii nucleoside kinase (MjNK) is an ATP-dependent non-allosteric phosphotransferase that shows high catalytic activity for guanosine, inosine and cytidine. MjNK is a member of the phosphofructokinase B family, but participates in the biosynthesis of nucleoside monophosphates rather than in glycolysis. MjNK was crystallized as the apoenzyme as well as in complex with an ATP analogue and Mg 2+ . The latter crystal form was also soaked with fructose-6-phosphate. Synchrotron-radiation data were collected to 1.70 Å for the apoenzyme crystals and 1.93 Å for the complex crystals. All crystals exhibit orthorhombic symmetry; however, the apoenzyme crystals contain one monomer per asymmetric unit whereas the complex crystals contain a dimer
Gaston, Kirk W; Limbach, Patrick A
2014-01-01
The analysis of ribonucleic acids (RNA) by mass spectrometry has been a valuable analytical approach for more than 25 years. In fact, mass spectrometry has become a method of choice for the analysis of modified nucleosides from RNA isolated out of biological samples. This review summarizes recent progress that has been made in both nucleoside and oligonucleotide mass spectral analysis. Applications of mass spectrometry in the identification, characterization and quantification of modified nucleosides are discussed. At the oligonucleotide level, advances in modern mass spectrometry approaches combined with the standard RNA modification mapping protocol enable the characterization of RNAs of varying lengths ranging from low molecular weight short interfering RNAs (siRNAs) to the extremely large 23 S rRNAs. New variations and improvements to this protocol are reviewed, including top-down strategies, as these developments now enable qualitative and quantitative measurements of RNA modification patterns in a variety of biological systems. PMID:25616408
Gaston, Kirk W; Limbach, Patrick A
2014-01-01
The analysis of ribonucleic acids (RNA) by mass spectrometry has been a valuable analytical approach for more than 25 years. In fact, mass spectrometry has become a method of choice for the analysis of modified nucleosides from RNA isolated out of biological samples. This review summarizes recent progress that has been made in both nucleoside and oligonucleotide mass spectral analysis. Applications of mass spectrometry in the identification, characterization and quantification of modified nucleosides are discussed. At the oligonucleotide level, advances in modern mass spectrometry approaches combined with the standard RNA modification mapping protocol enable the characterization of RNAs of varying lengths ranging from low molecular weight short interfering RNAs (siRNAs) to the extremely large 23 S rRNAs. New variations and improvements to this protocol are reviewed, including top-down strategies, as these developments now enable qualitative and quantitative measurements of RNA modification patterns in a variety of biological systems.
International Nuclear Information System (INIS)
Scholes, M.L.; Schuchmann, M.N.; Sonntag, C. von
1992-01-01
The effect of pH on base release in the γ-radiolysis of N 2 O-saturated solutions of a number of nucleosides (including uridine, 3-methyluridine, 2', 3' -O-isopropylidene-uridine, and adenosine) has been investigated. For all these nucleosides, independent of the base or sugar moiety, base release is very low at pH below 10 (G∼(0.3-0.7) x 10 -7 mol J -1 ), but increases drastically to G∼(3-4) x 10 -7 mol J -1 at pH ≥ 13. It is concluded that the increase in base release at high pH is caused by the increasing participation of O .- , which, unlike . OH, attacks the nucleosides preferentially at their sugar moieties, and is not due to an OH - -induced radical transfer from the base to the sugar moiety. (author)
Conformal radiotherapy: principles and classification
International Nuclear Information System (INIS)
Rosenwald, J.C.; Gaboriaud, G.; Pontvert, D.
1999-01-01
'Conformal radiotherapy' is the name fixed by usage and given to a new form of radiotherapy resulting from the technological improvements observed during the last ten years. While this terminology is now widely used, no precise definition can be found in the literature. Conformal radiotherapy refers to an approach in which the dose distribution is more closely 'conformed' or adapted to the actual shape of the target volume. However, the achievement of a consensus on a more specific definition is hampered by various difficulties, namely in characterizing the degree of 'conformality'. We have therefore suggested a classification scheme be established on the basis of the tools and the procedures actually used for all steps of the process, i.e., from prescription to treatment completion. Our classification consists of four levels: schematically, at level 0, there is no conformation (rectangular fields); at level 1, a simple conformation takes place, on the basis of conventional 2D imaging; at level 2, a 3D reconstruction of the structures is used for a more accurate conformation; and level 3 includes research and advanced dynamic techniques. We have used our personal experience, contacts with colleagues and data from the literature to analyze all the steps of the planning process, and to define the tools and procedures relevant to a given level. The corresponding tables have been discussed and approved at the European level within the Dynarad concerted action. It is proposed that the term 'conformal radiotherapy' be restricted to procedures where all steps are at least at level 2. (author)
Conformal Cosmology and Supernova Data
Behnke, Danilo; Blaschke, David; Pervushin, Victor; Proskurin, Denis
2000-01-01
We define the cosmological parameters $H_{c,0}$, $\\Omega_{m,c}$ and $\\Omega_{\\Lambda, c}$ within the Conformal Cosmology as obtained by the homogeneous approximation to the conformal-invariant generalization of Einstein's General Relativity theory. We present the definitions of the age of the universe and of the luminosity distance in the context of this approach. A possible explanation of the recent data from distant supernovae Ia without a cosmological constant is presented.
Scalar perturbations and conformal transformation
International Nuclear Information System (INIS)
Fabris, J.C.; Tossa, J.
1995-11-01
The non-minimal coupling of gravity to a scalar field can be transformed into a minimal coupling through a conformal transformation. We show how to connect the results of a perturbation calculation, performed around a Friedman-Robertson-Walker background solution, before and after the conformal transformation. We work in the synchronous gauge, but we discuss the implications of employing other frames. (author). 16 refs
Cu(I)-catalyzed efficient synthesis of 2′-Triazolo-nucleoside conjugates
DEFF Research Database (Denmark)
Mathur, D.; Rana, N.; Olsen, Carl Erik
2015-01-01
-nucleoside conjugates, which can be evaluated for different biological activity for suitable drug development, were unambiguously identified on the basis of 1H NMR, 13C NMR, IR, and HRMS data analysis. These compounds have been synthesized for the first time and have not been reported in the literature earlier.......A small library of thirty-two 2′-triazolyl uridine and 2′-triazolyl-5-methyluridine has been synthesized by Cu(I)-catalyzed condensation of 2′-azido-2′-deoxyuridine and 2′-azido-2′-deoxy-5-methyluridine with different alkynes and aryl propargyl ethers in almost quantitative yields. Triazolo...
Directory of Open Access Journals (Sweden)
Nicolas Sluis-Cremer
2013-11-01
Full Text Available HIV-1 reverse transcriptase (RT plays a central role in HIV infection. Current United States Federal Drug Administration (USFDA-approved antiretroviral therapies can include one of five approved non-nucleoside RT inhibitors (NNRTIs, which are potent inhibitors of RT activity. Despite their crucial clinical role in treating and preventing HIV-1 infection, their mechanism of action remains elusive. In this review, we introduce RT and highlight major advances from experimental and computational biophysical experiments toward an understanding of RT function and the inhibitory mechanism(s of NNRTIs.
Pyrimidine and nucleoside gamma-esters of L-Glu-Sar
DEFF Research Database (Denmark)
Eriksson, André H; Elm, Peter L; Begtrup, Mikael
2005-01-01
-tetrahydrofuran-3-yl ester)-Sar (I), l-Glu(thymine-1-yl-methyl ester)-Sar (II) and l-Glu(acyclothymidine)-Sar (III) were synthesised and in vitro stability was studied in various aqueous and biological media. Affinity to and translocation via hPEPT1 was investigated in mature Caco-2 cell monolayers, grown......The aim of the present study was to improve the synthetic pathway of bioreversible dipeptide derivatives as well as evaluate the potential of using l-Glu-Sar as a pro-moiety for delivering three newly synthesised nucleoside and pyrimidine l-Glu-Sar derivatives. l-Glu(trans-2-thymine-1-yl...
Evaluation of localized bacterial infection using radioisotope-labeled nucleosides imaging modality
Energy Technology Data Exchange (ETDEWEB)
Jang, Su Jin; Kang, Joo Hyun; Lee, Yong Jin; Lee, Tae Sup; Kim, Kwang Il; Lee, Kyo Chul; An, Gwang II; Cheon, Gi Jeong; Lim, Sang Moo [KIRAMS, Seoul (Korea, Republic of); Lim, Sang Yong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2011-10-15
Conventional diagnostic methods for infections are difficult to distinguish localized bacterial infections from sites of sterile inflammation. For this reason, the importance of developing methods to image bacterial infections is widely recognized. In this study to acquire bacterial infection imaging with radiolabeled nucleosides, in vitro bacterial thymidine kinase (tk) activities of Salmonella typhimurium with [{sup 18}F]FLT and [{sup 125}I]IVDU were measured and localized infections model in BALB/c mice was imaged with [{sup 18}F]FLT or [{sup 125}I]FIAU
Template-directed addition of nucleosides to DNA by the BfiI restriction enzyme
Sasnauskas, Giedrius; Connolly, Bernard A.; Halford, Stephen E.; Siksnys, Virginijus
2008-01-01
Restriction endonucleases catalyse DNA cleavage at specific sites. The BfiI endonuclease cuts DNA to give staggered ends with 1-nt 3′-extensions. We show here that BfiI can also fill in the staggered ends: while cleaving DNA, it can add a 2′-deoxynucleoside to the reaction product to yield directly a blunt-ended DNA. We propose that nucleoside incorporation proceeds through a two-step reaction, in which BfiI first cleaves the DNA to make a covalent enzyme–DNA intermediate and then resolves it...
Synthesis and in vitro growth inhibitory activity of novel silyl- and trityl-modified nucleosides
CSIR Research Space (South Africa)
Panayides, Jenny-Lee
2016-06-01
Full Text Available -Farkas d, Hajierah Davids d,e , Leonie Harmse d , M. E. Christine Rey f , Ivan R. Green g, Stephen C. Pelly g, Robert Kiss c, Alexander Kornienko h, Willem A. L. van Otterlo a,g,⇑ a Molecular Sciences Institute, School of Chemistry, University..., Matieland 7602, South Africa hDepartment of Chemistry and Biochemistry, Texas State University, San Marcos, TX 78666, USA Abstract Seventeen silyl- and trityl-modified (5'-O- and 3',5'-di-O-) nucleosides were synthesized with the aim of investigating...
Verification of the Rigidity of the Coulomb Field in Motion
Blinov, S. V.; Bulyzhenkov, I. É.
2018-06-01
Laplace, analyzing the stability of the Solar System, was the first to calculate that the velocity of the motion of force fields can significantly exceed the velocity of light waves. In electrodynamics, the Coulomb field should rigidly accompany its source for instantaneous force action in distant regions. Such rigid motion was recently inferred from experiments at the Frascati Beam Test Facility with short beams of relativistic electrons. The comments of the authors on their observations are at odds with the comments of theoreticians on retarded potentials, which motivates a detailed study of the positions of both sides. Predictions of measurements, based on the Lienard-Wiechert potentials, are used to propose an unambiguous scheme for testing the rigidity of the Coulomb field. Realization of the proposed experimental scheme could independently refute or support the assertions of the Italian physicists regarding the rigid motion of Coulomb fields and likewise the nondual field approach to macroscopic reality.
Oscillations of rigid bar in the special relativity
International Nuclear Information System (INIS)
Paiva, F.M.; Teixeira, A.F.F.
2011-12-01
In the special relativity, a rigid bar slides on herself, with a extreme oscillating harmonically. We have discovered at the movement amplitude and in the bar length, indispensable for the elimination of non physical solutions
Rigid body motion in stereo 3D simulation
International Nuclear Information System (INIS)
Zabunov, Svetoslav
2010-01-01
This paper addresses the difficulties experienced by first-grade students studying rigid body motion at Sofia University. Most quantities describing the rigid body are in relations that the students find hard to visualize and understand. They also lose the notion of cause-result relations between vector quantities, such as the relation between torque and angular momentum. Consequently, the understanding of physical laws and conservation principles in free rigid body motion is hampered. This paper presents the capabilities of a 3D simulation, which aims to clarify these questions to the students, who are taught mechanics in the general physics course. The rigid body motion simulations may be observed at http://ialms.net/sim/, and are intended to complement traditional learning practices, not replace them, as the author shares the opinion that no simulation may fully resemble reality.
Resin Infusion Rigidized Inflatable Concept Development and Demonstration
National Aeronautics and Space Administration — A novel concept utilizing resin infusion to rigidize inflatable structures was developed at JSC ES. This ICA project intends to complete manufacturing of a prototype...
Genus Ranges of 4-Regular Rigid Vertex Graphs.
Buck, Dorothy; Dolzhenko, Egor; Jonoska, Nataša; Saito, Masahico; Valencia, Karin
2015-01-01
A rigid vertex of a graph is one that has a prescribed cyclic order of its incident edges. We study orientable genus ranges of 4-regular rigid vertex graphs. The (orientable) genus range is a set of genera values over all orientable surfaces into which a graph is embedded cellularly, and the embeddings of rigid vertex graphs are required to preserve the prescribed cyclic order of incident edges at every vertex. The genus ranges of 4-regular rigid vertex graphs are sets of consecutive integers, and we address two questions: which intervals of integers appear as genus ranges of such graphs, and what types of graphs realize a given genus range. For graphs with 2 n vertices ( n > 1), we prove that all intervals [ a, b ] for all a genus ranges. For graphs with 2 n - 1 vertices ( n ≥ 1), we prove that all intervals [ a, b ] for all a genus ranges. We also provide constructions of graphs that realize these ranges.
Re-analysis of exponential rigid-rotor astron equilibria
International Nuclear Information System (INIS)
Lovelace, R.V.; Larrabee, D.A.; Fleischmann, H.H.
1978-01-01
Previous studies of exponential rigid-rotor astron equilibria include particles which are not trapped in the self-field of the configuration. The modification of these studies required to exclude untrapped particles is derived
Rigidity theorem for Willmore surfaces in a sphere
Indian Academy of Sciences (India)
Home; Journals; Proceedings – Mathematical Sciences; Volume 126; Issue 2. Rigidity ... Center of Mathematical Sciences, Zhejiang University, Hangzhou 310027, People's Republic of China; College of Mathematics and Information Science, Jiangxi Normal University, Nanchang 330022, People's Republic of China ...
Role of Rigid Endoscopic Detorsion in the Management of Sigmoid ...
African Journals Online (AJOL)
had emergency surgery, with gangrenous bowel noted in 43 (72%) ... of any stable patient with clinical and radiological features ... peritonitis, underwent repeat rigid sigmoidoscopy. ... endoscopic detorsion was successful in all six cases.
Magnetism and magnetostriction in a degenerate rigid band
International Nuclear Information System (INIS)
Kulakowski, K.; Barbara, B.
1990-09-01
We investigate the influence of the spin-orbit coupling on the magnetic and magnetoelastic phenomena in ferromagnetic band systems. The description is within the Stoner model of a degenerate rigid band, for temperature T = O. (author). 14 refs
Stabilization of Rigid Body Dynamics by Internal and External Torques
National Research Council Canada - National Science Library
Bloch, A. M; Krishnaprasad, P. S; Marsden, J. E; Sanchez de Alvarez, G
1990-01-01
...] with quadratic feedback torques for internal rotors. We show that with such torques, the equations for the rigid body with momentum wheels are Hamiltonian with respect to a Lie-Poisson bracket structure. Further...
Anti-synchronization of the rigid body exhibiting chaotic dynamics ...
African Journals Online (AJOL)
Based on a method derived from nonlinear control theory, we present a ... In this framework, the active control technique is modified and employed to design control ... state space of the two rigid bodies was verified by numerical simulations.
Ortiz, Diana; Valdés, Raquel; Sanchez, Marco A.; Hayenga, Johanna; Elya, Carolyn; Detke, Siegfried; Landfear, Scott M.
2010-01-01
Leishmania and other parasitic protozoa are unable to synthesize purines de novo and are reliant upon purine nucleoside and nucleobase transporters to import preformed purines from their hosts. To study the roles of the four purine permeases NT1-NT4 in Leishmania major, null mutants in each transporter gene were prepared and the effect of each gene deletion on purine uptake was monitored. Deletion of the NT3 purine nucleobase transporter gene or both NT3 and the NT2 nucleoside transporter gen...
1981-09-01
of the nitrate salt or degradation of the starting heterocycle. An alternate procedure for obtaining aromatic nitro compounds is the oxidation of the...SAcO OAc AcO OAc RO OR S102 99103, R-Ac 1--04, RC H -OH N HcO 0 cOY RO HO O Ac RO OR 102 0_6 103, R - Ac 108, R = H 6- mercaptopurine riboside...occurring C-nucleoside antibiotic and unlike N-nucleosides, formycin B will not suffer enzymatic cleavage * 29 and degradation by phosphorolysis
Quantum Conformal Algebras and Closed Conformal Field Theory
Anselmi, D
1999-01-01
We investigate the quantum conformal algebras of N=2 and N=1 supersymmetric gauge theories. Phenomena occurring at strong coupling are analysed using the Nachtmann theorem and very general, model-independent, arguments. The results lead us to introduce a novel class of conformal field theories, identified by a closed quantum conformal algebra. We conjecture that they are the exact solution to the strongly coupled large-N_c limit of the open conformal field theories. We study the basic properties of closed conformal field theory and work out the operator product expansion of the conserved current multiplet T. The OPE structure is uniquely determined by two central charges, c and a. The multiplet T does not contain just the stress-tensor, but also R-currents and finite mass operators. For this reason, the ratio c/a is different from 1. On the other hand, an open algebra contains an infinite tower of non-conserved currents, organized in pairs and singlets with respect to renormalization mixing. T mixes with a se...
[Determination of 5 nucleosides components in culture of Paecilomyces hepialid by HPLC].
Yang, Dan; Ma, Yun-shu; Huang, Ting-ting; Chen, Cheng
2015-08-01
The concentration of 5 nucleosides, uracil, uridine, guanidine, adenine and adenosine in culture of Paecilomyces hepialid was determined by the developed method of HPLC. The HPLC method was performed on a Waters SunFire C18 (4.6 mm x 250 mm, 5 μm) column with methanol-water gradient elution as the mobile phase. The detection wavelength was 260 nm and the colunmn temperature was controlled at 30 °C. The linear range was 10.00-200.00 mg · L(-1) (r = 0.9994) for uracil, 10.10-202.00 mg · L(-1) (r = 0.9992) for uridine, 10.00-200.00 mg · L(-1) (r = 0.9991) for guanidine, 10.30-206.00 mg · L(-1) (r = 0.9992) for adenine and 10.45-209.00 mg · L(-1) (r = 0.9991) for adenosine, respectively. The RSD of precision was 0.032%, 0.035%, 0.039%, 0.049%, 0.00080%, respectively. The average recoveries of uracil, guanidine, adenine, and adenosine were 97.34%, 99.10%, 101.6%, 98.61% and 100.2% with RSD of 1.3%, 2.1%, 0.96%, 0.95%, and 1.3% respectively. The method showed high sensitivity, good selectivity, linearity and repeatability, which was suitable for the content analysis of 5 nucleosides components in P. hepialid and its extracts.
International Nuclear Information System (INIS)
Gómez Barroso, J. A.; Pereira, H.; Miranda, M.; Pereira, C.; Garratt, R. C.; Aguilar, C. F.
2010-01-01
T. cruzi TcNDPK1 was overexpressed in Escherichia coli as an N-terminally poly-His-tagged fusion protein and crystallized. The flagellated protozoan parasite Trypanosoma cruzi is the aetiological agent of Chagas disease. Nucleoside diphosphate kinases (NDPKs) are enzymes that are involved in energy management and nucleoside balance in the cell. T. cruzi TcNDPK1, a canonical isoform, was overexpressed in Escherichia coli as an N-terminally poly-His-tagged fusion protein and crystallized. Crystals grew after 72 h in 0.2 M MgCl 2 , 20% PEG 3350. Data were collected to 3.5 Å resolution using synchrotron X-ray radiation at the National Synchrotron Light Laboratory (Campinas, Brazil). The crystals belonged to the trigonal space group P3, with unit-cell parameters a = b = 127.84, c = 275.49 Å. Structure determination is under way and will provide relevant information that may lead to the first step in rational drug design for the treatment of Chagas disease
Crystallization and preliminary X ray analysis of nucleoside diphosphate kinase 1 from T. cruzi
International Nuclear Information System (INIS)
Gomez Barroso, J.A.; Aguilar, C.F.; Miranda, M.R.; Pereira, C.A.
2009-01-01
Introduction: Trypanosoma cruzi is the etiologic agent of Chagas disease. The Nucleoside diphosphate kinases (NDPKs) are enzymes involved in energy management and nucleoside balance in the cell. T. cruzi TcNDPK1, a canonical isoform. The objective of this work is obtaining protein's crystals, diffract and process the data for tridimensional structure resolution. Materials and Methods: TcNDPK1 was expressed in E. coli as a fusion protein with Nterminal His-tag. TcNDPK1 was overexpressed and purified by FPLC. Crystallization was assayed by sitting drop and hanging drop vapor diffusion method. Crystals was frozen and diffracted on synchrotron x-ray radiation in Campinas (Brasil). The data set collected was reduced and merged using MOSFLM and SCALA programs. Results and Discussion: His-TcNDPK was overexpressed, purified and crystallized. The crystals are diffracted and collected the data to 3.5A. The crystals belong to the trigonal space group P3, with unit cell parameters a=127.94, b=127.84, c=275.49. Structure determination is under way. These results will provide relevant information that could be the first step in rational drug design for treating Chagas disease.(authors)
Methylated nucleosides in tRNA and tRNA methyltransferases
Directory of Open Access Journals (Sweden)
Hiroyuki eHori
2014-05-01
Full Text Available To date, more than 90 modified nucleosides have been found in tRNA and the biosynthetic pathways of the majority of tRNA modifications include a methylation step(s. Recent studies of the biosynthetic pathways have demonstrated that the availability of methyl group donors for the methylation in tRNA is important for correct and efficient protein synthesis. In this review, I focus on the methylated nucleosides and tRNA methyltransferases. The primary functions of tRNA methylations are linked to the different steps of protein synthesis, such as the stabilization of tRNA structure, reinforcement of the codon–anticodon interaction, regulation of wobble base pairing, and prevention of frameshift errors. However, beyond these basic functions, recent studies have demonstrated that tRNA methylations are also involved in the RNA quality control system and regulation of tRNA localization in the cell. In a thermophilic eubacterium, tRNA modifications and the modification enzymes form a network that responses to temperature changes. Furthermore, several modifications are involved in genetic diseases, infections, and the immune response. Moreover, structural, biochemical, and bioinformatics studies of tRNA methyltransferases have been clarifying the details of tRNA methyltransferases and have enabled these enzymes to be classified. In the final section, the evolution of modification enzymes is discussed.
Sadek, Jouliana; Hernandez-Hopkins, Denise; Akar, Gunkut; Barelli, Peter J.; Sahai, Michelle A.; Zhou, Hufeng; Totonchy, Jennifer; Jayabalan, David; Niesvizky, Ruben; Guasparri, Ilaria; Liu, Yifang; Sei, Shizuko; Shoemaker, Robert H.; Elemento, Olivier; Kaye, Kenneth M.
2017-01-01
Primary effusion lymphoma (PEL) is a largely incurable malignancy of B cell origin with plasmacytic differentiation. Here, we report the identification of a highly effective inhibitor of PEL. This compound, 6-ethylthioinosine (6-ETI), is a nucleoside analog with toxicity to PEL in vitro and in vivo, but not to other lymphoma cell lines tested. We developed and performed resistome analysis, an unbiased approach based on RNA sequencing of resistant subclones, to discover the molecular mechanisms of sensitivity. We found different adenosine kinase–inactivating (ADK-inactivating) alterations in all resistant clones and determined that ADK is required to phosphorylate and activate 6-ETI. Further, we observed that 6-ETI induces ATP depletion and cell death accompanied by S phase arrest and DNA damage only in ADK-expressing cells. Immunohistochemistry for ADK served as a biomarker approach to identify 6-ETI–sensitive tumors, which we documented for other lymphoid malignancies with plasmacytic features. Notably, multiple myeloma (MM) expresses high levels of ADK, and 6-ETI was toxic to MM cell lines and primary specimens and had a robust antitumor effect in a disseminated MM mouse model. Several nucleoside analogs are effective in treating leukemias and T cell lymphomas, and 6-ETI may fill this niche for the treatment of PEL, plasmablastic lymphoma, MM, and other ADK-expressing cancers. PMID:28504647
Nayar, Utthara; Sadek, Jouliana; Reichel, Jonathan; Hernandez-Hopkins, Denise; Akar, Gunkut; Barelli, Peter J; Sahai, Michelle A; Zhou, Hufeng; Totonchy, Jennifer; Jayabalan, David; Niesvizky, Ruben; Guasparri, Ilaria; Hassane, Duane; Liu, Yifang; Sei, Shizuko; Shoemaker, Robert H; Warren, J David; Elemento, Olivier; Kaye, Kenneth M; Cesarman, Ethel
2017-06-01
Primary effusion lymphoma (PEL) is a largely incurable malignancy of B cell origin with plasmacytic differentiation. Here, we report the identification of a highly effective inhibitor of PEL. This compound, 6-ethylthioinosine (6-ETI), is a nucleoside analog with toxicity to PEL in vitro and in vivo, but not to other lymphoma cell lines tested. We developed and performed resistome analysis, an unbiased approach based on RNA sequencing of resistant subclones, to discover the molecular mechanisms of sensitivity. We found different adenosine kinase-inactivating (ADK-inactivating) alterations in all resistant clones and determined that ADK is required to phosphorylate and activate 6-ETI. Further, we observed that 6-ETI induces ATP depletion and cell death accompanied by S phase arrest and DNA damage only in ADK-expressing cells. Immunohistochemistry for ADK served as a biomarker approach to identify 6-ETI-sensitive tumors, which we documented for other lymphoid malignancies with plasmacytic features. Notably, multiple myeloma (MM) expresses high levels of ADK, and 6-ETI was toxic to MM cell lines and primary specimens and had a robust antitumor effect in a disseminated MM mouse model. Several nucleoside analogs are effective in treating leukemias and T cell lymphomas, and 6-ETI may fill this niche for the treatment of PEL, plasmablastic lymphoma, MM, and other ADK-expressing cancers.
Wendelsdorf, Katherine V.; Song, Zhuo; Cao, Yang; Samuels, David C.
2009-01-01
Nucleoside analogs used in antiretroviral treatment have been associated with mitochondrial toxicity. The polymerase-γ hypothesis states that this toxicity stems from the analogs' inhibition of the mitochondrial DNA polymerase (polymerase-γ) leading to mitochondrial DNA (mtDNA) depletion. We have constructed a computational model of the interaction of polymerase-γ with activated nucleoside and nucleotide analog drugs, based on experimentally measured reaction rates and base excision rates, together with the mtDNA genome size, the human mtDNA sequence, and mitochondrial dNTP concentrations. The model predicts an approximately 1000-fold difference in the activated drug concentration required for a 50% probability of mtDNA strand termination between the activated di-deoxy analogs d4T, ddC, and ddI (activated to ddA) and the activated forms of the analogs 3TC, TDF, AZT, FTC, and ABC. These predictions are supported by experimental and clinical data showing significantly greater mtDNA depletion in cell culture and patient samples caused by the di-deoxy analog drugs. For zidovudine (AZT) we calculated a very low mtDNA replication termination probability, in contrast to its reported mitochondrial toxicity in vitro and clinically. Therefore AZT mitochondrial toxicity is likely due to a mechanism that does not involve strand termination of mtDNA replication. PMID:19132079
Thioflavin T templates amyloid β(1-40) conformation and aggregation pathway
DEFF Research Database (Denmark)
Di Carlo, Maria Giovanna; Minicozzi, Velia; Foderà, Vito
2015-01-01
Aβ(1-40) peptide supramolecular assembly and fibril formation processes are widely recognized to have direct implications in the progression of Alzheimer's disease. The molecular basis of this biological process is still unknown and there is a strong need of developing effective strategies...... in turn rests on the reliability of the probe/labels involved. Here we present evidences of the effect of Thioflavin T (ThT), a worldwide used fluorescent dye to monitor amyloid growth, on the Aβ(1-40) conformation, stability and aggregation. By combining experimental information and Molecular Dynamics...... simulation results, we show that the presence of ThT in solution affects peptide conformation inducing peculiar supramolecular association. In particular ThT interactions with specific Aβ(1-40) residues promote a rigid partially-folded conformation which shifts the balance between different species...
Gauge fixing problem in the conformal QED
International Nuclear Information System (INIS)
Ichinose, Shoichi
1986-01-01
The gauge fixing problem in the conformal (spinor and scalar) QED is examined. For the analysis, we generalize Dirac's manifestly conformal-covariant formalism. It is shown that the (vector and matter) fields must obey a certain mixed (conformal and gauge) type of transformation law in order to fix the local gauge symmetry preserving the conformal invariance in the Lagrangian. (orig.)
40 CFR 93.154 - Conformity analysis.
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Conformity analysis. 93.154 Section 93...) DETERMINING CONFORMITY OF FEDERAL ACTIONS TO STATE OR FEDERAL IMPLEMENTATION PLANS Determining Conformity of General Federal Actions to State or Federal Implementation Plans § 93.154 Conformity analysis. Any Federal...
Conformal tension in string theories and M-theory
International Nuclear Information System (INIS)
Barros, Manuel; Ferrandez, Angel; Lucas, Pascual
2000-01-01
This paper deals with string theories and M-theories on backgrounds of the form AdSxM,M being a compact principal U(1)-bundle. These configurations are the natural settings to study Hopf T-dualities (Duff et al., Nucl. Phys. B 544 (1999) 145), and so to define duality chains connecting different string theories and M-theories. There is an increasing great interest in studying those properties (physical or geometrical) which are preserved along the duality chains. For example, it is known that Hopf T-dualities preserve the black hole entropies (Duff et al., Nucl. Phys. B 544 (1999) 145). In this paper we consider a two-parameter family of actions which constitutes a natural variation of the conformal total tension action (also known as Willmore-Chen functional in differential geometry). Then, we show that the existence of wide families of solutions (in particular compact solutions) for the corresponding motion equations is preserved along those duality chains. In particular, we exhibit ample classes of Willmore-Chen submanifolds with a reasonable degree of symmetry in a wide variety of conformal string theories and conformal M-theories, that in addition are solutions of a second variational problem known as the area-volume isoperimetric problem. These are good reasons to refer those submanifolds as the best worlds one can find in a conformal universe. The method we use to obtain this invariant under Hopf T-dualities is based on the principle of symmetric criticality. However, it is used in a two-fold sense. First to break symmetry and so to reduce variables. Second to gain rigidity in direct approaches to integrate the Euler-Lagrange equations. The existence of generalized elastic curves is also important in the explicit exhibition of those configurations. The relationship between solutions and elasticae can be regarded as a holographic property
Conformational Clusters of Phosphorylated Tyrosine.
Abdelrasoul, Maha; Ponniah, Komala; Mao, Alice; Warden, Meghan S; Elhefnawy, Wessam; Li, Yaohang; Pascal, Steven M
2017-12-06
Tyrosine phosphorylation plays an important role in many cellular and intercellular processes including signal transduction, subcellular localization, and regulation of enzymatic activity. In 1999, Blom et al., using the limited number of protein data bank (PDB) structures available at that time, reported that the side chain structures of phosphorylated tyrosine (pY) are partitioned into two conserved conformational clusters ( Blom, N.; Gammeltoft, S.; Brunak, S. J. Mol. Biol. 1999 , 294 , 1351 - 1362 ). We have used the spectral clustering algorithm to cluster the increasingly growing number of protein structures with pY sites, and have found that the pY residues cluster into three distinct side chain conformations. Two of these pY conformational clusters associate strongly with a narrow range of tyrosine backbone conformation. The novel cluster also highly correlates with the identity of the n + 1 residue, and is strongly associated with a sequential pYpY conformation which places two adjacent pY side chains in a specific relative orientation. Further analysis shows that the three pY clusters are associated with distinct distributions of cognate protein kinases.
Directory of Open Access Journals (Sweden)
Keskin Ozlem
2007-05-01
Full Text Available Abstract Background How antibodies recognize and bind to antigens can not be totally explained by rigid shape and electrostatic complimentarity models. Alternatively, pre-existing equilibrium hypothesis states that the native state of an antibody is not defined by a single rigid conformation but instead with an ensemble of similar conformations that co-exist at equilibrium. Antigens bind to one of the preferred conformations making this conformation more abundant shifting the equilibrium. Results Here, two antibodies, a germline antibody of 36–65 Fab and a monoclonal antibody, SPE7 are studied in detail to elucidate the mechanism of antibody-antigen recognition and to understand how a single antibody recognizes different antigens. An elastic network model, Anisotropic Network Model (ANM is used in the calculations. Pre-existing equilibrium is not restricted to apply to antibodies. Intrinsic fluctuations of eight proteins, from different classes of proteins, such as enzymes, binding and transport proteins are investigated to test the suitability of the method. The intrinsic fluctuations are compared with the experimentally observed ligand induced conformational changes of these proteins. The results show that the intrinsic fluctuations obtained by theoretical methods correlate with structural changes observed when a ligand is bound to the protein. The decomposition of the total fluctuations serves to identify the different individual modes of motion, ranging from the most cooperative ones involving the overall structure, to the most localized ones. Conclusion Results suggest that the pre-equilibrium concept holds for antibodies and the promiscuity of antibodies can also be explained this hypothesis: a limited number of conformational states driven by intrinsic motions of an antibody might be adequate to bind to different antigens.
Renyi entropy and conformal defects
Energy Technology Data Exchange (ETDEWEB)
Bianchi, Lorenzo [Humboldt-Univ. Berlin (Germany). Inst. fuer Physik; Hamburg Univ. (Germany). II. Inst. fuer Theoretische Physik; Meineri, Marco [Scuola Normale Superiore, Pisa (Italy); Perimeter Institute for Theoretical Physics, Waterloo, ON (Canada); Istituto Nazionale di Fisica Nucleare, Pisa (Italy); Myers, Robert C. [Perimeter Institute for Theoretical Physics, Waterloo, ON (Canada); Smolkin, Michael [California Univ., Berkely, CA (United States). Center for Theoretical Physics and Department of Physics
2016-04-18
We propose a field theoretic framework for calculating the dependence of Renyi entropies on the shape of the entangling surface in a conformal field theory. Our approach rests on regarding the corresponding twist operator as a conformal defect and in particular, we define the displacement operator which implements small local deformations of the entangling surface. We identify a simple constraint between the coefficient defining the two-point function of the displacement operator and the conformal weight of the twist operator, which consolidates a number of distinct conjectures on the shape dependence of the Renyi entropy. As an example, using this approach, we examine a conjecture regarding the universal coefficient associated with a conical singularity in the entangling surface for CFTs in any number of spacetime dimensions. We also provide a general formula for the second order variation of the Renyi entropy arising from small deformations of a spherical entangling surface, extending Mezei's results for the entanglement entropy.
Conformal dimension theory and application
Mackay, John M
2010-01-01
Conformal dimension measures the extent to which the Hausdorff dimension of a metric space can be lowered by quasisymmetric deformations. Introduced by Pansu in 1989, this concept has proved extremely fruitful in a diverse range of areas, including geometric function theory, conformal dynamics, and geometric group theory. This survey leads the reader from the definitions and basic theory through to active research applications in geometric function theory, Gromov hyperbolic geometry, and the dynamics of rational maps, amongst other areas. It reviews the theory of dimension in metric spaces and of deformations of metric spaces. It summarizes the basic tools for estimating conformal dimension and illustrates their application to concrete problems of independent interest. Numerous examples and proofs are provided. Working from basic definitions through to current research areas, this book can be used as a guide for graduate students interested in this field, or as a helpful survey for experts. Background needed ...
Elementary introduction to conformal invariance
International Nuclear Information System (INIS)
Grandati, Y.
1992-01-01
These notes constitute an elementary introduction to the concept of conformal invariance and its applications to the study of bidimensional critical phenomena. The aim is to give an access as pedestrian as possible to this vast subject. After a brief account of the general properties of conformal transformation in D dimensions, we study more specifically the case D = 2. The center of the discussion is then the consequences of the action of this symmetry group on bidimensional field theories, and in particular the links between the representations of the Virasoro algebra and the structure of the correlation functions of conformal field theories. Finally after showing how the Ising model reduces to a Majorana fermionic field theory, we see how the general formalism previously discussed can be applied to the Ising case at the critical point. (orig.)
Conformal geometry and quasiregular mappings
Vuorinen, Matti
1988-01-01
This book is an introduction to the theory of spatial quasiregular mappings intended for the uninitiated reader. At the same time the book also addresses specialists in classical analysis and, in particular, geometric function theory. The text leads the reader to the frontier of current research and covers some most recent developments in the subject, previously scatterd through the literature. A major role in this monograph is played by certain conformal invariants which are solutions of extremal problems related to extremal lengths of curve families. These invariants are then applied to prove sharp distortion theorems for quasiregular mappings. One of these extremal problems of conformal geometry generalizes a classical two-dimensional problem of O. Teichmüller. The novel feature of the exposition is the way in which conformal invariants are applied and the sharp results obtained should be of considerable interest even in the two-dimensional particular case. This book combines the features of a textbook an...
Renyi entropy and conformal defects
International Nuclear Information System (INIS)
Bianchi, Lorenzo; Myers, Robert C.; Smolkin, Michael
2016-01-01
We propose a field theoretic framework for calculating the dependence of Renyi entropies on the shape of the entangling surface in a conformal field theory. Our approach rests on regarding the corresponding twist operator as a conformal defect and in particular, we define the displacement operator which implements small local deformations of the entangling surface. We identify a simple constraint between the coefficient defining the two-point function of the displacement operator and the conformal weight of the twist operator, which consolidates a number of distinct conjectures on the shape dependence of the Renyi entropy. As an example, using this approach, we examine a conjecture regarding the universal coefficient associated with a conical singularity in the entangling surface for CFTs in any number of spacetime dimensions. We also provide a general formula for the second order variation of the Renyi entropy arising from small deformations of a spherical entangling surface, extending Mezei's results for the entanglement entropy.
Blanckenberg, Daniel H.; Wood, Robin; Horban, Andrzej; Beniowski, Marek; Boron-Kaczmarska, Anna; Trocha, Hanna; Halota, Waldemar; Schmidt, Reinhold E.; Fatkenheuer, G.; Jessen, Heiko; Lange, Joep M. A.
2004-01-01
Objective: To examine the effect of adding nevirapine (NVP) and/or hydroxyurea (HU) to a triple nucleoside analogue reverse transcriptase inhibitor (NRTI) regimen in terms of efficacy and tolerability. Methods: HIV-1-infected, treatment-naive adults were randomized, using a factorial design, to add
Czech Academy of Sciences Publication Activity Database
Břehová, Petra; Česnek, Michal; Dračínský, Martin; Holý, Antonín; Janeba, Zlatko
2011-01-01
Roč. 67, č. 38 (2011), s. 7379-7385 ISSN 0040-4020 R&D Projects: GA MŠk 1M0508 Institutional research plan: CEZ:AV0Z40550506 Keywords : Liebeskind-Srogl cross - coupling * acyclic nucleoside phosphonates * pyrimidines * arylboronic acids * microwave Subject RIV: CC - Organic Chemistry Impact factor: 3.025, year: 2011
Czech Academy of Sciences Publication Activity Database
Kaiser, Martin Maxmilian; Baszczyňski, Ondřej; Hocková, Dana; Poštová Slavětínská, Lenka; Dračínský, Martin; Keough, D. T.; Guddat, L. W.; Janeba, Zlatko
2017-01-01
Roč. 12, č. 14 (2017), s. 1133-1141 ISSN 1860-7179 R&D Projects: GA ČR(CZ) GA16-06049S Institutional support: RVO:61388963 Keywords : inhibitors * nucleosides * malaria * phosphonates * purine salvage Subject RIV: CC - Organic Chemistry OBOR OECD: Organic chemistry Impact factor: 3.225, year: 2016
Czech Academy of Sciences Publication Activity Database
Kaiser, Martin Maxmilian; Hocková, Dana; Wang, T. H.; Dračínský, Martin; Poštová Slavětínská, Lenka; Procházková, Eliška; Edstein, M. D.; Chavchich, M.; Keough, D. T.; Guddat, L. W.; Janeba, Zlatko
2015-01-01
Roč. 10, č. 10 (2015), s. 1707-1723 ISSN 1860-7179 R&D Projects: GA MV VG20102015046; GA ČR GAP207/11/0108 Institutional support: RVO:61388963 Keywords : 6-oxopurine * acyclic nucleoside phosphonates * phosphoribosyltransferases * malaria * phosphoramidates Subject RIV: CC - Organic Chemistry Impact factor: 2.980, year: 2015
SUSY Unparticle and Conformal Sequestering
Energy Technology Data Exchange (ETDEWEB)
Nakayama, Yu; Nakayama, Yu
2007-07-17
We investigate unparticle physics with supersymmetry (SUSY). The SUSY breaking effects due to the gravity mediation induce soft masses for the SUSY unparticles and hence break the conformal invariance. The unparticle physics observable in near future experiments is only consistent if the SUSY breakingeffects from the hidden sector to the standard model sector are dominated by the gauge mediation, or if the SUSY breaking effects to the unparticle sector are sufficiently sequestered. We argue that the natural realization of the latter possibility is the conformal sequestering scenario.
Epigenetic dominance of prion conformers.
Directory of Open Access Journals (Sweden)
Eri Saijo
2013-10-01
Full Text Available Although they share certain biological properties with nucleic acid based infectious agents, prions, the causative agents of invariably fatal, transmissible neurodegenerative disorders such as bovine spongiform encephalopathy, sheep scrapie, and human Creutzfeldt Jakob disease, propagate by conformational templating of host encoded proteins. Once thought to be unique to these diseases, this mechanism is now recognized as a ubiquitous means of information transfer in biological systems, including other protein misfolding disorders such as those causing Alzheimer's and Parkinson's diseases. To address the poorly understood mechanism by which host prion protein (PrP primary structures interact with distinct prion conformations to influence pathogenesis, we produced transgenic (Tg mice expressing different sheep scrapie susceptibility alleles, varying only at a single amino acid at PrP residue 136. Tg mice expressing ovine PrP with alanine (A at (OvPrP-A136 infected with SSBP/1 scrapie prions propagated a relatively stable (S prion conformation, which accumulated as punctate aggregates in the brain, and produced prolonged incubation times. In contrast, Tg mice expressing OvPrP with valine (V at 136 (OvPrP-V136 infected with the same prions developed disease rapidly, and the converted prion was comprised of an unstable (U, diffusely distributed conformer. Infected Tg mice co-expressing both alleles manifested properties consistent with the U conformer, suggesting a dominant effect resulting from exclusive conversion of OvPrP-V136 but not OvPrP-A136. Surprisingly, however, studies with monoclonal antibody (mAb PRC5, which discriminates OvPrP-A136 from OvPrP-V136, revealed substantial conversion of OvPrP-A136. Moreover, the resulting OvPrP-A136 prion acquired the characteristics of the U conformer. These results, substantiated by in vitro analyses, indicated that co-expression of OvPrP-V136 altered the conversion potential of OvPrP-A136 from the S to
Topics in conformal field theory
International Nuclear Information System (INIS)
Kiritsis, E.B.
1988-01-01
In this work two major topics in Conformal Field Theory are discussed. First a detailed investigation of N = 2 Superconformal theories is presented. The structure of the representations of the N = 2 superconformal algebras is investigated and the character formulae are calculated. The general structure of N = 2 superconformal theories is elucidated and the operator algebra of the minimal models is derived. The first minimal system is discussed in more detail. Second, applications of the conformal techniques are studied in the Ashkin-Teller model. The c = 1 as well as the c = 1/2 critical lines are discussed in detail
Semiflexible polymer conformation, distribution and migration in microcapillary flows
Energy Technology Data Exchange (ETDEWEB)
Chelakkot, Raghunath; Gompper, Gerhard [Institut fuer Festkoerperforschung, Forschungszentrum Juelich, 52425 Juelich (Germany); Winkler, Roland G [Institute for Advanced Simulation, Forschungszentrum Juelich, 52425 Juelich (Germany)
2011-05-11
The flow behavior of a semiflexible polymer in microchannels is studied using multiparticle collision dynamics, a particle-based hydrodynamic simulation technique. Conformations, distributions, and radial cross-streamline migration are investigated for various bending rigidities, with persistence lengths L{sub p} in the range 0.5 {<=} L{sub p}/L{sub r} {<=} 30. The flow behavior is governed by the competition between a hydrodynamic lift force and steric repulsion from the wall, which lead to migration away from the wall, and a locally varying flow induced orientation, which drives the polymer away from the channel center and towards the wall. The different dependences of these effects on the polymer bending rigidity and the flow velocity results in a complex dynamical behavior. However, a generic effect is the appearance of a maximum in the monomer and the center-of-mass distributions, which occurs at the channel center for small flow velocities, but moves off-center at higher velocities.
Large area nanoimprint by substrate conformal imprint lithography (SCIL)
Verschuuren, Marc A.; Megens, Mischa; Ni, Yongfeng; van Sprang, Hans; Polman, Albert
2017-06-01
Releasing the potential of advanced material properties by controlled structuring materials on sub-100-nm length scales for applications such as integrated circuits, nano-photonics, (bio-)sensors, lasers, optical security, etc. requires new technology to fabricate nano-patterns on large areas (from cm2 to 200 mm up to display sizes) in a cost-effective manner. Conventional high-end optical lithography such as stepper/scanners is highly capital intensive and not flexible towards substrate types. Nanoimprint has had the potential for over 20 years to bring a cost-effective, flexible method for large area nano-patterning. Over the last 3-4 years, nanoimprint has made great progress towards volume production. The main accelerator has been the switch from rigid- to wafer-scale soft stamps and tool improvements for step and repeat patterning. In this paper, we discuss substrate conformal imprint lithography (SCIL), which combines nanometer resolution, low patterns distortion, and overlay alignment, traditionally reserved for rigid stamps, with the flexibility and robustness of soft stamps. This was made possible by a combination of a new soft stamp material, an inorganic resist, combined with an innovative imprint method. Finally, a volume production solution will be presented, which can pattern up to 60 wafers per hour.
Soft-matter composites with electrically tunable elastic rigidity
International Nuclear Information System (INIS)
Shan, Wanliang; Lu, Tong; Majidi, Carmel
2013-01-01
We use a phase-changing metal alloy to reversibly tune the elastic rigidity of an elastomer composite. The elastomer is embedded with a sheet of low-melting-point Field’s metal and an electric Joule heater composed of a serpentine channel of liquid-phase gallium–indium–tin (Galinstan ® ) alloy. At room temperature, the embedded Field’s metal is solid and the composite remains elastically rigid. Joule heating causes the Field’s metal to melt and allows the surrounding elastomer to freely stretch and bend. Using a tensile testing machine, we measure that the effective elastic modulus of the composite reversibly changes by four orders of magnitude when powered on and off. This dramatic change in rigidity is accurately predicted with a model for an elastic composite. Reversible rigidity control is also accomplished by replacing the Field’s metal with shape memory polymer. In addition to demonstrating electrically tunable rigidity with an elastomer, we also introduce a new technique to rapidly produce soft-matter electronics and multifunctional materials in several minutes with laser-patterned adhesive film and masked deposition of liquid-phase metal alloy. (paper)
Soft-matter composites with electrically tunable elastic rigidity
Shan, Wanliang; Lu, Tong; Majidi, Carmel
2013-08-01
We use a phase-changing metal alloy to reversibly tune the elastic rigidity of an elastomer composite. The elastomer is embedded with a sheet of low-melting-point Field’s metal and an electric Joule heater composed of a serpentine channel of liquid-phase gallium-indium-tin (Galinstan®) alloy. At room temperature, the embedded Field’s metal is solid and the composite remains elastically rigid. Joule heating causes the Field’s metal to melt and allows the surrounding elastomer to freely stretch and bend. Using a tensile testing machine, we measure that the effective elastic modulus of the composite reversibly changes by four orders of magnitude when powered on and off. This dramatic change in rigidity is accurately predicted with a model for an elastic composite. Reversible rigidity control is also accomplished by replacing the Field’s metal with shape memory polymer. In addition to demonstrating electrically tunable rigidity with an elastomer, we also introduce a new technique to rapidly produce soft-matter electronics and multifunctional materials in several minutes with laser-patterned adhesive film and masked deposition of liquid-phase metal alloy.
Unified Creep Plasticity Damage (UCPD) Model for Rigid Polyurethane Foams.
Energy Technology Data Exchange (ETDEWEB)
Neilsen, Michael K. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lu, Wei-Yang [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Scherzinger, William M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hinnerichs, Terry D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lo, Chi S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2015-06-01
Numerous experiments were performed to characterize the mechanical response of several different rigid polyurethane foams (FR3712, PMDI10, PMDI20, and TufFoam35) to large deformation. In these experiments, the effects of load path, loading rate, and temperature were investigated. Results from these experiments indicated that rigid polyurethane foams exhibit significant volumetric and deviatoric plasticity when they are compressed. Rigid polyurethane foams were also found to be very strain-rate and temperature dependent. These foams are also rather brittle and crack when loaded to small strains in tension or to larger strains in compression. Thus, a new Unified Creep Plasticity Damage (UCPD) model was developed and implemented into SIERRA with the name Foam Damage to describe the mechanical response of these foams to large deformation at a variety of temperatures and strain rates. This report includes a description of recent experiments and experimental findings. Next, development of a UCPD model for rigid, polyurethane foams is described. Selection of material parameters for a variety of rigid polyurethane foams is then discussed and finite element simulations with the new UCPD model are compared with experimental results to show behavior that can be captured with this model.
Satishkumar, Sakilam; Poudapally, Suresh; Vuram, Prasanna K; Gurram, Venkateshwarlu; Pottabathini, Narender; Sebastian, Dellamol; Yang, Lijia; Pradhan, Padmanava; Lakshman, Mahesh K
2017-11-09
In this work we have assessed reactions of N 6 -([1,1'-biaryl]-2-yl)adenine nucleosides with Pd(OAc) 2 and PhI(OAc) 2 , via a Pd II /Pd IV redox cycle. The substrates are readily obtained by Pd/Xantphos-catalyzed reaction of adenine nucleosides with 2-bromo-1,1'-biaryls. In PhMe, the N 6 -biarylyl nucleosides gave C6-carbazolyl nucleoside analogues by C-N bond formation with the exocyclic N 6 nitrogen atom. In the solvent screening for the Pd-catalyzed reactions, an uncatalyzed process was found to be operational. It was observed that the carbazolyl products could also be obtained in the absence of a metal catalyst by reaction with PhI(OAc) 2 in 1,1,1,3,3,3-hexafluoroisopropanol (HFIP). Thus, under Pd catalysis and in HFIP, reactions proceed to provide carbazolyl nucleoside analogues, with some differences. If reactions of N 6 -biarylyl nucleoside substrates were conducted in MeCN, formation of aryl benzimidazopurinyl nucleoside derivatives was observed in many cases by C-N bond formation with the N 1 ring nitrogen atom of the purine (carbazole and benzimidazole isomers are readily separated by chromatography). Whereas Pd II /Pd IV redox is responsible for carbazole formation under the metal-catalyzed conditions, in HFIP and MeCN radical cations and/or nitrenium ions can be intermediates. An extensive set of radical inhibition experiments was conducted and the data are presented.
Directory of Open Access Journals (Sweden)
Sujatha P Koduvayur
Full Text Available Cytotoxic drugs, such as nucleoside analogs and toxins, commonly suffer from off-target effects. One approach to mitigate this problem is to deliver the cytotoxic drug selectively to the intended site. While for toxins this can be achieved by conjugating the cell-killing moiety to a targeting moiety, it is not an option for nucleoside analogs, which rely on intracellular enzymes to convert them to their active triphosphorylated form. To overcome this limitation, and achieve site-targeted activation of nucleoside analogs, we fused the coding region of a prodrug-activating enzyme, deoxycytidine kinase (dCK, to affinity reagents that bind to the Her2 cell surface protein. We evaluated dCK fusions to an anti-Her2 affibody and Designed Ankyrin Repeat Protein (DARPin for their ability to kill cancer cells by promoting the activation of the nucleoside analog fludarabine. Cell staining and flow cytometry experiments with three Her2 positive cancer cell lines (BT-474-JB, JIMT-1 and SK-OV-3 indicate dCK fusions binding and cellular internalization. In contrast, these reagents bind only weakly to the Her2 negative cell line, MCF-7. Cell proliferation assays indicate that SK-OV-3 and BT-474-JB cell lines exhibit significantly reduced proliferation rates when treated with targeting-module fused dCK and fludarabine, compared to fludarabine alone. These findings demonstrate that we have succeeded in delivering active dCK into the Her2-positive cells, thereby increasing the activation of fludarabine, which ultimately reduces the dose of nucleoside analog needed for cell killing. This strategy may help establish the therapeutic index required to differentiate between healthy tissues and cancer cells.
Rigid external maxillary distraction and rhinoplasty for pyknodysostosis.
Varol, Altan; Sabuncuoglu, Fidan Alakus; Sencimen, Metin; Akcam, Timur; Olmez, Hüseyin; Basa, Selçuk
2011-05-01
This article reports the treatment of an 33-year-old female patient with pyknodysostosis by rigid external distraction II midface distraction system. The patient with pyknodysostosis described in this report had severe midfacial hypoplasia. Correction of this by use of routine orthognathic surgery would require osteosynthesis and bone grafting. Risk of infection and/or nonunion after such a surgical procedure was considered too great, and therefore the possibility of treatment by distraction osteogenesis of the maxilla was evaluated. The rigid external distraction II midface distraction system was used to relocate the hypoplastic maxilla at anterior-inferior projection. Distraction osteogenesis should be considered as the primary reconstructive method for maxillofacial deformities in patients with sclerosing bone dysplasias, since this is the second reported case treated successfully with rigid external distraction.
Rigidity of outermost MOTS: the initial data version
Galloway, Gregory J.
2018-03-01
In the paper Commun Anal Geom 16(1):217-229, 2008, a rigidity result was obtained for outermost marginally outer trapped surfaces (MOTSs) that do not admit metrics of positive scalar curvature. This allowed one to treat the "borderline case" in the author's work with R. Schoen concerning the topology of higher dimensional black holes (Commun Math Phys 266(2):571-576, 2006). The proof of this rigidity result involved bending the initial data manifold in the vicinity of the MOTS within the ambient spacetime. In this note we show how to circumvent this step, and thereby obtain a pure initial data version of this rigidity result and its consequence concerning the topology of black holes.
Authoritarianism, cognitive rigidity, and the processing of ambiguous visual information.
Duncan, Lauren E; Peterson, Bill E
2014-01-01
Intolerance of ambiguity and cognitive rigidity are unifying aspects of authoritarianism as defined by Adorno, Frenkel-Brunswik, Levinson, and Sanford (1982/1950), who hypothesized that authoritarians view the world in absolute terms (e.g., good or evil). Past studies have documented the relationship between authoritarianism and intolerance of ambiguity and rigidity. Frenkel-Brunswik (1949) hypothesized that this desire for absolutism was rooted in perceptual processes. We present a study with three samples that directly tests the relationship between right wing authoritarianism (RWA) and the processing of ideologically neutral but ambiguous visual stimuli. As hypothesized, in all three samples we found that RWA was related to the slower processing of visual information that required participants to recategorize objects. In a fourth sample, RWA was unrelated to speed of processing visual information that did not require recategorization. Overall, results suggest a relationship between RWA and rigidity in categorization.
Mitral stenosis due to pannus overgrowth after rigid ring annuloplasty.
Oda, Takeshi; Kato, Seiya; Tayama, Eiki; Fukunaga, Shuji; Akashi, Hidetoshi; Aoyagi, Shigeaki
2010-03-01
Although mitral stenosis (MS) due to pannus overgrowth after mitral valve repair for rheumatic mitral regurgitation (MR) is not uncommon, it is extremely rare in relation to non-rheumatic mitral regurgitation. Whilst it has been suggested that the rigid annuloplasty ring induces pannus overgrowth in the same manner as the flexible ring, to date only in cases using the flexible ring has pannus formation been confirmed by a pathological examination after redo surgery. The case is described of a woman who had undergone mitral valve repair using a 28 mm rigid ring three years previously because of non-rheumatic MR, and subsequently suffered from MS due to pannus formation over the annuloplasty ring. To the present authors' knowledge, this is the first report of MS due to pannus formation after mitral valve repair using a rigid annuloplasty ring to treat non-rheumatic MR documented at reoperation.
Rigid-plastic seismic design of reinforced concrete structures
DEFF Research Database (Denmark)
Costa, Joao Domingues; Bento, R.; Levtchitch, V.
2007-01-01
structural strength with respect to a pre-defined performance parameter using a rigid-plastic response spectrum, which is characteristic of the ground motion alone. The maximum strength demand at any point is solely dependent on the intensity of the ground motion, which facilitates the task of distributing......In this paper a new seismic design procedure for Reinforced Concrete (R/C) structures is proposed-the Rigid-Plastic Seismic Design (RPSD) method. This is a design procedure based on Non-Linear Time-History Analysis (NLTHA) for systems expected to perform in the non-linear range during a lifetime...... earthquake event. The theoretical background is the Theory of Plasticity (Rigid-Plastic Structures). Firstly, a collapse mechanism is chosen and the corresponding stress field is made safe outside the regions where plastic behaviour takes place. It is shown that this allows the determination of the required...
A concise introduction to mechanics of rigid bodies multidisciplinary engineering
Huang, L
2017-01-01
This updated second edition broadens the explanation of rotational kinematics and dynamics — the most important aspect of rigid body motion in three-dimensional space and a topic of much greater complexity than linear motion. It expands treatment of vector and matrix, and includes quaternion operations to describe and analyze rigid body motion which are found in robot control, trajectory planning, 3D vision system calibration, and hand-eye coordination of robots in assembly work, etc. It features updated treatments of concepts in all chapters and case studies. The textbook retains its comprehensiveness in coverage and compactness in size, which make it easily accessible to the readers from multidisciplinary areas who want to grasp the key concepts of rigid body mechanics which are usually scattered in multiple volumes of traditional textbooks. Theoretical concepts are explained through examples taken from across engineering disciplines and links to applications and more advanced courses (e.g. industrial rob...
Spin-4 extended conformal algebras
International Nuclear Information System (INIS)
Kakas, A.C.
1988-01-01
We construct spin-4 extended conformal algebras using the second hamiltonian structure of the KdV hierarchy. In the presence of a U(1) current a family of spin-4 algebras exists but the additional requirement that the spin-1 and spin-4 currents commute fixes the algebra uniquely. (orig.)
Defects in conformal field theory
International Nuclear Information System (INIS)
Billò, Marco; Gonçalves, Vasco; Lauria, Edoardo; Meineri, Marco
2016-01-01
We discuss consequences of the breaking of conformal symmetry by a flat or spherical extended operator. We adapt the embedding formalism to the study of correlation functions of symmetric traceless tensors in the presence of the defect. Two-point functions of a bulk and a defect primary are fixed by conformal invariance up to a set of OPE coefficients, and we identify the allowed tensor structures. A correlator of two bulk primaries depends on two cross-ratios, and we study its conformal block decomposition in the case of external scalars. The Casimir equation in the defect channel reduces to a hypergeometric equation, while the bulk channel blocks are recursively determined in the light-cone limit. In the special case of a defect of codimension two, we map the Casimir equation in the bulk channel to the one of a four-point function without defect. Finally, we analyze the contact terms of the stress-tensor with the extended operator, and we deduce constraints on the CFT data. In two dimensions, we relate the displacement operator, which appears among the contact terms, to the reflection coefficient of a conformal interface, and we find unitarity bounds for the latter.
Conformal symmetry and holographic cosmology
Bzowski, A.W.
2013-01-01
This thesis presents a novel approach to cosmology using gauge/gravity duality. Analysis of the implications of conformal invariance in field theories leads to quantitative cosmological predictions which are in agreement with current data. Furthermore, holographic cosmology extends the theory of
Checking behavioral conformance of artifacts
Fahland, D.; Leoni, de M.; Dongen, van B.F.; Aalst, van der W.M.P.
2011-01-01
The usefulness of process models (e.g., for analysis, improvement, or execution) strongly depends on their ability to describe reality. Conformance checking is a technique to validate how good a given process model describes recorded executions of the actual process. Recently, artifacts have been
Conformation analysis of oligomeric flavanoids
Jan P. Steynberg; E. Vincent Brandt; Daneel Ferreira; Carin A. Helfer; Wayne L. Mattice; Dominika Gornik; Richard W. Hemingway
1995-01-01
The profisetinidins are the most important polyflavanoids of commerce, making up the major constituents of wattle and quebracho tannins. Within the dimeric profisetinidins, substantial complexity exists because of stereo-, regio, rotational and conformational isomers. Definition of the stereochemistry of the upper and lower flavan units, the location of the...
Conformational analysis of oligomeric flavanoids
Jan P. Steynberg; E. Vincent Brandt; Daneel Ferreira; Carin A. Helfer; Wayne L. Mattice; Dominika Gornik; Richard W. Hemingway
1995-01-01
The profisetinidins are the most important polyflavanoids of commerce, making up the major constituents of wattle and quebracho tannins. Even within the dimeric profisetinidins, substantial complexity exists because of stereo-, regio-, rotational and conformational isomers. Definition of the stereochemistry of the upper and lower flavan units, the location of the...
Inversion theory and conformal mapping
Blair, David E
2000-01-01
It is rarely taught in an undergraduate or even graduate curriculum that the only conformal maps in Euclidean space of dimension greater than two are those generated by similarities and inversions in spheres. This is in stark contrast to the wealth of conformal maps in the plane. The principal aim of this text is to give a treatment of this paucity of conformal maps in higher dimensions. The exposition includes both an analytic proof in general dimension and a differential-geometric proof in dimension three. For completeness, enough complex analysis is developed to prove the abundance of conformal maps in the plane. In addition, the book develops inversion theory as a subject, along with the auxiliary theme of circle-preserving maps. A particular feature is the inclusion of a paper by Carath�odory with the remarkable result that any circle-preserving transformation is necessarily a M�bius transformation, not even the continuity of the transformation is assumed. The text is at the level of advanced undergr...
Defects in conformal field theory
Energy Technology Data Exchange (ETDEWEB)
Billò, Marco [Dipartimento di Fisica, Università di Torino, and Istituto Nazionale di Fisica Nucleare - sezione di Torino,Via P. Giuria 1 I-10125 Torino (Italy); Gonçalves, Vasco [Centro de Física do Porto,Departamento de Física e Astronomia Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal); ICTP South American Institute for Fundamental Research Instituto de Física Teórica,UNESP - University Estadual Paulista,Rua Dr. Bento T. Ferraz 271, 01140-070, São Paulo, SP (Brazil); Lauria, Edoardo [Institute for Theoretical Physics, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Meineri, Marco [Perimeter Institute for Theoretical Physics,Waterloo, Ontario, N2L 2Y5 (Canada); Scuola Normale Superiore, and Istituto Nazionale di Fisica Nucleare - sezione di Pisa,Piazza dei Cavalieri 7 I-56126 Pisa (Italy)
2016-04-15
We discuss consequences of the breaking of conformal symmetry by a flat or spherical extended operator. We adapt the embedding formalism to the study of correlation functions of symmetric traceless tensors in the presence of the defect. Two-point functions of a bulk and a defect primary are fixed by conformal invariance up to a set of OPE coefficients, and we identify the allowed tensor structures. A correlator of two bulk primaries depends on two cross-ratios, and we study its conformal block decomposition in the case of external scalars. The Casimir equation in the defect channel reduces to a hypergeometric equation, while the bulk channel blocks are recursively determined in the light-cone limit. In the special case of a defect of codimension two, we map the Casimir equation in the bulk channel to the one of a four-point function without defect. Finally, we analyze the contact terms of the stress-tensor with the extended operator, and we deduce constraints on the CFT data. In two dimensions, we relate the displacement operator, which appears among the contact terms, to the reflection coefficient of a conformal interface, and we find unitarity bounds for the latter.
Supertwistor connection and conformal supergravity
International Nuclear Information System (INIS)
Merkulov, S.A.
1985-01-01
Supersymmetry expansion of the geometry of local twistors is suggested. Definition of the space of local supertwistors is given and its differential geometry is formulated. Variational principles are discussed, and it is shown that corresponding Euler-Lagrange equations also coincide and result in superzero equations of N=1 conformal supergravitation, which generalize Bach equations
Conformal symmetry and string theories
International Nuclear Information System (INIS)
Kumar, A.
1987-01-01
This thesis is devoted to the study of various aspects of the 2-dimensional conformal field theory and its applications to strings. We make a short review of the conformal field theory and its supersymmetric extension, called superconformal field theory. We present an elegant superspace formulation of these theories and solve the condition for the closure of the superconformal algebra. The we go on to classify the superconformal field theories according to these solutions. We prove that N ≥ 5 superconformal algebra, with N being the number of supersymmetries, does not have central charge. We find the primary representations of all the interesting superconformal algebra. We study the quantization of the superconformal theories and derive the constraints on the central charge of the algebra that has to be satisfied for a consistent quantum theory. This quantization process also determines the ground state energy of the system and the spectrum of the model. We study the global aspects of the conformal symmetry and its role in the construction of consistent heterotic string theories. We prove the uniqueness of heterotic superstring theories in 10 dimensions in the fermionic constructions. We show how the vertex operators are closely associated with the primary field representation of the conformal algebra. We utilize these vertex operator constructions to obtain tree amplitudes in the 10-dimensional heterotic string theory. We show by explicit calculation at the 3-point level that the scattering amplitudes derived from the heterotic superstring are same as the ones obtained from 10-dimensional supergravity theories
Exceptional and Spinorial Conformal Windows
DEFF Research Database (Denmark)
Mojaza, Matin; Pica, Claudio; Ryttov, Thomas
2012-01-01
We study the conformal window of gauge theories containing fermionic matter fields, where the gauge group is any of the exceptional groups with the fermions transforming according to the fundamental and adjoint representations and the orthogonal groups where the fermions transform according...
Anomalous Dimensions of Conformal Baryons
DEFF Research Database (Denmark)
Pica, Claudio; Sannino, Francesco
2016-01-01
We determine the anomalous dimensions of baryon operators for the three color theory as function of the number of massless flavours within the conformal window to the maximum known order in perturbation theory. We show that the anomalous dimension of the baryon is controllably small, within...
Topology-Preserving Rigid Transformation of 2D Digital Images.
Ngo, Phuc; Passat, Nicolas; Kenmochi, Yukiko; Talbot, Hugues
2014-02-01
We provide conditions under which 2D digital images preserve their topological properties under rigid transformations. We consider the two most common digital topology models, namely dual adjacency and well-composedness. This paper leads to the proposal of optimal preprocessing strategies that ensure the topological invariance of images under arbitrary rigid transformations. These results and methods are proved to be valid for various kinds of images (binary, gray-level, label), thus providing generic and efficient tools, which can be used in particular in the context of image registration and warping.
Non-rigid image registration using bone growth model
DEFF Research Database (Denmark)
Bro-Nielsen, Morten; Gramkow, Claus; Kreiborg, Sven
1997-01-01
Non-rigid registration has traditionally used physical models like elasticity and fluids. These models are very seldom valid models of the difference between the registered images. This paper presents a non-rigid registration algorithm, which uses a model of bone growth as a model of the change...... between time sequence images of the human mandible. By being able to register the images, this paper at the same time contributes to the validation of the growth model, which is based on the currently available medical theories and knowledge...
Rigid particle revisited: Extrinsic curvature yields the Dirac equation
Energy Technology Data Exchange (ETDEWEB)
Deriglazov, Alexei, E-mail: alexei.deriglazov@ufjf.edu.br [Depto. de Matemática, ICE, Universidade Federal de Juiz de Fora, MG (Brazil); Laboratory of Mathematical Physics, Tomsk Polytechnic University, 634050 Tomsk, Lenin Ave. 30 (Russian Federation); Nersessian, Armen, E-mail: arnerses@ysu.am [Yerevan State University, 1 Alex Manoogian St., Yerevan 0025 (Armenia); Laboratory of Mathematical Physics, Tomsk Polytechnic University, 634050 Tomsk, Lenin Ave. 30 (Russian Federation)
2014-03-01
We reexamine the model of relativistic particle with higher-derivative linear term on the first extrinsic curvature (rigidity). The passage from classical to quantum theory requires a number of rather unexpected steps which we report here. We found that, contrary to common opinion, quantization of the model in terms of so(3.2)-algebra yields massive Dirac equation. -- Highlights: •New way of canonical quantization of relativistic rigid particle is proposed. •Quantization made in terms of so(3.2) angular momentum algebra. •Quantization yields massive Dirac equation.
Elastic properties of rigid fiber-reinforced composites
Chen, J.; Thorpe, M. F.; Davis, L. C.
1995-05-01
We study the elastic properties of rigid fiber-reinforced composites with perfect bonding between fibers and matrix, and also with sliding boundary conditions. In the dilute region, there exists an exact analytical solution. Around the rigidity threshold we find the elastic moduli and Poisson's ratio by decomposing the deformation into a compression mode and a rotation mode. For perfect bonding, both modes are important, whereas only the compression mode is operative for sliding boundary conditions. We employ the digital-image-based method and a finite element analysis to perform computer simulations which confirm our analytical predictions.
Extremal surfaces and the rigidity of null geodesic incompleteness
International Nuclear Information System (INIS)
Silva, I P Costa e; Flores, J L
2015-01-01
An important, if relatively less well known aspect of the singularity theorems in Lorentzian geometry, is to understand how their conclusions fare upon weakening or suppression of one or more of their hypotheses. Then, theorems with modified conclusion may arise, showing that those conclusions will fail only in special cases, at least some of which may be described. These are the so-called rigidity theorems, and have many important examples in the specialized literature. In this paper, we prove rigidity results for generalized plane waves and certain globally hyperbolic spacetimes in the presence of extremal compact surfaces. (paper)
Structure-Activity Relationships of Acyclic Selenopurine Nucleosides as Antiviral Agents
Directory of Open Access Journals (Sweden)
Pramod K. Sahu
2017-07-01
Full Text Available A series of acyclic selenopurine nucleosides 3a–f and 4a–g were synthesized based on the bioisosteric rationale between oxygen and selenium, and then evaluated for antiviral activity. Among the compounds tested, seleno-acyclovir (4a exhibited the most potent anti-herpes simplex virus (HSV-1 (EC50 = 1.47 µM and HSV-2 (EC50 = 6.34 µM activities without cytotoxicity up to 100 µM, while 2,6-diaminopurine derivatives 4e–g exhibited significant anti-human cytomegalovirus (HCMV activity, which is slightly more potent than the guanine derivative 4d, indicating that they might act as prodrugs of seleno-ganciclovir (4d.
DEFF Research Database (Denmark)
Andersen, Ellen Sloth; Weiland, Ola; Leutscher, Peter
2011-01-01
Abstract Objective. Case reports and short-term clinical trials have suggested that treatment for chronic hepatitis B (CHB) may lead to improvement of cirrhosis. The aim of the present study was to measure liver stiffness in patients diagnosed with advanced fibrosis or cirrhosis prior to prolonged...... treatment with nucleoside or nucleotide analogs (NUCs) for CHB. Materials and methods. Patients with CHB and advanced fibrosis or cirrhosis prior to treatment with NUCs for at least 1 year were offered inclusion in the study. We measured liver stiffness using transient elastography (TE) at follow-up. TE cut...... duration was 50.5 months. Among patients with cirrhosis prior to treatment, 26 (49%) had liver stiffness below 11.0 kPa at follow-up, suggesting regression of cirrhosis. Among patients with advanced fibrosis (F3) prior to treatment, 10 (77%) had liver stiffness below 8.1 kPa after treatment, suggesting...
Complete inactivation of HIV-1 using photo-labeled non-nucleoside reverse transcriptase inhibitors.
Rios, Adan; Quesada, Jorge; Anderson, Dallas; Goldstein, Allan; Fossum, Theresa; Colby-Germinario, Susan; Wainberg, Mark A
2011-01-01
We demonstrate that a photo-labeled derivative of the non-nucleoside reverse transcriptase inhibitor (NNRTI) dapivirine termed DAPY, when used together with exposure to ultraviolet light, was able to completely and irreversibly inactivate both HIV-1 RT activity as well as infectiousness in each of a T cell line and peripheral blood mononuclear cells. Control experiments using various concentrations of DAPY revealed that a combination of exposure to ultraviolet light together with use of the specific, high affinity photo-labeled compound was necessary for complete inactivation to occur. This method of HIV RT inactivation may have applicability toward preservation of an intact viral structure and warrants further investigation in regard to the potential of this approach to elicit a durable, broad protective immune response. Copyright © 2010 Elsevier B.V. All rights reserved.
Balón, M; Muñoz, M A; Carmona, C; Guardado, P; Galán, M
1999-07-19
Fluorescence binding studies of harmane to the elemental components of the nucleic acids were undertaken to investigate the origin of the interaction between the drug and DNA. Most of the tested substrates have been found to induce hypochromism in the absorption spectrum of harmane and to quench its fluorescence. The quenching process induced by the nucleobases and their nucleosides is mainly due to the formation of ground state 1:1 complexes. However, in the case of the mononucleotides a dynamic quenching component is also observed. This quenching component is likely due to the excited state interaction of harmane with the phosphate group of the nucleotides. UV-vis spectral changes and quenching measurements have been used to quantify the ground state association constants of the complexes and the quenching rate constants.
Absence of a Universal Mechanism of Mitochondrial Toxicity by Nucleoside Analogs▿
Lund, Kaleb C.; Peterson, LaRae L.; Wallace, Kendall B.
2007-01-01
Nucleoside analogs are associated with various mitochondrial toxicities, and it is becoming increasingly difficult to accommodate these differences solely in the context of DNA polymerase gamma inhibition. Therefore, we examined the toxicities of zidovudine (AZT) (10 and 50 μM; 2.7 and 13.4 μg/ml), didanosine (ddI) (10 and 50 μM; 2.4 and 11.8 μg/ml), and zalcitabine (ddC) (1 and 5 μM; 0.21 and 1.1 μg/ml) in HepG2 and H9c2 cells without the presumption of mitochondrial DNA (mtDNA) depletion. E...
International Nuclear Information System (INIS)
Samuelson, L.C.; Farber, R.A.
1985-01-01
The authors have determined the regional locations on mouse chromosome 14 of the genes for mouse adenosine kinase (ADK), nucleoside phosphorylase- 1 (NP-1), and esterase-10 (ES-10) by analysis of rearranged mouse chromosomes in gamma-irradiated Chinese hamster X mouse hybrid cell lines. Irradiated clones were screened for expression of the murine forms of these enzymes; segregant clones that expressed only one or two of the three markers were karyotyped. The patterns of enzyme expression in these segregants were correlated with the presence of rearranged chromosomes. The Adk gene was localized to bands A2 to B, Np-1 to bands B to C1, and Es-10 to bands D2 to E2
Radiolysis of nucleosides in aqueous solutions: base liberation by the base attack mechanism
International Nuclear Information System (INIS)
Fujita, S.
1984-01-01
On the radiolysis of uridine and some other nucleosides in aqueous solution, a pH-dependent liberation of uracil or the corresponding base was found. e - sub(aq) and HOsup(anion radicals) 2 gave no freed bases, although many oxidizing radicals, including OH, Clsup(anion radicals) 2 , Brsup(anion radicals) 2 , (CNS)sup(anion radicals) 2 and SOsup(anion radicals) 4 , did cause the release of unaltered bases, depending on the pH of the solutions. The base yields were generally high at pH >= 11, with the exception of SOsup(anion radicals) 4 , which gave a rather high yield of uracil (from uridine) even in the pH region of - , present at high pH as the dissociated form of OH, may act partly as an oxidizing radical. A plausible mechanism of 3 1 -radical formation is discussed. (author)
de Carvalho, Otavio Valério; Félix, Daniele Mendes; de Mendonça, Leila Rodrigues; de Araújo, Catarina Maria Cataldi Sabino; de Oliveira Franca, Rafael Freitas; Cordeiro, Marli Tenório; Silva Júnior, Abelardo; Pena, Lindomar José
2017-12-01
Since the emergence of Zika virus (ZIKV) in Brazil in 2015, 48 countries and territories in the Americas have confirmed autochthonous cases of disease caused by the virus. ZIKV-associated neurological manifestations and congenital defects make the development of safe and effective antivirals against ZIKV of utmost importance. Here we evaluated the antiviral activity of 6-methylmercaptopurine riboside (6MMPr), a thiopurine nucleoside analogue derived from the prodrug azathioprine, against the epidemic ZIKV strain circulating in Brazil. In all of the assays, an epithelial (Vero) and a human neuronal (SH-SY5Y) cell line were used to evaluate the cytotoxicity and effective concentrations of 6MMPr against ZIKV. Levels of ZIKV-RNA, viral infectious titre and the percentage of infected cells in the presence or absence of 6MMPr were used to determine antiviral efficacy. 6MMPr decreased ZIKV production by >99% in both cell lines in a dose- and time-dependent manner. Interestingly, 6MMPr was 1.6 times less toxic to SH-SY5Y cells compared with Vero cells, presenting a 50% cytotoxic concentrations (CC 50 ) of 460.3 µM and 291 µM, respectively. The selectivity index of 6MMPr for Vero and SH-SY5Y cells was 11.9 and 22.7, respectively, highlighting the safety profile of the drug to neuronal cells. Taken together, these results identify, for the first time, the thiopurine nucleoside analogue 6MMPr as a promising antiviral candidate against ZIKV that warrants further in vivo evaluation. Copyright © 2017 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.
Directory of Open Access Journals (Sweden)
Eikan Mishima
Full Text Available The biological roles of RNA modifications are still largely not understood. Thus, developing a method for detecting RNA modifications is important for further clarification. We developed a method for detecting RNA modifications called immuno-northern blotting (INB analysis and herein introduce its various capabilities. This method involves the separation of RNAs using either polyacrylamide or agarose gel electrophoresis, followed by transfer onto a nylon membrane and subsequent immunoblotting using antibodies against modified nucleosides for the detection of specific modifications. We confirmed that INB with the antibodies for 1-methyladenosine (m1A, N6-methyladenosine (m6A, pseudouridine, and 5-methylcytidine (m5C showed different modifications in a variety of RNAs from various species and organelles. INB with the anti-m5C antibody revealed that the antibody cross-reacted with another modification on DNA, suggesting the application of this method for characterization of the antibody for modified nucleosides. Additionally, using INB with the antibody for m1A, which is a highly specific modification in eukaryotic tRNA, we detected tRNA-derived fragments known as tiRNAs under the cellular stress response, suggesting the application for tracking target RNA containing specific modifications. INB with the anti-m6A antibody confirmed the demethylation of m6A by the specific demethylases fat mass and obesity-associated protein (FTO and ALKBH5, suggesting its application for quantifying target modifications in separated RNAs. Furthermore, INB demonstrated that the knockdown of FTO and ALKBH5 increased the m6A modification in small RNAs as well as in mRNA. The INB method has high specificity, sensitivity, and quantitative capability, and it can be employed with conventional experimental apparatus. Therefore, this method would be useful for research on RNA modifications and metabolism.
Mishima, Eikan; Jinno, Daisuke; Akiyama, Yasutoshi; Itoh, Kunihiko; Nankumo, Shinnosuke; Shima, Hisato; Kikuchi, Koichi; Takeuchi, Yoichi; Elkordy, Alaa; Suzuki, Takehiro; Niizuma, Kuniyasu; Ito, Sadayoshi; Tomioka, Yoshihisa; Abe, Takaaki
2015-01-01
The biological roles of RNA modifications are still largely not understood. Thus, developing a method for detecting RNA modifications is important for further clarification. We developed a method for detecting RNA modifications called immuno-northern blotting (INB) analysis and herein introduce its various capabilities. This method involves the separation of RNAs using either polyacrylamide or agarose gel electrophoresis, followed by transfer onto a nylon membrane and subsequent immunoblotting using antibodies against modified nucleosides for the detection of specific modifications. We confirmed that INB with the antibodies for 1-methyladenosine (m1A), N6-methyladenosine (m6A), pseudouridine, and 5-methylcytidine (m5C) showed different modifications in a variety of RNAs from various species and organelles. INB with the anti-m5C antibody revealed that the antibody cross-reacted with another modification on DNA, suggesting the application of this method for characterization of the antibody for modified nucleosides. Additionally, using INB with the antibody for m1A, which is a highly specific modification in eukaryotic tRNA, we detected tRNA-derived fragments known as tiRNAs under the cellular stress response, suggesting the application for tracking target RNA containing specific modifications. INB with the anti-m6A antibody confirmed the demethylation of m6A by the specific demethylases fat mass and obesity-associated protein (FTO) and ALKBH5, suggesting its application for quantifying target modifications in separated RNAs. Furthermore, INB demonstrated that the knockdown of FTO and ALKBH5 increased the m6A modification in small RNAs as well as in mRNA. The INB method has high specificity, sensitivity, and quantitative capability, and it can be employed with conventional experimental apparatus. Therefore, this method would be useful for research on RNA modifications and metabolism.
Aquaporin 3 (AQP3) participates in the cytotoxic response to nucleoside-derived drugs
International Nuclear Information System (INIS)
Pérez-Torras, Sandra; Casado, F Javier; Pastor-Anglada, Marçal
2012-01-01
Nucleoside analogs used in the chemotherapy of solid tumors, such as the capecitabine catabolite 5 ′ -deoxy-5-fluorouridine (5 ′ -DFUR) trigger a transcriptomic response that involves the aquaglyceroporin aquaporin 3 along with other p53-dependent genes. Here, we examined whether up-regulation of aquaporin 3 (AQP3) mRNA in cancer cells treated with 5 ′ -DFUR represents a collateral transcriptomic effect of the drug, or conversely, AQP3 participates in the activity of genotoxic agents. The role of AQP3 in cell volume increase, cytotoxicity and cell cycle arrest was analyzed using loss-of-function approaches. 5 ′ -DFUR and gemcitabine, but not cisplatin, stimulated AQP3 expression and cell volume, which was partially and significantly blocked by knockdown of AQP3. Moreover, AQP3 siRNA significantly blocked other effects of nucleoside analogs, including G 1 /S cell cycle arrest, p21 and FAS up-regulation, and cell growth inhibition. Short incubations with 5-fluorouracil (5-FU) also induced AQP3 expression and increased cell volume, and the inhibition of AQP3 expression significantly blocked growth inhibition triggered by this drug. To further establish whether AQP3 induction is related to cell cycle arrest and apoptosis, cells were exposed to long incubations with escalating doses of 5-FU. AQP3 was highly up-regulated at doses associated with cell cycle arrest, whereas at doses promoting apoptosis induction of AQP3 mRNA expression was reduced. Based on the results, we propose that the aquaglyceroporin AQP3 is required for cytotoxic activity of 5’-DFUR and gemcitabine in the breast cancer cell line MCF7 and the colon adenocarcinoma cell line HT29, and is implicated in cell volume increase and cell cycle arrest
Wang, Xuelin; Zhang, Yuxin; Guo, Rui; Wang, Hongzhang; Yuan, Bo; Liu, Jing
2018-03-01
Conformable epidermal printed electronics enabled from gallium-based liquid metals (LMs), highly conductive and low-melting-point alloys, are proposed as the core to achieving immediate contact between skin surface and electrodes, which can avoid the skin deformation often caused by conventional rigid electrodes. When measuring signals, LMs can eliminate resonance problems with shorter time to reach steady state than Pt and gelled Pt electrodes. By comparing the contact resistance under different working conditions, it is demonstrated that both ex vivo and in vivo LM electrode-skin models have the virtues of direct and immediate contact with skin surface without the deformation encountered with conventional rigid electrodes. In addition, electrocardio electrodes composed of conformable LM printed epidermal electronics are adopted as smart devices to monitor electrocardiogram signals of rabbits. Furthermore, simulation treatment for smart defibrillation offers a feasible way to demonstrate the effect of liquid metal electrodes (LMEs) on the human body with less energy loss. The remarkable features of soft epidermal LMEs such as high conformability, good conductivity, better signal stability, and fine biocompatibility represent a critical step towards accurate medical monitoring and future smart treatments.
Conformal and Nearly Conformal Theories at Large N
Tarnoplskiy, Grigory M.
In this thesis we present new results in conformal and nearly conformal field theories in various dimensions. In chapter two, we study different properties of the conformal Quantum Electrodynamics (QED) in continuous dimension d. At first we study conformal QED using large Nf methods, where Nf is the number of massless fermions. We compute its sphere free energy as a function of d, ignoring the terms of order 1/Nf and higher. For finite Nf we use the epsilon-expansion. Next we use a large Nf diagrammatic approach to calculate the leading corrections to CT, the coefficient of the two-point function of the stress-energy tensor, and CJ, the coefficient of the two-point function of the global symmetry current. We present explicit formulae as a function of d and check them versus the expectations in 2 and 4 - epsilon dimensions. In chapter three, we discuss vacuum stability in 1 + 1 dimensional conformal field theories with external background fields. We show that the vacuum decay rate is given by a non-local two-form. This two-form is a boundary term that must be added to the effective in/out Lagrangian. The two-form is expressed in terms of a Riemann-Hilbert decomposition for background gauge fields, and is given by its novel "functional'' version in the gravitational case. In chapter four, we explore Tensor models. Such models possess the large N limit dominated by the melon diagrams. The quantum mechanics of a real anti-commuting rank-3 tensor has a large N limit similar to the Sachdev-Ye-Kitaev (SYK) model. We also discuss the quantum mechanics of a complex 3-index anti-commuting tensor and argue that it is equivalent in the large N limit to a version of SYK model with complex fermions. Finally, we discuss models of a commuting tensor in dimension d. We study the spectrum of the large N quantum field theory of bosonic rank-3 tensors using the Schwinger-Dyson equations. We compare some of these results with the 4 - epsilon expansion, finding perfect agreement. We
Conformal invariance in the quantum field theory
International Nuclear Information System (INIS)
Kurak, V.
1975-09-01
Basic features concerning the present knowledge of conformal symmetry are illustrated in a simple model. Composite field dimensions of this model are computed and related to the conformal group. (author) [pt
Viscoelastic materials with anisotropic rigid particles: stress-deformation behavior
Sagis, L.M.C.; Linden, van der E.
2001-01-01
In this paper we have derived constitutive equations for the stress tensor of a viscoelastic material with anisotropic rigid particles. We have assumed that the material has fading memory. The expressions are valid for slow and small deformations from equilibrium, and for systems that are nearly
Rigidity and bradykinesia reduce interlimb coordination in Parkinsonian gait
Winogrodzka, Ania; Wagenaar, Robert C.; Booij, Jan; Wolters, Eric C.
2005-01-01
Objective: To assess the influence of rigidity and bradykinesia and the extent of dopaminergic degeneration on interlimb coordination during walking in early, drug-naive patients with Parkinson's disease (PD). Design: The interlimb coordination was examined during a systematic manipulation of
Patient satisfaction related to rigid external distraction osteogenesis
van Eggermont, Bas; Jansma, J.; Bierman, M. W. J.; Stegenga, B.
2007-01-01
The aim of this study was to evaluate satisfaction with treatment among cleft lip and palate patients who underwent maxillary advancement using a rigid external distraction (RED) device. Nine patients (four boys, five girls), mean age 17.7 years (SD 4.0), were included in the study. Outcome measures
Short Communication: Statistical determination of the rigidity in ...
African Journals Online (AJOL)
From the graph of load against displacement, the rigidity in flexion at different moisture levels was determined from which the Young modulus was calculated. Linear regression models were fitted to the data and the results showed significant correlation coefficients between the Young modulus and moisture content for each ...
Connect-disconnect coupling for preadjusted rigid shafts
Bajkowski, F. W.; Holmberg, A.
1969-01-01
Coupling device enables a rigid shaft to be connected to or disconnected from a fixed base without disturbing the point of adjustment of the shaft in a socket or causing the shaft to rotate. The coupling consists of an externally threaded, internally slotted boss extending from the fixed base.
Rigidity percolation in dispersions with a structured viscoelastic matrix
Wilbrink, M.W.L.; Michels, M.A.J.; Vellinga, W.P.; Meijer, H.E.H.
2005-01-01
This paper deals with rigidity percolation in composite materials consisting of a dispersion of mineral particles in a microstructured viscoelastic matrix. The viscoelastic matrix in this specific case is a hydrocarbon refinery residue. In a set of model random composites the mean interparticle
Centrifuge modelling of rigid piles in soft clay
DEFF Research Database (Denmark)
Klinkvort, R.T.; Poder, M.; Truong, P.
2016-01-01
of this study is to employ centrifuge modelling in order to derive experimental p-y curves for rigid piles embedded in over-consolidated soft clay. A kaolin clay sample was prepared and pre-consolidated by applying a constant pressure at the soil surface, while different over-consolidation ratios were achieved...
Customizable rigid head fixation for infants: technical note.
Udayakumaran, Suhas; Onyia, Chiazor U
2016-01-01
The need and advantages of rigid fixation of the head in cranial surgeries are well documented (Berryhill et al., Otolaryngol Head Neck Surg 121:269-273, 1999). Head fixation for neurosurgical procedures in infants and in early years has been a challenge and is fraught with risk. Despite the fact that pediatric pins are designed, rigid head fixation involving direct application of pins to the head of infants and slightly older children is still generally not safe (Agrawal and Steinbok, Childs Nerv Syst 22:1473-1474, 2006). Yet, there are some surgeries in which some form of rigid fixation is required (Agrawal and Steinbok, Childs Nerv Syst 22:1473-1474, 2006). We describe a simple technique to achieve rigid fixation of the head in infants for neurosurgical procedures. This involves applying a head band made of Plaster of Paris (POP) around the head and then applying the fixation pins of the fixation frame directly on to the POP. We have used this technique of head fixation successfully for infants with no complications.
Study of rigidity of semiconducting vanadate glasses and its ...
Indian Academy of Sciences (India)
These parameters along with the coordination number of the glasses affect the glass transition temperature. The correlation between the elastic moduli and thermal properties of these samples showed that 0.25MoO3–0.25PbO–0.5V2O5 glass is the most rigid and has an applicable glass transition temperature for coating.
Rigidity theorem for Willmore surfaces in a sphere
Indian Academy of Sciences (India)
(Math. Sci.) Vol. 126, No. 2, May 2016, pp. 253–260. c Indian Academy of Sciences. Rigidity theorem for Willmore surfaces in a sphere. HONGWEI XU1 and DENGYUN YANG2,∗. 1Center of Mathematical Sciences, Zhejiang University, Hangzhou 310027,. People's Republic of China. 2College of Mathematics and ...
Accuracy limit of rigid 3-point water models
Izadi, Saeed; Onufriev, Alexey V.
2016-08-01
Classical 3-point rigid water models are most widely used due to their computational efficiency. Recently, we introduced a new approach to constructing classical rigid water models [S. Izadi et al., J. Phys. Chem. Lett. 5, 3863 (2014)], which permits a virtually exhaustive search for globally optimal model parameters in the sub-space that is most relevant to the electrostatic properties of the water molecule in liquid phase. Here we apply the approach to develop a 3-point Optimal Point Charge (OPC3) water model. OPC3 is significantly more accurate than the commonly used water models of same class (TIP3P and SPCE) in reproducing a comprehensive set of liquid bulk properties, over a wide range of temperatures. Beyond bulk properties, we show that OPC3 predicts the intrinsic charge hydration asymmetry (CHA) of water — a characteristic dependence of hydration free energy on the sign of the solute charge — in very close agreement with experiment. Two other recent 3-point rigid water models, TIP3PFB and H2ODC, each developed by its own, completely different optimization method, approach the global accuracy optimum represented by OPC3 in both the parameter space and accuracy of bulk properties. Thus, we argue that an accuracy limit of practical 3-point rigid non-polarizable models has effectively been reached; remaining accuracy issues are discussed.
Rigid rod spaced fullerene as building block for nanoclusters
Indian Academy of Sciences (India)
By using phenylacetylene based rigid-rod linkers (PhA), we have successfully synthesized two fullerene derivatives, C60-PhA and C60-PhA-C60. The absorption spectral features of C60, as well as that of the phenylacetylene moiety are retained in the monomeric forms of these fullerene derivatives, ruling out the possibility ...
Hydrodynamics of a flexible plate between pitching rigid plates
Kim, Junyoung; Kim, Daegyoum
2017-11-01
The dynamics of a flexible plate have been studied as a model problem in swimming and flying of animals and fluid-structure interaction of plants and flags. Motivated by fish schooling and an array of sea grasses, we investigate the dynamics of a flexible plate closely placed between two pitching rigid plates. In most studies on passive deformation of the flexible plate, the plate is immersed in a uniform flow or a wavy flow. However, in this study, the flexible plate experiences periodic deformation by the oscillatory flow generated by the prescribed pitching motion of the rigid plates. In our model, the pitching axes of the rigid plates and the clamping position of the flexible plate are aligned on the same line. The flexible plate shows various responses depending on length and pitching frequency of rigid plates, thickness of a flexible plate, and free-stream velocity. To find the effect of each variable on the response of the flexible plate, amplitude of a trailing edge and modal contribution of a flapping motion are compared, and flow structure around the flexible plate is examined.
Flexible (Polyactive®) versus rigid (hydroxyapatite) dental implants
Meijer, G.J.; Heethaar, J.; Cune, M.S.; de Putter, C.; van Blitterswijk, Clemens
1997-01-01
In a beagle dog study, the peri-implant bone changes around flexible (Polyactive®) and rigid hydroxyapatite (HA) implants were investigated radiographically by quantitative digital subtraction analysis and by assessment of marginal bone height, with the aid of a computerized method. A loss of
"Mind the trap": mindfulness practice reduces cognitive rigidity.
Directory of Open Access Journals (Sweden)
Jonathan Greenberg
Full Text Available Two experiments examined the relation between mindfulness practice and cognitive rigidity by using a variation of the Einstellung water jar task. Participants were required to use three hypothetical jars to obtain a specific amount of water. Initial problems were solvable by the same complex formula, but in later problems ("critical" or "trap" problems solving was possible by an additional much simpler formula. A rigidity score was compiled through perseverance of the complex formula. In Experiment 1, experienced mindfulness meditators received significantly lower rigidity scores than non-meditators who had registered for their first meditation retreat. Similar results were obtained in randomized controlled Experiment 2 comparing non-meditators who underwent an eight meeting mindfulness program with a waiting list group. The authors conclude that mindfulness meditation reduces cognitive rigidity via the tendency to be "blinded" by experience. Results are discussed in light of the benefits of mindfulness practice regarding a reduced tendency to overlook novel and adaptive ways of responding due to past experience, both in and out of the clinical setting.
A survey on stability and rigidity results for Lie algebras
Crainic, Marius; Schätz, Florian; Struchiner, Ivan
2014-01-01
We give simple and unified proofs of the known stability and rigidity results for Lie algebras, Lie subalgebras and Lie algebra homomorphisms. Moreover, we investigate when a Lie algebra homomorphism is stable under all automorphisms of the codomain (including outer automorphisms).
21 CFR 886.5916 - Rigid gas permeable contact lens.
2010-04-01
... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Rigid gas permeable contact lens. 886.5916 Section 886.5916 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... against the cornea of the eye to correct vision conditions. The device is made of various materials, such...
Knowledge-In-Action: An Example with Rigid Body Motion
Da Costa, Sayonara Salvador Cabral; Moreira, Marco Antonio
2005-01-01
This paper reports the analysis of the resolution of a paper-and-pencil problem, by eight undergraduate students majoring in engineering (six) and physics (two) at the Pontifcia Universidade Catlica do Rio Grande do Sul, in Porto Alegre, Brazil. The problem concerns kinetics of a rigid body, and the analysis was done in the light of Johnson-Lairds…
Non-rigid registration by geometry-constrained diffusion
DEFF Research Database (Denmark)
Andresen, Per Rønsholt; Nielsen, Mads
1999-01-01
Assume that only partial knowledge about a non-rigid registration is given so that certain point, curves, or surfaces in one 3D image map to certain points, curves, or surfaces in another 3D image. We are facing the aperture problem because along the curves and surfaces, point correspondences...
Exploiting conformational ensembles in modeling protein-protein interactions on the proteome scale
Kuzu, Guray; Gursoy, Attila; Nussinov, Ruth; Keskin, Ozlem
2013-01-01
Cellular functions are performed through protein-protein interactions; therefore, identification of these interactions is crucial for understanding biological processes. Recent studies suggest that knowledge-based approaches are more useful than ‘blind’ docking for modeling at large scales. However, a caveat of knowledge-based approaches is that they treat molecules as rigid structures. The Protein Data Bank (PDB) offers a wealth of conformations. Here, we exploited ensemble of the conformations in predictions by a knowledge-based method, PRISM. We tested ‘difficult’ cases in a docking-benchmark dataset, where the unbound and bound protein forms are structurally different. Considering alternative conformations for each protein, the percentage of successfully predicted interactions increased from ~26% to 66%, and 57% of the interactions were successfully predicted in an ‘unbiased’ scenario, in which data related to the bound forms were not utilized. If the appropriate conformation, or relevant template interface, is unavailable in the PDB, PRISM could not predict the interaction successfully. The pace of the growth of the PDB promises a rapid increase of ensemble conformations emphasizing the merit of such knowledge-based ensemble strategies for higher success rates in protein-protein interaction predictions on an interactome-scale. We constructed the structural network of ERK interacting proteins as a case study. PMID:23590674
Probing the conformational dynamics of photosystem I in unconfined and confined spaces.
Das, Gaurav; Chattoraj, Shyamtanu; Nandi, Somen; Mondal, Prasenjit; Saha, Abhijit; Bhattacharyya, Kankan; Ghosh, Surajit
2017-12-20
The fluorescence dynamics of Photosystem I (PSI) in bulk water and inside a confined environment like a liposome have been investigated using time resolved confocal microscopy. In bulk water, PSI exhibits a major emission peak at ∼680 nm, while in the liposome it exhibits a markedly blue shifted emission maximum at ∼485 nm. This is indicative of conformational changes due to entrapment and emergence of a stressed conformation of PSI inside the liposome. The observed time constants for the fluorescence lifetime of PSI inside the liposome are significantly high as opposed to PSI in bulk water. More interestingly, the fluorescence intensity of PSI in bulk water exhibits strong fluctuations with many high intensity jumps and these are anti-correlated with the fluorescence lifetime of PSI. In contrast, inside the liposome, no such anti-correlated behaviour is observed. We further demonstrated that PSI exhibits at least two conformational states in bulk water, whereas a single conformation is observed inside the liposome, indicating the conformational rigidity and locking of the PSI complex inside a liposome.
The Conformational Behaviour of Glucosamine
Peña, Isabel; Kolesniková, Lucie; Cabezas, Carlos; Bermúdez, Celina; Berdakin, Matías; Simao, Alcides; Alonso, José L.
2014-06-01
A laser ablation method has been successfully used to vaporize the bioactive amino monosaccharide D-glucosamine. Three cyclic α-4C1 pyranose forms have been identified using a combination of CP-FTMW and LA-MB-FTMW spectroscopy. Stereoelectronic hyperconjugative factors, like those associated with anomeric or gauche effects, as well as the cooperative OH\\cdotsO, OH\\cdotsN and NH\\cdotsO chains, extended along the entire molecule, are the main factors driving the conformational behavior. All observed conformers exhibit a counter-clockwise arrangement (cc) of the network of intramolecular hydrogen bonds. The results are compared with those recently obtained for D-glucose. J. L. Alonso, M. A. Lozoya, I. Peña, J. C. López, C. Cabezas, S. Mata, S. Blanco, Chem. Sci. 2014, 5, 515.
Conformal invariance from nonconformal gravity
International Nuclear Information System (INIS)
Meissner, Krzysztof A.; Nicolai, Hermann
2009-01-01
We discuss the conditions under which classically conformally invariant models in four dimensions can arise out of nonconformal (Einstein) gravity. As an 'existence proof' that this is indeed possible we show how to derive N=4 super Yang-Mills theory with any compact gauge group G from nonconformal gauged N=4 supergravity as a special flat space limit. We stress the role that the anticipated UV finiteness of the (so far unknown) underlying theory of quantum gravity would have to play in such a scheme, as well as the fact that the masses of elementary particles would have to arise via quantum gravitational effects which mimic the conformal anomalies of standard (flat space) UV divergent quantum field theory.
Conformal methods in general relativity
Valiente Kroon, Juan A
2016-01-01
This book offers a systematic exposition of conformal methods and how they can be used to study the global properties of solutions to the equations of Einstein's theory of gravity. It shows that combining these ideas with differential geometry can elucidate the existence and stability of the basic solutions of the theory. Introducing the differential geometric, spinorial and PDE background required to gain a deep understanding of conformal methods, this text provides an accessible account of key results in mathematical relativity over the last thirty years, including the stability of de Sitter and Minkowski spacetimes. For graduate students and researchers, this self-contained account includes useful visual models to help the reader grasp abstract concepts and a list of further reading, making this the perfect reference companion on the topic.
Gel dosimetry for conformal radiotherapy
Energy Technology Data Exchange (ETDEWEB)
Gambarini, G [Department of Physics of the University and INFN, Milan (Italy)
2005-07-01
With the continuum development of conformal radio therapies, aimed at delivering high dose to tumor tissue and low dose to the healthy tissue around, the necessities has appeared of suitable improvement of dosimetry techniques giving the possibility of obtaining dose images to be compared with diagnostic images. Also if wide software has been developed for calculating dose distributions in the fields of various radiotherapy units, experimental verifications are necessary, in particular in the case of complex geometries in conformal radiotherapy. Gel dosimetry is a promising method for imaging the absorbed dose in tissue-equivalent phantoms, with the possibility of 3D reconstruction of the spatial dose distribution, with milli metric resolution. Optical imaging of gel dosimeters, based on visible light absorbance analysis, has shown to be a reliable technique for achieving dose distributions. (Author)
Conformal manifolds: ODEs from OPEs
Behan, Connor
2018-03-01
The existence of an exactly marginal deformation in a conformal field theory is very special, but it is not well understood how this is reflected in the allowed dimensions and OPE coefficients of local operators. To shed light on this question, we compute perturbative corrections to several observables in an abstract CFT, starting with the beta function. This yields a sum rule that the theory must obey in order to be part of a conformal manifold. The set of constraints relating CFT data at different values of the coupling can in principle be written as a dynamical system that allows one to flow arbitrarily far. We begin the analysis of it by finding a simple form for the differential equations when the spacetime and theory space are both one-dimensional. A useful feature we can immediately observe is that our system makes it very difficult for level crossing to occur.
Conformal field theories and critical phenomena
International Nuclear Information System (INIS)
Xu, Bowei
1993-01-01
In this article we present a brief review of the conformal symmetry and the two dimensional conformal quantum field theories. As concrete applications of the conformal theories to the critical phenomena in statistical systems, we calculate the value of central charge and the anomalous scale dimensions of the Z 2 symmetric quantum chain with boundary condition. The results are compatible with the prediction of the conformal field theories
Conformal group actions and Segal's cosmology
International Nuclear Information System (INIS)
Werth, J.-E.
1984-01-01
A mathematical description of Segal's cosmological model in the framework of conformal group actions is presented. The relation between conformal and causal group actions on time-orientable Lorentzian manifolds is analysed and several examples are discussed. A criterion for the conformality of a map between Lorentzian manifolds is given. The results are applied to Segal's 'conformal compactification' of Minkowski space. Furthermore, the 'unitary formulation' of Segal's cosmology is regarded. (Author) [pt
Generative Models of Conformational Dynamics
Langmead, Christopher James
2014-01-01
Atomistic simulations of the conformational dynamics of proteins can be performed using either Molecular Dynamics or Monte Carlo procedures. The ensembles of three-dimensional structures produced during simulation can be analyzed in a number of ways to elucidate the thermodynamic and kinetic properties of the system. The goal of this chapter is to review both traditional and emerging methods for learning generative models from atomistic simulation data. Here, the term ‘generative’ refers to a...
Holographic multiverse and conformal invariance
Energy Technology Data Exchange (ETDEWEB)
Garriga, Jaume [Departament de Física Fonamental i Institut de Ciències del Cosmos, Universitat de Barcelona, Martí i Franquès 1, 08193 Barcelona (Spain); Vilenkin, Alexander, E-mail: jaume.garriga@ub.edu, E-mail: vilenkin@cosmos.phy.tufts.edu [Institute of Cosmology, Department of Physics and Astronomy, Tufts University, 212 College Ave., Medford, MA 02155 (United States)
2009-11-01
We consider a holographic description of the inflationary multiverse, according to which the wave function of the universe is interpreted as the generating functional for a lower dimensional Euclidean theory. We analyze a simple model where transitions between inflationary vacua occur through bubble nucleation, and the inflating part of spacetime consists of de Sitter regions separated by thin bubble walls. In this model, we present some evidence that the dual theory is conformally invariant in the UV.
Holographic multiverse and conformal invariance
International Nuclear Information System (INIS)
Garriga, Jaume; Vilenkin, Alexander
2009-01-01
We consider a holographic description of the inflationary multiverse, according to which the wave function of the universe is interpreted as the generating functional for a lower dimensional Euclidean theory. We analyze a simple model where transitions between inflationary vacua occur through bubble nucleation, and the inflating part of spacetime consists of de Sitter regions separated by thin bubble walls. In this model, we present some evidence that the dual theory is conformally invariant in the UV
Integrability of conformal fishnet theory
Gromov, Nikolay; Kazakov, Vladimir; Korchemsky, Gregory; Negro, Stefano; Sizov, Grigory
2018-01-01
We study integrability of fishnet-type Feynman graphs arising in planar four-dimensional bi-scalar chiral theory recently proposed in arXiv:1512.06704 as a special double scaling limit of gamma-deformed N = 4 SYM theory. We show that the transfer matrix "building" the fishnet graphs emerges from the R-matrix of non-compact conformal SU(2 , 2) Heisenberg spin chain with spins belonging to principal series representations of the four-dimensional conformal group. We demonstrate explicitly a relationship between this integrable spin chain and the Quantum Spectral Curve (QSC) of N = 4 SYM. Using QSC and spin chain methods, we construct Baxter equation for Q-functions of the conformal spin chain needed for computation of the anomalous dimensions of operators of the type tr( ϕ 1 J ) where ϕ 1 is one of the two scalars of the theory. For J = 3 we derive from QSC a quantization condition that fixes the relevant solution of Baxter equation. The scaling dimensions of the operators only receive contributions from wheel-like graphs. We develop integrability techniques to compute the divergent part of these graphs and use it to present the weak coupling expansion of dimensions to very high orders. Then we apply our exact equations to calculate the anomalous dimensions with J = 3 to practically unlimited precision at any coupling. These equations also describe an infinite tower of local conformal operators all carrying the same charge J = 3. The method should be applicable for any J and, in principle, to any local operators of bi-scalar theory. We show that at strong coupling the scaling dimensions can be derived from semiclassical quantization of finite gap solutions describing an integrable system of noncompact SU(2 , 2) spins. This bears similarities with the classical strings arising in the strongly coupled limit of N = 4 SYM.
Strategic rigidity and foresight for technology adoption among electric utilities
International Nuclear Information System (INIS)
Shah, Arsalan Nisar; Palacios, Miguel; Ruiz, Felipe
2013-01-01
The variation in the adoption of a technology as a major source of competitive advantage has been attributed to the wide-ranging strategic foresight and the integrative capability of a firm. These possible areas of competitive advantage can exist in the periphery of the firm's strategic vision and can get easily blurred as a result of rigidness and can permeate in the decision-making process of the firm. This article explores how electric utility firms with a renewable energy portfolio can become strategically rigid in terms of adoption of newer technologies. The reluctance or delay in the adoption of new technology can be characterized as strategic rigidness, brought upon as a result of a firm's core competence or core capability in the other, more conventional technology arrangement. This paper explores the implications of such rigidness on the performance of a firm and consequently on the energy eco-system. The paper substantiates the results by emphasizing the case of Iberdrola S.A., an incumbent firm as a wind energy developer and its adoption decision behavior. We illustrate that the very routines that create competitive advantage for firms in the electric utility industry are vulnerable as they might also develop as sources of competitive disadvantage, when firms confront environmental change and uncertainty. - Highlights: • Present a firm-level perspective on technology adoption behavior among electric utilities. • Firms with mature technology can become rigid towards newer technologies. • Case study analysis of a major electric utility firm. • Implications of ‘technology rigidness’ on the energy eco-system
Matrix rigidity regulates cancer cell growth and cellular phenotype.
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Robert W Tilghman
2010-09-01
Full Text Available The mechanical properties of the extracellular matrix have an important role in cell growth and differentiation. However, it is unclear as to what extent cancer cells respond to changes in the mechanical properties (rigidity/stiffness of the microenvironment and how this response varies among cancer cell lines.In this study we used a recently developed 96-well plate system that arrays extracellular matrix-conjugated polyacrylamide gels that increase in stiffness by at least 50-fold across the plate. This plate was used to determine how changes in the rigidity of the extracellular matrix modulate the biological properties of tumor cells. The cell lines tested fall into one of two categories based on their proliferation on substrates of differing stiffness: "rigidity dependent" (those which show an increase in cell growth as extracellular rigidity is increased, and "rigidity independent" (those which grow equally on both soft and stiff substrates. Cells which grew poorly on soft gels also showed decreased spreading and migration under these conditions. More importantly, seeding the cell lines into the lungs of nude mice revealed that the ability of cells to grow on soft gels in vitro correlated with their ability to grow in a soft tissue environment in vivo. The lung carcinoma line A549 responded to culture on soft gels by expressing the differentiated epithelial marker E-cadherin and decreasing the expression of the mesenchymal transcription factor Slug.These observations suggest that the mechanical properties of the matrix environment play a significant role in regulating the proliferation and the morphological properties of cancer cells. Further, the multiwell format of the soft-plate assay is a useful and effective adjunct to established 3-dimensional cell culture models.
Matrix Rigidity Regulates Cancer Cell Growth and Cellular Phenotype
Tilghman, Robert W.; Cowan, Catharine R.; Mih, Justin D.; Koryakina, Yulia; Gioeli, Daniel; Slack-Davis, Jill K.; Blackman, Brett R.; Tschumperlin, Daniel J.; Parsons, J. Thomas
2010-01-01
Background The mechanical properties of the extracellular matrix have an important role in cell growth and differentiation. However, it is unclear as to what extent cancer cells respond to changes in the mechanical properties (rigidity/stiffness) of the microenvironment and how this response varies among cancer cell lines. Methodology/Principal Findings In this study we used a recently developed 96-well plate system that arrays extracellular matrix-conjugated polyacrylamide gels that increase in stiffness by at least 50-fold across the plate. This plate was used to determine how changes in the rigidity of the extracellular matrix modulate the biological properties of tumor cells. The cell lines tested fall into one of two categories based on their proliferation on substrates of differing stiffness: “rigidity dependent” (those which show an increase in cell growth as extracellular rigidity is increased), and “rigidity independent” (those which grow equally on both soft and stiff substrates). Cells which grew poorly on soft gels also showed decreased spreading and migration under these conditions. More importantly, seeding the cell lines into the lungs of nude mice revealed that the ability of cells to grow on soft gels in vitro correlated with their ability to grow in a soft tissue environment in vivo. The lung carcinoma line A549 responded to culture on soft gels by expressing the differentiated epithelial marker E-cadherin and decreasing the expression of the mesenchymal transcription factor Slug. Conclusions/Significance These observations suggest that the mechanical properties of the matrix environment play a significant role in regulating the proliferation and the morphological properties of cancer cells. Further, the multiwell format of the soft-plate assay is a useful and effective adjunct to established 3-dimensional cell culture models. PMID:20886123
Initial Development of an Electronic Testis Rigidity Tester
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Petros Mirilas
2011-01-01
Full Text Available We aimed to develop our previously presented mechanical device, the Testis Rigidity Tester (TRT, into an electronic system (Electronic Testis Rigidity Tester, ETRT by applying tactile imaging, which has been used successfully with other solid organs. A measuring device, located at the front end of the ETRT incorporates a tactile sensor comprising an array of microsensors. By application of a predetermined deformation of 2 mm, increased pressure alters linearly the resistance of each microsensor, producing changes of voltage. These signals were amplified, filtered, and digitized, and then processed by an electronic collector system, which presented them as a color-filled contour plot of the area of the testis coming into contact with the sensor. Testis models of different rigidity served for initial evaluation of ETRT; their evacuated central spaces contained different, increasing glue masses. An independent method of rigidity measurement, using an electric weight scale and a micrometer, showed that the more the glue injected, the greater the force needed for a 2-mm deformation. In a preliminary test, a single sensor connected to a multimeter showed similar force measurement for the same deformation in these phantoms. For each of the testis models compressed in the same manner, the ETRT system offered a map of pressures, represented by a color scale within the contour plot of the contact area with the sensor. ETRT found certain differences in rigidity between models that had escaped detection by a blind observer. ETRT is easy to use and provides a color-coded “insight“ of the testis internal structure. After experimental testing, it could be valuable in intraoperative evaluation of testes, so that the surgeon can decide about orchectomy or orcheopexy.
Objective interpretation as conforming interpretation
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Lidka Rodak
2011-12-01
Full Text Available The practical discourse willingly uses the formula of “objective interpretation”, with no regards to its controversial nature that has been discussed in literature.The main aim of the article is to investigate what “objective interpretation” could mean and how it could be understood in the practical discourse, focusing on the understanding offered by judicature.The thesis of the article is that objective interpretation, as identified with textualists’ position, is not possible to uphold, and should be rather linked with conforming interpretation. And what this actually implies is that it is not the virtue of certainty and predictability – which are usually associated with objectivity- but coherence that makes the foundation of applicability of objectivity in law.What could be observed from the analyses, is that both the phenomenon of conforming interpretation and objective interpretation play the role of arguments in the interpretive discourse, arguments that provide justification that interpretation is not arbitrary or subjective. With regards to the important part of the ideology of legal application which is the conviction that decisions should be taken on the basis of law in order to exclude arbitrariness, objective interpretation could be read as a question “what kind of authority “supports” certain interpretation”? that is almost never free of judicial creativity and judicial activism.One can say that, objective and conforming interpretation are just another arguments used in legal discourse.
Conformational kinetics of aliphatic tails
Ferrarini, Alberta; Moro, Giorgio; Nordio, Pier Luigi
The master equation describing the random walk between sites identified with the stable conformers of a chain molecule, represents the extension to the time domain of the Rotational Isomeric State model. The asymptotic analysis of the multidimensional diffusion equation in the continuous torsional variables subjected to the configurational potential, provides a rigorous justification for the discrete models, and it supplies, without resorting to phenomenological parameters, molecular definitions of the kinetic rates for the conformational transitions occurring at each segment of the chain. The coupling between the torsional variables is fully taken into account, giving rise to cooperative effects. A complete calculation of the specific correlation functions which describe the time evolution of the angular functions probed by N.M.R. and dielectric relaxation measurements, has been performed for alkyl chains attached to a massive core. The resulting behaviour has been compared with the decay of trans and gauche populations of specific bonds, expressed in terms of suitable correlation functions whose time integrals lead quite naturally to the definition of effective kinetic constants for the conformational transitions.
Anomalies, conformal manifolds, and spheres
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Gomis, Jaume [Perimeter Institute for Theoretical Physics,Waterloo, Ontario, N2L 2Y5 (Canada); Hsin, Po-Shen [Department of Physics, Princeton University,Princeton, NJ 08544 (United States); Komargodski, Zohar; Schwimmer, Adam [Weizmann Institute of Science,Rehovot 76100 (Israel); Seiberg, Nathan [School of Natural Sciences, Institute for Advanced Study,Princeton, NJ 08540 (United States); Theisen, Stefan [Max-Planck-Institut für Gravitationsphysik, Albert-Einstein-Institut,14476 Golm (Germany)
2016-03-04
The two-point function of exactly marginal operators leads to a universal contribution to the trace anomaly in even dimensions. We study aspects of this trace anomaly, emphasizing its interpretation as a sigma model, whose target space M is the space of conformal field theories (a.k.a. the conformal manifold). When the underlying quantum field theory is supersymmetric, this sigma model has to be appropriately supersymmetrized. As examples, we consider in some detail N=(2,2) and N=(0,2) supersymmetric theories in d=2 and N=2 supersymmetric theories in d=4. This reasoning leads to new information about the conformal manifolds of these theories, for example, we show that the manifold is Kähler-Hodge and we further argue that it has vanishing Kähler class. For N=(2,2) theories in d=2 and N=2 theories in d=4 we also show that the relation between the sphere partition function and the Kähler potential of M follows immediately from the appropriate sigma models that we construct. Along the way we find several examples of potential trace anomalies that obey the Wess-Zumino consistency conditions, but can be ruled out by a more detailed analysis.