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Sample records for sphaeroides ii extended

  1. DNA-directed in vitro synthesis and assembly of the form II D-ribulose-1,5-bisphosphate carboxylase/oxygenase from Rhodopseudomonas sphaeroides.

    PubMed Central

    Chory, J; Muller, E D; Kaplan, S

    1985-01-01

    A biochemical analysis of the in vitro assembly of the form II ribulose-1,5-bisphosphate carboxylase/oxygenase from Rhodopseudomonas sphaeroides after transcription and translation from cloned DNA is presented. The predominant enzymatically active oligomeric forms of the in vitro-synthesized and -assembled ribulose-1,5-bisphosphate carboxylase are tetramers and hexamers. Assembly of the monomeric subunits to form active enzyme appears to be dependent on the presence of a minimum number of subunits in the cell extract. Assembly of ribulose-1,5-bisphosphate carboxylase also was observed when the protein-synthesizing extracts were prepared from cells which were partially derepressed for ribulose-1,5-bisphosphate carboxylase expression. Images PMID:3918003

  2. Phosphoribulokinase mediates nitrogenase-induced carbon dioxide fixation gene repression in Rhodobacter sphaeroides

    PubMed Central

    Farmer, Ryan M.

    2015-01-01

    In many organisms there is a balance between carbon and nitrogen metabolism. These observations extend to the nitrogen-fixing, nonsulfur purple bacteria, which have the classic family of P(II) regulators that coordinate signals of carbon and nitrogen status to regulate nitrogen metabolism. Curiously, these organisms also possess a reverse mechanism to regulate carbon metabolism based on cellular nitrogen status. In this work, studies in Rhodobacter sphaeroides firmly established that the activity of the enzyme that catalyses nitrogen fixation, nitrogenase, induces a signal that leads to repression of genes encoding enzymes of the Calvin–Benson–Bassham (CBB) CO2 fixation pathway. Additionally, genetic and metabolomic experiments revealed that NADH-activated phosphoribulokinase is an intermediate in the signalling pathway. Thus, nitrogenase activity appears to be linked to cbb gene repression through phosphoribulokinase. PMID:26306848

  3. Phosphoribulokinase mediates nitrogenase-induced carbon dioxide fixation gene repression in Rhodobacter sphaeroides.

    PubMed

    Farmer, Ryan M; Tabita, F Robert

    2015-11-01

    In many organisms there is a balance between carbon and nitrogen metabolism. These observations extend to the nitrogen-fixing, nonsulfur purple bacteria, which have the classic family of P(II) regulators that coordinate signals of carbon and nitrogen status to regulate nitrogen metabolism. Curiously, these organisms also possess a reverse mechanism to regulate carbon metabolism based on cellular nitrogen status. In this work, studies in Rhodobacter sphaeroides firmly established that the activity of the enzyme that catalyses nitrogen fixation, nitrogenase, induces a signal that leads to repression of genes encoding enzymes of the Calvin-Benson-Bassham (CBB) CO2 fixation pathway. Additionally, genetic and metabolomic experiments revealed that NADH-activated phosphoribulokinase is an intermediate in the signalling pathway. Thus, nitrogenase activity appears to be linked to cbb gene repression through phosphoribulokinase.

  4. Reliability and extended-life potential of EBR-II

    SciTech Connect

    King, R W

    1985-01-01

    Although the longlife potential of liquid-metal-cooled reactors (LMRs) has been only partially demonstrated, many factors point to the potential for exceptionally long life. EBR-II has the opportunity to become the first LMR to achieve an operational lifetime of 30 years or more. In 1984 a study of the extended-life potential of EBR-II identified the factors that contribute to the continued successful operation of EBR-II as a power reactor and experimental facility. Also identified were factors that could cause disruptions in the useful life of the facility. Although no factors were found that would inherently limit the life of EBR-II, measures were identified that could help ensure continued plant availability. These measures include the implementation of more effective surveillance, diagnostic, and control systems to complement the inherent safety and reliability features of EBR-II. An operating lifetime of well beyond 30 years is certainly feasible.

  5. Definition of the interaction domain for cytochrome c on cytochrome c oxidase. Ii. Rapid kinetic analysis of electron transfer from cytochrome c to Rhodobacter sphaeroides cytochrome oxidase surface mutants.

    PubMed

    Wang, K; Zhen, Y; Sadoski, R; Grinnell, S; Geren, L; Ferguson-Miller, S; Durham, B; Millett, F

    1999-12-31

    The reaction between cytochrome c (Cc) and Rhodobacter sphaeroides cytochrome c oxidase (CcO) was studied using a cytochrome c derivative labeled with ruthenium trisbipyridine at lysine 55 (Ru-55-Cc). Flash photolysis of a 1:1 complex between Ru-55-Cc and CcO at low ionic strength results in electron transfer from photoreduced heme c to Cu(A) with an intracomplex rate constant of k(a) = 4 x 10(4) s(-1), followed by electron transfer from Cu(A) to heme a with a rate constant of k(b) = 9 x 10(4) s(-1). The effects of CcO surface mutations on the kinetics follow the order D214N > E157Q > E148Q > D195N > D151N/E152Q approximately D188N/E189Q approximately wild type, indicating that the acidic residues Asp(214), Glu(157), Glu(148), and Asp(195) on subunit II interact electrostatically with the lysines surrounding the heme crevice of Cc. Mutating the highly conserved tryptophan residue, Trp(143), to Phe or Ala decreased the intracomplex electron transfer rate constant k(a) by 450- and 1200-fold, respectively, without affecting the dissociation constant K(D). It therefore appears that the indole ring of Trp(143) mediates electron transfer from the heme group of Cc to Cu(A). These results are consistent with steady-state kinetic results (Zhen, Y., Hoganson, C. W., Babcock, G. T., and Ferguson-Miller, S. (1999) J. Biol. Chem. 274, 38032-38041) and a computational docking analysis (Roberts, V. A., and Pique, M. E. (1999) J. Biol. Chem. 274, 38051-38060).

  6. Extended [C II] Emission in Local Luminous Infrared Galaxies

    NASA Astrophysics Data System (ADS)

    Díaz-Santos, T.; Armus, L.; Charmandaris, V.; Stacey, G.; Murphy, E. J.; Haan, S.; Stierwalt, S.; Malhotra, S.; Appleton, P.; Inami, H.; Magdis, G. E.; Elbaz, D.; Evans, A. S.; Mazzarella, J. M.; Surace, J. A.; van der Werf, P. P.; Xu, C. K.; Lu, N.; Meijerink, R.; Howell, J. H.; Petric, A. O.; Veilleux, S.; Sanders, D. B.

    2014-06-01

    We present Herschel/PACS observations of extended [C II] 157.7 μm line emission detected on ~1-10 kpc scales in 60 local luminous infrared galaxies (LIRGs) from the Great Observatories All-sky LIRG Survey. We find that most of the extra-nuclear emission show [C II]/FIR ratios >=4 × 10-3, larger than the mean ratio seen in the nuclei, and similar to those found in the extended disks of normal star-forming galaxies and the diffuse interstellar medium of our Galaxy. The [C II] "deficits" found in the most luminous local LIRGs are therefore restricted to their nuclei. There is a trend for LIRGs with warmer nuclei to show larger differences between their nuclear and extra-nuclear [C II]/FIR ratios. We find an anti-correlation between [C II]/FIR and the luminosity surface density, ΣIR, for the extended emission in the spatially resolved galaxies. However, there is an offset between this trend and that found for the LIRG nuclei. We use this offset to derive a beam filling-factor for the star-forming regions within the LIRG disks of ~6% relative to their nuclei. We confront the observed trend to photo-dissociation region models and find that the slope of the correlation is much shallower than the model predictions. Finally, we compare the correlation found between [C II]/FIR and ΣIR with measurements of high-redshift starbursting IR-luminous galaxies.

  7. Nitrate reductase from Rhodopseudomonas sphaeroides.

    PubMed Central

    Kerber, N L; Cardenas, J

    1982-01-01

    The facultative phototroph Rhodopseudomonas sphaeroides DSM158 was incapable of either assimilating or dissimilating nitrate, although the organism could reduce it enzymatically to nitrite either anaerobically in the light or aerobically in the dark. Reduction of nitrate was mediated by a nitrate reductase bound to chromatophores that could be easily solubilized and functioned with chemically reduced viologens or photochemically reduced flavins as electron donors. The enzyme was solubilized, and some of its kinetic and molecular parameters were determined. It seemed to be nonadaptive, ammonia did not repress its synthesis, and its activity underwent a rapid decline when the cells entered the stationary growth phase. Studies with inhibitors and with metal antagonists indicated that molybdenum and possibly iron participate in the enzymatic reduction of nitrate. The conjectural significance of this nitrate reductase in phototrophic bacteria is discussed. PMID:6978883

  8. Heat transfer through an extended surface containing He II

    SciTech Connect

    Van Sciver, S.W.

    1999-02-01

    A semi-analytic solution for the heat transfer process between a He II pressurized bath and a saturated tube-type heat exchanger is presented. The problem is modeled with an extended surface heat transfer formulation analogous to that in conventional conduction. The process is governed by Kapitza conductance and counterflow within the bulk fluid in the tube. The resulting nonlinear differential equation may be integrated for the special case of constant properties, yielding a simple solution applicable to design and analysis of practical heat exchangers.

  9. NEWLY IDENTIFIED EXTENDED GREEN OBJECTS (EGOs) FROM THE SPITZER GLIMPSE II SURVEY. II. MOLECULAR CLOUD ENVIRONMENTS

    SciTech Connect

    Chen Xi; Gan Conggui; Shen Zhiqiang; Ellingsen, Simon P.; Titmarsh, Anita; He Jinhua

    2013-06-01

    We have undertaken a survey of molecular lines in the 3 mm band toward 57 young stellar objects using the Australia Telescope National Facility Mopra 22 m radio telescope. The target sources were young stellar objects with active outflows (extended green objects (EGOs)) newly identified from the GLIMPSE II survey. We observe a high detection rate (50%) of broad line wing emission in the HNC and CS thermal lines, which combined with the high detection rate of class I methanol masers toward these sources (reported in Paper I) further demonstrates that the GLIMPSE II EGOs are associated with outflows. The physical and kinematic characteristics derived from the 3 mm molecular lines for these newly identified EGOs are consistent with these sources being massive young stellar objects with ongoing outflow activity and rapid accretion. These findings support our previous investigations of the mid-infrared properties of these sources and their association with other star formation tracers (e.g., infrared dark clouds, methanol masers and millimeter dust sources) presented in Paper I. The high detection rate (64%) of the hot core tracer CH{sub 3}CN reveals that the majority of these new EGOs have evolved to the hot molecular core stage. Comparison of the observed molecular column densities with predictions from hot core chemistry models reveals that the newly identified EGOs from the GLIMPSE II survey are members of the youngest hot core population, with an evolutionary time scale of the order of 10{sup 3} yr.

  10. GALACTIC CEPHEIDS WITH SPITZER. II. SEARCH FOR EXTENDED INFRARED EMISSION

    SciTech Connect

    Barmby, P.; Marengo, M.; Evans, N. R.; Huelsman, D.; Fazio, G. G.; Bono, G.; Su, K. Y. L.; Welch, D. L.

    2011-02-15

    A deep and detailed examination of 29 classical Cepheids with the Spitzer Space Telescope has revealed three stars with strong nearby extended emission detected in multiple bands which appears to be physically associated with the stars. RS Pup was already known to possess extended infrared emission, while the extended emission around the other two stars (S Mus and {delta} Cep) is newly discovered in our observations. Four other stars (GH Lup, l Car, T Mon, and X Cyg) show tentative evidence for extended infrared emission. An unusual elongated extended object next to SZ Tau appears to be a background or foreground object in a chance alignment with the Cepheid. The inferred mass-loss rate upper limits for S Mus and {delta} Cep are in the range from 10{sup -9} to 10{sup -8} M{sub sun} yr{sup -1}, with the upper limit for RS Pup as high as 10{sup -6} M{sub sun} yr{sup -1}. Mass loss during post-main-sequence evolution has been proposed as a resolution to the discrepancy between pulsational and dynamical masses of Cepheid variable stars: dust in the lost material would make itself known by the presence of an infrared bright nebula or unresolved infrared excess. The observed frequency of infrared circumstellar emission (<24%) and the mass-loss rate we estimate for our sources show that dusty mass loss can only account for part of the Cepheid mass-loss discrepancy. Nevertheless, our direct evidence that mass loss is active during the Cepheid phase is an important confirmation that these processes need to be included in evolutionary and pulsation models of these stars and should be taken into account in the calibration of the Cepheid distance scale.

  11. Enhancement of Rhodobacter sphaeroides growth and carotenoid production through biostimulation.

    PubMed

    Liu, Shuli; Zhang, Guangming; Li, Xiangkun; Wu, Pan; Zhang, Jie

    2015-07-01

    Bacillus thuringiensis/cereus L2 was added as a biostimulant to enhance the biomass accumulation and carotenoid yield of Rhodobacter sphaeroides using wastewater as the culturing medium. Results showed that biostimulation could significantly enhance the R. sphaeroides biomass production and carotenoid yield. The optimal biostimulant proportion was 40 μL (about 6.4×10(5) CFU). Through the use of biostimulation, chemical oxygen demand removal, R. sphaeroides biomass production, carotenoid concentration, and carotenoid yield were improved by 178%, 67%, 214%, and 70%, respectively. Theoretical analysis revealed that there were two possible reasons for such increases. One was that biostimulation enhanced the R. sphaeroides wastewater treatment efficiency. The other was that biostimulation significantly decreased the peroxidase activity in R. sphaeroides. The results showed that the highest peroxidase activity dropped by 87% and the induction ratio of the RSP_3419 gene was 3.1 with the addition of biostimulant. The enhanced carotenoid yield in R. sphaeroides could thus be explained by a decrease in peroxidase activity.

  12. Evidence for Fluorescent Fe II Emission from Extended Low Ionization Outflows in Obscured Quasars

    NASA Astrophysics Data System (ADS)

    Wang, Tinggui; Ferland, Gary J.; Yang, Chenwei; Wang, Huiyuan; Zhang, Shaohua

    2016-06-01

    Recent studies have shown that outflows in at least some broad absorption line (BAL) quasars are extended well beyond the putative dusty torus. Such outflows should be detectable in obscured quasars. We present four WISE selected infrared red quasars with very strong and peculiar ultraviolet Fe ii emission lines: strong UV Fe ii UV arising from transitions to ground/low excitation levels, and very weak Fe ii at wavelengths longer than 2800 Å. The spectra of these quasars display strong resonant emission lines, such as C iv, Al iii and Mg ii but sometimes, a lack of non-resonant lines such as C iii], S iii and He ii. We interpret the Fe ii lines as resonantly scattered light from the extended outflows that are viewed nearly edge-on, so that the accretion disk and broad line region are obscured by the dusty torus, while the extended outflows are not. We show that dust free gas exposed to strong radiation longward of 912 Å produces Fe ii emission very similar to that observed. The gas is too cool to collisionally excite Fe ii lines, accounting for the lack of optical emission. The spectral energy distribution from the UV to the mid-infrared can be modeled as emission from a clumpy dusty torus, with UV emission being reflected/scattered light either by the dusty torus or the outflow. Within this scenario, we estimate a minimum covering factor of the outflows from a few to 20% for the Fe ii scattering region, suggesting that Fe ii BAL quasars are at a special stage of quasar evolution.

  13. Ultraviolet illuminated molecular cloud boundaries: Extended (C II) 158 micrometer emission toward L1630

    NASA Technical Reports Server (NTRS)

    Jaffe, D. T.; Zhou, S.; Howe, J. E.; Herrmann, F.; Madden, S. C.; Poglitsch, A.; Vanderwerf, P. P.; Stacey, G. J.

    1994-01-01

    The construction of a large scale map of the 158 micrometer C+ line toward the L1630/Orion B molecular cloud, covering an approximately 35' by 45' area which includes the NGC 2024 H II region, zeta-Ori, the reflection nebula NGC 2023, and the Horsehead nebula, is reported. Emission in the C II line is very widespread. The line was detected at levels in excess of a few 0.0001 erg/sq cm/s/sr over almost the entire mapped region. Extended emission associated with the NGC 2024 H II region and its envelope accounts for more than half of the C II flux. Over this approximately 1.5 by 2.5 pc region, the amount of gas phase carbon in the form of C+ is comparable to the amount of carbon in CO. This result, together with the C II distribution implies that C II emission arises on the surface of clumps throughout the cloud rather than in a single layer at the H II region boundary. Away from the H II region, most of the C II emission comes from the western edge of the L1630 cloud and probably results from excitation by external OB stars. The overall extent of the C II emission is comparable to that of millimeter molecular lines but the distributions are different in detail. The difference in C II and molecular line distributions, in particular, the larger extent of the C II emission west of NGC 2024 implies large variations in the ratio of the C II and J = 1 towards 0 intensities. Models of photon dominated regions can explain the relation between C II and CO intensities only if the cloud edges and cloud interior are considered separately. A method for using C II and radio continuum emission to characterize the relationship between OB stars and photon dominated regions is proposed.

  14. Ultraviolet-illuminated molecular cloud boundaries: Extended (C II) 158 micron emission toward L1630

    NASA Technical Reports Server (NTRS)

    Jaffe, D. T.; Zhou, S.; Howe, J. E.; Herrmann, F.; Madden, S. C.; Poglitsch, A.; Van Der Werf, P. P.; Stacey, G. J.

    1994-01-01

    We have made a large-scale map of the 158 micrometers C(+) line toward the L1630/Orion B molecular cloud. The map covers a approximately 35 min x 45 min area which includes the NGC 2024 H II region, zeta Ori, the reflection nebula NGC 2023, and the Horsehead nebula. Emission in the (C II) line is very widespread. The line was detected at levels in excess of a few 10(exp -4) ergs/sq cm/s/sr over almost the entire mapped region. Extended emission associated with the NGC 2024 H II region and its envelope accounts for more than half of the (C II) flux. Over this approximately 1.5 x 2.5 pc region, the amount of gas-phase carbon in the form of C(+) is comparable to the amount of carbon in CO. This result, together with the (C II) distribution, implies that (C II) emission arises on the surfaces of clumps throughout the cloud rather than in a single layer at the H II region boundary. Away from the H II region, most of the (C II) emission comes from the western edge of the L1630 cloud and probably results from excitation by external OB stars. The overall extent of the (C II) emission is comparable to that of millimeter molecular lines, but the distributions are different in detail. The difference in (C II) and molecular line distributions, in particular, the larger extent of the (C II) emission west of NGC 2024 implies large variations in the radio of the (C II) and CO J = 1 goes to 0 intensities. Models of photon-dominated regions can explain the relation between (C II) and CO intensities only if one considers the cloud edges and cloud interior separately. We propose a method for using (C II) and radio continuum emission to characterize the relationship between OB stars and photon-dominated regions.

  15. Bioremediation of lead contaminated soil with Rhodobacter sphaeroides.

    PubMed

    Li, Xiaomin; Peng, Weihua; Jia, Yingying; Lu, Lin; Fan, Wenhong

    2016-08-01

    Bioremediation with microorganisms is a promising technique for heavy metal contaminated soil. Rhodobacter sphaeroides was previously isolated from oil field injection water and used for bioremediation of lead (Pb) contaminated soil in the present study. Based on the investigation of the optimum culturing conditions and the tolerance to Pb, we employed the microorganism for the remediation of Pb contaminated soil simulated at different contamination levels. It was found that the optimum temperature, pH, and inoculum size for R. sphaeroides is 30-35 °C, 7, and 2 × 10(8) mL(-1), respectively. Rhodobacter sphaeroides did not remove the Pb from soil but did change its speciation. During the bioremediation process, more available fractions were transformed to less accessible and inert fractions; in particular, the exchangeable phase was dramatically decreased while the residual phase was substantially increased. A wheat seedling growing experiment showed that Pb phytoavailability was reduced in amended soils. Results inferred that the main mechanism by which R. sphaeroides treats Pb contaminated soil is the precipitation formation of inert compounds, including lead sulfate and lead sulfide. Although the Pb bioremediation efficiency on wheat was not very high (14.78% root and 24.01% in leaf), R. sphaeroides remains a promising alternative for Pb remediation in contaminated soil.

  16. Embryonic, Larval, and Early Juvenile Development of the Tropical Sea Urchin, Salmacis sphaeroides (Echinodermata: Echinoidea)

    PubMed Central

    Rahman, M. Aminur; Yusoff, Fatimah Md.; Arshad, A.; Shamsudin, Mariana Nor; Amin, S. M. N.

    2012-01-01

    Salmacis sphaeroides (Linnaeus, 1758) is one of the regular echinoids, occuring in the warm Indo-West Pacific, including Johor Straits, between Malaysia and Singapore. In order to investigate the developmental basis of morphological changes in embryos and larvae, we documented the ontogeny of S. sphaeroides in laboratory condition. Gametes were obtained from adult individuals by 0.5 M KCl injection into the coelomic cavity. Fertilization rate at limited sperm concentration (10−5 dilution) was 96.6 ± 1.4% and the resulting embryos were reared at 24°C. First cleavage (2-cell), 4-cell, 8-cell, 16-cell, 32-cell, and multicell (Morulla) stages were achieved 01.12, 02.03, 02.28, 02.51, 03.12, and 03.32 h postfertilization. Ciliated blastulae with a mean length of 174.72 ± 4.43 μm hatched 08.45 h after sperm entry. The gastrulae formed 16.15 h postfertilization and the archenteron elongated constantly while ectodermal red-pigmented cells migrated synchronously to the apical plate. Pluteus larva started to feed unicellular algae in 2 d, grew continuously, and finally attained metamorphic competence in 35 d after fertilization. Metamorphosis took approximately 1 h 30 min from attachment to the complete resorption of larval tissues and the development of complete juvenile structure with adult spines, extended tubefeet and well-developed pedicellaria, the whole event of which usually took place within 1 d postsettlement. This study represents the first successful investigation on embryonic, larval, and early juvenile development of S. sphaeroides. The findings would greatly be helpful towards the understanding of ontogeny and life-history strategies, which will facilitate us to develop the breeding, seed production, and culture techniques of sea urchins in captive condition. PMID:23055824

  17. Embryonic, larval, and early juvenile development of the tropical sea urchin, Salmacis sphaeroides (Echinodermata: Echinoidea).

    PubMed

    Rahman, M Aminur; Yusoff, Fatimah Md; Arshad, A; Shamsudin, Mariana Nor; Amin, S M N

    2012-01-01

    Salmacis sphaeroides (Linnaeus, 1758) is one of the regular echinoids, occuring in the warm Indo-West Pacific, including Johor Straits, between Malaysia and Singapore. In order to investigate the developmental basis of morphological changes in embryos and larvae, we documented the ontogeny of S. sphaeroides in laboratory condition. Gametes were obtained from adult individuals by 0.5 M KCl injection into the coelomic cavity. Fertilization rate at limited sperm concentration (10(-5) dilution) was 96.6 ± 1.4% and the resulting embryos were reared at 24°C. First cleavage (2-cell), 4-cell, 8-cell, 16-cell, 32-cell, and multicell (Morulla) stages were achieved 01.12, 02.03, 02.28, 02.51, 03.12, and 03.32 h postfertilization. Ciliated blastulae with a mean length of 174.72 ± 4.43 μm hatched 08.45 h after sperm entry. The gastrulae formed 16.15 h postfertilization and the archenteron elongated constantly while ectodermal red-pigmented cells migrated synchronously to the apical plate. Pluteus larva started to feed unicellular algae in 2 d, grew continuously, and finally attained metamorphic competence in 35 d after fertilization. Metamorphosis took approximately 1 h 30 min from attachment to the complete resorption of larval tissues and the development of complete juvenile structure with adult spines, extended tubefeet and well-developed pedicellaria, the whole event of which usually took place within 1 d postsettlement. This study represents the first successful investigation on embryonic, larval, and early juvenile development of S. sphaeroides. The findings would greatly be helpful towards the understanding of ontogeny and life-history strategies, which will facilitate us to develop the breeding, seed production, and culture techniques of sea urchins in captive condition. PMID:23055824

  18. Embryonic, larval, and early juvenile development of the tropical sea urchin, Salmacis sphaeroides (Echinodermata: Echinoidea).

    PubMed

    Rahman, M Aminur; Yusoff, Fatimah Md; Arshad, A; Shamsudin, Mariana Nor; Amin, S M N

    2012-01-01

    Salmacis sphaeroides (Linnaeus, 1758) is one of the regular echinoids, occuring in the warm Indo-West Pacific, including Johor Straits, between Malaysia and Singapore. In order to investigate the developmental basis of morphological changes in embryos and larvae, we documented the ontogeny of S. sphaeroides in laboratory condition. Gametes were obtained from adult individuals by 0.5 M KCl injection into the coelomic cavity. Fertilization rate at limited sperm concentration (10(-5) dilution) was 96.6 ± 1.4% and the resulting embryos were reared at 24°C. First cleavage (2-cell), 4-cell, 8-cell, 16-cell, 32-cell, and multicell (Morulla) stages were achieved 01.12, 02.03, 02.28, 02.51, 03.12, and 03.32 h postfertilization. Ciliated blastulae with a mean length of 174.72 ± 4.43 μm hatched 08.45 h after sperm entry. The gastrulae formed 16.15 h postfertilization and the archenteron elongated constantly while ectodermal red-pigmented cells migrated synchronously to the apical plate. Pluteus larva started to feed unicellular algae in 2 d, grew continuously, and finally attained metamorphic competence in 35 d after fertilization. Metamorphosis took approximately 1 h 30 min from attachment to the complete resorption of larval tissues and the development of complete juvenile structure with adult spines, extended tubefeet and well-developed pedicellaria, the whole event of which usually took place within 1 d postsettlement. This study represents the first successful investigation on embryonic, larval, and early juvenile development of S. sphaeroides. The findings would greatly be helpful towards the understanding of ontogeny and life-history strategies, which will facilitate us to develop the breeding, seed production, and culture techniques of sea urchins in captive condition.

  19. Assembly of functional photosystem complexes in Rhodobacter sphaeroides incorporating carotenoids from the spirilloxanthin pathway.

    PubMed

    Chi, Shuang C; Mothersole, David J; Dilbeck, Preston; Niedzwiedzki, Dariusz M; Zhang, Hao; Qian, Pu; Vasilev, Cvetelin; Grayson, Katie J; Jackson, Philip J; Martin, Elizabeth C; Li, Ying; Holten, Dewey; Neil Hunter, C

    2015-02-01

    Carotenoids protect the photosynthetic apparatus against harmful radicals arising from the presence of both light and oxygen. They also act as accessory pigments for harvesting solar energy, and are required for stable assembly of many light-harvesting complexes. In the phototrophic bacterium Rhodobacter (Rba.) sphaeroides phytoene desaturase (CrtI) catalyses three sequential desaturations of the colourless carotenoid phytoene, extending the number of conjugated carbon-carbon double bonds, N, from three to nine and producing the yellow carotenoid neurosporene; subsequent modifications produce the yellow/red carotenoids spheroidene/spheroidenone (N=10/11). Genomic crtI replacements were used to swap the native three-step Rba. sphaeroides CrtI for the four-step Pantoea agglomerans enzyme, which re-routed carotenoid biosynthesis and culminated in the production of 2,2'-diketo-spirilloxanthin under semi-aerobic conditions. The new carotenoid pathway was elucidated using a combination of HPLC and mass spectrometry. Premature termination of this new pathway by inactivating crtC or crtD produced strains with lycopene or rhodopin as major carotenoids. All of the spirilloxanthin series carotenoids are accepted by the assembly pathways for LH2 and RC-LH1-PufX complexes. The efficiency of carotenoid-to-bacteriochlorophyll energy transfer for 2,2'-diketo-spirilloxanthin (15 conjugated CC bonds; N=15) in LH2 complexes is low, at 35%. High energy transfer efficiencies were obtained for neurosporene (N=9; 94%), spheroidene (N=10; 96%) and spheroidenone (N=11; 95%), whereas intermediate values were measured for lycopene (N=11; 64%), rhodopin (N=11; 62%) and spirilloxanthin (N=13; 39%). The variety and stability of these novel Rba. sphaeroides antenna complexes make them useful experimental models for investigating the energy transfer dynamics of carotenoids in bacterial photosynthesis.

  20. Extended Analysis of the Spectrum of Singly Ionized Chromium (Cr II)

    NASA Astrophysics Data System (ADS)

    Sansonetti, Craig J.; Nave, Gillian

    2014-08-01

    We have made new observations of the spectrum of singly ionized chromium (Cr II) in the region 2850-37900 Å with the National Institute of Standards and Technology 2 m Fourier transform spectrometer. These data extend our previously reported observations in the near-ultra-violet region. We present a comprehensive list of more than 5300 Cr II lines classified as transitions among 456 even and 457 odd levels, 179 of which are newly located in this work. Using highly excited levels of the 3d 4(5 D)5g, 3d 4(5 D)6g, and 3d 4(5D)6h configurations, we derive an improved ionization energy of 132971.02 ± 0.12 cm-1 (16.486305 ± 0.000015 eV).

  1. EXTENDED ANALYSIS OF THE SPECTRUM OF SINGLY IONIZED CHROMIUM (Cr II)

    SciTech Connect

    Sansonetti, Craig J.; Nave, Gillian

    2014-08-01

    We have made new observations of the spectrum of singly ionized chromium (Cr II) in the region 2850-37900 Å with the National Institute of Standards and Technology 2 m Fourier transform spectrometer. These data extend our previously reported observations in the near-ultra-violet region. We present a comprehensive list of more than 5300 Cr II lines classified as transitions among 456 even and 457 odd levels, 179 of which are newly located in this work. Using highly excited levels of the 3d {sup 4}({sup 5} D)5g, 3d {sup 4}({sup 5} D)6g, and 3d {sup 4}({sup 5}D)6h configurations, we derive an improved ionization energy of 132971.02 ± 0.12 cm{sup –1} (16.486305 ± 0.000015 eV)

  2. Extended estimations of neoclassical transport for the TJ-II stellarator: The bootstrap current

    SciTech Connect

    Tribaldos, V.; Beidler, C. D.; Turkin, Y.; Maassberg, H.

    2011-10-15

    This work extends previous Monte Carlo estimations of neoclassical transport for the TJ-II stellarator [V. Tribaldos, Phys. Plasmas 8, 1229 (2001)] to include, for the first time, the bootstrap current in low collisionality electron cyclotron resonance heated (ECRH) plasmas. The calculations are based on the mono-energetic coefficients calculated with DKES [W. I. van Rij and S. P. Hirshman, Phys. Fluids B 1, 563 (1989)] and MOCA codes. It is shown that despite the difficulties of calculating these coefficient in the long mean free path for TJ-II configurations, the bootstrap current can be accurately estimated based on the moderate temperatures measured in this device with and without enforcing momentum conservation [H. Maassberg et al., Phys. Plasmas 16, 072504 (2009)]. The computed bootstrap current is found to be in fair agreement with the currents being measured in ECRH regimes. Finally, the effect of the bootstrap current on the rotational transform profile is discussed.

  3. Genetic transformation of Rhodopseudomonas sphaeroides by plasmid DNA.

    PubMed Central

    Fornari, C S; Kaplan, S

    1982-01-01

    A broad-host-range cloning vector, pUI81, was constructed in vitro from plasmids RSF1010 and pSL25 (a pBR322 derivative) and used to assay for transformation in Rhodopseudomonas sphaeroides. Washing cells with 500 mM Tris was an effective means of inducing competence for DNA uptake. Transformation frequencies as high as 10(-5) (transformants per viable cell) have been achieved by incubating Tris-treated cells with plasmid DNA, 100 mM CaCl2, and 20% polyethylene glycol 6000. Maximum frequencies were obtained when recipient cells were spread onto selective media after a 6.5-h outgrowth period in antibiotic-free medium. The structure (open circular versus closed, covalent circular), size, and concentration of plasmid DNA all significantly affected the transformation frequency. Four different plasmids, all small and suitable as cloning vectors, have been introduced by transformation into several different R. sphaeroides strains. Recombinant DNA carried on small, nonconjugative plasmids with broad host ranges can now be directly transferred to R. sphaeroides by this method. Images PMID:6981642

  4. The mechanisms of protection of antioxidants on Nostoc sphaeroides against UV-B radiation

    NASA Astrophysics Data System (ADS)

    Wang, G. H.

    UV radiation is one of space harmful factor for earth organisms in space exploration In the present work we studied on the role of antioxidant system in Nostoc sphaeroides K u tz Cyanobacteria and the effects of exogenous antioxidant molecules on its photosynthetic rate under UV-B radiation It was found that UV-B radiation decreased the photosynthetic activity of cyanobacterium but promoted the activity of antioxidant system to protect photosystem II PSII and exogenous antioxidant sodium nitroprusside SNP N-acetylcysteine NAC had an obvious protection on PSII activity under UV-B radiation The activity of SOD Superoxide Dismutase EC 1 15 1 1 CAT Catalase EC 1 11 1 6 POD Peroxidase EC 1 11 1 7 and content of MDA and ASC were improved by 0 5mM and 1mM SNP but 0 1mM SNP decreased the activity of antioxide system Exogenous NAC addition decreased the activity of SOD POD CAT and the content MDA and ASC but exogenous NAC addition increased the content of GSH The results suggested that exogenous SNP and NAC may protect algae by different mechanisms in which SNP maybe play double roles as sources of reactive free radicals or ROS scavengers in formation of algae s protection of PSII under UV-B radiation while NAC does function as antioxidant reagent or precursor of glutathione which could protect PSII directly from UV-B radiation Keyword antioxidant system exogenous or endogenous antioxidant Nostoc sphaeroides photosynthesis UV-B radiation

  5. Triazine herbicide resistance in the photosynthetic bacterium Rhodopseudomonas sphaeroides

    SciTech Connect

    Brown, A.E.; Gilbert, C.W.; Guy, R.; Arntzen, C.J.

    1984-10-01

    The photoaffinity herbicide azidoatrazine (2-azido-4-ethylamino-6-isopropylamino-s-triazine) selectively labels the L subunit of the reaction center of the photosynthetic bacterium Rhodopseudomonas sphaeroides. Herbicide-resistant mutants retain the L subunit and have altered binding properties for methylthio- and chloro-substituted triazines as well as altered equilibrium constants for electron transfer between primary and secondary electron acceptors. We suggest that a subtle alteration in the L subunit is responsible for herbicide resistance and that the L subunit is the functional analog of the 32-kDa Q/sub B/ protein of chloroplast membranes. 42 references, 6 figures, 1 table.

  6. COMPASS II: extended coverage for polymer and drug-like molecule databases.

    PubMed

    Sun, Huai; Jin, Zhao; Yang, Chunwei; Akkermans, Reinier L C; Robertson, Struan H; Spenley, Neil A; Miller, Simon; Todd, Stephen M

    2016-02-01

    The COMPASS II force field has been developed by extending the coverage of the COMPASS force field (J Phys Chem B 102(38):7338-7364, 1998) to polymer and drug-like molecules found in popular databases. Using a fragmentation method to systematically construct small molecules that exhibit key functional groups found in these databases, parameters applicable to database compounds were efficiently obtained. Based on the same parameterization paradigm as used in the development of the COMPASS force field, new parameters were derived by a combination of fits to quantum mechanical data for valence parameters and experimental liquid and crystal data for nonbond parameters. To preserve the quality of the original COMPASS parameters, a quality assurance suite was used and updated to ensure that additional atom-types and parameters do not interfere with the existing ones. Validation against molecular properties, liquid and crystal densities, and enthalpies, demonstrates that the quality of COMPASS is preserved and the same quality of prediction is achieved for the additional coverage.

  7. Fate of Selenate and Selenite Metabolized by Rhodobacter sphaeroides

    PubMed Central

    Van Fleet-Stalder, Verena; Chasteen, Thomas G.; Pickering, Ingrid J.; George, Graham N.; Prince, Roger C.

    2000-01-01

    Cultures of a purple nonsulfur bacterium, Rhodobacter sphaeroides, amended with ∼1 or ∼100 ppm selenate or selenite, were grown phototrophically to stationary phase. Analyses of culture headspace, separated cells, and filtered culture supernatant were carried out using gas chromatography, X-ray absorption spectroscopy, and inductively coupled plasma spectroscopy-mass spectrometry, respectively. While selenium-amended cultures showed much higher amounts of SeO32− bioconversion than did analogous selenate experiments (94% uptake for SeO32− as compared to 9.6% for SeO42−-amended cultures from 100-ppm solutions), the chemical forms of selenium in the microbial cells were not very different except at exposure to high concentrations of selenite. Volatilization accounted for only a very small portion of the accumulated selenium; most was present in organic forms and the red elemental form. PMID:11055934

  8. Expression of the Rhodobacter sphaeroides cytochrome c2 structural gene.

    PubMed Central

    Brandner, J P; McEwan, A G; Kaplan, S; Donohue, T J

    1989-01-01

    A Rhodobacter sphaeroides mutant (CYCA1) lacking cytochrome c2 (cyt c2) was previously constructed (T. J. Donohue, A. G. McEwan, S. Van Doren, A. R. Crofts, and S. Kaplan, Biochemistry, 27: 1918-1924, 1988) by a combination of in vivo and in vitro molecular genetic techniques. CYCA1 was incapable of photosynthetic growth (PS-); in this presentation, we show that chemoheterotrophically grown CYCA1 contained significant quantities of a high potential soluble c-type cytochrome(s) with an alpha band of approximately 554 nm which had previously gone undetected under these physiological conditions in wild-type cells. In addition, the PS- phenotype of CYCA1 can be complemented in trans with stable low-copy-number (approximately 5 to 9 per R. sphaeroides genome) broad-host-range plasmids containing the wild-type cyt c2 structural gene (cycA) and upstream regulatory sequences. cyt c2 and cycA-specific mRNA levels were elevated in both the wild type and CYCA1 derivatives harboring intact cycA genes in trans, presumably as a result of increased gene dosage. Although photosynthetically grown wild-type cells contained approximately twofold more cycA-specific transcripts than chemoheterotrophically grown cells, there was an approximately four- to sevenfold increase in cyt c2 levels under photosynthetic conditions. Similarly, complemented CYCA1 strains contained between 1.3- and 2.3-fold more cycA mRNA under photosynthetic conditions than under chemoheterotrophic conditions and had 6- to 12-fold higher steady-state levels of cyt c2 under the same physiological conditions. These data are discussed in terms of possible posttranscriptional control over cyt c2. Images PMID:2536660

  9. Global insights into energetic and metabolic networks in Rhodobacter sphaeroides

    PubMed Central

    2013-01-01

    Background Improving our understanding of processes at the core of cellular lifestyles can be aided by combining information from genetic analyses, high-throughput experiments and computational predictions. Results We combined data and predictions derived from phenotypic, physiological, genetic and computational analyses to dissect the metabolic and energetic networks of the facultative photosynthetic bacterium Rhodobacter sphaeroides. We focused our analysis on pathways crucial to the production and recycling of pyridine nucleotides during aerobic respiratory and anaerobic photosynthetic growth in the presence of an organic electron donor. In particular, we assessed the requirement for NADH/NADPH transhydrogenase enzyme, PntAB during respiratory and photosynthetic growth. Using high-throughput phenotype microarrays (PMs), we found that PntAB is essential for photosynthetic growth in the presence of many organic electron donors, particularly those predicted to require its activity to produce NADPH. Utilizing the genome-scale metabolic model iRsp1095, we predicted alternative routes of NADPH synthesis and used gene expression analyses to show that transcripts from a subset of the corresponding genes were conditionally increased in a ΔpntAB mutant. We then used a combination of metabolic flux predictions and mutational analysis to identify flux redistribution patterns utilized in the ΔpntAB mutant to compensate for the loss of this enzyme. Data generated from metabolic and phenotypic analyses of wild type and mutant cells were used to develop iRsp1140, an expanded genome-scale metabolic reconstruction for R. sphaeroides with improved ability to analyze and predict pathways associated with photosynthesis and other metabolic processes. Conclusions These analyses increased our understanding of key aspects of the photosynthetic lifestyle, highlighting the added importance of NADPH production under these conditions. It also led to a significant improvement in the

  10. Incorporation of taurine and hypotaurine did not improve the efficiency of the Uppsala Equex II extender for dog semen freezing.

    PubMed

    Martins-Bessa, A; Rocha, A; Mayenco-Aguirre, A

    2007-11-01

    The working hypothesis of the present study was that supplementation of the Uppsala Equex II (UE) extender with the amino acid (AA), taurine (T) and hypotaurine (H) would improve dog sperm post-thaw quality, as previously seen for ram and bull semen, respectively. Five pools from 15 ejaculates of 15 dogs were used. Each AA was added to the UE extender at a concentration of 25, 50 and 7 5mM. Amino acid-free extender was used as a control. The following post-thaw parameters were evaluated: sperm motility by light microscopy and by CASA evaluation, longevity, viability (eosin-nigrosin staining), and flow cytometry (FC) was used to assess acrosome integrity and mitochondrial activity after PI/Fitc-PSA and PI-Rhodamine staining, respectively. Post-thaw sperm motility and velocity did not differ among extenders. Amplitude of lateral head displacement was lower for sperm frozen in the 25 mM H-supplemented extender. Semen frozen in the extender with 50 mM of T resulted in higher number of live sperm with damaged acrosomes after thawing. Higher numbers of live sperm with minimal mitochondrial activity were obtained for samples frozen with 25 and 50 mM T-supplemented extenders. Semen frozen in the control and 50 mM T-supplemented extenders had the highest number of live (eosin-nigrosin stain negative) sperm immediately post-thawing. We concluded that supplementation of the Uppsala extender with T or H did not improve sperm post-thaw mitochondrial activity or semen motility and viability.

  11. Extending the use of rubber dam isolation: alternative procedures. Part II.

    PubMed

    Liebenberg, W H

    1993-01-01

    This paper, in three parts, describes additional modified rubber dam utilizations that are generally not attempted with restrictive orthodox application methods. Part II covers alternative means of retention, with the emphasis on nuisance-free and easy application, during the preparatory, impression, and cementation phases of cast restorations.

  12. Extended study of the Surface Heterogeneity of candidate dwarf-planets (II)

    NASA Astrophysics Data System (ADS)

    Pinilla-Alonso, Noemi; Emery, Joshua; Cruikshank, Dale P.

    2016-08-01

    We propose to continue with our investigation of the volatile activity and migration of volatiles on dwarf-planets (DP) and some candidates to dwarf-planets (CDP). We also extend this study to cover the list of targets for the Kuiper Extended Mission (KEM, second phase of New horizons mission submitted by the New Horizons Team to NASA for extension, and yet to be approved) and extend our continuous monitoring of Pluto's surface. Surface heterogeneity on these bodies can be indicative of the presence of an atmosphere, and active collisional history, or even cometary activity. In cycle 12 we were awarded with ~ 38hr to study three DPs and three CDPs. Five of these objects have been announced in 2016 as targets of the KEM. On cycle 13 we ask for 145.5 hours to study 11 CDP plus five targets of the KEM (one object belongs to both lists but will be observed only once) plus Pluto. By using the proven capability of Spitzer to detect and map the presence of volatile ices, complex organics and silicates on the surface of these distant bodies, we will 1) test the hypothesis that KBOs on the scale of >450 km in diameter could retain a higher content of volatiles than the smaller and more abundant KBOs; 2) characterize the distribution of silicates/organics/ices on the surface of these bodies. These points are key to understanding chemical and dynamical history of the outer Solar System, which acts as a model for the new systems discovered around other stars. Our study will be be of special interest in the eve of James Webb Telescope operation, in 2019 and will pave the road for a detailed characterization of the targets of the Kuiper Extended Mission (if approved).

  13. Extended phenotypes in a boy and his mother with oto-palato-digital-syndrome type II

    PubMed Central

    Kaissi, Ali Al; Kraschl, Raimund; Kaulfersch, Wilhelm; Grill, Franz; Ganger, Rudolf

    2015-01-01

    Key Clinical Message We describe additional phenotypic features in a boy and his mother. Both manifested the phenotypic/genotypic correlation of oto-palato-digital syndrome type II. The mother′s radiographs showed wormian bones of the skull, and paranasal bossing, her feet showed bilateral fusion of the cuboid with the lateral cuneiform bone with subsequent development of metatarsus varus associated with dysplastic distal phalanges. PMID:26401283

  14. T cells induce extended class II MHC compartments in dendritic cells in a Toll-like receptor-dependent manner.

    PubMed

    Boes, Marianne; Bertho, Nicolas; Cerny, Jan; Op den Brouw, Marjolein; Kirchhausen, Tomas; Ploegh, Hidde

    2003-10-15

    Interaction of Ag-loaded dendritic cells with Ag-specific CD4 T cells induces the formation of long tubular class II MHC-positive compartments that polarize toward the T cell. We show involvement of a Toll-like receptor-mediated signal in this unusual form of intracellular class II MHC trafficking. First, wild-type dendritic cells loaded with LPS-free Ag failed to show formation of class II-positive tubules upon Ag-specific T cell engagement, but did so upon supplementation of the Ag with low concentrations of LPS. Second, Ag-loaded myeloid differentiation factor 88 -deficient dendritic cells failed to form these tubules upon interaction with T cells, regardless of the presence of LPS. Finally, inclusion of a cell-permeable peptide that blocks TNFR-associated factor 6 function, downstream of myeloid differentiation factor 88, blocked T cell-dependent tubulation. A Toll-like receptor-dependent signal is thus required to allow Ag-loaded dendritic cells to respond to T cell contact by formation of extended endosomal compartments. This activation does not result in massive translocation of class II MHC molecules to the cell surface.

  15. [Protein fluorescence of photosynthetic reaction centers from Rhodopseudomonas sphaeroides].

    PubMed

    Zakharova, N I; Permiakov, E A; Fabian, M; Kononenko, A A; Chamorovskiĭ, S K

    1984-01-01

    Luminescence emitted by tryptophan residues of reaction center (RC) preparations was studied. The RG preparations were isolated from the photosynthetic bacterium Rhodopseudomonas sphaeroides by treatment with lauryl dimethyl amine oxide (LDAO). After excitation at lambda 280 nm the quantum yield of luminescence is 0,02. It is shown that 60% of tryptophanyls are located inside the protein globule in the surrounding of relaxating polar groups and the rest approximately 40% on the outer surface of the globule--predominantly in the positively charged region of the LDAO-RC protein--in the surrounding of protein-bound water molecules. There is a correlation between the pH dependencies of the position of the peak of luminescence from tryptophanyls and effectivity of electron transfer from the primary (quinone) to secondary acceptor. The two parameters are invariant at pH from 7 to 9 and vary at pH less than 7 and pH greater than 9. The phenomena responsible for the observed correlation are discussed on the basis of pH-dependent changes in the RC protein which govern electron transport activity at the reaction center.

  16. The extended ROSAT-ESO flux limited X-ray galaxy cluster survey (REFLEX II) II. Construction and properties of the survey

    NASA Astrophysics Data System (ADS)

    Böhringer, H.; Chon, G.; Collins, C. A.; Guzzo, L.; Nowak, N.; Bobrovskyi, S.

    2013-07-01

    Context. Galaxy clusters provide unique laboratories to study astrophysical processes on large scales and are important probes for cosmology. X-ray observations are currently the best means of detecting and characterizing galaxy clusters. Therefore X-ray surveys for galaxy clusters are one of the best ways to obtain a statistical census of the galaxy cluster population. Aims: In this paper we describe the construction of the REFLEX II galaxy cluster survey based on the southern part of the ROSAT All-Sky Survey. REFLEX II extends the REFLEX I survey by a factor of about two down to a flux limit of 1.8 × 10-12 erg s cm (0.1-2.4 keV). Methods: We describe the determination of the X-ray parameters, the process of X-ray source identification, and the construction of the survey selection function. Results: The REFLEX II cluster sample comprises currently 915 objects. A standard selection function is derived for a lower source count limit of 20 photons in addition to the flux limit. The median redshift of the sample is z = 0.102. Internal consistency checks and the comparison to several other galaxy cluster surveys imply that REFLEX II is better than 90% complete with a contamination less than 10%. Conclusions: With this publication we give a comprehensive statistical description of the REFLEX II survey and provide all the complementary information necessary for a proper modeling of the survey for astrophysical and cosmological applications. Based on observations at the European Southern Observatory La Silla, ChileFull Tables 2 and 3 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/555/A30

  17. Comparing M31 and Milky Way satellites: The extended star formation histories of Andromeda II and Andromeda XVI

    SciTech Connect

    Weisz, Daniel R.; Skillman, Evan D.; McQuinn, Kristen B. W.; Hidalgo, Sebastian L.; Monelli, Matteo; Gallart, Carme; Aparicio, Antonio; McConnachie, Alan; Stetson, Peter B.; Bernard, Edouard J.; Boylan-Kolchin, Michael; Cassisi, Santi; Cole, Andrew A.; Ferguson, Henry C.; Irwin, Mike; Martin, Nicolas F.; Mayer, Lucio; Navarro, Julio F.

    2014-07-01

    We present the first comparison between the lifetime star formation histories (SFHs) of M31 and Milky Way (MW) satellites. Using the Advanced Camera for Surveys on board the Hubble Space Telescope, we obtained deep optical imaging of Andromeda II (And II; M{sub V} = –12.0; log(M {sub *}/M {sub ☉}) ∼ 6.7) and Andromeda XVI (And XVI; M{sub V} = –7.5; log(M {sub *}/M {sub ☉}) ∼ 4.9) yielding color-magnitude diagrams that extend at least 1 mag below the oldest main-sequence turnoff, and are similar in quality to those available for the MW companions. And II and And XVI show strikingly similar SFHs: both formed 50%-70% of their total stellar mass between 12.5 and 5 Gyr ago (z ∼ 5-0.5) and both were abruptly quenched ∼5 Gyr ago (z ∼ 0.5). The predominance of intermediate age populations in And XVI makes it qualitatively different from faint companions of the MW and clearly not a pre-reionization fossil. Neither And II nor And XVI appears to have a clear analog among MW companions, and the degree of similarity in the SFHs of And II and And XVI is not seen among comparably faint-luminous pairs of MW satellites. These findings provide hints that satellite galaxy evolution may vary substantially among hosts of similar stellar mass. Although comparably deep observations of more M31 satellites are needed to further explore this hypothesis, our results underline the need for caution when interpreting satellite galaxies of an individual system in a broader cosmological context.

  18. The two photocycles of photoactive yellow protein from Rhodobacter sphaeroides.

    PubMed

    Haker, Andrea; Hendriks, Johnny; van Stokkum, Ivo H M; Heberle, Joachim; Hellingwerf, Klaas J; Crielaard, Wim; Gensch, Thomas

    2003-03-01

    The absorption spectrum of the photoactive yellow protein from Rhodobacter sphaeroides (R-PYP) shows two maxima, absorbing at 360 nm (R-PYP(360)) and 446 nm (R-PYP(446)), respectively. Both forms are photoactive and part of a temperature- and pH-dependent equilibrium (Haker, A., Hendriks, J., Gensch, T., Hellingwerf, K. J., and Crielaard, W. (2000) FEBS Lett. 486, 52-56). At 20 degrees C, for PYP characteristic, the 446-nm absorbance band displays a photocycle, in which the depletion of the 446-nm ground state absorption occurs in at least three phases, with time constants of <30 ns, 0.5 micros, and 17 micros. Intermediates with both blue- and red-shifted absorption maxima are transiently formed, before a blue-shifted intermediate (pB(360), lambda(max) = 360 nm) is established. The photocycle is completed with a monophasic recovery of the ground state with a time constant of 2.5 ms. At 7 degrees C these photocycle transitions are slowed down 2- to 3-fold. Upon excitation of R-PYP(360) with a UV-flash (330 +/- 50 nm) a species with a difference absorption maximum at approximately 435 nm is observed that returns to R-PYP(360) on a minute time scale. Recovery can be accelerated by a blue light flash (450 nm). R-PYP(360) and R-PYP(446) differ in their overall protein conformation, as well as in the isomerization and protonation state of the chromophore, as determined with the fluorescent polarity probe Nile Red and Fourier Transform Infrared spectroscopy, respectively.

  19. Study of the Local Structure of II-Vi Ternary Alloys by Extended X-Ray Absorption Fine Structure

    NASA Astrophysics Data System (ADS)

    Pong, Way-Faung

    Bondlengths, Debye-Waller factors, and site occupancy in the diluted magnetic semiconductors Zn_ {rm 1 - x}Mn_{ rm x}Se and Hg_{ rm 1 - x}Mn_{rm x}Te, and the narrow-gap semiconductor Hg _{rm 1 - x}Cd _{rm x}Te have been measured using extended x-ray absorption fine structure (EXAFS). The nearest-neighbor bond lengths in all of these alloys are found to be constant as a function of alloy composition within the experimental uncertainty of 0.01A. Because the average cation-cation distance changes with Mn composition, these results necessarily imply distortion of the tetrahedral bond angles. In the case of Zn_{rm 1 - x}Mn_{rm x} Se, the anion sublattice is shown to suffer the largest distortion, but the cation sublattice also exhibits some relaxation. The repercussions of these results are discussed, in terms of the amount of cation and anion sublattice distortion at low temperature and its connection to the superexchange mechanism occurring between the Mn ^{+2} ions and mediated by the intervening anion in Zn_{rm 1 - x}Mn_{rm x} Se. From the NN bond length relaxation results shown in this study and those reported elsewhere for the III -V-based and II-VI-based ternary compounds and DMS alloys, it appears that substitution of Mn^{+2 } ions into II-VI-based compounds causes greater local distortion, in general, than otherwise observed when group II cations are substituted for one another. We believe that the tetrahedral bond weakening in DMS is due to MN 3d-orbital (t_2) and anion p-orbital hybridization in DMS, leaving fewer p-orbitals available for tetrahedral bonding. This leads to the weakening of the bond force constants alpha, beta, as well as the bond becoming more ionic as Mn^{+2} is substituted into the II-VI-based compounds. Finally, the experimentally extended electron energy loss fine structure (EXELFS) technique, with modulations in the differential inelastic electron scattering cross -section above an absorption core edge, has been used in recent years to

  20. RR Lyrae variables in the Small Magellanic Cloud - II. The extended area: chemical and structural analysis

    NASA Astrophysics Data System (ADS)

    Kapakos, E.; Hatzidimitriou, D.

    2012-11-01

    We have performed the Fourier decomposition analysis of 8- and 13-yr V-band light curves of a carefully selected sample of 454 fundamental-mode RR Lyrae variables (RRab type), detected in an ≃14 square degree area of the Small Magellanic Cloud (SMC) and listed in the Optical Gravitational Lensing Experiment, phase III, Catalogue of Variable Stars. The Fourier decomposition parameters were used to derive metal abundances and distance moduli, following the methodology described by Kapakos, Hatzidimitriou & Soszyński. The average metal abundance of the RRab stars on the new scale of Carretta et al. was found to be <[Fe/H]C09> = -1.69 ± 0.41 dex (std, with a standard error of 0.02 dex). A tentative metallicity gradient of -0.013 ± 0.007 dex kpc-1 was detected, with increasing metal abundance towards the dynamical centre of the SMC, but selection effects are also discussed. The distance modulus of the SMC was re-estimated and was found to be <μ> = 19.13 ± 0.19 (std) in a distance scale where the distance modulus of the Large Magellanic Cloud (LMC) is μLMC = 18.52 ± 0.06 (std). The average 1σ line-of-sight depth was found to be σ int =5.3±0.4 kpc (std), while spatial variations of the depth were detected. The SMC was found to be deeper in the north-eastern region, while metal-richer and metal-poorer objects in the sample seem to belong to different dynamical structures. The former have smaller scale height and may constitute a thick disc, its width being 10.40 ± 0.02 kpc, and a bulge whose size (radius) is estimated to be 2.09 ± 0.81 kpc. The latter seem to belong to a halo structure with a maximum depth along the line of sight extending over 16 kpc in the SMC central region and falling to ˜12 kpc in the outer regions.

  1. The Extended GMRT Radio Halo Survey. II. Further results and analysis of the full sample

    NASA Astrophysics Data System (ADS)

    Kale, R.; Venturi, T.; Giacintucci, S.; Dallacasa, D.; Cassano, R.; Brunetti, G.; Cuciti, V.; Macario, G.; Athreya, R.

    2015-07-01

    The intra-cluster medium contains cosmic rays and magnetic fields that are manifested through the large scale synchrotron sources, termed radio haloes, relics, and mini-haloes. The Extended Giant Metrewave Radio Telescope (GMRT) Radio Halo Survey (EGRHS) is an extension of the GMRT Radio Halo Survey (GRHS) designed to search for radio haloes using GMRT 610/235 MHz observations. The GRHS and EGRHS consists of 64 clusters in the redshift range 0.2-0.4 that have an X-ray luminosity larger than 5 × 1044 erg s-1 in the 0.1-2.4 keV band and declination, δ > -31° in the REFLEX and eBCS X-ray cluster catalogues. In this second paper in the series, GMRT 610/235 MHz data on the last batch of 11 galaxy clusters and the statistical analysis of the full sample are presented. A new mini-halo in RX J2129.6+0005 and candidate diffuse sources in Z5247, A2552, and Z1953 have been discovered. A unique feature of this survey are the upper limits on the detections of 1 Mpc sized radio haloes; 4 new are presented here, making a total of 31 in the survey. Of the sample, 58 clusters with adequately sensitive radio information were used to obtain the most accurate occurrence fractions so far. The occurrence fractions of radio haloes, mini-haloes and relics in our sample are ~22%, ~16% and ~5%, respectively. The P1.4 GHz-LX diagrams for the radio haloes and mini-haloes are presented. The morphological estimators - centroid shift (w), concentration parameter (c), and power ratios (P3/P0) derived from the Chandra X-ray images - are used as proxies for the dynamical states of the GRHS and EGRHS clusters. The clusters with radio haloes and mini-haloes occupy distinct quadrants in the c-w, c-P3/P0 and w-P3/P0 planes, corresponding to the more and less morphological disturbance, respectively. The non-detections span both the quadrants. Appendices are available in electronic form at http://www.aanda.org

  2. YOUNG STARLESS CORES EMBEDDED IN THE MAGNETICALLY DOMINATED PIPE NEBULA. II. EXTENDED DATA SET

    SciTech Connect

    Frau, P.; Girart, J. M.; Padovani, M.; Beltran, M. T.; Sanchez-Monge, A.; Busquet, G.; Morata, O.; Masque, J. M.; Estalella, R.; Alves, F. O.; Franco, G. A. P.

    2012-11-01

    The Pipe nebula is a massive, nearby, filamentary dark molecular cloud with a low star formation efficiency threaded by a uniform magnetic field perpendicular to its main axis. It harbors more than a hundred, mostly quiescent, very chemically young starless cores. The cloud is therefore a good laboratory to study the earliest stages of the star formation process. We aim to investigate the primordial conditions and the relation among physical, chemical, and magnetic properties in the evolution of low-mass starless cores. We used the IRAM 30 m telescope to map the 1.2 mm dust continuum emission of five new starless cores, which are in good agreement with previous visual extinction maps. For the sample of nine cores, which includes the four cores studied in a previous work, we derived an A {sub V} to N{sub H{sub 2}} factor of (1.27 {+-} 0.12) Multiplication-Sign 10{sup -21} mag cm{sup 2} and a background visual extinction of {approx}6.7 mag possibly arising from the cloud material. We derived an average core diameter of {approx}0.08 pc, density of {approx}10{sup 5} cm{sup -3}, and mass of {approx}1.7 M {sub Sun }. Several trends seem to exist related to increasing core density: (1) the diameter seems to shrink, (2) the mass seems to increase, and (3) the chemistry tends to be richer. No correlation is found between the direction of the surrounding diffuse medium magnetic field and the projected orientation of the cores, suggesting that large-scale magnetic fields seem to play a secondary role in shaping the cores. We also used the IRAM 30 m telescope to extend the previous molecular survey at 1 and 3 mm of early- and late-time molecules toward the same five new Pipe nebula starless cores, and analyzed the normalized intensities of the detected molecular transitions. We confirmed the chemical differentiation toward the sample and increased the number of molecular transitions of the 'diffuse' (e.g., the 'ubiquitous' CO, C{sub 2}H, and CS), 'oxo-sulfurated' (e.g., SO and

  3. Spectroscopic and genetic evidence for two heme-Cu-containing oxidases in Rhodobacter sphaeroides.

    PubMed Central

    Shapleigh, J P; Hill, J J; Alben, J O; Gennis, R B

    1992-01-01

    It has recently become evident that many bacterial respiratory oxidases are members of a superfamily that is related to the eukaryotic cytochrome c oxidase. These oxidases catalyze the reduction of oxygen to water at a heme-copper binuclear center. Fourier transform infrared (FTIR) spectroscopy has been used to examine the heme-copper-containing respiratory oxidases of Rhodobacter sphaeroides Ga. This technique monitors the stretching frequency of CO bound at the oxygen binding site and can be used to characterize the oxidases in situ with membrane preparations. Oxidases that have a heme-copper binuclear center are recognizable by FTIR spectroscopy because the bound CO moves from the heme iron to the nearby copper upon photolysis at low temperature, where it exhibits a diagnostic spectrum. The FTIR spectra indicate that the binuclear center of the R. sphaeroides aa3-type cytochrome c oxidase is remarkably similar to that of the bovine mitochondrial oxidase. Upon deletion of the ctaD gene, encoding subunit I of the aa3-type oxidase, substantial cytochrome c oxidase remains in the membranes of aerobically grown R. sphaeroides. This correlates with a second wild-type R. sphaeroides is grown photosynthetically, the chromatophore membranes lack the aa3-type oxidase but have this second heme-copper oxidase. Subunit I of the heme-copper oxidase superfamily contains the binuclear center. Amino acid sequence alignments show that this subunit is structurally very highly conserved among both eukaryotic and prokaryotic species. The polymerase chain reaction was used to show that the chromosome of R. sphaeroides contains at least one other gene that is a homolog of ctaD, the gene encoding subunit I of the aa3-type cytochrome c oxidase.(ABSTRACT TRUNCATED AT 250 WORDS) Images PMID:1313003

  4. Stable Carbon Isotope Discrimination by Form IC Rubisco Enzymes of the Extremely Metabolically Versatile Rhodobacter sphaeroides and Ralstonia eutropha}

    NASA Astrophysics Data System (ADS)

    Thomas, P. J.; Boller, A. J.; Zhao, Z.; Tabita, F. R.; Cavanaugh, C. M.; Scott, K. M.

    2006-12-01

    Variations in the relative amounts of 12C and 13C in microbial biomass can be used to infer the pathway(s) autotrophs use to fix and assimilate dissolved inorganic carbon. Discrimination against 13C by the enzymes catalyzing autotrophic carbon fixation is a major factor dictating biomass stable carbon isotopic compositions (δ13C = {[13C/12Csample/13C/12Cstandard] - 1} × 1000). Five different forms of RubisCO (IA, IB, IC, ID, and II) are utilized by algae and autotrophic bacteria reliant on the Calvin-Benson cycle for carbon fixation. To date, isotope discrimination has been measured for form IA, IB, and II RubisCOs, and their ɛ values (={[12k/13k] - 1} × 1000; 12k and 13k = rates of 12C and 13C fixation) range from 18 to 29‰, explaining the variation in biomass δ13C values of autotrophs utilizing these enzymes. Isotope discrimination by form IC RubisCO has not been measured, despite the presence of this enzyme in many proteobacteria of ecological interest, including marine manganese-oxidizing bacteria, some nitrifying and nitrogen-fixing bacteria, and extremely metabolically versatile organisms such as Rhodobacter sphaeroides and Ralstonia eutropha. The purpose of this work was to determine the ɛ values for form IC RubisCO enzymes from R. sphaeroides and R. eutropha. Recombinant form IC RubisCOs were purified by conventional column chromatography procedures. Assay conditions (pH, dissolved inorganic carbon concentration) were tested to determine which parameters were conducive to the high rates of carbon fixation necessary for ɛ determination. Under standard conditions (pH 8.5 and 5 mM DIC), form IC RubisCO activities were sufficient for ɛ determination. Experiments are currently being conducted to measure the ɛ values of these enzymes. Sampling the full phylogenetic breadth of RubisCO enzymes for isotopic discrimination makes it possible to constrain the range of δ13C values of organisms fixing carbon via the Calvin-Benson cycle. These results are

  5. Ultrafast Exciton Relaxation in the B850 Antenna Complex of Rhodobacter sphaeroides

    NASA Astrophysics Data System (ADS)

    Nagarajan, V.; Alden, R. G.; Williams, J. C.; Parson, W. W.

    1996-11-01

    Spectral changes were measured with femtosecond resolution following low-intensity, broad-band excitation of the peripheral antenna complex of the purple photosynthetic bacterium Rhodobacter sphaeroides. Absorption anisotropy decays also were measured. We identified a 35-fs relaxation of the absorption and emission spectra of the excited state, as well as a 20-fs anisotropy decay. We interpret these results as interlevel relaxation and dephasing, respectively, of extensively delocalized exciton states of the circular bacteriochlorophyll aggregate.

  6. Extended-criteria donors in liver transplantation Part II: reviewing the impact of extended-criteria donors on the complications and outcomes of liver transplantation.

    PubMed

    Nemes, Balázs; Gámán, György; Polak, Wojciech G; Gelley, Fanni; Hara, Takanobu; Ono, Shinichiro; Baimakhanov, Zhassulan; Piros, Laszlo; Eguchi, Susumu

    2016-07-01

    Extended-criteria donors (ECDs) have an impact on early allograft dysfunction (EAD), biliary complications, relapse of hepatitis C virus (HCV), and survivals. Early allograft dysfunction was frequently seen in grafts with moderate and severe steatosis. Donors after cardiac death (DCD) have been associated with higher rates of graft failure and biliary complications compared to donors after brain death. Extended warm ischemia, reperfusion injury and endothelial activation trigger a cascade, leading to microvascular thrombosis, resulting in biliary necrosis, cholangitis, and graft failure. The risk of HCV recurrence increased by donor age, and associated with using moderately and severely steatotic grafts. With the administration of protease inhibitors sustained virological response was achieved in majority of the patients. Donor risk index and EC donor scores (DS) are reported to be useful, to assess the outcome. The 1-year survival rates were 87% and 40% respectively, for donors with a DS of 0 and 3. Graft survival was excellent up to a DS of 2, however a DS >2 should be avoided in higher-risk recipients. The 1, 3 and 5-year survival of DCD recipients was comparable to optimal donors. However ECDs had minor survival means of 85%, 78.6%, and 72.3%. The graft survival of split liver transplantation (SLT) was comparable to that of whole liver orthotopic liver transplantation. SLT was not regarded as an ECD factor in the MELD era any more. Full-right-full-left split liver transplantation has a significant advantage to extend the high quality donor pool. Hypothermic oxygenated machine perfusion can be applied clinically in DCD liver grafts. Feasibility and safety were confirmed. Reperfusion injury was also rare in machine perfused DCD livers. PMID:26831547

  7. Wheat straw degradation and production of alternative substrates for nitrogenase of Rhodobacter sphaeroides.

    PubMed

    Dziga, Dariusz; Jagiełło-Flasińska, Dominika

    2015-01-01

    Cellulose is a major component of plant biomass and could be applied in the production of biofuels, especially bioethanol. An alternative approach is production of a clean fuel - hydrogen from cellulosic biomass. In this paper an innovatory model of cellulosic waste degradation has been proposed to verify the possibility of utilization of cellulose derivatives by purple non-sulfur bacteria. The concept is based on a two-step process of wheat straw conversion by bacteria in order to obtain an organic acid mixture. In the next stage such products are consumed by Rhodobacter sphaeroides, the known producer of hydrogen. It has been documented that Cellulomonas uda expresses cellulolytic activity in the presence of wheat straw as an only source of carbon. R. sphaeroides applied in this research can effectively consume organic acids released from straw by C. uda and Lactobacillus rhamnosus and is able to grow in the presence of these substrates. Additionally, an increased nitrogenase activity of R. sphaeroides has been indicated when bacteria were cultivated in the presence of cellulose derivatives which suggests that hydrogen production occurs.

  8. Wheat straw degradation and production of alternative substrates for nitrogenase of Rhodobacter sphaeroides.

    PubMed

    Dziga, Dariusz; Jagiełło-Flasińska, Dominika

    2015-01-01

    Cellulose is a major component of plant biomass and could be applied in the production of biofuels, especially bioethanol. An alternative approach is production of a clean fuel - hydrogen from cellulosic biomass. In this paper an innovatory model of cellulosic waste degradation has been proposed to verify the possibility of utilization of cellulose derivatives by purple non-sulfur bacteria. The concept is based on a two-step process of wheat straw conversion by bacteria in order to obtain an organic acid mixture. In the next stage such products are consumed by Rhodobacter sphaeroides, the known producer of hydrogen. It has been documented that Cellulomonas uda expresses cellulolytic activity in the presence of wheat straw as an only source of carbon. R. sphaeroides applied in this research can effectively consume organic acids released from straw by C. uda and Lactobacillus rhamnosus and is able to grow in the presence of these substrates. Additionally, an increased nitrogenase activity of R. sphaeroides has been indicated when bacteria were cultivated in the presence of cellulose derivatives which suggests that hydrogen production occurs. PMID:26192769

  9. Transient dynamic phenotypes as criteria for model discrimination: fold-change detection in Rhodobacter sphaeroides chemotaxis.

    PubMed

    Hamadeh, Abdullah; Ingalls, Brian; Sontag, Eduardo

    2013-03-01

    The chemotaxis pathway of the bacterium Rhodobacter sphaeroides shares many similarities with that of Escherichia coli. It exhibits robust adaptation and has several homologues of the latter's chemotaxis proteins. Recent theoretical results have correctly predicted that the E. coli output behaviour is unchanged under scaling of its ligand input signal; this property is known as fold-change detection (FCD). In the light of recent experimental results suggesting that R. sphaeroides may also show FCD, we present theoretical assumptions on the R. sphaeroides chemosensory dynamics that can be shown to yield FCD behaviour. Furthermore, it is shown that these assumptions make FCD a property of this system that is robust to structural and parametric variations in the chemotaxis pathway, in agreement with experimental results. We construct and examine models of the full chemotaxis pathway that satisfy these assumptions and reproduce experimental time-series data from earlier studies. We then propose experiments in which models satisfying our theoretical assumptions predict robust FCD behaviour where earlier models do not. In this way, we illustrate how transient dynamic phenotypes such as FCD can be used for the purposes of discriminating between models that reproduce the same experimental time-series data.

  10. Nostoc sphaeroides Kützing, an excellent candidate producer for CELSS

    NASA Astrophysics Data System (ADS)

    Hao, Zongjie; Li, Dunhai; Li, Yanhui; Wang, Zhicong; Xiao, Yuan; Wang, Gaohong; Liu, Yongding; Hu, Chunxiang; Liu, Qifang

    2011-11-01

    Some phytoplankton can be regarded as possible candidates in the establishment of Controlled Ecological Life Support System (CELSS) for some intrinsic characteristics, the first characteristic is that they should grow rapidly, secondly, they should be able to endure some stress factors and develop some corresponding adaptive strategies; also it is very important that they could provide food rich in nutritious protein and vitamins for the crew; the last but not the least is they can also fulfill the other main functions of CELSS, including supplying oxygen, removing carbon dioxide and recycling the metabolic waste. According to these characteristics, Nostoc sphaeroides, a potential healthy food in China, was selected as the potential producer in CELSS. It was found that the oxygen average evolution rate of this algae is about 150 μmol O 2 mg -1 h -1, and the size of them are ranged from 2 to 20 mm. Also it can be cultured with high population density, which indicated that the potential productivity of Nostoc sphaeroides is higher than other algae in limited volume. We measured the nutrient contents of the cyanobacterium and concluded it was a good food for the crew. Based on above advantages, Nostoc sphaeroides was assumed to a suitable phytoplankton for the establishment of Controlled Ecological Life Support System. We plan to develop suitable bioreactor with the cyanobacterium for supplying oxygen and food in future space missions.

  11. Transient dynamic phenotypes as criteria for model discrimination: fold-change detection in Rhodobacter sphaeroides chemotaxis.

    PubMed

    Hamadeh, Abdullah; Ingalls, Brian; Sontag, Eduardo

    2013-03-01

    The chemotaxis pathway of the bacterium Rhodobacter sphaeroides shares many similarities with that of Escherichia coli. It exhibits robust adaptation and has several homologues of the latter's chemotaxis proteins. Recent theoretical results have correctly predicted that the E. coli output behaviour is unchanged under scaling of its ligand input signal; this property is known as fold-change detection (FCD). In the light of recent experimental results suggesting that R. sphaeroides may also show FCD, we present theoretical assumptions on the R. sphaeroides chemosensory dynamics that can be shown to yield FCD behaviour. Furthermore, it is shown that these assumptions make FCD a property of this system that is robust to structural and parametric variations in the chemotaxis pathway, in agreement with experimental results. We construct and examine models of the full chemotaxis pathway that satisfy these assumptions and reproduce experimental time-series data from earlier studies. We then propose experiments in which models satisfying our theoretical assumptions predict robust FCD behaviour where earlier models do not. In this way, we illustrate how transient dynamic phenotypes such as FCD can be used for the purposes of discriminating between models that reproduce the same experimental time-series data. PMID:23293140

  12. Dimerization of core complexes as an efficient strategy for energy trapping in Rhodobacter sphaeroides.

    PubMed

    Chenchiliyan, Manoop; Timpmann, Kõu; Jalviste, Erko; Adams, Peter G; Hunter, C Neil; Freiberg, Arvi

    2016-06-01

    In the purple phototrophic bacterium Rhodobacter sphaeroides, light harvesting LH2 complexes transfer absorbed solar energy to RC-LH1-PufX core complexes, which are mainly found in the dimeric state. Many other purple phototrophs have monomeric core complexes and the basis for requiring dimeric cores is not fully established, so we analysed strains of Rba. sphaeroides that contain either native dimeric core complexes or altered monomeric cores harbouring a deletion of the first 12 residues from the N-terminus of PufX, which retains the PufX polypeptide but removes the major determinant of core complex dimerization. Membranes were purified from strains with dimeric or monomeric cores, and with either high or low levels of the LH2 complex. Samples were interrogated with absorption, steady-state fluorescence, and picosecond time-resolved fluorescence kinetic spectroscopies to reveal their light-harvesting and energy trapping properties. We find that under saturating excitation light intensity the photosynthetic membranes containing LH2 and monomeric core complexes have fluorescence lifetimes nearly twice that of membranes with LH2 plus dimeric core complexes. This trend of increased lifetime is maintained with RCs in the open state as well, and for two different levels of LH2 content. Thus, energy trapping is more efficient when photosynthetic membranes of Rba. sphaeroides consist of RC-LH1-PufX dimers and LH2 complexes. PMID:27013332

  13. Structure and orientation of the Mn4Ca cluster in plant photosystem II membranes studied by polarized range-extended x-ray absorption spectroscopy.

    PubMed

    Pushkar, Yulia; Yano, Junko; Glatzel, Pieter; Messinger, Johannes; Lewis, Azul; Sauer, Kenneth; Bergmann, Uwe; Yachandra, Vittal

    2007-03-01

    X-ray absorption spectroscopy has provided important insights into the structure and function of the Mn(4)Ca cluster in the oxygen-evolving complex of Photosystem II (PS II). The range of manganese extended x-ray absorption fine structure data collected from PS II until now has been, however, limited by the presence of iron in PS II. Using a crystal spectrometer with high energy resolution to detect solely the manganese Kalpha fluorescence, we are able to extend the extended x-ray absorption fine structure range beyond the onset of the iron absorption edge. This results in improvement in resolution of the manganese-backscatterer distances in PS II from 0.14 to 0.09A(.) The high resolution data obtained from oriented spinach PS II membranes in the S(1) state show that there are three di-mu-oxo-bridged manganese-manganese distances of approximately 2.7 and approximately 2.8A in a 2:1 ratio and that these three manganese-manganese vectors are aligned at an average orientation of approximately 60 degrees relative to the membrane normal. Furthermore, we are able to observe the separation of the Fourier peaks corresponding to the approximately 3.2A manganese-manganese and the approximately 3.4A manganese-calcium interactions in oriented PS II samples and determine their orientation relative to the membrane normal. The average of the manganese-calcium vectors at approximately 3.4A is aligned along the membrane normal, while the approximately 3.2A manganese-manganese vector is oriented near the membrane plane. A comparison of this structural information with the proposed Mn(4)Ca cluster models based on spectroscopic and diffraction data provides input for refining and selecting among these models.

  14. Comparison of reaction centers from Rhodobacter sphaeroides and rhodopseudomonas viridis: Overall archistecture and protein-pigment interactions

    SciTech Connect

    Elkabbani, Ossama; Chang, Chonghwan; Tiede, D.; Norris, J.; Schiffer, M. )

    1991-06-04

    Photosynthetic reaction centers (RCs) from the photosynthetic bacteria Rhodobacter sphaeroides and Rhodopseudomonas viridis are protein complexes closely related in both structure and function. The structure of the Rps. viridis RC was used to determine the structure of the RC from Rb. sphaeroides. Small but meaningful differences between the positions of the helices and the cofactors in the two complexes were identified. The distances between helices A{sub L} adn A{sub M}, between B{sub L} and B{sub M}, and between bacteriopheophytins BP{sub L} and BP{sub M} are significantly shorter in Rps. viridis than they are in Rb. sphaeroides RCs. There are a number of differences in the amino acid residues that surround the cofactors; some of these residues form hydrogen bonds with the cofactors. Differences in chemical properties of the two RCs.

  15. Skin Anti-Aging Activities of Bacteriochlorophyll a from Photosynthetic Bacteria, Rhodobacter sphaeroides.

    PubMed

    Kim, Nam Young; Yim, Tae Bin; Lee, Hyeon Yong

    2015-10-01

    In this work, the anti-aging skin effects of bacteriochlorophyll a isolated from Rhodobacter sphaeroides are first reported, with notably low cytotoxicity in the range of 1% to 14% in adding 0.00078 (% (w/w)) of the extracts, compared with the normal growth of both human dermal fibroblast and keratinocyte cells without any treatment as a control. The highest production of procollagen from human fibroblast cells (CCD-986sk) was observed as 221.7 ng/ml with 0.001 (% (w/w)) of bacteriochlorophyll a, whereas 150 and 200 ng/ml of procollagen production resulted from addition of 0.001 (% (w/w)) of the photosynthetic bacteria. The bacteriochlorophylla- induced TNF-α production increased to 63.8%, which was lower secretion from HaCaT cells than that from addition of 0.00005 (% (w/w)) of bacteriochlorophyll a. Additionally, bacteriochlorophyll a upregulated the expression of genes related to skin anti-aging (i.e., keratin 10, involucrin, transglutaminase-1, and MMPs), by up to 4-15 times those of the control. However, crude extracts from R. sphaeroides did not enhance the expression level of these genes. Bacteriochlorophyll a showed higher antioxidant activity of 63.8% in DPPH free radical scavenging than those of water, ethanol, and 70% ethanol extracts (14.0%, 57.2%, and 12.6%, respectively). It was also shown that the high antioxidant activity could be attributed to the skin anti-aging effect of bacteriochlorophyll a, although R. sphaeroides itself would not exhibit significant anti-aging activities.

  16. Extract from a mutant Rhodobacter sphaeroides as an enriched carotenoid source

    PubMed Central

    Wang, Chih-Chiang; Ding, Shangwu; Chiu, Kuo-Hsun; Liu, Wen-Sheng; Lin, Tai-Jung; Wen, Zhi-Hong

    2016-01-01

    Background The extract Lycogen™ from the phototrophic bacterium Rhodobacter sphaeroides (WL-APD911) has attracted significant attention because of its promising potential as a bioactive mixture, attributed in part to its anti-inflammatory properties and anti-oxidative activity. Objective This study aims to investigate the components of Lycogen™ and its anti-inflammatory properties and anti-oxidative activity. Design and results The mutant strain R. sphaeroides (WL-APD911) whose carotenoid 1,2-hydratase gene has been altered by chemical mutagenesis was used for the production of a new carotenoid. The strain was grown at 30°C on Luria–Bertani (LB) agar plates. After a 4-day culture period, the mutant strain displayed a 3.5-fold increase in carotenoid content, relative to the wild type. In the DPPH test, Lycogen™ showed more potent anti-oxidative activity than lycopene from the wild-type strain. Primary skin irritation test with hamsters showed no irritation response in hamster skins after 30 days of treatment with 0.2% Lycogen™. Chemical investigations of Lycogen™ using nuclear magnetic resonance (NMR) 1H, 13C, and COSY/DQCOSY spectra have identified spheroidenone and methoxyneurosporene. Quantitative analysis of these identified compounds based on spectral intensities indicates that spheroidenone and methoxyneurosporene are major components (approximately 1:1); very small quantities of other derivatives are also present in the sample. Conclusions In this study, we identified the major carotenoid compounds contained in Lycogen™, including spheroidenone and methoxyneurosporene by high-resolution NMR spectroscopy analysis. The carotenoid content of this mutant strain of R. sphaeroides was 3.5-fold higher than that in normal strain. Furthermore, Lycogen™ from the mutant strain is more potent than lycopene from the wild-type strain and does not cause irritation in hamster skins. These findings suggest that this mutant strain has the potential to be used

  17. Structure of the reaction center from Rhodobacter sphaeroides R-26: the cofactors

    SciTech Connect

    Allen, J.P.; Feher, G.; Yeates, T.O.; Komiya, H.; Rees, D.C.

    1987-08-01

    The three-dimensional structure of the cofactors of the reaction center of Rhodobacter sphaeroides R-26 has been determined by x-ray diffraction and refined at a resolution of 2.8 A with an R value of 26%. The main features of the structure are similar to the ones determined for Rhodopseudomonas viridis. The cofactors are arranged along two branches, which are approximately related to each other by a 2-fold symmetry axis. The structure is well suited to produce light-induced charge separation across the membrane. Most of the structural features predicted from physical and biochemical measurements are confirmed by the x-ray structure.

  18. Brominated lipids identify lipid binding sites on the surface of the reaction center from Rhodobacter sphaeroides.

    PubMed

    Roszak, Aleksander W; Gardiner, Alastair T; Isaacs, Neil W; Cogdell, Richard J

    2007-03-20

    This study describes the use of brominated phospholipids to distinguish between lipid and detergent binding sites on the surface of a typical alpha-helical membrane protein. Reaction centers isolated from Rhodobacter sphaeroides were cocrystallized with added brominated phospholipids. X-ray structural analysis of these crystals has revealed the presence of two lipid binding sites from the characteristic strong X-ray scattering from the bromine atoms. These results demonstrate the usefulness of this approach to mapping lipid binding sites at the surface of membrane proteins.

  19. Primary reactions in photosynthetic reaction centers of Rhodobacter sphaeroides - Time constants of the initial electron transfer

    NASA Astrophysics Data System (ADS)

    Dominguez, Pablo Nahuel; Himmelstoss, Matthias; Michelmann, Jeff; Lehner, Florian Thomas; Gardiner, Alastair T.; Cogdell, Richard J.; Zinth, Wolfgang

    2014-05-01

    The primary dynamics of reaction centers from Rhodobacter sphaeroides at room temperature are studied at low excitation intensities and low excitation rates. Analysis based on singular value decomposition yields three time constants in the picosecond range (ca. 1.2 ps, 3.5 ps and 220 ps). The spectral and temporal signatures are fully consistent with the step-wise electron transfer model published previously, with a first electron transfer to the bacteriochlorophyll with a time constant of 3.5 ps and a second 1.2 ps transfer to the bacteriopheophytin. No indications for adiabatic electron transfer are found in the time range >0.5 ps.

  20. Transcriptome dynamics during the transition from anaerobic photosynthesis to aerobic respiration in Rhodobacter sphaeroides 2.4.1.

    PubMed

    Arai, Hiroyuki; Roh, Jung Hyeob; Kaplan, Samuel

    2008-01-01

    Rhodobacter sphaeroides 2.4.1 is a facultative photosynthetic anaerobe that grows by anoxygenic photosynthesis under anaerobic-light conditions. Changes in energy generation pathways under photosynthetic and aerobic respiratory conditions are primarily controlled by oxygen tensions. In this study, we performed time series microarray analyses to investigate transcriptome dynamics during the transition from anaerobic photosynthesis to aerobic respiration. Major changes in gene expression profiles occurred in the initial 15 min after the shift from anaerobic-light to aerobic-dark conditions, with changes continuing to occur up to 4 hours postshift. Those genes whose expression levels changed significantly during the time series were grouped into three major classes by clustering analysis. Class I contained genes, such as that for the aa3 cytochrome oxidase, whose expression levels increased after the shift. Class II contained genes, such as those for the photosynthetic apparatus and Calvin cycle enzymes, whose expression levels decreased after the shift. Class III contained genes whose expression levels temporarily increased during the time series. Many genes for metabolism and transport of carbohydrates or lipids were significantly induced early during the transition, suggesting that those endogenous compounds were initially utilized as carbon sources. Oxidation of those compounds might also be required for maintenance of redox homeostasis after exposure to oxygen. Genes for the repair of protein and sulfur groups and uptake of ferric iron were temporarily upregulated soon after the shift, suggesting they were involved in a response to oxidative stress. The flagellar-biosynthesis genes were expressed in a hierarchical manner at 15 to 60 min after the shift. Numerous transporters were induced at various time points, suggesting that the cellular composition went through significant changes during the transition from anaerobic photosynthesis to aerobic respiration

  1. The response of antioxidant systems in Nostoc sphaeroides against UV-B radiation and the protective effects of exogenous antioxidants

    NASA Astrophysics Data System (ADS)

    Wang, Gaohong; Hu, Chunxiang; Li, Dunhai; Zhang, Delu; Li, Xiaoyan; Chen, Kun; Liu, Yongding

    UV radiation is one of many harmful factors found in space that are detrimental to organisms on earth in space exploration. In the present work, we examined the role of antioxidant system in Nostoc sphaeroides Kütz (Cyanobacterium) and the effects of exogenously applied antioxidant molecules on its photosynthetic rate under UV-B radiation. It was found that UV-B radiation promoted the activity of antioxidant system to protect photosystem II (PSII) and exogenously applied antioxidant: sodium nitroprusside (SNP) and N-acetylcysteine (NAC) had an obvious protection on PSII activity under UV-B radiation. The activity of superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6), peroxidase (POD, EC 1.11.1.7) and content of MDA (malondialdehyde) and ASC (ascorbate) were improved by 0.5 mM and 1 mM SNP, but 0.1 mM SNP decreased the activity of antioxidant system. Addition of exogenous NAC decreased the activity of SOD, POD, CAT and the content MDA and ASC. In contrast, exogenously applied NAC increased GSH content. The results suggest that exogenous SNP and NAC may protect algae by different mechanisms: SNP may play double roles as both sources of reactive free radicals as well as ROS scavengers in mediating the protective role of PSII on algae under UV-B radiation. On the other hand, NAC functions as an antioxidant or precursor of glutathione, which could protect PSII directly from UV-B radiation.

  2. Mutations of the AMH type II receptor in two extended families with persistent Müllerian duct syndrome: lack of phenotype/genotype correlation.

    PubMed

    Abduljabbar, Mohammad; Taheini, Khalid; Picard, Jean-Yves; Cate, Richard L; Josso, Nathalie

    2012-01-01

    Our goal was to compare phenotype and genotype in two extended Middle-Eastern families affected by persistent Müllerian duct syndrome due to mutations of the type II anti-Müllerian hormone receptor (AMHR-II). The first, consanguineous, family consisted of 6 boys and 2 girls, the second consisted of 4 girls and 2 boys. In family I, 4 boys and 1 girl were homozygous for a stop mutation in the 9th exon of AMHR-II, removing part of the intracellular domain of the protein. In family II, 1 girl and 1 boy were homozygous for a transversion changing conserved histidine 254 into a glutamine. Both homozygous girls were normal. In the homozygous males, the degree of development of Müllerian derivatives was variable. The uterus was well developed in 2 boys of family I and in the patient from family II; however, in 1 subject from family I, Müllerian derivatives were undetectable. Taken together, the diversity of clinical symptoms within the same sibship and the lack of correlation between the development of the Müllerian derivatives and the severity of the molecular defects suggest highly variable penetrance of the abnormal alleles and/or the existence of other genetic or epigenetic modifiers of gene expression. PMID:22584735

  3. Photophysical and Electrochemical Studies of Multinuclear Complexes of Iron(II) with Acetate and Extended Conjugated N-Donor Ligands

    PubMed Central

    Mohd Said, Suhana; Roslan, Muhamad Faris; Azil, Afiq; Nordin, Abdul Rahman

    2015-01-01

    A dimeric iron(II) complex, trans-[Fe2(CH3COO)4(L1)2] (1), and a trinuclear iron(II) complex, [Fe3(CH3COO)4(H2O)4(L2)] (2), were studied as potential dye-sensitised solar cell materials. The structures of both complexes were deduced by a combination of instrumental analyses and molecular modelling. Variable-temperature magnetic susceptibility data suggested that 1 was made up of 56.8% high-spin (HS) and 43.2% low-spin (LS) Fe(II) atoms at 294 K and has a moderate antiferromagnetic interaction (J = −81.2 cm−1) between the two Fe(II) centres, while 2 was made up of 27.7% HS and 72.3% LS Fe(II) atoms at 300 K. The optical band gaps (Eo) for 1 were 1.9 eV (from absorption spectrum) and 2.2 eV (from fluorescence spectrum), electrochemical bandgap (Ee) was 0.83 eV, excited state lifetime (τ) was 0.67 ns, and formal redox potential (E′(FeIII/FeII)) was +0.63 V. The corresponding values for 2 were 3.5 eV (from absorption spectrum), 1.8 eV (from fluorescence spectrum), 0.69 eV, 2.8 ns, and +0.41 V. PMID:25879076

  4. 77 FR 30173 - Amendment of Americans With Disabilities Act Title II and Title III Regulations To Extend...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-21

    ... September 30, 2004, 69 FR 58768, and two Notices of Proposed Rulemaking (NPRM) on June 17, 2008, 73 FR 34466 (title II) and 73 FR 34508 (title III). The Department also held a public hearing on the NPRMs and... commercial facilities) on September 15, 2010. See 75 FR 56164, 56236 (September 15, 2010). The revised...

  5. Reconstruction of a kinetic model of the chromatophore vesicles from Rhodobacter sphaeroides.

    PubMed

    Geyer, Tihamér; Helms, Volkhard

    2006-08-01

    We present a molecular model of a chromatophore vesicle from Rhodobacter sphaeroides. These vesicles are ideal benchmark systems for molecular and systemic simulations, because they have been well studied, they are small, and they are naturally separated from their cellular environment. To set up a photosynthetic chain working under steady-state conditions, we compiled from the experimental literature the specific activities and geometries that have been determined for their constituents. This data then allowed defining the stoichiometries for all membrane proteins. This article contains the kinetic part of the reconstructed model, while the spatial reconstruction is presented in a companion article. By considering the transport properties of the Cytochrome c(2) and ubiquinone pools, we show that their size and oxidation states allow for an efficient buffering of the statistical fluctuations that arise from the small size of the vesicles. Stoichiometric and kinetic considerations indicate that a typical chromatophore vesicle of Rb. sphaeroides with a diameter of 45 nm should contain approximately five bc(1) monomers. PMID:16714340

  6. Stark effect spectroscopy of Rhodobacter sphaeroides and Rhodopseudomonas viridis reaction centers

    PubMed Central

    Lockhart, David J.; Boxer, Steven G.

    1988-01-01

    The nature of the initially excited state of the primary electron donor or special pair has been investigated by Stark effect spectroscopy for reaction centers from the photosynthetic bacteria Rhodopseudomonas viridis and Rhodobacter sphaeroides at 77 K. The data provide values for the magnitude of the difference in permanent dipole moment between the ground and excited state, [unk]Δμ[unk], and the angle [unk] between Δμ and the transition dipole moment for the electronic transition. [unk]Δμ[unk] and [unk] for the lowest-energy singlet electronic transition associated with the special pair primary electron donor were found to be very similar for the two species. [unk]Δμ[unk] for this transition is substantially larger than for the Qy transitions of the monomeric pigments in the reaction center or for pure monomeric bacteriochlorophylls, for which Stark data are also reported. We conclude that the excited state of the special pair has substantial charge-transfer character, and we suggest that charge separation in bacterial photosynthesis is initiated immediately upon photoexcitation of the special pair. Data for Rhodobacter sphaeroides between 340 and 1340 nm are presented and discussed in the context of the detection of charge-transfer states by Stark effect spectroscopy. PMID:16578825

  7. Light-induced division and genomic synchrony in phototrophically growing cultures of Rhodopseudomonas sphaeroides.

    PubMed

    Lueking, D R; Campbell, T B; Burghardt, R C

    1981-05-01

    An experimental procedure for rapidly obtaining cell populations of phototrophically growing Rhodopseudomonas sphaeroides which display division and genomic synchrony has been developed. The basis of the procedure resides with the normal physiological response displayed by cells of R. sphaeroides that have been subjected to an immediate decrease in incident light intensity. After an abrupt high- to low-light transition of an asynchronously dividing cell population, an immediate cessation of increases in culture turbidity, total cell number, and net accumulations of culture deoxyribonucleic acid and phospholipid occurs. Total cell number remains constant for 2.5 h after the transition to low light, after which time, it undergoes a sharp increase. Reinitiation of high-light conditions of growth 1 h subsequent to this increase in total cell number results in a cell population possessing a high degree of division and genomic synchrony. A characterization of this procedure, together with a demonstration of its utility for studies on intracytoplasmic membrane assembly, is presented. PMID:7012139

  8. Regulation and function of cytochrome c' in Rhodobacter sphaeroides 2.4.3.

    PubMed

    Choi, Peter S; Grigoryants, Vladimir M; Abruña, Hector D; Scholes, Charles P; Shapleigh, James P

    2005-06-01

    Cytochrome c' (Cyt c') is a c-type cytochrome with a pentacoordinate heme iron. The gene encoding this protein in Rhodobacter sphaeroides 2.4.3, designated cycP, was isolated and sequenced. Northern blot analysis and beta-galactosidase assays demonstrated that cycP transcription increased as oxygen levels decreased and was not repressed under denitrifying conditions as observed in another Rhodobacter species. CO difference spectra performed with extracts of cells grown under different conditions revealed that Cyt c' levels were highest during photosynthetic denitrifying growth conditions. The increase in Cyt c' under this condition was higher than would be predicted from transcriptional studies. Electron paramagnetic resonance analysis of whole cells demonstrated that Cyt c' binds NO during denitrification. Mass spectrometric analysis of nitrogen oxides produced by cells and purified protein did not indicate that Cyt c' has NO reductase activity. Taken together, these results suggest a model where Cyt c' in R. sphaeroides 2.4.3 may shuttle NO to the membrane, where it can be reduced.

  9. Nostoc sphaeroides Kütz, a candidate producer par excellence for CELSS

    NASA Astrophysics Data System (ADS)

    Wang, Gaohong; Hao, Zongjie; Liu, Yongding

    A lot of aquatic organisms could be regarded as suitable candidates par excellence in the establishment of CELSS, since they are relatively easy and fast to grow and resistant to changes in environmental condition as well as providing nutritious, protein-and vitamin-rich foods for the crew, which can fulfill the main functions of CELSS, including supplying oxygen, water and food, removing carbon dioxide and making daily life waste reusable. Our labotory has developed mass culture of Nostoc sphaeroides Kütz, which is one of traditional healthy food in China and. The oxygen evolution rate of the cyanobacterium is about 150 molO2.mg-1.h-1, and it usually grows into colony with size between 2-20mm, which is easy to be harvested. It also can be cultured with high density, which show that the productivity of the cyanobacterium in limited volume is higher than other microalgae. We had measured the nutrient content of the cyanobacterium and developed some Chinese Dishes and Soups with Nostoc sphaeroides Kütz, which showed that it was a good food for crew. Using remote sensing technique, we also investigated its growth in Closed System under microgravity by SHENZHOU-2 spacecraft in January 2001. We plan to develop suitable bioreactor with the cyanobacterium for supplying oxygen and food to crew in future.

  10. A molecular brake, not a clutch, stops the Rhodobacter sphaeroides flagellar motor

    PubMed Central

    Pilizota, Teuta; Brown, Mostyn T.; Leake, Mark C.; Branch, Richard W.; Berry, Richard M.; Armitage, Judith P.

    2009-01-01

    Many bacterial species swim by employing ion-driven molecular motors that power the rotation of helical filaments. Signals are transmitted to the motor from the external environment via the chemotaxis pathway. In bidirectional motors, the binding of phosphorylated CheY (CheY-P) to the motor is presumed to instigate conformational changes that result in a different rotor-stator interface, resulting in rotation in the alternative direction. Controlling when this switch occurs enables bacteria to accumulate in areas favorable for their survival. Unlike most species that swim with bidirectional motors, Rhodobacter sphaeroides employs a single stop-start flagellar motor. Here, we asked, how does the binding of CheY-P stop the motor in R. sphaeroides—using a clutch or a brake? By applying external force with viscous flow or optical tweezers, we show that the R. sphaeroides motor is stopped using a brake. The motor stops at 27–28 discrete angles, locked in place by a relatively high torque, approximately 2–3 times its stall torque. PMID:19571004

  11. Color-sensitive motility and methanol release responses in Rhodobacter sphaeroides.

    PubMed

    Kort, R; Crielaard, W; Spudich, J L; Hellingwerf, K J

    2000-06-01

    Blue-light-induced repellent and demethylation responses, characteristic of behavioral adaptation, were observed in Rhodobacter sphaeroides. They were analyzed by computer-assisted motion analysis and through the release of volatile tritiated compounds from [methyl-(3)H]methionine-labeled cells, respectively. Increases in the stop frequency and the rate of methanol release were induced by exposure of cells to repellent light signals, such as an increase in blue- and a decrease in infrared-light intensity. At a lambda of >500 nm the amplitude of the methanol release response followed the absorbance spectrum of the photosynthetic pigments, suggesting that they function as photosensors for this response. In contrast to the previously reported motility response to a decrease in infrared light, the blue-light response reported here does not depend on the number of photosynthetic pigments per cell, suggesting that it is mediated by a separate sensor. Therefore, color discrimination in taxis responses in R. sphaeroides involves two photosensing systems: the photosynthetic pigments and an additional photosensor, responding to blue light. The signal generated by the former system could result in the migration of cells to a light climate beneficial for photosynthesis, while the blue-light system could allow cells to avoid too-high intensities of (harmful) blue light.

  12. Novel Methods for Analysing Bacterial Tracks Reveal Persistence in Rhodobacter sphaeroides

    PubMed Central

    Rosser, Gabriel; Fletcher, Alexander G.; Wilkinson, David A.; de Beyer, Jennifer A.; Yates, Christian A.; Armitage, Judith P.; Maini, Philip K.; Baker, Ruth E.

    2013-01-01

    Tracking bacteria using video microscopy is a powerful experimental approach to probe their motile behaviour. The trajectories obtained contain much information relating to the complex patterns of bacterial motility. However, methods for the quantitative analysis of such data are limited. Most swimming bacteria move in approximately straight lines, interspersed with random reorientation phases. It is therefore necessary to segment observed tracks into swimming and reorientation phases to extract useful statistics. We present novel robust analysis tools to discern these two phases in tracks. Our methods comprise a simple and effective protocol for removing spurious tracks from tracking datasets, followed by analysis based on a two-state hidden Markov model, taking advantage of the availability of mutant strains that exhibit swimming-only or reorientating-only motion to generate an empirical prior distribution. Using simulated tracks with varying levels of added noise, we validate our methods and compare them with an existing heuristic method. To our knowledge this is the first example of a systematic assessment of analysis methods in this field. The new methods are substantially more robust to noise and introduce less systematic bias than the heuristic method. We apply our methods to tracks obtained from the bacterial species Rhodobacter sphaeroides and Escherichia coli. Our results demonstrate that R. sphaeroides exhibits persistence over the course of a tumbling event, which is a novel result with important implications in the study of this and similar species. PMID:24204227

  13. Modelling and analysis of bacterial tracks suggest an active reorientation mechanism in Rhodobacter sphaeroides

    PubMed Central

    Rosser, Gabriel; Baker, Ruth E.; Armitage, Judith P.; Fletcher, Alexander G.

    2014-01-01

    Most free-swimming bacteria move in approximately straight lines, interspersed with random reorientation phases. A key open question concerns varying mechanisms by which reorientation occurs. We combine mathematical modelling with analysis of a large tracking dataset to study the poorly understood reorientation mechanism in the monoflagellate species Rhodobacter sphaeroides. The flagellum on this species rotates counterclockwise to propel the bacterium, periodically ceasing rotation to enable reorientation. When rotation restarts the cell body usually points in a new direction. It has been assumed that the new direction is simply the result of Brownian rotation. We consider three variants of a self-propelled particle model of bacterial motility. The first considers rotational diffusion only, corresponding to a non-chemotactic mutant strain. Two further models incorporate stochastic reorientations, describing ‘run-and-tumble’ motility. We derive expressions for key summary statistics and simulate each model using a stochastic computational algorithm. We also discuss the effect of cell geometry on rotational diffusion. Working with a previously published tracking dataset, we compare predictions of the models with data on individual stopping events in R. sphaeroides. This provides strong evidence that this species undergoes some form of active reorientation rather than simple reorientation by Brownian rotation. PMID:24872500

  14. Manganese oxidation by modified reaction centers from Rhodobacter sphaeroides.

    PubMed

    Kálmán, L; LoBrutto, R; Allen, J P; Williams, J C

    2003-09-23

    The transfer of an electron from exogenous manganese (II) ions to the bacteriochlorophyll dimer, P, of bacterial reaction centers was characterized for a series of mutants that have P/P(+) midpoint potentials ranging from 585 to 765 mV compared to 505 mV for wild type. Light-induced changes in optical and EPR spectra of the mutants were measured to monitor the disappearance of the oxidized dimer upon electron donation by manganese in the presence of bicarbonate. The extent of electron transfer was strongly dependent upon the P/P(+) midpoint potential. The midpoint potential of the Mn(2+)/Mn(3+) couple was calculated to decrease linearly from 751 to 623 mV as the pH was raised from 8 to 10, indicating the involvement of a proton. The electron donation had a second order rate constant of approximately 9 x 10(4) M(-1) s(-1), determined from the linear increase in rate for Mn(2+) concentrations up to 200 microM. Weak dissociation constants of 100-200 microM were found. Quantitative EPR analysis of the six-line free Mn(2+) signal revealed that up to seven manganese ions were associated with the reaction centers at a 1 mM concentration of manganese. The association and the electron transfer between manganese and the reaction centers could be inhibited by Ca(2+) and Na(+) ions. The ability of reaction centers with high potentials to oxidize manganese suggests that manganese oxidation could have preceded water oxidation in the evolutionary development of photosystem II. PMID:12974637

  15. Treatment of stage i and ii mediastinal Hodgkin disease: a comparison of involved fields, extended fields, and involved fields followed by MOPP in patients stage by laparotomy

    SciTech Connect

    Hagemeister, F.B.; Fuller, L.M.; Sullivan, J.A.; North, L.; Velasquez, W.; Conrad, F.G.; McLaughlin, P.; Butter, J.J.; Shullenberger, C.C.

    1981-12-01

    Three treatment programs for Stage I and II mediastinal Hodgkin disease (established by laparotomy) were compared. Involved-field radiotherapy + MOPP gave a disease-free survival rate of 97%, significantly different from 62% and 55% for involved and extended fields, respectively. Corresponding survival figures of 97%, 88%, and 84% were not signiticantly different statistically due to salvage with radiotherapy and/or chemotherapy. Among patients given radiotherapy alone, the survival figure of 94% for limited mediastinal disease was significantly better than 63% for extensive mediastinal and hilar disease; corresponding disease-free figures of 72% and 35% were also significantly different. Constitutional symptoms were an important prognostic factor in disease-free survival following the use of involved fields; hilar disease was important only with large mediastinal masses. Most relapses were intrathoracic; MOPP alone salvaged only 47%. Treatment of State I and II Hodgkin disease should be based on symptoms, extent of mediastinal disease, and hilar involvement.

  16. The Non-Relativistic Limit of Relativistic Extended Thermodynamics with Many - Part II:. how it Includes the Mass, Momentum and Energy Conservation

    NASA Astrophysics Data System (ADS)

    Carrisi, M. C.; Demontis, F.; Pennisi, S.

    2006-03-01

    In part I of this article, Borghero, Demontis and Pennisi have obtained the limits for light speed c going to infty, of the balance equations in Relativistic Extended Thermodynamics with many moments. In order to obtain independent equations, they have taken a suitable linear combination of the equations, before taking the limit. What happens with this procedure to the relativistic conservation laws of mass, momentum and energy? Obviously, they transform in their classical counterparts; but proof of this property is not easy and is treated in this part II of the article.

  17. Construction and Validation of the Rhodobacter sphaeroides 2.4.1 DNA Microarray: Transcriptome Flexibility at Diverse Growth Modes

    SciTech Connect

    Pappas, Christopher T.; Sram, Jakub; Moskvin, Oleg V.; Ivanov, Pavel S.; Mackenzie, Christopher; Choudhary, Madhusudan; Land, Miriam L; Larimer, Frank W; Kaplan, Samuel; Gomelsky, Mark

    2004-07-01

    A high-density oligonucleotide DNA microarray, a genechip, representing the 4.6-Mb genome of the facultative phototrophic proteobacterium, Rhodobacter sphaeroides 2.4.1, was custom-designed and manufactured by Affymetrix, Santa Clara, Calif. The genechip contains probe sets for 4,292 open reading frames (ORFs), 47 rRNA and tRNA genes, and 394 intergenic regions. The probe set sequences were derived from the genome annotation generated by Oak Ridge National Laboratory after extensive revision, which was based primarily upon codon usage characteristic of this GC-rich bacterium. As a result of the revision, numerous missing ORFs were uncovered, nonexistent ORFs were deleted, and misidentified start codons were corrected. To evaluate R. sphaeroides transcriptome flexibility, expression profiles for three diverse growth modes-aerobic respiration, anaerobic respiration in the dark, and anaerobic photosynthesis-were generated. Expression levels of one-fifth to one-third of the R. sphaeroides ORFs were significantly different in cells under any two growth modes. Pathways involved in energy generation and redox balance maintenance under three growth modes were reconstructed. Expression patterns of genes involved in these pathways mirrored known functional changes, suggesting that massive changes in gene expression are the major means used by R. sphaeroides in adaptation to diverse conditions. Differential expression was observed for genes encoding putative new participants in these pathways (additional photosystem genes, duplicate NADH dehydrogenase, ATP synthases), whose functionality has yet to be investigated. The DNA microarray data correlated well with data derived from quantitative reverse transcription-PCR, as well as with data from the literature, thus validating the R. sphaeroides genechip as a powerful and reliable tool for studying unprecedented metabolic versatility of this bacterium.

  18. Extended Cahill-Glauber formalism for finite-dimensional spaces. II. Applications in quantum tomography and quantum teleportation

    SciTech Connect

    Marchiolli, Marcelo A.; Ruzzi, Maurizio; Galetti, Diogenes

    2005-10-15

    By means of a mod(N)-invariant operator basis, s-parametrized phase-space functions associated with bounded operators in a finite-dimensional Hilbert space are introduced in the context of the extended Cahill-Glauber formalism, and their properties are discussed in details. The discrete Glauber-Sudarshan, Wigner, and Husimi functions emerge from this formalism as specific cases of s-parametrized phase-space functions where, in particular, a hierarchical process among them is promptly established. In addition, a phase-space description of quantum tomography and quantum teleportation is presented and new results are obtained.

  19. Modeling Spitzer Observations of VV Ser. II. An Extended Quantum-heated Nebula and a Disk Shadow

    NASA Astrophysics Data System (ADS)

    Pontoppidan, Klaus M.; Dullemond, Cornelis P.; Blake, Geoffrey A.; Evans, Neal J., II; Geers, Vincent C.; Harvey, Paul M.; Spiesman, William

    2007-02-01

    We present mid-infrared Spitzer IRAC and MIPS images of the UX Orionis star VV Ser and the surrounding cloud. The 5.6-70 μm images show bright, localized, and nebulous emission extended over 4' centered on VV Ser. This nebulosity is due to transiently heated grains excited by UV photons emitted by VV Ser. Imprinted on the nebulosity is a wedge-shaped dark band, centered on the star. We interpret this as the shadow cast by the inner regions of a near-edge-on disk, allowing the PAHs to be excited only outside of this shadow. We extend an axisymmetric radiative transfer model of the VV Ser disk described in a companion paper to include quantum-heated PAH molecules and very small grains (VSGs) in the thermal cooling approximation. The presence of a disk shadow strongly constrains the inclination as well as the position angle of the disk. The nebulosity at 5.6-8.0 μm and the 2175 Å absorption feature seen in an archival spectrum from the IUE can be fit using only PAHs, consistent with the main carrier of the 2175 Å feature being due to the graphite-like structure of the PAHs. The PAH component is found to be relatively smoothly distributed in the cloud, while the population of VSGs emitting at 20-70 μm is strongly concentrated ~50'' to the southeast of VV Ser. Depending on the adopted PAH opacity, the abundance of PAHs in the surrounding cloud is constrained to 5%+/-2% of the total dust mass. Although relatively rare, quantum-heated nebulosities surrounding single, well-defined stars are well-suited for gaining unique insights into the physics of very small particles in molecular clouds.

  20. Azadipyrromethene cyclometalation in neutral Ru(II) complexes: photosensitizers with extended near-infrared absorption for solar energy conversion applications.

    PubMed

    Bessette, André; Cibian, Mihaela; Ferreira, Janaina G; DiMarco, Brian N; Bélanger, Francis; Désilets, Denis; Meyer, Gerald J; Hanan, Garry S

    2016-06-28

    In the on-going quest to harvest near-infrared (NIR) photons for energy conversion applications, a novel family of neutral ruthenium(ii) sensitizers has been developed by cyclometalation of an azadipyrromethene chromophore. These rare examples of neutral ruthenium complexes based on polypyridine ligands exhibit an impressive panchromaticity achieved by the cyclometalation strategy, with strong light absorption in the 600-800 nm range that tails beyond 1100 nm in the terpyridine-based adducts. Evaluation of the potential for Dye-Sensitized Solar Cells (DSSC) and Organic Photovoltaic (OPV) applications is made through rationalization of the structure-property relationship by spectroscopic, electrochemical, X-ray structural and computational modelization investigations. Spectroscopic evidence for photo-induced charge injection into the conduction band of TiO2 is also provided. PMID:27264670

  1. Very long-distance magnetic coupling in a dicopper(II) metallacyclophane with extended π-conjugated diphenylethyne bridges.

    PubMed

    Castellano, María; Fortea-Pérez, Francisco R; Stiriba, Salah-Eddine; Julve, Miguel; Lloret, Francesc; Armentano, Donatella; De Munno, Giovanni; Ruiz-García, Rafael; Cano, Joan

    2011-11-21

    Self-assembly of the rigid rodlike ligand N,N'-4,4'-diphenylethynebis(oxamate) (dpeba) and Cu(2+) ions affords a novel dinuclear copper(II) metallacyclophane (nBu(4)N)(4)[Cu(2)(dpeba)(2)]·4MeOH·2Et(2)O (1) featuring a very long intermetallic distance (r = 15.0 Å). Magnetic susceptibility measurements for 1 reveal a moderately weak but nonnegligible intramolecular antiferromagnetic coupling between the two metal centers across the double para-substituted diphenylethynediamidate bridge (J = -3.9 cm(-1); H = -JS(1)S(2), where S(1) = S(2) = S(Cu) = (1)/(2)). Density functional electronic structure calculations on 1 support the occurrence of a spin polarization mechanism.

  2. π-Extended and six-coordinate iron(II) complexes: structures, magnetic properties, and the electrochemical synthesis of a conducting iron(II) metallopolymer.

    PubMed

    Djukic, Brandon; Seda, Takele; Gorelsky, Serge I; Lough, Alan J; Lemaire, Martin T

    2011-08-01

    Herein, we describe the preparation of three new bidentate π-extended derivatives of the ligand N-phenyl-2-pyridinalimine (ppi) containing a 3-thienyl (4) substituent at position 4 of the aniline ring or 2-thienyl (6) or phenyl (2) substituents at each of the 2,5 positions of the aniline rings. Three iron(2+) complexes (7-9) containing these ligands were prepared by combining two equivalents each of 2, 4, or 6 with Fe(NCS)(2), and the resulting neutral, six-coordinate complexes were fully characterized, including with single crystal X-ray diffraction experiments in the case of complexes 7 and 9. Variable temperature magnetic susceptibility and Mössbauer experiments confirm the presence of spin-crossover in complexes 7 and 8, and the unusual solid state variable temperature magnetic properties of complex 9 likely result from crystal packing forces. Electropolymerization of the 2,5-dithienyl-substituted complex (9) produces a conducting and electrochromic metallopolymer film (poly-9).

  3. Extending the mirror neuron system model, II: what did I just do? A new role for mirror neurons.

    PubMed

    Bonaiuto, James; Arbib, Michael A

    2010-04-01

    A mirror system is active both when an animal executes a class of actions (self-actions) and when it sees another execute an action of that class. Much attention has been given to the possible roles of mirror systems in responding to the actions of others but there has been little attention paid to their role in self-actions. In the companion article (Bonaiuto et al. Biol Cybern 96:9-38, 2007) we presented MNS2, an extension of the Mirror Neuron System model of the monkey mirror system trained to recognize the external appearance of its own actions as a basis for recognizing the actions of other animals when they perform similar actions. Here we further extend the study of the mirror system by introducing the novel hypotheses that a mirror system may additionally help in monitoring the success of a self-action and may also be activated by recognition of one's own apparent actions as well as efference copy from one's intended actions. The framework for this computational demonstration is a model of action sequencing, called augmented competitive queuing, in which action choice is based on the desirability of executable actions. We show how this "what did I just do?" function of mirror neurons can contribute to the learning of both executability and desirability which in certain cases supports rapid reorganization of motor programs in the face of disruptions.

  4. Tyre-road grip coefficient assessment - Part II: online estimation using instrumented vehicle, extended Kalman filter, and neural network

    NASA Astrophysics Data System (ADS)

    Luque, Pablo; Mántaras, Daniel A.; Fidalgo, Eloy; Álvarez, Javier; Riva, Paolo; Girón, Pablo; Compadre, Diego; Ferran, Jordi

    2013-12-01

    The main objective of this work is to determine the limit of safe driving conditions by identifying the maximal friction coefficient in a real vehicle. The study will focus on finding a method to determine this limit before reaching the skid, which is valuable information in the context of traffic safety. Since it is not possible to measure the friction coefficient directly, it will be estimated using the appropriate tools in order to get the most accurate information. A real vehicle is instrumented to collect information of general kinematics and steering tie-rod forces. A real-time algorithm is developed to estimate forces and aligning torque in the tyres using an extended Kalman filter and neural networks techniques. The methodology is based on determining the aligning torque; this variable allows evaluation of the behaviour of the tyre. It transmits interesting information from the tyre-road contact and can be used to predict the maximal tyre grip and safety margin. The maximal grip coefficient is estimated according to a knowledge base, extracted from computer simulation of a high detailed three-dimensional model, using Adams® software. The proposed methodology is validated and applied to real driving conditions, in which maximal grip and safety margin are properly estimated.

  5. Extended Statistical Short-Range Guidance for Peak Wind Speed Analyses at the Shuttle Landing Facility: Phase II Results

    NASA Technical Reports Server (NTRS)

    Lambert, Winifred C.

    2003-01-01

    This report describes the results from Phase II of the AMU's Short-Range Statistical Forecasting task for peak winds at the Shuttle Landing Facility (SLF). The peak wind speeds are an important forecast element for the Space Shuttle and Expendable Launch Vehicle programs. The 45th Weather Squadron and the Spaceflight Meteorology Group indicate that peak winds are challenging to forecast. The Applied Meteorology Unit was tasked to develop tools that aid in short-range forecasts of peak winds at tower sites of operational interest. A seven year record of wind tower data was used in the analysis. Hourly and directional climatologies by tower and month were developed to determine the seasonal behavior of the average and peak winds. Probability density functions (PDF) of peak wind speed were calculated to determine the distribution of peak speed with average speed. These provide forecasters with a means of determining the probability of meeting or exceeding a certain peak wind given an observed or forecast average speed. A PC-based Graphical User Interface (GUI) tool was created to display the data quickly.

  6. Moko Disease-Causing Strains of Ralstonia solanacearum from Brazil Extend Known Diversity in Paraphyletic Phylotype II.

    PubMed

    Albuquerque, Greecy M R; Santos, Liliana A; Felix, Kátia C S; Rollemberg, Christtianno L; Silva, Adriano M F; Souza, Elineide B; Cellier, Gilles; Prior, Philippe; Mariano, Rosa L R

    2014-11-01

    The epidemic situation of Moko disease-causing strains in Latin America and Brazil is unclear. Thirty-seven Ralstonia solanacearum strains from Brazil that cause the Moko disease on banana and heliconia plants were sampled and phylogenetically typed using the endoglucanase (egl) and DNA repair (mutS) genes according to the phylotype and sequevar classification. All of the strains belonged to phylotype II and a portion of the strains was typed as the Moko disease-related sequevars IIA-6 and IIA-24. Nevertheless, two unsuspected sequevars also harbored the Moko disease-causing strains IIA-41 and IIB-25, and a new sequevar was described and named IIA-53. All of the strains were pathogenic to banana and some of the strains of sequevars IIA-6, IIA-24, and IIA-41 were also pathogenic to tomato. The Moko disease-causing strains from sequevar IIB-25 were pathogenic to potato but not to tomato. These results highlight the high diversity of strains of Moko in Brazil, reinforce the efficiency of the egl gene to reveal relationships among these strains, and contribute to a better understanding of the diversity of paraphyletic Moko disease-causing strains of the R. solanacearum species complex, where the following seven distinct genetic clusters have been described: IIA-6, IIA-24, IIA-41, IIA-53, IIB-3, IIB-4, and IIB-25.

  7. Femtosecond infrared spectroscopy of reaction centers from Rhodobacter sphaeroides between 1000 and 1800 cm-1.

    PubMed Central

    Hamm, P; Zurek, M; Mäntele, W; Meyer, M; Scheer, H; Zinth, W

    1995-01-01

    Time-resolved pump-and-probe experiments of reaction centers of the purple bacterium Rhodobacter sphaeroides (R26) in the mid-IR region between 1000 and 1800 cm-1 are recorded with a time resolution of 300-400 fs. The difference spectra of the states P*, P+HA-, and P+QA- with respect to the ground state P predominantly reflect changes of the special pair. They show positive and negative bands due to changes of distinct vibrational modes superimposed on a broad background of enhanced absorption. A number of certain bands can be assigned to the special pair P, to the bacteriopheophytin HA, and to the quinone QA. The temporal evolution of the IR absorbance changes is well described by the time constants known from femtosecond spectroscopy of the electronic states. Differences occur only at very early times, which are indicative of fast vibrational relaxation with a time constant of a few hundred femtoseconds. PMID:7892185

  8. Time-resolved tryptophan fluorescence in photosynthetic reaction centers from Rhodobacter sphaeroides

    NASA Technical Reports Server (NTRS)

    Godik, V. I.; Blankenship, R. E.; Causgrove, T. P.; Woodbury, N.

    1993-01-01

    Tryptophan fluorescence of reaction centers isolated from Rhodobacter sphaeroides, both stationary and time-resolved, was studied. Fluorescence kinetics were found to fit best a sum of four discrete exponential components. Half of the initial amplitude was due to a component with a lifetime of congruent to 60 ps, belonging to Trp residues, capable of efficient transfer of excitation energy to bacteriochlorophyll molecules of the reaction center. The three other components seem to be emitted by Trp ground-state conformers, unable to participate in such a transfer. Under the influence of intense actinic light, photooxidizing the reaction centers, the yield of stationary fluorescence diminished by congruent to 1.5 times, while the number of the kinetic components and their life times remained practically unchanged. Possible implications of the observed effects for the primary photosynthesis events are considered.

  9. Bioremediation of cadmium by growing Rhodobacter sphaeroides: kinetic characteristic and mechanism studies.

    PubMed

    Bai, Hong-Juan; Zhang, Zhao-Ming; Yang, Guan-E; Li, Bao-Zhen

    2008-11-01

    The removal kinetic characteristic and mechanism of cadmium by growing Rhodobacter sphaeroides were investigated. The removal data were fitted to the second-order equation, with a correlation coefficient, R2=0.9790-0.9916. Furthermore, it was found that the removal mechanism of cadmium was predominantly governed by bioprecipitation as cadmium sulfide with biosorption contributing to a minor extent. Also, the results revealed that the activities of cysteine desulfhydrase in strains grown in the presence of 10 and 20 mg/l of cadmium were higher than in the control, while the activities in the presence of 30 and 40 mg/l of cadmium were lower than in the control. Content analysis of subcellular fractionation showed that cadmium was mostly removed and transformed by precipitation on the cell wall.

  10. Femtosecond infrared spectroscopy of reaction centers from Rhodobacter sphaeroides between 1000 and 1800 cm-1.

    PubMed

    Hamm, P; Zurek, M; Mäntele, W; Meyer, M; Scheer, H; Zinth, W

    1995-03-14

    Time-resolved pump-and-probe experiments of reaction centers of the purple bacterium Rhodobacter sphaeroides (R26) in the mid-IR region between 1000 and 1800 cm-1 are recorded with a time resolution of 300-400 fs. The difference spectra of the states P*, P+HA-, and P+QA- with respect to the ground state P predominantly reflect changes of the special pair. They show positive and negative bands due to changes of distinct vibrational modes superimposed on a broad background of enhanced absorption. A number of certain bands can be assigned to the special pair P, to the bacteriopheophytin HA, and to the quinone QA. The temporal evolution of the IR absorbance changes is well described by the time constants known from femtosecond spectroscopy of the electronic states. Differences occur only at very early times, which are indicative of fast vibrational relaxation with a time constant of a few hundred femtoseconds.

  11. Decoherence dynamics of coherent electronic excited states in the photosynthetic purple bacterium Rhodobacter sphaeroides.

    PubMed

    Liang, Xian-Ting; Zhang, Wei-Min; Zhuo, Yi-Zhong

    2010-01-01

    In this paper, we present a theoretical description to the quantum coherence and decoherence phenomena of energy transfer in photosynthesis observed in a recent experiment [Science 316, 1462 (2007)]. As a successive two-color laser pulses with selected frequencies cast on a sample of the photosynthetic purple bacterium Rb. sphaeroides two resonant excitations of electrons in chromophores can be generated. However, this effective two-level subsystem will interact with its protein environment and decoherence is inevitable. We describe this subsystem coupled with its environment as a dynamical spin-boson model. The non-Markovian decoherence dynamics is described using a quasiadiabatic propagator path integral (QUAPI) approach. With the photon-induced effective time-dependent level splitting energy and level flip coupling coefficient between the two excited states and the environment-induced non-Markovian decoherence dynamics, our theoretical result is in good agreement with the experimental data.

  12. Glutamine as a feedback inhibitor of the Rhodopseudomonas sphaeroides nitrogenase system.

    PubMed Central

    Jones, B L; Monty, K J

    1979-01-01

    In whole cells of Rhodopseudomonas sphaeroides, nitrogen fixation, as measured by hydrogen production and acetylene reduction, was totally inhibited by micromolar concentrations of ammonia. This inhibition could not be duplicated by glutamate or glutamine alone. The inhibition by ammonia was abolished by methionine sulfoximine, a glutamine synthetase inhibitor. Inhibition by glutamine was complete in the presence of methionine sulfone, a preferential inhibitor of glutamate synthase, presumably by permitting a rise in the glutamine pool. The results indicated that the level of the glutamine pool controlled the activity of nitrogenase. None of these effects could be duplicated with cell-free nitrogenase, indicating there is probably a mediator which responds to the glutamine pool and inhibits nitrogenase, rather than glutamine itself being a direct inhibitor. PMID:314444

  13. Thioredoxin Is Involved in Oxygen-Regulated Formation of the Photosynthetic Apparatus of Rhodobacter sphaeroides

    PubMed Central

    Pasternak, Cecile; Haberzettl, Kerstin; Klug, Gabriele

    1999-01-01

    Thioredoxin, a redox active protein, has been previously demonstrated to be essential for growth of the anoxygenic photosynthetic bacterium Rhodobacter sphaeroides. In the present study, the involvement of thioredoxin in the formation of the photosynthetic apparatus of R. sphaeroides WS8 was investigated by construction and analysis of a mutant strain disrupted for the chromosomal trxA copy and carrying a plasmid-borne copy of trxA under the control of the hybrid ptrc promoter inducible by IPTG (isopropyl-β-d-thiogalactopyranoside). This strain was viable in the absence of IPTG but was affected in pigmentation. When shifted from high to low oxygen tension conditions, the trxA mutant showed a reduced bacteriochlorophyll content in comparison to that of the wild type. Although thioredoxin is able to regulate aminolevulinic acid (ALA) synthase (the first enzyme of the tetrapyrrole biosynthetic pathway) activity by a dithiol-disulfide exchange, our mutant strain exhibited a level of ALA synthase activity identical to that of the wild type, suggesting that thioredoxin is involved in other steps to regulate the synthesis of the photosynthetic apparatus. Accordingly, we showed that the trxA mutation affects the oxygen-regulated expression of the puf operon encoding the pigment-binding proteins of the light-harvesting and reaction center complexes. Upon transition from aerobic to semiaerobic growth conditions, the maximal puf mRNA level was found to be 40 to 50% lower in the mutant strain than in the wild type. The stability of the puf transcripts was identical in both strains grown under low oxygen tension, indicating that the role of thioredoxin in regulating puf expression occurs at the transcriptional level. PMID:9864318

  14. 5-Aminolevulinate production by Escherichia coli containing the Rhodobacter sphaeroides hemA gene

    SciTech Connect

    Van Der Werf, M.J.; Zeikus, J.G. |

    1996-10-01

    The Rhodobacter sphaeroides hemA gene codes for 5-aminolevulinate (ALA) synthase. This enzyme catalyzes the pyridoxal phosphate-dependent condensation of succinyl coenzyme A and glycine-forming ALA. The R. sphaeroides hemA gene in the pUC18/19 vector system was transformed into Escherichia coli. The effects of both genetic and physiological factors on the expression of ALA synthase and the production of ALA were studied. ALA synthase activity levels were maximal when hemA had the same transcription direction as the lac promoter. The distance between the lac promoter and hemA affected the expression of ALA synthase on different growth substrates. The E. coli host strain used had an enormous effect on the ALA synthase activity level and on the production of ALA, with E. coli DH1 being best suited. The ALA synthase activity level was also dependent on the carbon source. Succinate, L-malate, fumarate, and L-aspartate gave the highest levels of ALA synthase activity, while the use of lactose as a carbon source resulted in a repression of ALA synthase. After growth on succinate, ALA synthase represented {approx}5% of total cellular protein. The ALA synthase activity level was also dependent on the pH of the medium, with maximal activity occurring at pH 6.5. ALA production by whole cells was limited by the availability of glycine, and the addition of 2 g of glycine per liter to the growth medium increased the production of ALA fivefold, to 2.25 mM. In recombinant E. coli extracts, up to 22 mM ALA was produced from succinate, glycine, and ATP. 58 refs., 4 figs., 7 tabs.

  15. Advancing Rhodobacter sphaeroides as a platform for expression of functional membrane proteins.

    PubMed

    Erbakan, Mustafa; Curtis, Brandon S; Nixon, B Tracy; Kumar, Manish; Curtis, Wayne R

    2015-11-01

    Membrane protein overexpression is often hindered by toxic effects on the expression host, limiting achievable volumetric productivity. Moreover, protein structure and function may be impaired due to inclusion body formation and proteolytic degradation. To address these challenges, we employed the photosynthetic bacterium, Rhodobacter sphaeroides for expression of challenging membrane proteins including human aquaporin 9 (hAQP9), human tight junction protein occludin (Occ), Escherichia coli toxin peptide GhoT, cellulose synthase enzyme complex (BcsAB) of R. sphaeroides and cytochrome-cy (Cyt-cy) from Rhodobacter capsulatus. Titers of 47 mg/L for Cyt-cy, 7.5 mg/L for Occ, 1.5 mg/L for BcsAB and 0.5 mg/L for hAQP9 were achieved from affinity purification. While purification of GhoT was not successful, transformants displayed a distinct growth phenotype that correlated with GhoT expression. We also evaluated the functionality of these proteins by performing water transport studies for hAQP9, peroxidase activity for cytochrome-cy, and in vitro cellulose synthesis activity assay for BcsAB. While previous studies with Rhodobacter have utilized oxygen-limited semi-aerobic growth for membrane protein expression, substantial titer improvements are achieved as a result of a 3-fold increase in biomass yield using the anaerobic photoheterotrophic growth regime, which utilizes the strong native puc promoter. This versatile platform is shown to enable recovery of a wide variety of difficult-to-express membrane proteins in functional form.

  16. Biochemical Characterization of the Flagellar Rod Components of Rhodobacter sphaeroides: Properties and Interactions

    PubMed Central

    Osorio-Valeriano, Manuel; de la Mora, Javier; Camarena, Laura

    2015-01-01

    ABSTRACT The flagellar basal body is a rotary motor that spans the cytoplasmic and outer membranes. The rod is a drive shaft that transmits torque generated by the motor through the hook to the filament that propels the bacterial cell. The assembly and structure of the rod are poorly understood. In a first attempt to characterize this structure in the alphaproteobacterium Rhodobacter sphaeroides, we overexpressed and purified FliE and the four related rod proteins (FlgB, FlgC, FlgF, and FlgG), and we analyzed their ability to form homo-oligomers. We found that highly purified preparations of these proteins formed high-molecular-mass oligomers that tended to dissociate in the presence of NaCl. As predicted by in silico modeling, the four rod proteins share architectural features. Using affinity blotting, we detected the heteromeric interactions between these proteins. In addition, we observed that deletion of the N- and C-terminal regions of FlgF and FlgG severely affected heteromeric but not homomeric interactions. On the basis of our findings, we propose a model of rod assembly in this bacterium. IMPORTANCE Despite the considerable amount of research on the structure and assembly of other flagellar axial structures that has been conducted, the rod has been barely studied. An analysis of the biochemical characteristics of the flagellar rod components of the Fla1 system of R. sphaeroides is presented in this work. We also analyze the interactions of these proteins with each other and with their neighbors, and we propose a model for the order in which they are assembled. PMID:26574514

  17. Planck's Dusty GEMS. II. Extended [CII] emission and absorption in the Garnet at z = 3.4 seen with ALMA

    NASA Astrophysics Data System (ADS)

    Nesvadba, N.; Kneissl, R.; Cañameras, R.; Boone, F.; Falgarone, E.; Frye, B.; Gerin, M.; Koenig, S.; Lagache, G.; Le Floc'h, E.; Malhotra, S.; Scott, D.

    2016-08-01

    We present spatially resolved ALMA [CII] observations of the bright (flux density S350 = 400 mJy at 350 μm), gravitationally lensed, starburst galaxy PLCK G045.1+61.1 at z = 3.427, the "Garnet". This source is part of our set of "Planck's Dusty GEMS", discovered with the Planck's all-sky survey. Two emission-line clouds with a relative velocity offset of ~600 km s-1 extend towards north-east and south-west, respectively, of a small, intensely star-forming clump with a star-formation intensity of 220 M⊙ yr-1 kpc-2, akin to maximal starbursts. [CII] is also seen in absorption, with a redshift of +350 km s-1 relative to the brightest CO component. [CII] absorption has previously only been found in the Milky Way along sightlines toward bright high-mass star-forming regions, and this is the first detection in another galaxy. Similar to Galactic environments, the [CII] absorption feature is associated with [CI] emission, implying that this is diffuse gas shielded from the UV radiation of the clump, and likely at large distances from the clump. Since absorption can only be seen in front of a continuum source, the gas in this structure can definitely be attributed to gas flowing towards the clump. The absorber could be part of a cosmic filament or merger debris being accreted onto the galaxy. We discuss our results also in light of the on-going debate of the origin of the [CII] deficit in dusty star-forming galaxies. Based on data obtained with ALMA in program 2013.1.01230.S, and with EMIR on the IRAM 30 m telescope in program 223-13.

  18. Probing the Extended Atmosphere and Wind of Betelgeuse with SOFIA-EXES: Exploiting the Forbidden Fe II Ladder

    NASA Astrophysics Data System (ADS)

    Harper, Graham M.; Richter, Matthew; O'Gorman, Eamon; DeWitt, Curtis; Guinan, Edward F.; EXES Instrument Team

    2016-01-01

    Betelgeuse is a proving ground for theories of mass loss from cool massive stars: it has little circumstellar dust and low molecular abundances, but it is still able to drive a massive outflow just like its dusty cousins of later spectral-types. To constrain the physical processes causing mass loss we need to examine the conditions in the wind acceleration zone where most of the required energy is deposited. To study the dynamics and thermodynamics in this zone requires spectrally-resolved line profiles from diagnostics with different excitation energies.Forbidden mid-IR Fe II transitions from within the first three terms, with Texc=540 K, 3,400 K, and 11,700 K, provide just such diagnostics. NASA-DLR SOFIA with the Echelon-Cross-Echelle Spectrograph (EXES) provide the required low water vapor (42,000~ft) and spectral resolution (R=50,000) for two of the transitions, while the 17.94 μm line can be observed with TEXES on NASA's IRTF.We present key spectra from our Cycle 2 SOFIA program, which also enabled us to explore the mid-IR signature of the two cm-radio hot-spots that had recently been reported from eMERLIN interferometry. Our high S/N spectra place tight constraints on the amount of warm chromospheric plasma, and we have resolved the 25.99 μm ground-state line for the first time, showing blue-shifted emission from the outflow. Please note that the nature of the puzzling radio-hot spots are now understood.

  19. Early steps in carotenoid biosynthesis: sequences and transcriptional analysis of the crtI and crtB genes of Rhodobacter sphaeroides and overexpression and reactivation of crtI in Escherichia coli and R. sphaeroides.

    PubMed

    Lang, H P; Cogdell, R J; Gardiner, A T; Hunter, C N

    1994-07-01

    In the purple photosynthetic bacterium Rhodobacter sphaeroides, the desaturation of phytoene has already been implicated in the assembly of the light-harvesting 2 complex (H.P. Lang and C.N. Hunter, Biochem. J. 298:197-205, 1994). The phytoene synthase and desaturase enzymes mediate the first steps specific for carotenoid biosynthesis up to and including the synthesis of the colored carotenoid neurosporene. In this report, we present the DNA and deduced amino acid sequences of the genes encoding these proteins, namely, crtB and crtI, from R. sphaeroides and present evidence for the existence of a crtIB operon. Both genes have been shown to possess putative puc and puf operon-like promoter sequences, and oxygen regulation and the point of initiation of the crtI transcript have been demonstrated. The complete crtI gene has been overexpressed in Escherichia coli and R. sphaeroides and shown to catalyze three desaturations of phytoene to give neurosporene. This activity was shown to be ATP dependent, and the cofactor requirement was investigated by using a spectroscopic assay for in vitro carotenogenic activity. Although the crtI and crtB genes have been sequenced from a number of different organisms, the transcriptional organization and regulation of these genes have not been analyzed in detail. In this report, we have located the transcription initiation point and have shown that R. sphaeroides possesses an oxygen-regulated CrtI-type phytoene desaturase gene that forms a transcriptional operon with crtB.

  20. Mono- and dinuclear nickel(II) complexes of resolved Schiff-base ligands with extended quinoline substituents.

    PubMed

    Prema, Dipesh; Oshin, Kayode; Desper, John; Levy, Christopher J

    2012-04-28

    The coordination chemistry of four enantiopure tetradentate bis(iminoquinoline) ligands with nickel(II) salts is reported. The previously reported ligands CBQ, CPQ, BBQ, and BPQ result from the condensation of (1R,2R)-cyclohexyldiamine or (R)-BINAM with two equivalents of 2-formylbenzo[h]quinoline or 8-isopropyl-2-quinolinecarboxaldehyde {CBQ = (1R,2R)-cyclohexanediamine-N,N'-bis(benzo[h]quinoline-2-ylmethylene), CPQ = (1R,2R)-cyclohexanediamine-N,N'-bis[[(8-isopropyl)-2-quinolinyl]methylene], BBQ = [(R)-1,1'-binaphthalene]-2,2'-diamine-N,N'-bis(benzo[h]quinoline-2-ylmethylene), BPQ = [(R)-1,1'-binaphthalene]-2,2'-diamine-N,N'-bis[[(8-isopropyl)-2-quinolinyl]methylene]}. Reaction of NiI(2) with the (1R,2R)-cyclohexyl ligands gives the mononuclear distorted trigonal-bipyramidal (TBP) complexes [Ni(N(3)-CBQ)I(2)] and [Ni(N(3)-CPQ)I(2)]. Incomplete iodide abstraction from [Ni(N(3)-CPQ)I(2)] with AgOTf leads to partial replacement of the iodide with hydroxide from adventitious water to give [Ni(N(3)-CPQ)I(1.6)(OH)(0.4)] (distorted TBP). The corresponding reaction with [Ni(N(3)-CBQ)I(2)] again fails to remove all of the iodide, resulting instead in conversion to the syn dinuclear [Ni(2)(CBQ)(μ-X)(2)I(2)] (X = Cl(0.925)I(0.075)) complex, where chloride abstraction from the solvent (CH(2)Cl(2)) has resulted in a mixed halide system and the metal centers are square-pyramidal. Reaction of Ni(OTf)(2) with CBQ leads to the isolation of the octahedral cation [Ni(CMBQ)(2)](2+), with CMBQ [(1R,2R)-cyclohexanediamine-mono-N-(benzo[h]quinoline-2-ylmethylene)] being the partial hydrolysis product of CBQ. [Ni(CMBQ)(2)][OTf](2) crystallizes as a 1:1 mixture of P and M helical diastereomers. The coordination of NiI(2) with the (R)-BINAM derived ligands yields the anti dinuclear P-helical complexes [Ni(2)(BBQ)(μ-I)(2)I(2)] and [Ni(2)(BPQ)(μ-I)(2)I(2)]: one nickel ion is coordinated in each bidentate iminoquinoline pocket and the geometry at the metal centers is distorted square

  1. Oxygen Radical Scavenger Activity, EPR, NMR, Molecular Mechanics and Extended-Hückel Molecular Orbital Investigation of the Bis(Piroxicam)Copper(II) Complex.

    PubMed

    Cini, R; Pogni, R; Basosi, R; Donati, A; Rossi, C; Sabadini, L; Rollo, L; Lorenzini, S; Gelli, R; Marcolongo, R

    1995-01-01

    stoichiometry was in fact prepared. (13)C spin-lattice relaxation rates of neutral, zwitterionic and anionic piroxicam, in DMSO solution are explained by the thermal equilibrium between the three most stable structures of the three forms, thus confirming the high quality of the force field. The EPR spectrum of [Cu(II)(Pir)(2)(DMF)(2)] (DMSO/GLY, 2:1, v/v, 298 and 110 K) agrees with a N2O2+O2 pseudo-octahedral coordination geometry. The EPR spectrum of [Cu(II)(Pir)(2).0.5DMF agrees with a pseudo-tetrahedral coordination geometry. The parameters extracted from the room temperature spectra of the solution phases are in agreement with the data reported for powder and frozen solutions. The extended-Hückel calculations on minimum energy structures of [Cu(II)(Pir)(2)(DMF)(2)] and [Cu(II)(Pir)(2)] (square planar) revealed that the HOMOs have a relevant character of d(x) (2)-y(2). On the other hand the HOMO of a computer generated structure for [Cu(II)(Pir)(2)] (pseudo-tetrahedral) has a relevant character of d(xy) atomic orbital. A d(xy) orbital is better suited to allow a dpi-ppi interaction to the O(2) (-) anion. Therefore this work shows that the anti-inflammatory activity of piroxicam could be due in part to the formation of [Cu(II)(Pir)(2)] chelates, which can exert a SOD-like activity. PMID:18472745

  2. An Extended Chain and Trinuclear Complexes Based on Pt(II)-M (M = Tl(I), Pb(II)) Bonds: Contrasting Photophysical Behavior.

    PubMed

    Forniés, Juan; Giménez, Nora; Ibáñez, Susana; Lalinde, Elena; Martín, Antonio; Moreno, M Teresa

    2015-05-01

    The syntheses and structural characterizations of a Pt-Tl chain [{Pt(bzq)(C6F5)2}Tl(Me2CO)]n 1 and two trinuclear Pt2M clusters (NBu4)[{Pt(bzq)(C6F5)2}2Tl] 2 and [{Pt(bzq)(C6F5)2}2Pb] 3 (bzq = 7,8-benzoquinolinyl), stabilized by donor-acceptor Pt → M bonds, are reported. The one-dimensional heterometallic chain 1 is formed by alternate "Pt(bzq)(C6F5)2" and "Tl(Me2CO)" fragments, with Pt-Tl bond separations in the range of 2.961(1)-3.067(1) Å. The isoelectronic trinuclear complexes 2 (which crystallizes in three forms, namely, 2a, 2b, and 2c) and 3 present a sandwich structure in which the Tl(I) or Pb(II) is located between two "Pt(bzq)(C6F5)2" subunits. NMR studies suggest equilibria in solution implying cleavage and reformation of Pt-M bonds. The lowest-lying absorption band in the UV-vis spectra in CH2Cl2 and tetrahydrofuran (THF) of 1, associated with (1)MLCT/(1)L'LCT (1)[5dπ(Pt) → π*(bzq)]/(1)[(C6F5) → bzq], displays a blue shift in relation to the precursor, suggesting the cleavage of the chain maintaining bimetallic Pt-Tl fragments in solution, also supported by NMR spectroscopy. In 2 and 3, it shows a blue shift in THF and a red shift in CH2Cl2, supporting a more extensive cleavage of the Pt-M bonds in THF solutions than in CH2Cl2, where the trinuclear entities are predominant. The Pt-Tl chain 1 displays in solid state a bright orange-red emission ascribed to (3)MM'CT (M' = Tl). It exhibits remarkable and fast reversible vapochromic and vapoluminescent response to donor vapors (THF and Et2O), related to the coordination/decoordination of the guest molecule to the Tl(I) ion, and mechanochromic behavior, associated with the shortening of the intermetallic Pt-Tl separations in the chain induced by grinding. In frozen solutions (THF, acetone, and CH2Cl2) 1 shows interesting luminescence thermochromism with emissions strongly dependent on the solvent, concentration, and excitation wavelengths. The Pt2Tl complex 2 shows an emission close to 1, ascribed to

  3. Optimization of Influencing Factors on Biomass Accumulation and 5-Aminolevulinic Acid (ALA) Yield in Rhodobacter sphaeroides Wastewater Treatment.

    PubMed

    Liu, Shuli; Li, Xiangkun; Zhang, Guangming; Zhang, Jie

    2015-11-01

    This study aimed to optimize four factors affecting biomass accumulation and 5-aminolevulinic acid (ALA) yield together with pollutants removal in Rhodobacter sphaeroides wastewater treatment. Results showed that it was feasible to produce biomass and ALA in R. sphaeroides wastewater treatment. Microaerobic, 1,000-3,000 lux, and pH 7.0 were optimal conditions for the highest ALA yield of 4.5 ± 0.5 mg/g-biomass. Under these conditions, COD removal and biomass production rate were 93.3 ± 0.9% and 31.8 ± 0.5 mg/l/h, respectively. In addition, trace elements Fe(2+), Mg(2+), Ni(2+), and Zn(2+) further improved the ALA yield, COD removal, and biomass production rate. Specifically, the highest ALA yield (12.5 ± 0.6 mg/g-biomass) was achieved with Fe(2+) addition.

  4. FTIR spectroscopy of the photoreduction of the bacteriopheophytin electron acceptor in reaction centers of Rb. sphaeroides and Rps. viridis.

    NASA Astrophysics Data System (ADS)

    Nabedryk, E.; Andrianambinintsoa, S.; Dejonghe, D.; Breton, J.

    1995-05-01

    The photoreduction of the bacteriopheophytin electron acceptor H A in reaction centers from Rhodobacter sphaeroides and Rhodopseudomonas viridis has been monitored by light-induced FTIR difference spectroscopy at 10°C, in the presence of reductant and mediator. The striking similarity of the H A-/H A spectra obtained for Rb. sphaeroides and Rps. viridis reflects comparable interactions of the bacteriopheophytin electron acceptor with the protein in both reaction centers and implies that the photoreduction of H A affects conserved amino acid residues. The H A-/H A spectra are interpreted by comparison with model compound spectra of the anion radicals of bacteriopheophytin a and b,a nd by analysis of 1H/2H isotope effects. The downshift of the 1677 cm -1 mode in Rb. sphaeroides (1681 cm -1 in Rps. viridis) reaction centers with respect to the model compound is interpreted in terms of a strongly perturbed 9-keto carbonyl of H A. This perturbation most probably originates from hydrogen bonding to Glu L104. At least part of the positive signal at 1591 cm -1 in Rb. sphaeroides and at 1601 cm -1 in Rps. viridis is assigned to the 9-keto carbonyl mode of H A-. From 1H/2H exchange experiments, it is proposed that the COO 1H side chain of Glu L104 contributes to the 1745-1735 cm -1 spectral range with the corresponding COO 2H signal displaced to lower frequencies and partly hidden under the 1732 cm -1 band.

  5. New dicyano cyclometalated compounds containing Pd(II)-Tl(I) bonds as building blocks in 2D extended structures: synthesis, structure, and luminescence studies.

    PubMed

    Sicilia, Violeta; Forniés, Juan; Fuertes, Sara; Martín, Antonio

    2012-10-15

    New mixed metal complexes [PdTl(C^N)(CN)(2)] [C^N = 7,8-benzoquinolinate (bzq, 3); 2-phenylpyridinate (ppy, 4)] have been synthesized by reaction of their corresponding precursors (NBu(4))[Pd(C^N)(CN)(2)] [C^N = bzq (1), ppy (2)] with TlPF(6). Compounds 3 and 4 were studied by X-ray diffraction, showing the not-so-common Pd(II)-Tl(I) bonds. Both crystal structures exhibit 2-D extended networks fashioned by organometallic "PdTl(C^N)(CN)(2)" units, each one containing a donor-acceptor Pd(II)-Tl(I) bond, which are connected through additional Tl···N≡C contacts and weak Tl···π (bzq) contacts in the case of 3. Solid state emissions are red-shifted compared with those of the precursors and have been assigned to metal-metal'-to-ligand charge transfer (MM'LCT [d/s σ*(Pd,Tl) → π*(C^N)]) mixed with some intraligand ((3)IL[π(C^N) → π*(C^N)]) character. In diluted solution either at room temperature or 77 K, the Pd-Tl bond is no longer retained as confirmed by mass spectrometry, NMR, and UV-vis spectroscopic techniques.

  6. HLA Class I and Class II Conserved Extended Haplotypes and Their Fragments or Blocks in Mexicans: Implications for the Study of Genetic Diversity in Admixed Populations

    PubMed Central

    Ohashi, Marina; Lebedeva, Tatiana; Acuña-Alonzo, Víctor; Yunis, María; Granados-Montiel, Julio; Cruz-Lagunas, Alfredo; Vargas-Alarcón, Gilberto; Rodríguez-Reyna, Tatiana S.; Fernandez-Viña, Marcelo; Granados, Julio; Yunis, Edmond J.

    2013-01-01

    Major histocompatibility complex (MHC) genes are highly polymorphic and informative in disease association, transplantation, and population genetics studies with particular importance in the understanding of human population diversity and evolution. The aim of this study was to describe the HLA diversity in Mexican admixed individuals. We studied the polymorphism of MHC class I (HLA-A, -B, -C), and class II (HLA-DRB1, -DQB1) genes using high-resolution sequence based typing (SBT) method and we structured the blocks and conserved extended haplotypes (CEHs) in 234 non-related admixed Mexican individuals (468 haplotypes) by a maximum likelihood method. We found that HLA blocks and CEHs are primarily from Amerindian and Caucasian origin, with smaller participation of African and recent Asian ancestry, demonstrating a great diversity of HLA blocks and CEHs in Mexicans from the central area of Mexico. We also analyzed the degree of admixture in this group using short tandem repeats (STRs) and HLA-B that correlated with the frequency of most probable ancestral HLA-C/−B and -DRB1/−DQB1 blocks and CEHs. Our results contribute to the analysis of the diversity and ancestral contribution of HLA class I and HLA class II alleles and haplotypes of Mexican admixed individuals from Mexico City. This work will help as a reference to improve future studies in Mexicans regarding allotransplantation, immune responses and disease associations. PMID:24086347

  7. New dicyano cyclometalated compounds containing Pd(II)-Tl(I) bonds as building blocks in 2D extended structures: synthesis, structure, and luminescence studies.

    PubMed

    Sicilia, Violeta; Forniés, Juan; Fuertes, Sara; Martín, Antonio

    2012-10-15

    New mixed metal complexes [PdTl(C^N)(CN)(2)] [C^N = 7,8-benzoquinolinate (bzq, 3); 2-phenylpyridinate (ppy, 4)] have been synthesized by reaction of their corresponding precursors (NBu(4))[Pd(C^N)(CN)(2)] [C^N = bzq (1), ppy (2)] with TlPF(6). Compounds 3 and 4 were studied by X-ray diffraction, showing the not-so-common Pd(II)-Tl(I) bonds. Both crystal structures exhibit 2-D extended networks fashioned by organometallic "PdTl(C^N)(CN)(2)" units, each one containing a donor-acceptor Pd(II)-Tl(I) bond, which are connected through additional Tl···N≡C contacts and weak Tl···π (bzq) contacts in the case of 3. Solid state emissions are red-shifted compared with those of the precursors and have been assigned to metal-metal'-to-ligand charge transfer (MM'LCT [d/s σ*(Pd,Tl) → π*(C^N)]) mixed with some intraligand ((3)IL[π(C^N) → π*(C^N)]) character. In diluted solution either at room temperature or 77 K, the Pd-Tl bond is no longer retained as confirmed by mass spectrometry, NMR, and UV-vis spectroscopic techniques. PMID:22998590

  8. Structural and genetic analysis of a mutant of Rhodobacter sphaeroides WS8 deficient in hook length control.

    PubMed Central

    González-Pedrajo, B; Ballado, T; Campos, A; Sockett, R E; Camarena, L; Dreyfus, G

    1997-01-01

    Motility in the photosynthetic bacterium Rhodobacter sphaeroides is achieved by the unidirectional rotation of a single subpolar flagellum. In this study, transposon mutagenesis was used to obtain nonmotile flagellar mutants from this bacterium. We report here the isolation and characterization of a mutant that shows a polyhook phenotype. Morphological characterization of the mutant was done by electron microscopy. Polyhooks were obtained by shearing and were used to purify the hook protein monomer (FlgE). The apparent molecular mass of the hook protein was 50 kDa. N-terminal amino acid sequencing and comparisons with the hook proteins of other flagellated bacteria indicated that the Rhodobacter hook protein has consensus sequences common to axial flagellar components. A 25-kb fragment from an R. sphaeroides WS8 cosmid library restored wild-type flagellation and motility to the mutant. Using DNA adjacent to the inserted transposon as a probe, we identified a 4.6-kb SalI restriction fragment that contained the gene responsible for the polyhook phenotype. Nucleotide sequence analysis of this region revealed an open reading frame with a deduced amino acid sequence that was 23.4% identical to that of FliK of Salmonella typhimurium, the polypeptide responsible for hook length control in that enteric bacterium. The relevance of a gene homologous to fliK in the uniflagellated bacterium R. sphaeroides is discussed. PMID:9352903

  9. Quantifying the effects of light intensity on bioproduction and maintenance energy during photosynthetic growth of Rhodobacter sphaeroides.

    PubMed

    Imam, Saheed; Fitzgerald, Colin M; Cook, Emily M; Donohue, Timothy J; Noguera, Daniel R

    2015-02-01

    Obtaining a better understanding of the physiology and bioenergetics of photosynthetic microbes is an important step toward optimizing these systems for light energy capture or production of valuable commodities. In this work, we analyzed the effect of light intensity on bioproduction, biomass formation, and maintenance energy during photoheterotrophic growth of Rhodobacter sphaeroides. Using data obtained from steady-state bioreactors operated at varying dilution rates and light intensities, we found that irradiance had a significant impact on biomass yield and composition, with significant changes in photopigment, phospholipid, and biopolymer storage contents. We also observed a linear relationship between incident light intensity and H2 production rate between 3 and 10 W m(-2), with saturation observed at 100 W m(-2). The light conversion efficiency to H2 was also higher at lower light intensities. Photosynthetic maintenance energy requirements were also significantly affected by light intensity, with links to differences in biomass composition and the need to maintain redox homeostasis. Inclusion of the measured condition-dependent biomass and maintenance energy parameters and the measured photon uptake rate into a genome-scale metabolic model for R. sphaeroides (iRsp1140) significantly improved its predictive performance. We discuss how our analyses provide new insights into the light-dependent changes in bioenergetic requirements and physiology during photosynthetic growth of R. sphaeroides and potentially other photosynthetic organisms.

  10. The extended ROSAT-ESO Flux-Limited X-ray Galaxy Cluster Survey (REFLEX II) - III. Construction of the first flux-limited supercluster sample

    NASA Astrophysics Data System (ADS)

    Chon, Gayoung; Böhringer, Hans; Nowak, Nina

    2013-03-01

    We present the first supercluster catalogue constructed with the extended ROSAT-ESO Flux-Limited X-ray (REFLEX II) Galaxy Cluster survey data, which comprises 919 X-ray selected galaxy clusters with a flux limit of 1.8 × 10-12 erg s-1 cm-2. Based on this cluster catalogue we construct a supercluster catalogue using a friends-of-friends algorithm with a linking length depending on the (local) cluster density, which thus varies with redshift. The resulting catalogue comprises 164 superclusters at redshift z ≤ 0.4. The choice of the linking length in the friends-of-friends method modifies the properties of the superclusters. We study the properties of different catalogues such as the distributions of the redshift, extent and multiplicity by varying the choice of parameters. In addition to the supercluster catalogue for the entire REFLEX II sample, we compile a large volume-limited cluster sample from REFLEX II with the redshift and luminosity constraints of z ≤ 0.1 and LX ≥ 5 × 1043 erg s-1. With this catalogue we construct a volume-limited sample of superclusters. This sample is built with a homogeneous linking length, and hence selects effectively the same type of superclusters. By increasing the luminosity cut we can build a hierarchical tree structure of the volume-limited samples, where systems at the top of the tree are only formed via the most luminous clusters. This allows us to test if the same superclusters are found when only the most luminous clusters are visible, comparable to the situation at higher redshift in the REFLEX II sample. We find that the selection of superclusters is very robust, independent of the luminosity cut, and the contamination of spurious superclusters among cluster pairs is expected to be small. Numerical simulations and observations of the substructure of clusters suggest that regions of high cluster number density provide an astrophysically different environment for galaxy clusters, where the mass function and X

  11. Bioremediation of petroleum hydrocarbon contaminated soil by Rhodobacter sphaeroides biofertilizer and plants.

    PubMed

    Jiao, Haihua; Luo, Jinxue; Zhang, Yiming; Xu, Shengjun; Bai, Zhihui; Huang, Zhanbin

    2015-09-01

    Bio-augmentation is a promising technique for remediation of polluted soils. This study aimed to evaluate the bio-augmentation effect of Rhodobacter sphaeroides biofertilizer (RBF) on the bioremediation of total petroleum hydrocarbons (TPH) contaminated soil. A greenhouse pot experiment was conducted over a period of 120 days, three methods for enhancing bio-augmentation were tested on TPH contaminated soils, including single addition RBF, planting, and combining of RBF and three crop species, such as wheat (W), cabbage (C) and spinach (S), respectively. The results demonstrated that the best removal of TPH from contaminated soil in the RBF bio-augmentation rhizosphere soils was found to be 46.2%, 65.4%, 67.5% for W+RBF, C+RBF, S+RBF rhizosphere soils respectively. RBF supply impacted on the microbial community diversity (phospholipid fatty acids, PLFA) and the activity of soil enzymes, such as dehydrogenase (DH), alkaline phosphatase (AP) and urease (UR). There were significant difference among the soil only containing crude oil (CK), W, C and S rhizosphere soils and RBF bio-augmentation soils. Moreover, the changes were significantly distinct depended on crops species. It was concluded that the RBF is a valuable material for improving effect of remediation of TPH polluted soils. PMID:26525019

  12. Membrane-bound, pyridine nucleotide-independent L-lactate dehydrogenase of Rhodopseudomonas sphaeroides.

    PubMed Central

    Markwell, J P; Lascelles, J

    1978-01-01

    Rhodopseudomonas sphaeroides has a pyridine nucleotide-independent L-lactate dehydrogenase associated with the membrane fraction of cells grown either aerobically or phototrophically. The dehydrogenase is present in cells grown on a variety of carbon sources, but at levels less than 20% of that found in cells grown with DL-lactate. The dehydrogenase has been purified 45-fold from membranes of strain L-57, a non-photosynthetic mutant, by steps involving solubilization with lauryl dimethylamine oxide and three anion-exchange chromatography steps. The purified enzyme was specific for the L-isomer of lactate. The Km of the purified enzyme for L-lactate is 1.4 mM, whereas that of the membrane-associated enzyme is 0.5 mM. The enzyme activity was inhibited competitively by D-lactate and non-competitively by oxalate and oxamate. Quinacrine, a flavin analog, also inhibited the activity. The inducible enzyme may serve as a marker of membrane protein in studies of membrane development. PMID:304854

  13. Delipidation of cytochrome c oxidase from Rhodobacter sphaeroides destabilizes its quaternary structure.

    PubMed

    Musatov, Andrej; Varhač, Rastislav; Hosler, Jonathan P; Sedlák, Erik

    2016-06-01

    Delipidation of detergent-solubilized cytochrome c oxidase isolated from Rhodobacter sphaeroides (Rbs-CcO) has no apparent structural and/or functional effect on the protein, however affects its resistance against thermal or chemical denaturation. Phospholipase A2 (PLA2) hydrolysis of phospholipids that are co-purified with the enzyme removes all but two tightly bound phosphatidylethanolamines. Replacement of the removed phospholipids with nonionic detergent decreases both thermal stability of the enzyme and its resilience against the effect of chemical denaturants such as urea. In contrast to nondelipidated Rbs-CcO, the enzymatic activity of PLA2-treated Rbs-CcO is substantially diminished after exposure to high (>4 M) urea concentration at room temperature without an alteration of its secondary structure. Absorbance spectroscopy and sedimentation velocity experiments revealed a strong correlation between intact tertiary structure of heme regions and quaternary structure, respectively, and the enzymatic activity of the protein. We concluded that phospholipid environment of Rbs-CcO has the protective role for stability of its tertiary and quaternary structures. PMID:26923069

  14. Bioremediation of petroleum hydrocarbon contaminated soil by Rhodobacter sphaeroides biofertilizer and plants.

    PubMed

    Jiao, Haihua; Luo, Jinxue; Zhang, Yiming; Xu, Shengjun; Bai, Zhihui; Huang, Zhanbin

    2015-09-01

    Bio-augmentation is a promising technique for remediation of polluted soils. This study aimed to evaluate the bio-augmentation effect of Rhodobacter sphaeroides biofertilizer (RBF) on the bioremediation of total petroleum hydrocarbons (TPH) contaminated soil. A greenhouse pot experiment was conducted over a period of 120 days, three methods for enhancing bio-augmentation were tested on TPH contaminated soils, including single addition RBF, planting, and combining of RBF and three crop species, such as wheat (W), cabbage (C) and spinach (S), respectively. The results demonstrated that the best removal of TPH from contaminated soil in the RBF bio-augmentation rhizosphere soils was found to be 46.2%, 65.4%, 67.5% for W+RBF, C+RBF, S+RBF rhizosphere soils respectively. RBF supply impacted on the microbial community diversity (phospholipid fatty acids, PLFA) and the activity of soil enzymes, such as dehydrogenase (DH), alkaline phosphatase (AP) and urease (UR). There were significant difference among the soil only containing crude oil (CK), W, C and S rhizosphere soils and RBF bio-augmentation soils. Moreover, the changes were significantly distinct depended on crops species. It was concluded that the RBF is a valuable material for improving effect of remediation of TPH polluted soils.

  15. Redox potential tuning through differential quinone binding in the photosynthetic reaction center of Rhodobacter sphaeroides.

    PubMed

    Vermaas, Josh V; Taguchi, Alexander T; Dikanov, Sergei A; Wraight, Colin A; Tajkhorshid, Emad

    2015-03-31

    Ubiquinone forms an integral part of the electron transport chain in cellular respiration and photosynthesis across a vast number of organisms. Prior experimental results have shown that the photosynthetic reaction center (RC) from Rhodobacter sphaeroides is only fully functional with a limited set of methoxy-bearing quinones, suggesting that specific interactions with this substituent are required to drive electron transport and the formation of quinol. The nature of these interactions has yet to be determined. Through parameterization of a CHARMM-compatible quinone force field and subsequent molecular dynamics simulations of the quinone-bound RC, we have investigated and characterized the interactions of the protein with the quinones in the Q(A) and Q(B) sites using both equilibrium simulation and thermodynamic integration. In particular, we identify a specific interaction between the 2-methoxy group of ubiquinone in the Q(B) site and the amide nitrogen of GlyL225 that we implicate in locking the orientation of the 2-methoxy group, thereby tuning the redox potential difference between the quinones occupying the Q(A) and Q(B) sites. Disruption of this interaction leads to weaker binding in a ubiquinone analogue that lacks a 2-methoxy group, a finding supported by reverse electron transfer electron paramagnetic resonance experiments of the Q(A)⁻Q(B)⁻ biradical and competitive binding assays. PMID:25734689

  16. Modification of galactitol dehydrogenase from Rhodobacter sphaeroides D for immobilization on polycrystalline gold surfaces.

    PubMed

    Kornberger, P; Gajdzik, J; Natter, H; Wenz, G; Giffhorn, F; Kohring, G W; Hempelmann, R

    2009-10-20

    Galactitol dehydrogenase (GatDH) from Rhodobacter sphaeroides is a multifunctional enzyme that catalyzes in the presence of oxidized beta-nicotinamide adenine dinucleotide (NAD(+)) the interconversion of various multivalent aliphatic alcohols to the corresponding ketones. The recombinant GatDH was provided with an N-terminal His(6)-tag to which distally up to three cysteine residues were attached. This protein construct maintained nearly full enzymatic activity, and it could be covalently immobilized via thiol bonds onto the surface of a gold electrode. Binding of GatDH onto the gold electrode was verified by SPR measurements, and residual enzyme activity was measured by cyclic voltammetry using 1,2-hexanediol as substrate, the cofactor NAD(+) and the redox mediator CTFM (4-carboxy-2,5,7-trinitrofluorenyliden-malonnitrile) in solute form. The results demonstrate the possibility of a directed functional immobilization of proteins on gold surfaces, which represents a proof-of-concept for the development of reactors for electrochemical synthon preparation using dehydrogenases.

  17. Molecular Cloning, Overexpression and Characterization of a Novel Water Channel Protein from Rhodobacter sphaeroides

    PubMed Central

    Erbakan, Mustafa; Shen, Yue-xiao; Grzelakowski, Mariusz; Butler, Peter J.; Kumar, Manish; Curtis, Wayne R.

    2014-01-01

    Aquaporins are highly selective water channel proteins integrated into plasma membranes of single cell organisms; plant roots and stromae; eye lenses, renal and red blood cells in vertebrates. To date, only a few microbial aquaporins have been characterized and their physiological importance is not well understood. Here we report on the cloning, expression and characterization of a novel aquaporin, RsAqpZ, from a purple photosynthetic bacterium, Rhodobacter sphaeroides ATCC 17023. The protein was expressed homologously at a high yield (∼20 mg/L culture) under anaerobic photoheterotrophic growth conditions. Stopped-flow light scattering experiments demonstrated its high water permeability (0.17±0.05 cm/s) and low energy of activation for water transport (2.93±0.60 kcal/mol) in reconstituted proteoliposomes at a protein to lipid ratio (w/w) of 0.04. We developed a fluorescence correlation spectroscopy based technique and utilized a fluorescent protein fusion of RsAqpZ, to estimate the single channel water permeability of RsAqpZ as 1.24 (±0.41) x 10−12 cm3/s or 4.17 (±1.38)×1010 H2O molecules/s, which is among the highest single channel permeability reported for aquaporins. Towards application to water purification technologies, we also demonstrated functional incorporation of RsAqpZ in amphiphilic block copolymer membranes. PMID:24497982

  18. Temperature-dependent conformational changes in the bacteriopheophytins of Rhodobacter sphaeroides reaction centers.

    PubMed

    Peloquin, J M; Violette, C A; Frank, H A; Bocian, D F

    1990-05-22

    Resonance Raman (RR) spectra are reported for the photosynthetic reaction center (RC) protein from Rhodobacter sphaeroides 2.4.1. The spectra were obtained with a variety of excitation wavelengths, spanning the UV, violet, and yellow-green regions of the absorption spectrum, and at a number of temperatures ranging from 30 to 270 K. The RR data indicate that the frequencies of certain vibrational modes of the bacteriochlorin pigments in the RC shift with temperature. These shifts are reversible and do not depend on external factors such as solvent or detergent. The acetyl carbonyl bands exhibit the largest shifts with temperature. These shifts are attributed to thermal effects involving the torsional vibrations of the acetyl groups of several (or all) of the bacteriochlorins rather than to specific pigment-protein interactions. The frequency of the structure-sensitive skeletal mode near 1610 cm-1 of one of the two bacteriopheophytins (BPhs) in the RC is also sensitive to temperature. In contrast, no temperature sensitivity is observed for the analogous modes of the bacteriochlorophylls or other BPhs. Over the range 160-100 K, the skeletal mode of the BPh upshifts by approximately 4 cm-1. This upshift is attributed to a flattening of the macrocycle at low temperatures. It is suggested that the BPh active in the electron-transfer process is the pigment whose structure is temperature dependent. It is further suggested that such structural changes could be responsible in part for the temperature dependence of the electron-transfer rates in photosynthetic RCs.

  19. Native Mass Spectrometry Characterizes the Photosynthetic Reaction Center Complex from the Purple Bacterium Rhodobacter sphaeroides

    NASA Astrophysics Data System (ADS)

    Zhang, Hao; Harrington, Lucas B.; Lu, Yue; Prado, Mindy; Saer, Rafael; Rempel, Don; Blankenship, Robert E.; Gross, Michael L.

    2016-08-01

    Native mass spectrometry (MS) is an emerging approach to study protein complexes in their near-native states and to elucidate their stoichiometry and topology. Here, we report a native MS study of the membrane-embedded reaction center (RC) protein complex from the purple photosynthetic bacterium Rhodobacter sphaeroides. The membrane-embedded RC protein complex is stabilized by detergent micelles in aqueous solution, directly introduced into a mass spectrometer by nano-electrospray (nESI), and freed of detergents and dissociated in the gas phase by collisional activation. As the collision energy is increased, the chlorophyll pigments are gradually released from the RC complex, suggesting that native MS introduces a near-native structure that continues to bind pigments. Two bacteriochlorophyll a pigments remain tightly bound to the RC protein at the highest collision energy. The order of pigment release and their resistance to release by gas-phase activation indicates the strength of pigment interaction in the RC complex. This investigation sets the stage for future native MS studies of membrane-embedded photosynthetic pigment-protein and related complexes.

  20. Early Bacteriopheophytin Reduction in Charge Separation in Reaction Centers of Rhodobacter sphaeroides

    PubMed Central

    Zhu, Jingyi; van Stokkum, Ivo H.M.; Paparelli, Laura; Jones, Michael R.; Groot, Marie Louise

    2013-01-01

    A question at the forefront of biophysical sciences is, to what extent do quantum effects and protein conformational changes play a role in processes such as biological sensing and energy conversion? At the heart of photosynthetic energy transduction lie processes involving ultrafast energy and electron transfers among a small number of tetrapyrrole pigments embedded in the interior of a protein. In the purple bacterial reaction center (RC), a highly efficient ultrafast charge separation takes place between a pair of bacteriochlorophylls: an accessory bacteriochlorophyll (B) and bacteriopheophytin (H). In this work, we applied ultrafast spectroscopy in the visible and near-infrared spectral region to Rhodobacter sphaeroides RCs to accurately track the timing of the electron on BA and HA via the appearance of the BA and HA anion bands. We observed an unexpectedly early rise of the HA− band that challenges the accepted simple picture of stepwise electron transfer with 3 ps and 1 ps time constants. The implications for the mechanism of initial charge separation in bacterial RCs are discussed in terms of a possible adiabatic electron transfer step between BA and HA, and the effect of protein conformation on the electron transfer rate. PMID:23746522

  1. Physiological roles for two periplasmic nitrate reductases in Rhodobacter sphaeroides 2.4.3 (ATCC 17025).

    PubMed

    Hartsock, Angela; Shapleigh, James P

    2011-12-01

    The metabolically versatile purple bacterium Rhodobacter sphaeroides 2.4.3 is a denitrifier whose genome contains two periplasmic nitrate reductase-encoding gene clusters. This work demonstrates nonredundant physiological roles for these two enzymes. One cluster is expressed aerobically and repressed under low oxygen while the second is maximally expressed under low oxygen. Insertional inactivation of the aerobically expressed nitrate reductase eliminated aerobic nitrate reduction, but cells of this strain could still respire nitrate anaerobically. In contrast, when the anaerobic nitrate reductase was absent, aerobic nitrate reduction was detectable, but anaerobic nitrate reduction was impaired. The aerobic nitrate reductase was expressed but not utilized in liquid culture but was utilized during growth on solid medium. Growth on a variety of carbon sources, with the exception of malate, the most oxidized substrate used, resulted in nitrite production on solid medium. This is consistent with a role for the aerobic nitrate reductase in redox homeostasis. These results show that one of the nitrate reductases is specific for respiration and denitrification while the other likely plays a role in redox homeostasis during aerobic growth. PMID:21949073

  2. Structure and physical map of Rhodopseudomonas sphaeroides bacteriophage RS1 DNA.

    PubMed Central

    Donohue, T J; Chory, J; Goldsand, T E; Lynn, S P; Kaplan, S

    1985-01-01

    We analyzed, by restriction endonuclease mapping and electron microscopy, the genome of the lytic Rhodopseudomonas sphaeroides-specific bacteriophage RS1 and characterized it as a linear molecule of approximately 60 to 65 kilobases. When the DNA from purified phage particles was examined by several independent methods, considerable size heterogeneity was apparent in the RS1 DNA. This size heterogeneity was concluded to be of biological origin, was independent of the specific host strain used to propagate virus, and was not due to the presence of host DNA within or nonspecifically associated with purified virions. In addition, treatment of RS1 DNA with either BAL 31 nuclease or DNA polymerase I Klenow fragment revealed that several distinct regions exist within the viral chromosome which contain free 3' hydroxyl groups. A restriction endonuclease map of the RS1 genome was constructed by using the restriction endonucleases EcoRI, ClaI, KpnI, BamHI, MluI, SmaI, and BclI; thereby allowing the positioning of some 40 restriction sites within the viral genome. The results are discussed in terms of the significance and the possible biological origin of the unique features discovered within the phage RS1 DNA. Images PMID:2989552

  3. Mechanism of nitrogenase switch-off by oxygen. [Klebsiella pneumoniae; Rhodopseudomonas sphaeroides f. sp. denitrificans; Rhodopseudomonas capsulate

    SciTech Connect

    Goldberg, I.; Nadler, V.; Hochman, A.

    1987-02-01

    Oxygen caused a reversible inhibition (switch-off) of nitrogenase activity in whole cells of four strains of diazotrophs, the facultative anaerobe Klebsiella pneumoniae and three strains of photosynthetic bacteria (Rhodopseudomonas sphaeroides f. sp. denitrificans and Rhodopseudomonas capsulata strians AD2 and BK5). In K. pneumoniae 50% inhibition of acetylene reduction was attained at an O/sub 2/ concentration of 0.37 ..mu..M. Cyanide (90 ..mu..M), which did not affect acetylene reduction but inhibited whole-cell respiration by 60 to 70%, shifted the O/sub 2/ concentration that caused 50% inhibition of nitrogenase activity to 2.9 ..mu..M. A mutant strain of K. pneumoniae, strain AH11, has a respiration rate that is 65 to 75% higher than that of the wild type, but is nitrogenase activity is similar to wild-type activity. Acetylene reduction by whole cells of this mutant was inhibited 50% by 0.20 ..mu..M O/sub 2/. Inhibition by CN/sup -/ of 40 to 50% of the O/sub 2/ uptake in the mutant shifted the O/sub 2/ concentration that caused 50% inhibition of nitrogenase to 1.58 ..mu..M. Thus, when the respiration rates were lower, higher oxygen concentrations were required to inhibit nitrogenase. Reversible inhibition of nitrogenase activity in vivo was caused under anaerobic conditions by other electron acceptors. Addition of 2 mM sulfite to cell suspensions of R. capsulata B10 and R. sphaeroides inhibited nitrogenase activity. Nitrite also inhibited acetylene reduction in whole cells of the photodenitrifier R. sphaeroides but not in R. capsulata B10, which is not capable of enzymatic reduction of NO/sub 2//sup -/. Lower concentrations of NO/sub 2//sup -/ were required to inhibit the activity in NO/sub 3//sup -/-grown cells, which have higher activities of nitrite reductase.

  4. Gene co-expression network analysis in Rhodobacter capsulatus and application to comparative expression analysis of Rhodobacter sphaeroides

    SciTech Connect

    Pena-Castillo, Lourdes; Mercer, Ryan; Gurinovich, Anastasia; Callister, Stephen J.; Wright, Aaron T.; Westbye, Alexander; Beatty, J. T.; Lang, Andrew S.

    2014-08-28

    The genus Rhodobacter contains purple nonsulfur bacteria found mostly in freshwater environments. Representative strains of two Rhodobacter species, R. capsulatus and R. sphaeroides, have had their genomes fully sequenced and both have been the subject of transcriptional profiling studies. Gene co-expression networks can be used to identify modules of genes with similar expression profiles. Functional analysis of gene modules can then associate co-expressed genes with biological pathways, and network statistics can determine the degree of module preservation in related networks. In this paper, we constructed an R. capsulatus gene co-expression network, performed functional analysis of identified gene modules, and investigated preservation of these modules in R. capsulatus proteomics data and in R. sphaeroides transcriptomics data. Results: The analysis identified 40 gene co-expression modules in R. capsulatus. Investigation of the module gene contents and expression profiles revealed patterns that were validated based on previous studies supporting the biological relevance of these modules. We identified two R. capsulatus gene modules preserved in the protein abundance data. We also identified several gene modules preserved between both Rhodobacter species, which indicate that these cellular processes are conserved between the species and are candidates for functional information transfer between species. Many gene modules were non-preserved, providing insight into processes that differentiate the two species. In addition, using Local Network Similarity (LNS), a recently proposed metric for expression divergence, we assessed the expression conservation of between-species pairs of orthologs, and within-species gene-protein expression profiles. Conclusions: Our analyses provide new sources of information for functional annotation in R. capsulatus because uncharacterized genes in modules are now connected with groups of genes that constitute a joint functional

  5. Induction and anisotropy of fluorescence of reaction center from photosynthetic bacterium Rhodobacter sphaeroides.

    PubMed

    Sipka, Gábor; Maróti, Péter

    2016-01-01

    Submillisecond dark-light changes of the yield (induction) and anisotropy of fluorescence under laser diode excitation were measured in the photosynthetic reaction center of the purple bacterium Rhodobacter sphaeroides. Narrow band (1-2 nm) laser diodes emitting at 808 and 865 nm were used to selectively excite the accessory bacteriochlorophyll (B, 800 nm) or the upper excitonic state of the bacteriochlorophyll dimer (P-, 810 nm) and the lower excitonic state of the dimer (P+, 865 nm), respectively. The fluorescence spectrum of the wild type showed two bands centered at 850 nm (B) and 910 nm (P-). While the monotonous decay of the fluorescence yield at 910 nm tracked the light-induced oxidation of the dimer, the kinetics of the fluorescence yield at 850 nm showed an initial rise before a decrease. The anisotropy of the fluorescence excited at 865 nm (P-) was very close to the limiting value (0.4) across the whole spectral range. The excitation of both B and P- at 808 nm resulted in wavelength-dependent depolarization of the fluorescence from 0.35 to 0.24 in the wild type and from 0.30 to 0.24 in the reaction center of triple mutant (L131LH-M160LH-M197FH). The additivity law of the anisotropies of the fluorescence species accounts for the wavelength dependence of the anisotropy. The measured fluorescence yields and anisotropies are interpreted in terms of very fast energy transfer from (1)B* to (1)P- (either directly or indirectly by internal conversion from (1)P+) and to the oxidized dimer.

  6. Ultrafast Electron Transfer Kinetics in the LM Dimer of Bacterial Photosynthetic Reaction Center from Rhodobacter sphaeroides.

    PubMed

    Sun, Chang; Carey, Anne-Marie; Gao, Bing-Rong; Wraight, Colin A; Woodbury, Neal W; Lin, Su

    2016-06-23

    It has become increasingly clear that dynamics plays a major role in the function of many protein systems. One system that has proven particularly facile for studying the effects of dynamics on protein-mediated chemistry is the bacterial photosynthetic reaction center from Rhodobacter sphaeroides. Previous experimental and computational analysis have suggested that the dynamics of the protein matrix surrounding the primary quinone acceptor, QA, may be particularly important in electron transfer involving this cofactor. One can substantially increase the flexibility of this region by removing one of the reaction center subunits, the H-subunit. Even with this large change in structure, photoinduced electron transfer to the quinone still takes place. To evaluate the effect of H-subunit removal on electron transfer to QA, we have compared the kinetics of electron transfer and associated spectral evolution for the LM dimer with that of the intact reaction center complex on picosecond to millisecond time scales. The transient absorption spectra associated with all measured electron transfer reactions are similar, with the exception of a broadening in the QX transition and a blue-shift in the QY transition bands of the special pair of bacteriochlorophylls (P) in the LM dimer. The kinetics of the electron transfer reactions not involving quinones are unaffected. There is, however, a 4-fold decrease in the electron transfer rate from the reduced bacteriopheophytin to QA in the LM dimer compared to the intact reaction center and a similar decrease in the recombination rate of the resulting charge-separated state (P(+)QA(-)). These results are consistent with the concept that the removal of the H-subunit results in increased flexibility in the region around the quinone and an associated shift in the reorganization energy associated with charge separation and recombination. PMID:27243380

  7. Characterization of Ornithine and Glutamine Lipids Extracted from Cell Membranes of Rhodobacter sphaeroides

    PubMed Central

    Zhang, Xi; Ferguson-Miller, Shelagh M.; Reid, Gavin E.

    2009-01-01

    The identification and structural characterization of a series of ornithine lipids extracted from the cell membranes of wild-type Rhodobacter sphaeroides, as well as from a glycerophosphocholine-deficient strain, has been achieved by multistage tandem mass spectrometry of their protonated and deprotonated precursor ions in a linear quadrupole ion trap. Systematic examination of the multistage gas-phase fragmentation reactions of these ions, combined with the use of hydrogen/deuterium exchange, has enabled the pathways responsible for sequential losses of the 3-hydroxy linked fatty acyl chain and the amide linked 3-OH fatty acid chain from these lipids, as well as for formation of the previously reported ornithine specific positively charged ‘fingerprint’ ion at m/z 115, to be determined. Additionally, the fragmentation pathways responsible for formation of a previously unreported ornithine lipid head group specific product ion at m/z 131 in negative ion mode have been examined. Based on these results, and by comparison with the fragmentation behavior of model lipoamino acid standard compounds, a series of novel glutamine containing lipids have also been identified, with analogous structures but with masses 14 Da higher than several of the ornithine lipids observed in this study. Characteristic ‘fingerprint’ ions indicative of these glutamine lipids were found at m/z 147, 130 and 129 in positive ion mode, and at m/z 145 and 127 in negative ion mode. The results from this study establish an experimental basis for future efforts aimed at the sensitive identification, characterization and quantitative analysis of ornithine and glutamine lipids in complex unfractionated cellular extracts. PMID:18835523

  8. Physiological and structural analysis of light-harvesting mutants of Rhodobacter sphaeroides.

    PubMed

    Kiley, P J; Varga, A; Kaplan, S

    1988-03-01

    Two mutants of Rhodobacter sphaeroides defective in formation of light-harvesting spectral complexes were examined in detail. Mutant RS103 lacked the B875 spectral complex despite the fact that substantial levels of the B875-alpha polypeptide (and presumably the beta polypeptide) were present. The B800-850 spectral complex was derepressed in RS103, even at high light intensities, and the growth rate was near normal at high light intensity but decreased relative to the wild type as the light intensity used for growth decreased. Mutant RS104 lacked colored carotenoids and the B800-850 spectral complex, as well as the cognate apoproteins. This strain grew normally at high light intensity and, as with RS103, the growth rate decreased as the light intensity used for growth decreased. At very low light intensities, however, RS104 would grow, whereas RS103 would not. Structural analysis of these mutants as well as others revealed that the morphology of the intracytoplasmic membrane invaginations is associated with the presence or absence of the B800-850 complex as well as of carotenoids. A low-molecular-weight intracytoplasmic membrane polypeptide, which may play a role in B800-850 complex formation, is described, as is a 62,000-dalton polypeptide whose abundance is directly related to light intensity as well as the absence of either of the light-harvesting spectral complexes. These data, obtained from studies of mutant strains and the wild type, are discussed in light of photosynthetic membrane formation and the abundance of spectral complexes per unit area of membrane. Finally, a method for the bulk preparation of the B875 complex from wild-type strain 2.4.1 is reported.

  9. Kinetics and yields of bacteriochlorophyll fluorescence: redox and conformation changes in reaction center of Rhodobacter sphaeroides.

    PubMed

    Maróti, Péter

    2008-09-01

    Induction of the bacteriochlorophyll fluorescence under rectangular shape of intense laser diode illumination (1 W cm(-2), 808 nm) was measured over wide time range from 10 microseconds to 4 s in whole cells, chromatophore and isolated reaction center protein of wild type and carotenoid-less mutant (R-26.1) of purple photosynthetic bacterium Rhodobacter sphaeroides. While the antenna-containing species showed large and positive variable fluorescence (Fv) to initial fluorescence (F0) (Fv/F0 approximately 4.5 in whole cells), the isolated RC had negative change (Fv/F0 approximately -0.6) during photochemistry. In chromatophore from R-26.1, only seven times higher rate was measured than in isolated reaction center under identical experimental conditions. The enhancement effect of large antenna on the rate of photochemistry in chromatophore was partially compensated by the favorable pigment absorption properties in isolated RC. The transition from membrane bound to isolated form of the reaction center was probed by titration of zwitterionic detergent LDAO in chromatophore, and at 0.03% LDAO concentration, sharp change of the variable fluorescence was observed. The sudden drop was explained by the formation of LDAO micelles. After the photochemical phase, additional change of fluorescence yield could be observed in isolated RC considered as manifestation of long-living conformations of the trapped redox states of the protein characterized by non-exponential kinetics. Strong support was provided for use of the fluorescence induction to track structural and conformation changes at their earliest phases in chromatophores and isolated reaction centers.

  10. Accumulation of a novel glycolipid and a betaine lipid in cells of Rhodobacter sphaeroides grown under phosphate limitation.

    PubMed

    Benning, C; Huang, Z H; Gage, D A

    1995-02-20

    Cells of the photosynthetic bacterium Rhodobacter sphaeroides grown under phosphate-limiting conditions accumulated nonphosphorous glycolipids and lipids carrying head groups derived from amino acids. Concomitantly, the relative amount of phosphoglycerolipids decreased from 90 to 22 mol% of total polar lipids in the membranes. Two lipids, not detectable in cells grown under standard conditions, were synthesized during phosphate-limited growth. Fast atom bombardment mass spectroscopy, exact mass measurements, 1H NMR spectroscopy, sugar composition analysis, and methylation analysis of the predominant glycolipid led to the identification of the novel compound 1,2-di-O-acyl-3-O-[alpha-D-glucopyranosyl-(1-->4)-O-beta-D-galactopyr anosyl]glycerol. The second lipid was identified as the betaine lipid 1,2-di-O-acyl-[4'-(N,N,N-trimethyl)-homoserine]glycerol by cochromatography employing an authentic standard from Chlamydomonas reinhardtii, fast atom bombardment mass spectroscopy, exact mass measurements, and 1H NMR spectroscopy. Prior to this observation, the occurrence of this lipid was thought to be restricted to lower plants and algae. Apparently, these newly synthesized nonphosphorous lipids, in addition to the sulfo- and the ornithine lipid also found in R. sphaeroides grown under optimal conditions, take over the role of phosphoglycerolipids in phosphate-deprived cells. PMID:7872771

  11. Structural model and excitonic properties of the dimeric RC-LH1-PufX complex from Rhodobacter sphaeroides

    PubMed Central

    Şener, Melih; Hsin, Jen; Trabuco, Leonardo G.; Villa, Elizabeth; Qian, Pu; Hunter, C. Neil; Schulten, Klaus

    2009-01-01

    The light-harvesting apparatus of the purple bacterial photosynthetic unit consists of a pool of peripheral light-harvesting complexes that transfer excitation energy to a reaction center (RC) via the surrounding pigment-protein complex LH1. Recent electron microscopy and atomic force microscopy studies have revealed that RC-LH1 units of Rhodobacter sphaeroides form membrane-bending dimeric complexes together with the polypeptide PufX. We present a structural model for these RC-LH1-PufX dimeric complexes constructed using the molecular dynamics flexible fitting method based on an EM density map. The arrangement of the LH1 BChls displays a distortion near the proposed location of the PufX polypeptide. The resulting atomic model for BChl arrays is used to compute the excitonic properties of the dimeric RC-LH1 complex. A comparison is presented between the structural and excitonic features of the S-shaped dimeric BChl array of Rhodobacter sphaeroides and the circular BChl arrangement found in other purple bacteria. PMID:20161332

  12. Characteristics of Pos19 – A Small Coding RNA in the Oxidative Stress Response of Rhodobacter sphaeroides

    PubMed Central

    Eisenhardt, Benjamin D.; Remes, Bernhard; Klug, Gabriele

    2016-01-01

    The phototrophic bacterium Rhodobacter sphaeroides induces several small RNAs (sRNAs) when singlet oxygen (1O2) levels are elevated, a situation also referred to as photo-oxidative stress. An RNA-seq study identified the RSs0019 sRNA, which is renamed Pos19 (photo-oxidative stress induced sRNA 19). Pos19 is part of the RpoE regulon and consequently induced upon 1O2 and peroxide stress. The 219 nt long Pos19 transcript contains a small open reading frame (sORF) of 150 nt, which is translated in vivo. Over-expression of Pos19 results in reduced mRNA levels for several genes, of which numerous are involved in sulfur metabolism. The negative effect on the potential targets is maintained even when translation of the sORF is abolished, arguing that regulation is entailed by the sRNA itself. Reporter studies further revealed that regulation of the most affected mRNA, namely RSP_0557, by Pos19 is Hfq-dependent. Direct binding of Pos19 to Hfq was shown by co-immunoprecipitation. Physiological experiments indicated Pos19 to be involved in the balance of glutathione biosynthesis. Moreover, a lack of Pos19 leads to elevated reactive oxygen species levels. Taken together our data identify the sRNA Pos19 as a coding sRNA with a distinct expression pattern and potential role under oxidative stress in the phototrophic bacterium R. sphaeroides. PMID:27669425

  13. Photobiological transformation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) using Rhodobacter sphaeroides.

    PubMed

    Millerick, Kayleigh A; Johnston, Juliet T; Finneran, Kevin T

    2016-09-01

    Pump-and-treat strategies for groundwater containing explosives may be necessary when the contaminated water approaches sensitive receptors. This project investigated bacterial photosynthesis as a strategy for ex situ treatment, using light as the primary energy source to facilitate RDX transformation. The objective was to characterize the ability of photosynthetic Rhodobacter sphaeroides (strain ATCC(®) 17023 ™) to transform the high-energy explosive RDX. R. sphaeroides transformed 30 μM RDX within 40 h under light conditions; RDX was not fully transformed in the dark (non-photosynthetic conditions), suggesting that photosynthetic electron transfer was the primary mechanism. Experiments with RDX demonstrated that succinate and malate were the most effective electron donors for photosynthesis, but glycerol was also utilized as a photosynthetic electron donor. RDX was transformed irrespective of the presence of carbon dioxide. The electron shuttling compound anthraquinone-2,6-disulfonate (AQDS) increased transformation kinetics in the absence of CO2, when the cells had excess NADPH that needed to be re-oxidized because there was limited CO2 for carbon fixation. When CO2 was added, the cells generated more biomass, and AQDS had no stimulatory effect. End products indicated that RDX carbon became CO2, biomass, and a soluble, uncharacterized aqueous metabolite, determined using (14)C-labeled RDX. These data are the first to suggest that photobiological explosives transformation is possible and will provide a framework for which phototrophy can be used in environmental restoration of explosives contaminated water. PMID:27285383

  14. Accumulation of a novel glycolipid and a betaine lipid in cells of Rhodobacter sphaeroides grown under phosphate limitation.

    PubMed

    Benning, C; Huang, Z H; Gage, D A

    1995-02-20

    Cells of the photosynthetic bacterium Rhodobacter sphaeroides grown under phosphate-limiting conditions accumulated nonphosphorous glycolipids and lipids carrying head groups derived from amino acids. Concomitantly, the relative amount of phosphoglycerolipids decreased from 90 to 22 mol% of total polar lipids in the membranes. Two lipids, not detectable in cells grown under standard conditions, were synthesized during phosphate-limited growth. Fast atom bombardment mass spectroscopy, exact mass measurements, 1H NMR spectroscopy, sugar composition analysis, and methylation analysis of the predominant glycolipid led to the identification of the novel compound 1,2-di-O-acyl-3-O-[alpha-D-glucopyranosyl-(1-->4)-O-beta-D-galactopyr anosyl]glycerol. The second lipid was identified as the betaine lipid 1,2-di-O-acyl-[4'-(N,N,N-trimethyl)-homoserine]glycerol by cochromatography employing an authentic standard from Chlamydomonas reinhardtii, fast atom bombardment mass spectroscopy, exact mass measurements, and 1H NMR spectroscopy. Prior to this observation, the occurrence of this lipid was thought to be restricted to lower plants and algae. Apparently, these newly synthesized nonphosphorous lipids, in addition to the sulfo- and the ornithine lipid also found in R. sphaeroides grown under optimal conditions, take over the role of phosphoglycerolipids in phosphate-deprived cells.

  15. Biohydrogen and polyhydroxyalkanoate co-production by Enterobacter aerogenes and Rhodobacter sphaeroides from Calophyllum inophyllum oil cake.

    PubMed

    Arumugam, A; Sandhya, M; Ponnusami, V

    2014-07-01

    The feasibility of coupled biohydrogen and polyhydroxyalkanoate production by Enterobacter aerogenes and Rhodobacter sphaeroides using Calophyllum inophyllum oil cake was studied under dark and photo fermentation conditions. The utilization of a non-edible acidic oil cake (C. inophyllum), and exploitation of a modified minimal salt media led to reduction in the cost of media. Cost of fermentation is reduced by implementation of alternate dark-photo fermentative periods and through the use of a co-culture consisting of a dark fermentative (E. aerogenes) and a photo fermentative (R. sphaeroides) bacterium. The biohydrogen and polyhydroxyalkanoate produced were 7.95 L H2/L media and 10.73 g/L media, respectively, under alternate dark and photo fermentation and were 3.23 L H2/L media and 5.6g/L media, respectively under complete dark fermentation. The characteristics of the oil cake and alternate dark (16 h) and photo (8h) fermentative conditions were found to be supportive in producing high biohydrogen and polyhydroxyalkanoate (PHA) yield.

  16. Photobiological transformation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) using Rhodobacter sphaeroides.

    PubMed

    Millerick, Kayleigh A; Johnston, Juliet T; Finneran, Kevin T

    2016-09-01

    Pump-and-treat strategies for groundwater containing explosives may be necessary when the contaminated water approaches sensitive receptors. This project investigated bacterial photosynthesis as a strategy for ex situ treatment, using light as the primary energy source to facilitate RDX transformation. The objective was to characterize the ability of photosynthetic Rhodobacter sphaeroides (strain ATCC(®) 17023 ™) to transform the high-energy explosive RDX. R. sphaeroides transformed 30 μM RDX within 40 h under light conditions; RDX was not fully transformed in the dark (non-photosynthetic conditions), suggesting that photosynthetic electron transfer was the primary mechanism. Experiments with RDX demonstrated that succinate and malate were the most effective electron donors for photosynthesis, but glycerol was also utilized as a photosynthetic electron donor. RDX was transformed irrespective of the presence of carbon dioxide. The electron shuttling compound anthraquinone-2,6-disulfonate (AQDS) increased transformation kinetics in the absence of CO2, when the cells had excess NADPH that needed to be re-oxidized because there was limited CO2 for carbon fixation. When CO2 was added, the cells generated more biomass, and AQDS had no stimulatory effect. End products indicated that RDX carbon became CO2, biomass, and a soluble, uncharacterized aqueous metabolite, determined using (14)C-labeled RDX. These data are the first to suggest that photobiological explosives transformation is possible and will provide a framework for which phototrophy can be used in environmental restoration of explosives contaminated water.

  17. Electronic structure of Q-A in reaction centers from Rhodobacter sphaeroides. I. Electron paramagnetic resonance in single crystals.

    PubMed Central

    Isaacson, R A; Lendzian, F; Abresch, E C; Lubitz, W; Feher, G

    1995-01-01

    The magnitude and orientation of the electronic g-tensor of the primary electron acceptor quinone radical anion, Q-A, has been determined in single crystals of zinc-substituted reaction centers of Rhodobacter sphaeroides R-26 at 275 K and at 80 K. To obtain high spectral resolution, EPR experiments were performed at 35 GHz and the native ubiquinone-10 (UQ10) in the reaction center was replaced by fully deuterated UQ10. The principal values and the direction cosines of the g-tensor axes with respect to the crystal axes a, b, c were determined. Freezing of the single crystals resulted in only minor changes in magnitude and orientation of the g-tensor. The orientation of Q-A as determined by the g-tensor axes deviates only by a few degrees (< or = 8 degrees) from the orientation of the neutral QA obtained from an average of four different x-ray structures of Rb. sphaeroides reaction centers. This deviation lies within the accuracy of the x-ray structure determinations. The g-tensor values measured in single crystals agree well with those in frozen solutions. Variations in g-values between Q-A, Q-B, and UQ10 radical ion in frozen solutions were observed and attributed to different environments. Images FIGURE 1 FIGURE 2 FIGURE 3 FIGURE 9 PMID:8527644

  18. EXpanding Treatment for Existing Neurological Disease (EXTEND): An Open-Label Phase II Clinical Trial of Hydroxyurea Treatment in Sickle Cell Anemia

    PubMed Central

    Little, Courtney R; Reid, Marvin E; Soares, Deanne P; Taylor-Bryan, Carolyn; Knight-Madden, Jennifer M; Stuber, Susan E; Badaloo, Asha V; Aldred, Karen; Wisdom-Phipps, Margaret E; Latham, Teresa; Ware, Russell E

    2016-01-01

    Background Cerebral vasculopathy in sickle cell anemia (SCA) begins in childhood and features intracranial arterial stenosis with high risk of ischemic stroke. Stroke risk can be reduced by transcranial doppler (TCD) screening and chronic transfusion therapy; however, this approach is impractical in many developing countries. Accumulating evidence supports the use of hydroxyurea for the prevention and treatment of cerebrovascular disease in children with SCA. Recently we reported that hydroxyurea significantly reduced the conversion from conditional TCD velocities to abnormal velocities; whether hydroxyurea can be used for children with newly diagnosed severe cerebrovascular disease in place of starting transfusion therapy remains unknown. Objective The primary objective of the EXpanding Treatment for Existing Neurological Disease (EXTEND) trial is to investigate the effect of open label hydroxyurea on the maximum time-averaged mean velocity (TAMV) after 18 months of treatment compared to the pre-treatment value. Secondary objectives include the effects of hydroxyurea on serial TCD velocities, the incidence of neurological and non-neurological events, quality of life (QOL), body composition and metabolism, toxicity and treatment response, changes to brain magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA), genetic and serologic markers of disease severity, and cognitive and pulmonary function. Methods This prospective Phase II trial will enroll children with SCA in Jamaica, between the ages of 2 and 17 years, with either conditional (170-199 cm/sec) or abnormal (≥ 200 cm/sec) TCD velocities. Oral hydroxyurea will be administered daily and escalated to the maximum tolerated dose (MTD). Participants will be seen in the Sickle Cell Unit (SCU) in Kingston, Jamaica monthly until achieving MTD, and then every 3 months. TCD will be performed every 6 months. Results Currently, 43 participants have been enrolled out of a projected 50. There was one

  19. Integration of energy and electron transfer processes in the photosynthetic membrane of Rhodobacter sphaeroides

    PubMed Central

    Cartron, Michaël L.; Olsen, John D.; Sener, Melih; Jackson, Philip J.; Brindley, Amanda A.; Qian, Pu; Dickman, Mark J.; Leggett, Graham J.; Schulten, Klaus; Hunter, C. Neil

    2014-01-01

    Photosynthesis converts absorbed solar energy to a protonmotive force, which drives ATP synthesis. The membrane network of chlorophyll–protein complexes responsible for light absorption, photochemistry and quinol (QH2) production has been mapped in the purple phototrophic bacterium Rhodobacter (Rba.) sphaeroides using atomic force microscopy (AFM), but the membrane location of the cytochrome bc1 (cytbc1) complexes that oxidise QH2 to quinone (Q) to generate a protonmotive force is unknown. We labelled cytbc1 complexes with gold nanobeads, each attached by a Histidine10 (His10)-tag to the C-terminus of cytc1. Electron microscopy (EM) of negatively stained chromatophore vesicles showed that the majority of the cytbc1 complexes occur as dimers in the membrane. The cytbc1 complexes appeared to be adjacent to reaction centre light-harvesting 1-PufX (RC-LH1-PufX) complexes, consistent with AFM topographs of a gold-labelled membrane. His-tagged cytbc1 complexes were retrieved from chromatophores partially solubilised by detergent; RC-LH1-PufX complexes tended to co-purify with cytbc1, whereas LH2 complexes became detached, consistent with clusters of cytbc1 complexes close to RC-LH1-PufX arrays, but not with a fixed, stoichiometric cytbc1-RC-LH1-PufX supercomplex. This information was combined with a quantitative mass spectrometry (MS) analysis of the RC, cytbc1, ATP synthase, cytaa3 and cytcbb3 membrane protein complexes, to construct an atomic-level model of a chromatophore vesicle comprising 67 LH2 complexes, 11 LH1-RC-PufX dimers & 2 RC-LH1-PufX monomers, 4 cytbc1 dimers and 2 ATP synthases. Simulation of the interconnected energy, electron and proton transfer processes showed a half-maximal ATP turnover rate for a light intensity equivalent to only 1% of bright sunlight. Thus, the photosystem architecture of the chromatophore is optimised for growth at low light intensities. PMID:24530865

  20. The Q gene of Rhodobacter sphaeroides: its role in puf operon expression and spectral complex assembly.

    PubMed Central

    Gong, L; Lee, J K; Kaplan, S

    1994-01-01

    The Q gene of the facultative photoheterotroph Rhodobacter sphaeroides, localized immediately upstream of the oxygen- and light-regulated puf operon, encodes a 77-amino-acid polypeptide. The 5' and 3' ends of the 561-bp Q transcript were determined. To gain insight into the role of the Q gene product, a number of Q mutations were constructed by oligonucleotide-directed mutagenesis and subsequent substitution of the mutated form of the gene in single copy for the chromosomal copy via homologous recombination. The resulting mutants can grow photosynthetically, with the exception of QSTART, in which the initiation codon for the Q protein was altered. Spectral analysis of the intracytoplasmic membranes showed that one of the missense mutants (QdA) was deficient in the formation of detectable B875 light-harvesting complex (LHC), whereas deletion of the stem-loop structure (Qloop) failed to form B800-850 LHC when grown anaerobically either in the dark or under light intensity of 100 W/m2. Other missense mutants (QuA and QuB) contained either more B800-850 LHC or more B875 LHC, respectively, than the wild type. Although the levels of puf and puc transcripts isolated from QSTART grown anaerobically on succinate-dimethyl sulfoxide in the dark were comparable to wild-type levels, no B875 spectral complex was detected and there was a greater than 90% reduction in the level of the B800-850 pigment-protein complex. It has also been confirmed that the ultimate cellular levels of either the B875 or B800-850 spectral complexes can vary over wide limits without any change in the level(s) of complex specific transcripts. When the wild-type Q gene was reintroduced in trans into the Q mutations, QSTART was able to grow photosynthetically and both B800-850 and B875 spectral complexes were formed in either QdA or Qloop. Finally, we demonstrated that the level of each puf-specific mRNA behaves independently of one another as well as independently of the level(s) of Q gene-specific m

  1. Modelling extended chromospheres

    NASA Technical Reports Server (NTRS)

    Linsky, J. L.

    1986-01-01

    Attention is given to the concept that the warm, partially ionized plasma (presently called chromosphere) associated with such stars as Alpha Boo and Rho Per extends outwards at least several photospheric radii. Calculations are presented for the Mg II K line in light of two input model atmospheres. Specific predictions are deduced from the results obtained by each of the two models.

  2. Binding-protein-dependent alanine transport in Rhodobacter sphaeroides is regulated by the internal pH.

    PubMed

    Abee, T; van der Wal, F J; Hellingwerf, K J; Konings, W N

    1989-09-01

    The properties of an L-alanine uptake system in Rhodobacter sphaeroides were studied and compared with those of H+/lactose symport in R. sphaeroides 4P1, a strain in which the lactose carrier of Escherichia coli has been cloned and functionally expressed (F. E. Nano, Ph.D. thesis, University of Illinois, Urbana, 1984). Previous studies indicated that both transport systems were active only when electron transfer took place in the respiratory or cyclic electron transfer chain, while uptake of L-alanine also required the presence of K+ (M. G. L. Elferink, Ph.D. thesis, University of Groningen, Groningen, The Netherlands, 1986). The results presented in this paper offer an explanation for these findings. Transport of the nonmetabolizable L-alanine analog 2-alpha-aminoisobutyric acid (AIB) is mediated by a shock-sensitive transport system. The apparently unidirectional uptake of AIB results in accumulation levels which exceed 7 x 10(3). The finding of L-alanine-binding activity in the concentrated crude shock fluid indicates that L-alanine is taken up by a binding-protein-dependent transport system. Transport of the nonmetabolizable lactose analog methyl-beta-D-thiogalactopyranoside (TMG) by the lactose carrier under anaerobic conditions in the dark was observed in cells and membrane vesicles. This indicates that the H+/lactose symport system is active without electron transfer. Uptake of AIB, but not that of TMG, is inhibited by vanadate with a 50% inhibitory concentration of 50 microM, which suggests a role of a phosphorylated intermediate in AIB transport. Uptake of TMG and AIB is regulated by the internal pH. The initial rates of uptake increased with the internal pH, and and pKa values of 7.2 for TMG and 7.8 for AIB. At an internal pH of 7, no AIB uptake occurred, and the rate of TMG uptake was only 30% of the rate at an internal pH of 8. In a previous study, we found that K+ plays an essential role in regulating the internal pH (T. Abee, K. J. Hellingwerf, and W

  3. Syntheses, structural variations and fluorescence studies of two dinuclear zinc(II) complexes of a Schiff base ligand with an extended carboxylate side arm

    NASA Astrophysics Data System (ADS)

    Shit, Shyamapada; Sasmal, Ashok; Dhal, Piu; Rizzoli, Corrado; Mitra, Samiran

    2016-03-01

    A potentially tetradentate Schiff base ligand containing carboxylic acid group, HL, (E)-2-((pyridin-2-yl)methyleneamino)-5-chlorobenzoic acid is synthesized and characterized. Reaction of HL with hydrated zinc(II) trichloroacetate and zinc(II) trifluoroacetate under similar reaction condition yields two discrete dinuclear complexes, [Zn(L)(Cl)]2 (1) and [Zn(L)(CF3COO)]2 (2) and characterized by different physicochemical methods. Single crystal X-ray structural characterization reveals different ligating properties of the coordinated anionic ligand (L-) in its zinc(II) complexes. The side arm carboxylate of L- shows μ1,3-carboxylato-bridging mode in 1 and connects zinc(II) atoms in syn-anti fashion while it exhibits a μ1,1-carboxylato-bridging mode in 2. The metal ions display distorted square pyramidal geometries in both the structures and associated with different degrees of distortions. The fluorescence spectra of HL and its zinc(II) complexes recorded in methanol at room temperature which reveal the enhancement of emission intensity for the complexes compared to that of the free ligand. Thermogravimetric analyses (TGA) reveal high thermal stabilities of the complexes.

  4. Allosteric regulation of the state of adenylylation of glutamine synthetase in permeabilized cell preparations of Rhodopseudomonas sphaeroides.

    PubMed

    Wang, X; Song, H Y

    1989-08-01

    Following a freeze-thaw cycle, and the treatment of Rhodopseudomonas sphaeroides with the nonionic detergent Lubrol PX, the permeabilized cell suspensions can be assayed directly both for the intracellular levels of glutamine synthetase and the state of adenylylation (i.e. the average number n of adenylylated subunits/dodecameric molecules). It seems that all components of the bicycle system are retained if cells grown with low concentrations of ammonia as the sole nitrogen source are used. The value of n was dependent upon the concentration of substrates (ATP, Pi) and allosteric effectors (ATP, glutamine and alpha-ketoglutarate) of adenylytransferase. The value of n affected by UTP, the specific substrate of the uridylyltransferase shows first the evidence that the bicycle cascade control system studied in Escherichia coli may exist in this phototrophic bacterium. PMID:2575389

  5. Kinetics of cytochrome c oxidase from R. sphaeroides initiated by direct electron transfer followed by tr-SEIRAS.

    PubMed

    Steininger, Christoph; Reiner-Rozman, Ciril; Schwaighofer, Andreas; Knoll, Wolfgang; Naumann, Renate L C

    2016-12-01

    Time-resolved surface-enhanced IR-absorption spectroscopy (tr-SEIRAS) has been performed on cytochrome c oxidase from Rhodobacter sphaeroides. The enzyme was converted electrochemically into the fully reduced state. Thereafter, in the presence of oxygen, the potential was switched to open circuit potential (OCP). Under these conditions, the enzyme is free to undergo enzymatic oxidation in the absence of an external electric field. Tr-SEIRAS was performed using the step-scan technique, triggered by periodic potential pulses switching between - 800mV and OCP. Single bands were resolved in a broad band in the amide I region using phase sensitive detection. Amplitudes of these bands were analyzed as a function of time. Time constants in the ms time scale were considered in terms of conformational changes of the protein secondary structures associated with the enzymatic turnover of the protein. PMID:27398977

  6. Direct visualization of exciton reequilibration in the LH1 and LH2 complexes of Rhodobacter sphaeroides by multipulse spectroscopy.

    PubMed

    Cohen Stuart, Thomas A; Vengris, Mikas; Novoderezhkin, Vladimir I; Cogdell, Richard J; Hunter, C Neil; van Grondelle, Rienk

    2011-05-01

    The dynamics of the excited states of the light-harvesting complexes LH1 and LH2 of Rhodobacter sphaeroides are governed, mainly, by the excitonic nature of these ring-systems. In a pump-dump-probe experiment, the first pulse promotes LH1 or LH2 to its excited state and the second pulse dumps a portion of the excited state. By selective dumping, we can disentangle the dynamics normally hidden in the excited-state manifold. We find that by using this multiple-excitation technique we can visualize a 400-fs reequilibration reflecting relaxation between the two lowest exciton states that cannot be directly explored by conventional pump-probe. An oscillatory feature is observed within the exciton reequilibration, which is attributed to a coherent motion of a vibrational wavepacket with a period of ∼150 fs. Our disordered exciton model allows a quantitative interpretation of the observed reequilibration processes occurring in these antennas.

  7. Direct Visualization of Exciton Reequilibration in the LH1 and LH2 Complexes of Rhodobacter sphaeroides by Multipulse Spectroscopy

    PubMed Central

    Cohen Stuart, Thomas A.; Vengris, Mikas; Novoderezhkin, Vladimir I.; Cogdell, Richard J.; Hunter, C. Neil; van Grondelle, Rienk

    2011-01-01

    The dynamics of the excited states of the light-harvesting complexes LH1 and LH2 of Rhodobacter sphaeroides are governed, mainly, by the excitonic nature of these ring-systems. In a pump-dump-probe experiment, the first pulse promotes LH1 or LH2 to its excited state and the second pulse dumps a portion of the excited state. By selective dumping, we can disentangle the dynamics normally hidden in the excited-state manifold. We find that by using this multiple-excitation technique we can visualize a 400-fs reequilibration reflecting relaxation between the two lowest exciton states that cannot be directly explored by conventional pump-probe. An oscillatory feature is observed within the exciton reequilibration, which is attributed to a coherent motion of a vibrational wavepacket with a period of ∼150 fs. Our disordered exciton model allows a quantitative interpretation of the observed reequilibration processes occurring in these antennas. PMID:21539791

  8. Characerization of photosynthetic reaction centres from Rhodobacter sphaeroides at the air-water interface and in Langmuir-Blodgett films

    SciTech Connect

    Fang, J.Y.; Gaul, D.F.; Chumanov, G.; Cotton, T.M.; Uphaus, R.A. |

    1995-11-01

    Monolayers of the reaction center complex from Rhodobacter sphaeroides were prepared from dodecyl {Beta}-maltoside suspensions at an air-water interface. The stability of these monolayers was determined. A value of 28 nm{sup 2} per complex was obtained for the cross-sectional area from the equilibrium surface pressure-area isotherms. Multilayer films of alternating arachidic acid-reaction center monolayers were constructed on quartz slides by the Langmuir-Blodgett technique. Absorption spectroscopy was used to confirm the structural integrity of the complex and to determine the transfer ratio. Low-angle X-ray diffraction measurements were performed on these multilayers. A value of 64 A was obtained for the thickness of the reaction center monolayer in the multilayer film. This novel approach can be used to study multilayers of other membrane-bound proteins. 20 refs., 9 figs.

  9. Characterization of D-tagatose-3-epimerase from Rhodobacter sphaeroides that converts D-fructose into D-psicose.

    PubMed

    Zhang, Longtao; Mu, Wanmeng; Jiang, Bo; Zhang, Tao

    2009-06-01

    A non-characterized gene, previously proposed as the D-tagatose-3-epimerase gene from Rhodobacter sphaeroides, was cloned and expressed in Escherichia coli. Its molecular mass was estimated to be 64 kDa with two identical subunits. The enzyme specificity was highest with D-fructose and decreased for other substrates in the order: D-tagatose, D-psicose, D-ribulose, D-xylulose and D-sorbose. Its activity was maximal at pH 9 and 40 degrees C while being enhanced by Mn(2+). At pH 9 and 40 degrees C, 118 g D-psicose l(-1) was produced from 700 g D-fructose l(-1) after 3 h.

  10. Biohydrogen production by purple non-sulfur bacteria Rhodobacter sphaeroides: Effect of low-intensity electromagnetic irradiation.

    PubMed

    Gabrielyan, Lilit; Sargsyan, Harutyun; Trchounian, Armen

    2016-09-01

    The present work was focused on the effects of low-intensity (the flux capacity was of 0.06mWcm(-2)) electromagnetic irradiation (EMI) of extremely high frequencies or millimeter waves on the growth and hydrogen (H2) photoproduction by purple non-sulfur bacteria Rhodobacter sphaeroides MDC6521 (from Armenian mineral springs). After exposure of R. sphaeroides, grown under anaerobic conditions upon illumination, to EMI (51.8GHz and 53.0GHz) for 15min an increase of specific growth rate by ~1.2-fold, in comparison with control (non-irradiated cells), was obtained. However, the effect of EMI depends on the duration of irradiation: the exposure elongation up to 60min caused the delay of the growth lag phase and the decrease specific growth rate by ~1.3-fold, indicating the bactericidal effect of EMI. H2 yield of the culture, irradiated by EMI for 15min, determined during 72h growth, was ~1.2-fold higher than H2 yield of control cells, whereas H2 production by cultures, irradiated by EMI for 60min was not observed during 72h growth. This difference in the effects of extremely high frequency EMI indicates a direct effect of radiation on the membrane transfer and the enzymes of these bacteria. Moreover, EMI increased DCCD-inhibited H(+) fluxes across the bacterial membrane and DCCD-sensitive ATPase activity of membrane vesicles, indicating that the proton FoF1-ATPase is presumably a basic target for extremely high frequency EMI related to H2 production by cultures. PMID:27479839

  11. Regulation of nap Gene Expression and Periplasmic Nitrate Reductase Activity in the Phototrophic Bacterium Rhodobacter sphaeroides DSM158

    PubMed Central

    Gavira, Mónica; Roldán, M. Dolores; Castillo, Francisco; Moreno-Vivián, Conrado

    2002-01-01

    Bacterial periplasmic nitrate reductases (Nap) can play different physiological roles and are expressed under different conditions depending on the organism. Rhodobacter sphaeroides DSM158 has a Nap system, encoded by the napKEFDABC gene cluster, but nitrite formed is not further reduced because this strain lacks nitrite reductase. Nap activity increases in the presence of nitrate and oxygen but is unaffected by ammonium. Reverse transcription-PCR and Northern blots demonstrated that the napKEFDABC genes constitute an operon transcribed as a single 5.5-kb product. Northern blots and nap-lacZ fusions revealed that nap expression is threefold higher under aerobic conditions but is regulated by neither nitrate nor ammonium, although it is weakly induced by nitrite. On the other hand, nitrate but not nitrite causes a rapid enzyme activation, explaining the higher Nap activity found in nitrate-grown cells. Translational nap′-′lacZ fusions reveal that the napK and napD genes are not efficiently translated, probably due to mRNA secondary structures occluding the translation initiation sites of these genes. Neither butyrate nor caproate increases nap expression, although cells growing phototrophically on these reduced substrates show a very high Nap activity in vivo (nitrite accumulation is sevenfold higher than in medium with malate). Phototrophic growth on butyrate or caproate medium is severely reduced in the NapA− mutants. Taken together, these results indicate that nitrate reduction in R. sphaeroides is mainly regulated at the level of enzyme activity by both nitrate and electron supply and confirm that the Nap system is involved in redox balancing using nitrate as an ancillary oxidant to dissipate excess reductant. PMID:11872721

  12. A comparison of the surface nanostructure from two different types of gram-negative cells: Escherichia coli and Rhodobacter sphaeroides.

    PubMed

    Oestreicher, Zachery; Taoka, Azuma; Fukumori, Yoshihiro

    2015-05-01

    Bacteria have been studied using different microscopy methods for many years. Recently, the developments of high-speed atomic force microscopy have opened the doors to study bacteria in new ways due to the fact that it uses much less force on the sample while imaging. This makes the high-speed atomic force microscope an indispensable technique for imaging the surface of living bacterial cells because it allows for the high-resolution visualization of surface proteins in their natural condition without disrupting the cell or the activity of the proteins. Previous work examining living cells of Magnetospirillum magneticum AMB-1 demonstrated that the surface of these bacteria was covered with a net-like structure that is mainly composed of porin molecules. However, it was unclear whether or not this feature was unique to other living bacteria. In this study we used the high-speed atomic force microscope to examine the surface of living cells of Escherichia coli and Rhodobacter sphaeroides to compare their structure with that of M. magneticum. Our research clearly demonstrated that both of these types of cells have an outer surface that is covered in a network of nanometer-sized holes similar to M. magneticum. The diameter of the holes was 8.0±1.5 nm for E. coli and 6.6±1.1 nm for R. sphaeroides. The results in this paper confirm that this type of outer surface structure exists in other types of bacteria and it is not unique to Magnetospirillum.

  13. Local electrostatic field induced by the carotenoid bound to the reaction center of the purple photosynthetic bacterium Rhodobacter sphaeroides.

    PubMed

    Yanagi, Kazuhiro; Shimizu, Madoka; Hashimoto, Hideki; Gardiner, Alastair T; Roszak, Aleksander W; Cogdell, Richard J

    2005-01-20

    Electroabsorption (EA) spectra were recorded in the region of the reaction center (RC) Qy absorption bands of bacteriochlorophyll (Bchl) and bacteriopheophytin, to investigate the effect of carotenoid (Car) on the electrostatic environment of the RCs of the purple bacterium Rhodobacter (Rb.) sphaeroides. Two different RCs were prepared from Rb. sphaeroides strain R26.1 (R26.1-RC); R26.1 RC lacking Car and a reconstituted RC (R26.1-RC+ Car) prepared by incorporating a synthetic Car (3,4-dihydrospheroidene). Although there were no detectable differences between these two RCs in their near infrared (NIR) absorption spectra at 79 and 293 K, or in their EA spectra at 79 K, significant differences were detected in their EA spectra at 293 K. Three nonlinear optical parameters of each RC were determined in order to evaluate quantitatively these differences; transition dipole-moment polarizability and hyperpolarizability (D factor), the change in polarizability upon photoexcitation (Deltaalpha), and the change in dipole-moment upon photoexcitation (Deltamu). The value of D or Deltaalpha determined for each absorption band of the two RC samples showed similar values at 77 or 293 K. However, the Deltamu values of the special pair Bchls (P) and the monomer Bchls absorption bands showed significant differences between the two RCs at 293 K. X-ray crystallography of the two RCs has revealed that a single molecule of the solubilizing detergent LDAO occupies part of the carotenoid binding site in the absence of a carotenoid. The difference in the value of Deltamu therefore represents the differential effect of the detergent LDAO and the carotenoid on P. The change of electrostatic field around P induced by the presence of Car was determined to be 1.7 x 10(5) [V/cm], corresponding to a approximately 10% change in the electrostatic field around P.

  14. Aspects of Rhodobacter sphaeroides ChrR required for stimuli to promote dissociation of σE/ChrR complexes

    PubMed Central

    Greenwell, Roger; Nam, Tae-Wook; Donohue, Timothy J.

    2011-01-01

    In the photosynthetic bacterium Rhodobacter sphaeroides, a transcriptional response to the reactive oxygen species singlet oxygen (1O2) is mediated by ChrR, a zinc metalloprotein that binds to and inhibits activity of the alternative sigma factor, σE. We provide evidence that 1O2 promotes dissociation of σE from ChrR to activate transcription in vivo. To identify what is required for 1O2 to promote dissociation of σE/ChrR complexes, we analyzed the in vivo properties of variant ChrR proteins with amino acid changes in conserved residues of the C-terminal cupin-like domain (ChrR-CLD). We found that 1O2 was unable to promote detectable dissociation of σE/ChrR complexes when the ChrR-CLD zinc ligands (His141, His143, Glu147, and His177) were substituted with alanine, even though individual substitutions caused a 2- to 10-fold decrease in zinc affinity for this domain relative to that of wild-type ChrR (Kd ∼4.6 × 10−10 M). We conclude that the side chains of these invariant residues play a crucial role in the response to 1O2. Additionally, we found that cells containing variant ChrR proteins with single amino acid substitutions at Cys187 or Cys189 exhibited σE activity similar to those containing wild-type ChrR when exposed to 1O2, suggesting that these thiol side chains are not required for 1O2 to induce σE activity in vivo. Finally, we found that the same aspects of R. sphaeroides ChrR needed for a response to 1O2 are required for dissociation of σE/ChrR in the presence of the organic hydroperoxide, tert-butyl hydroperoxide (t-BOOH). PMID:21295582

  15. Structural and Catalytic Effects of Proline Substitution and Surface Loop Deletion in the Extended Active Site of Human Carbonic Anhydrase II

    PubMed Central

    Boone, Christopher D.; Rasi, Valerio; Tu, Chingkuang; McKenna, Robert

    2015-01-01

    The bioengineering of a thermophilic enzyme starting from a mesophilic scaffold has proven to be a significant challenge as several stabilizing elements have been proposed to be the foundation of thermal stability including disulfide bridges, surface loop reduction, ionic pair networks, proline substitutions, and aromatic clusters. This study emphasizes the impact of increasing the rigidity of human carbonic anhydrase II (HCA II) via incorporation of proline residues at positions 170 and 234, which are located in surface loops that are able to accommodate restrictive main-chain conformations without rearrangement of the surrounding peptide backbone. Additionally, the effect of compactness of HCA II was examined by way of deletion of a surface loop (residues 230 through 240), which had been previously identified as a possible source of thermal stability for the hyperthermophilic CA isolated from the bacterium Sulfurihydrogenibium yellowstonense YO3AOP1. Differential scanning calorimetry analysis of these HCA II variants revealed that these structural modifications had a minimum effect on the thermal stability of the enzyme while kinetic studies showed unexpected effects on the catalytic efficiency and proton transfer rates. X-ray crystallographic analysis of these HCA II variants showed the electrostatic potential and configuration of the highly acidic loop (residues 230 and 240) plays an important role in its high catalytic activity. Based on these observations and the literature, a picture is emerging of the various components within the general structural architecture of HCA II that are key to stability. These elements could provide the blueprints for the rational thermal stability engineering of other enzymes. PMID:25683338

  16. The Semiquinone at the Qi Site of the bc1 Complex Explored Using HYSCORE Spectroscopy and Specific Isotopic Labeling of Ubiquinone in Rhodobacter sphaeroides via 13C Methionine and Construction of a Methionine Auxotroph

    PubMed Central

    2015-01-01

    Specific isotopic labeling at the residue or substituent level extends the scope of different spectroscopic approaches to the atomistic level. Here we describe 13C isotopic labeling of the methyl and methoxy ring substituents of ubiquinone, achieved through construction of a methionine auxotroph in Rhodobacter sphaeroides strain BC17 supplemented with l-methionine with the side chain methyl group 13C-labeled. Two-dimensional electron spin echo envelope modulation (HYSCORE) was applied to study the 13C methyl and methoxy hyperfine couplings in the semiquinone generated in situ at the Qi site of the bc1 complex in its membrane environment. The data were used to characterize the distribution of unpaired spin density and the conformations of the methoxy substituents based on density functional theory calculations of 13C hyperfine tensors in the semiquinone of the geometry-optimized X-ray structure of the bc1 complex (Protein Data Bank entry 1PP9) with the highest available resolution. Comparison with other proteins indicates individual orientations of the methoxy groups in each particular case are always different from the methoxy conformations in the anion radical prepared in a frozen alcohol solution. The protocol used in the generation of the methionine auxotroph is more generally applicable and, because it introduces a gene deletion using a suicide plasmid, can be applied repeatedly. PMID:25184535

  17. Whole-genome shotgun optical mapping of Rhodobacter sphaeroides strain 2.4. 1 and its use for whole-genome shotgun sequence assembly

    SciTech Connect

    Shou, S.; Kvikstad, E.; Kile, A.; Severin, J.; Forrest, D.; Runnheim, R.; Churas, C.; Hickman, J. W.; Mackenzie, C.; Choudhary, M.; Donohue, T.; Kaplan, S.; Schwartz, D. C.

    2003-09-01

    Rhodobacter sphaeroides 2.4.1 is a facultative photoheterotrophic bacterium with tremendous metabolic diversity, which has significantly contributed to our understanding of the molecular genetics of photosynthesis, photoheterotrophy, nitrogen fixation, hydrogen metabolism, carbon dioxide fixation, taxis, and tetrapyrrole biosynthesis. To further understand this remarkable bacterium, and to accelerate an ongoing sequencing project, two whole-genome restriction maps (EcoRI and HindIII) of R. sphaeroides strain 2.4.1 were constructed using shotgun optical mapping. The approach directly mapped genomic DNA by the random mapping of single molecules. The two maps were used to facilitate sequence assembly by providing an optical scaffold for high-resolution alignment and verification of sequence contigs. Our results show that such maps facilitated the closure of sequence gaps by the early detection of nascent sequence contigs during the course of the whole-genome shotgun sequencing process.

  18. Acetate-dependent photoheterotrophic growth and the differential requirement for the Calvin-Benson-Bassham reductive pentose phosphate cycle in Rhodobacter sphaeroides and Rhodopseudomonas palustris.

    PubMed

    Laguna, Rick; Tabita, F Robert; Alber, Birgit E

    2011-02-01

    Rhodobacter sphaeroides ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO)-deletion strain 16 was capable of photoheterotrophic growth with acetate, while Rhodopseudomonas palustris RubisCO-deletion strain 2040 could not grow under these conditions. The reason for this difference lies in the fact that Rba. sphaeroides and Rps. palustris use different pathways for acetate assimilation, the ethylmalonyl-CoA pathway, and glyoxylate-bypass cycle, respectively. The ethylmalonyl-CoA pathway is distinct from the glyoxylate cycle as one molecule of CO(2) and one molecule of HCO(3) (-) per three molecules of acetyl-CoA are co-assimilated to form two malate molecules. The glyoxylate cycle directly converts two acetyl-CoA molecules to malate. Each pathway, therefore, also dictates at what point, CO(2) and reductant are consumed, thereby determining the requirement for the Calvin-Benson-Bassham reductive pentose phosphate cycle.

  19. Analysis of the motA flagellar motor gene from Rhodobacter sphaeroides, a bacterium with a unidirectional, stop-start flagellum.

    PubMed

    Shah, D S; Sockett, R E

    1995-09-01

    Rhodobacter sphaeroides swims by unidirectional rotation of a single medial flagellum, re-orienting randomly by Brownian motion when flagellar rotation stops and restarts. Previously we identified a mutant with a paralysed flagellum, which was complemented by a Rhodobacter gene that had homology to motB of Escherichia coli, a bacterium with bidirectional flagella. In the current work, interposon mutagenesis upstream of the Rhodobacter motB gene gave rise to another paralysed mutant, RED5. DNA sequence analysis of this upstream region showed one open reading frame, the predicted polypeptide sequence of which shows homology to the MotA protein of E. coli. MotA is thought to be a proton 'pore' involved in converting proton-motive force into flagellar rotation. Several potential proton-binding amino acids were conserved between putative membrane-spanning regions of R. sphaeroides and E. coli MotA sequences, along with a highly charged cytoplasmic linker region. Complementation studies with mutant RED5 showed the presence of an active promoter upstream from motA which was found to be necessary for expression of both motA and motB. Examination of the upstream DNA sequence showed only one putative promoter-like sequence which resembled a sigma 54-type promoter, including a potential enhancer binding site. The overall similarities between the R. sphaeroides MotA protein and those from other bacteria suggest that, despite the novel unidirectional rotation of the R. sphaeroides flagellum, the function of the MotA protein is similar to that in bacteria with bidirectional flagella.

  20. IscR of Rhodobacter sphaeroides functions as repressor of genes for iron-sulfur metabolism and represents a new type of iron-sulfur-binding protein.

    PubMed

    Remes, Bernhard; Eisenhardt, Benjamin D; Srinivasan, Vasundara; Klug, Gabriele

    2015-10-01

    IscR proteins are known as transcriptional regulators for Fe-S biogenesis. In the facultatively phototrophic bacterium, Rhodobacter sphaeroides IscR is the product of the first gene in the isc-suf operon. A major role of IscR in R. sphaeroides iron-dependent regulation was suggested in a bioinformatic study (Rodionov et al., PLoS Comput Biol 2:e163, 2006), which predicted a binding site in the upstream regions of several iron uptake genes, named Iron-Rhodo-box. Most known IscR proteins have Fe-S clusters featuring (Cys)3 (His)1 ligation. However, IscR proteins from Rhodobacteraceae harbor only a single-Cys residue and it was considered unlikely that they can ligate an Fe-S cluster. In this study, the role of R. sphaeroides IscR as transcriptional regulator and sensor of the Fe-S cluster status of the cell was analyzed. A mutant lacking IscR is more impaired in growth under iron limitation than the wild-type and exhibits significantly increased ROS levels in iron-replete and iron-deplete conditions. Expression studies reveal that R. sphaeroides IscR in its cluster-bound form functions as transcriptional repressor of genes involved in iron metabolism by direct binding to the promoter region of genes preceded by the motif. A total of 110 genes are directly or indirectly affected by IscR. Furthermore, IscR possesses a unique Fe-S cluster ligation scheme with only a single cysteine involved.

  1. Seasat over-land scatterometer data. II - Selection of extended area land-target sites for the calibration of spaceborne scatterometers

    NASA Technical Reports Server (NTRS)

    Kennett, Rosemary G.; Li, Fuk K.

    1989-01-01

    The post-launch performance verification for future scatterometers can use extended area land targets to calibrate antenna gain patterns and to verify and monitor deployment configurations. For the Ku-band Seasat scatterometer, a region of tropical rain forest in the Amazon basin was used as a homogeneous extended-area land target. As this region is continuously being deforested, other regions are investigated for calibrating scatterometers. The global backscatter coefficients (sigma0) are compared to classifications of natural vegetation and cultivation intensity and the variability with time during the three-month mission is studied. The statistical variability of sigma0 is compared with prior estimates resulting from the known variability of the instrument parameters and communication noise. Data from selected forested regions with relatively homogeneous sigma0 and little time-dependence are presented.

  2. Quenching Capabilities of Long-Chain Carotenoids in Light-Harvesting-2 Complexes from Rhodobacter sphaeroides with an Engineered Carotenoid Synthesis Pathway.

    PubMed

    Dilbeck, Preston L; Tang, Qun; Mothersole, David J; Martin, Elizabeth C; Hunter, C Neil; Bocian, David F; Holten, Dewey; Niedzwiedzki, Dariusz M

    2016-06-23

    Six light-harvesting-2 complexes (LH2) from genetically modified strains of the purple photosynthetic bacterium Rhodobacter (Rb.) sphaeroides were studied using static and ultrafast optical methods and resonance Raman spectroscopy. These strains were engineered to incorporate carotenoids for which the number of conjugated groups (N = NC═C + NC═O) varies from 9 to 15. The Rb. sphaeroides strains incorporate their native carotenoids spheroidene (N = 10) and spheroidenone (N = 11), as well as longer-chain analogues including spirilloxanthin (N = 13) and diketospirilloxantion (N = 15) normally found in Rhodospirillum rubrum. Measurements of the properties of the carotenoid first singlet excited state (S1) in antennas from the Rb. sphaeroides set show that carotenoid-bacteriochlorophyll a (BChl a) interactions are similar to those in LH2 complexes from various other bacterial species and thus are not significantly impacted by differences in polypeptide composition. Instead, variations in carotenoid-to-BChl a energy transfer are primarily regulated by the N-determined energy of the carotenoid S1 excited state, which for long-chain (N ≥ 13) carotenoids is not involved in energy transfer. Furthermore, the role of the long-chain carotenoids switches from a light-harvesting supporter (via energy transfer to BChl a) to a quencher of the BChl a S1 excited state B850*. This quenching is manifested as a substantial (∼2-fold) reduction of the B850* lifetime and the B850* fluorescence quantum yield for LH2 housing the longest carotenoids. PMID:27285777

  3. Cardiolipin Deficiency in Rhodobacter sphaeroides Alters the Lipid Profile of Membranes and of Crystallized Cytochrome Oxidase, but Structure and Function Are Maintained

    SciTech Connect

    Zhang, Xi; Tamot, Banita; Hiser, Carrie; Reid, Gavin E.; Benning, Christoph; Ferguson-Miller, Shelagh

    2012-05-08

    Many recent studies highlight the importance of lipids in membrane proteins, including in the formation of well-ordered crystals. To examine the effect of changes in one lipid, cardiolipin, on the lipid profile and the production, function, and crystallization of an intrinsic membrane protein, cytochrome c oxidase, we mutated the cardiolipin synthase (cls) gene of Rhodobacter sphaeroides, causing a >90% reduction in cardiolipin content in vivo and selective changes in the abundances of other lipids. Under these conditions, a fully native cytochrome c oxidase (CcO) was produced, as indicated by its activity, spectral properties, and crystal characteristics. Analysis by MALDI tandem mass spectrometry (MS/MS) revealed that the cardiolipin level in CcO crystals, as in the membranes, was greatly decreased. Lipid species present in the crystals were directly analyzed for the first time using MS/MS, documenting their identities and fatty acid chain composition. The fatty acid content of cardiolipin in R. sphaeroides CcO (predominantly 18:1) differs from that in mammalian CcO (18:2). In contrast to the cardiolipin dependence of mammalian CcO activity, major depletion of cardiolipin in R. sphaeroides did not impact any aspect of CcO structure or behavior, suggesting a greater tolerance of interchange of cardiolipin with other lipids in this bacterial system.

  4. Quenching Capabilities of Long-Chain Carotenoids in Light-Harvesting-2 Complexes from Rhodobacter sphaeroides with an Engineered Carotenoid Synthesis Pathway

    PubMed Central

    2016-01-01

    Six light-harvesting-2 complexes (LH2) from genetically modified strains of the purple photosynthetic bacterium Rhodobacter (Rb.) sphaeroides were studied using static and ultrafast optical methods and resonance Raman spectroscopy. These strains were engineered to incorporate carotenoids for which the number of conjugated groups (N = NC=C + NC=O) varies from 9 to 15. The Rb. sphaeroides strains incorporate their native carotenoids spheroidene (N = 10) and spheroidenone (N = 11), as well as longer-chain analogues including spirilloxanthin (N = 13) and diketospirilloxantion (N = 15) normally found in Rhodospirillum rubrum. Measurements of the properties of the carotenoid first singlet excited state (S1) in antennas from the Rb. sphaeroides set show that carotenoid-bacteriochlorophyll a (BChl a) interactions are similar to those in LH2 complexes from various other bacterial species and thus are not significantly impacted by differences in polypeptide composition. Instead, variations in carotenoid-to-BChl a energy transfer are primarily regulated by the N-determined energy of the carotenoid S1 excited state, which for long-chain (N ≥ 13) carotenoids is not involved in energy transfer. Furthermore, the role of the long-chain carotenoids switches from a light-harvesting supporter (via energy transfer to BChl a) to a quencher of the BChl a S1 excited state B850*. This quenching is manifested as a substantial (∼2-fold) reduction of the B850* lifetime and the B850* fluorescence quantum yield for LH2 housing the longest carotenoids. PMID:27285777

  5. Rhodobacter sphaeroides rdxA, a homolog of Rhizobium meliloti fixG, encodes a membrane protein which may bind cytoplasmic [4Fe-4S] clusters.

    PubMed Central

    Neidle, E L; Kaplan, S

    1992-01-01

    In the photosynthetic bacterium Rhodobacter sphaeroides, a chromosomal gene, rdxA, which encodes a 52-kDa protein, was found to be homologous to fixG, the first gene of a Rhizobium meliloti nitrogen fixation operon on the pSym plasmid (D. Kahn, M. David, O. Domergue, M.-L. Daveran, J. Ghai, P. R. Hirsch, and J. Batut, J. Bacteriol. 171:929-939, 1989). The deduced amino acid sequences of RdxA and FixG are 53% identical and 73% similar; sequence analyses suggested that each has five transmembrane helices and a central region resembling bacterial-type ferredoxins. Translational fusion proteins with an alkaline phosphatase reporter group were expressed in both R. sphaeroides and Escherichia coli and were used to assess the membrane topology of RdxA. Its ferredoxinlike sequence, which may bind two [4Fe-4S] centers, was found to be cytoplasmically located. Genetic disruptions showed that rdxA is not essential for nitrogen fixation in R. sphaeroides. Immediately downstream of rdxA, an open reading frame (ORFT2) that encoded a 48-kDa protein was found. This DNA sequence was not homologous to any region of the R. meliloti fixG operon. The N-terminal sequence of the ORFT2 gene product resembled amino acid sequences found in members of the GntR family of regulatory proteins (D. J. Haydon and J. R. Guest, FEMS Microbiol. Lett. 79:291-296, 1991). The rdxA gene was localized to the smaller of two R. sphaeroides chromosomes, upstream of and divergently transcribed from hemT, which encodes one of two 5-aminolevulinate synthase isozymes. The rdxA and hemT genes may share a transcriptional regulatory region. Southern hybridization analysis demonstrated the presence of an rdxA homolog on the R. sphaeroides large chromosome. The functions of this homolog, like those of rdxA, remain to be determined, but roles in oxidation-reduction processes are likely. Images PMID:1400197

  6. Spin Crossover Properties of Iron(ii) Complexes with a N4O2 Donor Set by Extended Π-CONJUGATED Schiff-Base Ligands

    NASA Astrophysics Data System (ADS)

    Kuroda, Takayoshi

    2013-09-01

    The preparation and magnetic properties of three Fe(II) Schiff-base complexes, [Fe(qnal-21)2]•CH2Cl2 (1), [Fe(qnal-12)2]•2C6H6 (2) and [Fe(Hqsalc)2] (3), (Hqnal-21 = N-(8'-quinolyl)-2-hydroxy-1-naphthaldimine, Hqnal-12 = N-(8'-quinolyl)-1-hydroxy-2-naphthaldimine, H2qsalc = 4-hydroxy-3-[(8-quinolinylimino)methyl]benzoic acid) are reported. X-ray single crystal structure analyses of 1 and 2 reveal that an Fe(II) ion in each complex is coordinated by two Schiff-base ligands, qnal-21 or qnal-12, in a meridional fashion. Molecular packing of 2 shows that a qnal-12 interacts with neighboring two qnal-12's through π-π interactions, which results in the formation of one-dimensional chain. Although the magnetic property of 2 shows a high-spin state at all the temperature range measured, the χT-T plot of 3 shows abrupt spin crossover behavior with a wide hysteresis of 21 K, probably due to the hydrogen-bond network originated by carboxyl groups.

  7. The extended ROSAT-ESO Flux Limited X-ray Galaxy Cluster Survey (REFLEX II). IV. X-ray luminosity function and first constraints on cosmological parameters

    NASA Astrophysics Data System (ADS)

    Böhringer, Hans; Chon, Gayoung; Collins, Chris A.

    2014-10-01

    The X-ray luminosity function that is closely related to the cluster mass function is an important statistic of the census of galaxy clusters in our Universe. It is also an important means to probe the cosmological model of our Universe. Based on our recently completed REFLEX II cluster sample comprising 910 galaxy clusters with redshifts we construct the X-ray luminosity function of galaxy clusters for the nearby Universe and discuss its implications. We derived the X-ray luminosity function of the REFLEX II clusters on the basis of a precisely constructed selection function for the full sample and for several redshift slices from z = 0 to z = 0.4. In this redshift interval we find no significant signature of redshift evolution of the luminosity function. We provide the results of fits of a parameterized Schechter function and extensions of it which provide a reasonable characterization of the data. We also use a model for structure formation and galaxy cluster evolution to compare the observed X-ray luminosity function with the theoretical predictions for different cosmological models. The most interesting constraints can be derived for the cosmological parameters Ωm and σ8. We explore the influence of several model assumptions on which our analysis is based. We find that the scaling relation of X-ray luminosity and mass introduces the largest systematic uncertainty. From the statistical uncertainty alone we can constrain the matter density parameter, Ωm ~ 0.27 ± 0.03 and the amplitude parameter of the matter density fluctuations, σ8 ~ 0.80 ± 0.03. Marginalizing over the most important uncertainties, the normalisation and slope of the LX - M scaling relation, we have larger error bars and a result of Ωm ~ 0.29 ± 0.04 and σ8 ~ 0.77 ± 0.07 (1σ confidence limits). We compare our results with those of the SZ-cluster survey provided by the Planck mission and we find very good agreement with the results using Planck clusters as cosmological probes, but there

  8. Functional assembly of the foreign carotenoid lycopene into the photosynthetic apparatus of Rhodobacter sphaeroides, achieved by replacement of the native 3-step phytoene desaturase with its 4-step counterpart from Erwinia herbicola.

    PubMed

    Garcia-Asua, Guillermo; Cogdell, Richard J; Hunter, C Neil

    2002-04-01

    Photosynthetic organisms synthesize a diverse range of carotenoids. These pigments are important for the assembly, function and stability of photosynthetic pigment-protein complexes, and they are used to quench harmful radicals. The photosynthetic bacterium Rhodobacter sphaeroides was used as a model system to explore the origin of carotenoid diversity. Replacing the native 3-step phytoene desaturase (CrtI) with the 4-step enzyme from Erwinia herbicola results in significant flux down the spirilloxanthin pathway for the first time in Rb. sphaeroides. In Rb. sphaeroides, the completion of four desaturations to lycopene by the Erwinia CrtI appears to require the absence of CrtC and, in a crtC background, even the native 3-step enzyme can synthesize a significant amount (13%) of lycopene, in addition to the expected neurosporene. We suggest that the CrtC hydroxylase can intervene in the sequence of reactions catalyzed by phytoene desaturase. We investigated the properties of the lycopene-synthesizing strain of Rb. sphaeroides. In the LH2 light-harvesting complex, lycopene transfers absorbed light energy to the bacteriochlorophylls with an efficiency of 54%, which compares favourably with other LH2 complexes that contain carotenoids with 11 conjugated double bonds. Thus, lycopene can join the assembly pathway for photosynthetic complexes in Rb. sphaeroides, and can perform its role as an energy donor to bacteriochlorophylls.

  9. UV-TO-FIR ANALYSIS OF SPITZER/IRAC SOURCES IN THE EXTENDED GROTH STRIP. II. PHOTOMETRIC REDSHIFTS, STELLAR MASSES, AND STAR FORMATION RATES

    SciTech Connect

    Barro, G.; Perez-Gonzalez, P. G.; Gallego, J.; Villar, V.; Zamorano, J.; Ashby, M. L. N.; Kajisawa, M.; Yamada, T.; Miyazaki, S.

    2011-04-01

    Based on the ultraviolet to far-infrared photometry already compiled and presented in a companion paper (Paper I), we present a detailed spectral energy distribution (SED) analysis of nearly 80,000 IRAC 3.6 + 4.5 {mu}m selected galaxies in the Extended Groth Strip. We estimate photometric redshifts, stellar masses, and star formation rates (SFRs) separately for each galaxy in this large sample. The catalog includes 76,936 sources with [3.6] {<=} 23.75 (85% completeness level of the IRAC survey) over 0.48 deg{sup 2}. The typical photometric redshift accuracy is {Delta}z/(1 + z) = 0.034, with a catastrophic outlier fraction of just 2%. We quantify the systematics introduced by the use of different stellar population synthesis libraries and initial mass functions in the calculation of stellar masses. We find systematic offsets ranging from 0.1 to 0.4 dex, with a typical scatter of 0.3 dex. We also provide UV- and IR-based SFRs for all sample galaxies, based on several sets of dust emission templates and SFR indicators. We evaluate the systematic differences and goodness of the different SFR estimations using the deep FIDEL 70 {mu}m data available in the Extended Groth Strip. Typical random uncertainties of the IR-bases SFRs are a factor of two, with non-negligible systematic effects at z {approx}> 1.5 observed when only MIPS 24 {mu}m data are available. All data products (SEDs, postage stamps from imaging data, and different estimations of the photometric redshifts, stellar masses, and SFRs of each galaxy) described in this and the companion paper are publicly available, and they can be accessed through our the Web interface utility Rainbow-navigator.

  10. 13C MAS NMR evidence for a homogeneously ordered environment of tyrosine M210 in reaction centres of Rhodobacter sphaeroides

    NASA Astrophysics Data System (ADS)

    Shochat, S.; Gast, P.; Hoff, A. J.; Boender, G. J.; van Leeuwen, S.; van Liemt, W. B. S.; Vijgenboom, E.; Raap, J.; Lugtenburg, J.; de Groot, H. J. M.

    1995-01-01

    The initial electron transfer time in the photosynthetic reaction centre of Rhodobacter sphaeroides is highly sensitive to the replacement of tyrosine M210 by a tryptophan residue. Low-temperature magic angle spinning 13C NMR is used to study Rhodobacter sphaeroides 2.4.1 (M)Y210W mutant reaction centres that are labelled with [4'- 13C]tyrosine. The response of (M)Y210 in R26 is assigned unambiguously to the most upfield narrow signal (linewidth 34 Hz) at σi = 152.2 ppm, in the region where non-hydrogen bonded tyrosine signals are expected. From the comparison with the signal of labelled R26 it follows that the chemical environment of the (M)Y210 label is unique. The Y(M)210 is in a structurally and electrostatically homogeneous region on the sensitivity scale of the MAS NMR technique. The environment of M210 is structurally stable and the observation of a narrow line shows that the (M)Y210 side chain can be considered static with respect to rotational diffusion on time scales as long as 10 -2s. The narrow signals from the remaining labels in the protein interior for the 2.4.1 (M)Y210W mutant are remarkably similar to those observed for R26. Using a commonly accepted ratio of 150 ppm shift per positive charge equivalent for aromatic carbons, the chemical shift differences between mutant and R26 translate into small variations of the order of 10 -3 electronic equivalents of charge polarization. Also the linewidths are similar, except for a narrow response at σi = 156.4 ppm that sharpens slightly in the (M)Y210W mutant. Thus, the influence of the (M)Y210W mutation on the global electrostatic properties and structure of the protein, as probed by the tyrosine labels, is minimal. This strongly argues against an explanation of slow and non-exponential electron transfer kinetics in the (M)Y210W RC in terms of loss of structural integrity upon mutation. In contrast, the NMR results strongly support current opinions that (M)Y210 contributes to the fine-tuning of the

  11. Intergalactic Medium Emission Observations with the Cosmic Web Imager. II. Discovery of Extended, Kinematically Linked Emission around SSA22 Lyα Blob 2

    NASA Astrophysics Data System (ADS)

    Martin, D. Christopher; Chang, Daphne; Matuszewski, Matt; Morrissey, Patrick; Rahman, Shahin; Moore, Anna; Steidel, Charles C.; Matsuda, Yuichi

    2014-05-01

    The intergalactic medium (IGM) is the dominant reservoir of baryons, delineates the large-scale structure of the universe at low to moderate overdensities, and provides gas from which galaxies form and evolve. Simulations of a cold-dark-matter- (CDM-) dominated universe predict that the IGM is distributed in a cosmic web of filaments and that galaxies should form along and at the intersections of these filaments. While observations of QSO absorption lines and the large-scale distribution of galaxies have confirmed the CDM paradigm, the cosmic web of IGM has never been confirmed by direct imaging. Here we report our observation of the Lyα blob 2 (LAB2) in SSA22 with the Cosmic Web Imager (CWI). This is an integral field spectrograph optimized for low surface brightness, extended emission. With 22 hr of total on- and off-source exposure, CWI has revealed that LAB2 has extended Lyα emission that is organized into azimuthal zones consistent with filaments. We perform numerous tests with simulations and the data to secure the robustness of this result, which relies on data with modest signal-to-noise ratios. We have developed a smoothing algorithm that permits visualization of data cube slices along image or spectral image planes. With both raw and smoothed data cubes we demonstrate that the filaments are kinematically associated with LAB2 and display double-peaked profiles characteristic of optically thick Lyα emission. The flux is 10-20 times brighter than expected for the average emission from the IGM but is consistent with boosted fluorescence from a buried QSO or gravitation cooling radiation. Using simple emission models, we infer a baryon mass in the filaments of at least 1-4 × 1011 M ⊙, and the dark halo mass is at least 2 × 1012 M ⊙. The spatial-kinematic morphology is more consistent with inflow from the cosmic web than outflow from LAB2, although an outflow feature maybe present at one azimuth. LAB2 and the surrounding gas have significant and

  12. Intergalactic medium emission observations with the cosmic web imager. II. Discovery of extended, kinematically linked emission around SSA22 Lyα BLOB 2

    SciTech Connect

    Christopher Martin, D.; Chang, Daphne; Matuszewski, Matt; Morrissey, Patrick; Rahman, Shahin; Moore, Anna; Steidel, Charles C.; Matsuda, Yuichi

    2014-05-10

    The intergalactic medium (IGM) is the dominant reservoir of baryons, delineates the large-scale structure of the universe at low to moderate overdensities, and provides gas from which galaxies form and evolve. Simulations of a cold-dark-matter- (CDM-) dominated universe predict that the IGM is distributed in a cosmic web of filaments and that galaxies should form along and at the intersections of these filaments. While observations of QSO absorption lines and the large-scale distribution of galaxies have confirmed the CDM paradigm, the cosmic web of IGM has never been confirmed by direct imaging. Here we report our observation of the Lyα blob 2 (LAB2) in SSA22 with the Cosmic Web Imager (CWI). This is an integral field spectrograph optimized for low surface brightness, extended emission. With 22 hr of total on- and off-source exposure, CWI has revealed that LAB2 has extended Lyα emission that is organized into azimuthal zones consistent with filaments. We perform numerous tests with simulations and the data to secure the robustness of this result, which relies on data with modest signal-to-noise ratios. We have developed a smoothing algorithm that permits visualization of data cube slices along image or spectral image planes. With both raw and smoothed data cubes we demonstrate that the filaments are kinematically associated with LAB2 and display double-peaked profiles characteristic of optically thick Lyα emission. The flux is 10-20 times brighter than expected for the average emission from the IGM but is consistent with boosted fluorescence from a buried QSO or gravitation cooling radiation. Using simple emission models, we infer a baryon mass in the filaments of at least 1-4 × 10{sup 11} M {sub ☉}, and the dark halo mass is at least 2 × 10{sup 12} M {sub ☉}. The spatial-kinematic morphology is more consistent with inflow from the cosmic web than outflow from LAB2, although an outflow feature maybe present at one azimuth. LAB2 and the surrounding gas

  13. Extended BCDM

    NASA Astrophysics Data System (ADS)

    Occhionero, Franco; Baccigalupi, Carlo; Amendola, Luca

    1999-05-01

    We propose a new inflationary toy model that produces two episodes of phase transitions. With the first one, super-horizon-sized bubbles are nucleated, which are seen from inside as open universes, thereby reconciling inflation with the recent observations of a low Ω0. With the second transition, a distribution of sub-horizon voids, of sizes typically around 10-100 Mpc/h are generated inside the open universes. These primordial voids can be the seeds of the present large scale voids that are detected in redshift surveys, and provide a non-Gaussian signal on the microwave background. The model realizes this sequence along the same slow-rolling path, by modulating the energy difference between the vacuum states. In this model, that we call extended Bubbly CDM, openness and bubblyness, rather than flatness and homogeneity, are the main products of inflation.

  14. Inhibitor-complexed Structures of the Cytochrome bc[subscript 1] from the Photosynthetic Bacterium Rhodobacter sphaeroides

    SciTech Connect

    Esser, Lothar; Elberry, Maria; Zhou, Fei; Yu, Chang-An; Yu, Linda; Xia, Di

    2008-06-30

    The cytochrome bc{sub 1} complex (bc{sub 1}) is a major contributor to the proton motive force across the membrane by coupling electron transfer to proton translocation. The crystal structures of wild type and mutant bc{sub 1} complexes from the photosynthetic purple bacterium Rhodobacter sphaeroides (Rsbc{sub 1}), stabilized with the quinol oxidation (Q{sub P}) site inhibitor stigmatellin alone or in combination with the quinone reduction (Q{sub N}) site inhibitor antimycin, were determined. The high quality electron density permitted assignments of a new metal-binding site to the cytochrome c1 subunit and a number of lipid and detergent molecules. Structural differences between Rsbc{sub 1} and its mitochondrial counterparts are mostly extra membranous and provide a basis for understanding the function of the predominantly longer sequences in the bacterial subunits. Functional implications for the bc{sub 1} complex are derived from analyses of 10 independent molecules in various crystal forms and from comparisons with mitochondrial complexes.

  15. Coupling of cytochrome and quinone turnovers in the photocycle of reaction centers from the photosynthetic bacterium Rhodobacter sphaeroides.

    PubMed

    Osváth, S; Maróti, P

    1997-08-01

    A minimal kinetic model of the photocycle, including both quinone (Q-6) reduction at the secondary quinone-binding site and (mammalian) cytochrome c oxidation at the cytochrome docking site of isolated reaction centers from photosynthetic purple bacteria Rhodobacter sphaeroides, was elaborated and tested by cytochrome photooxidation under strong continuous illumination. The typical rate of photochemical excitation by a laser diode at 810 nm was 2.200 s-1, and the rates of stationary turnover of the reaction center (one-half of that of cytochrome photooxidation) were 600 +/- 70 s-1 at pH 6 and 400 +/- 50 s-1 at pH 8. The rate of turnover showed strong pH dependence, indicating the contribution of different rate-limiting processes. The kinetic limitation of the photocycle was attributed to the turnover of the cytochrome c binding site (pH < 6), light intensity and quinone/quinol exchange (6 < pH < 8), and proton-coupled second electron transfer in the quinone acceptor complex (pH > 8). The analysis of the double-reciprocal plot of the rate of turnover versus light intensity has proved useful in determining the light-independent (maximum) turnover rate of the reaction center (445 +/- 50 s-1 at pH 7.8).

  16. Optimization of Biomass and 5-Aminolevulinic Acid Production by Rhodobacter sphaeroides ATCC17023 via Response Surface Methodology.

    PubMed

    Liu, Shuli; Zhang, Guangming; Li, Jianzheng; Li, Xiangkun; Zhang, Jie

    2016-06-01

    Microbial 5-aminolevulinic acid (ALA) produced from wastewater is considered as potential renewable energy. However, many hurdles are needed to be overcome such as the regulation of key influencing factors on ALA yield. Biomass and ALA production by Rhodobacter sphaeroides was optimized using response surface methodology. The culturing medium was artificial volatile fatty acids wastewater. Three additives were optimized, namely succinate and glycine that are precursors of ALA biosynthesis, and D-glucose that is an inhibitor of ALA dehydratase. The optimal conditions were achieved by analyzing the response surface plots. Statistical analysis showed that succinate at 8.56 mmol/L, glycine at 5.06 mmol/L, and D-glucose at 7.82 mmol/L were the best conditions. Under these optimal conditions, the highest biomass production and ALA yield of 3.55 g/L and 5.49 mg/g-biomass were achieved. Subsequent verification experiments at optimal values had the maximum biomass production of 3.41 ± 0.002 g/L and ALA yield of 5.78 ± 0.08 mg/g-biomass. PMID:26875086

  17. Dissociation of the light-harvesting membrane protein complex I from Rhodobacter sphaeroides under high hydrostatic pressure

    NASA Astrophysics Data System (ADS)

    Puusepp, Marit; Kangur, Liina; Freiberg, Arvi

    2015-04-01

    The light-harvesting complex 1 (LH1) from Rhodobacter sphaeroides is an excellent model system for investigating the stability of oligomeric membrane proteins under high hydrostatic pressure. The currently investigated LH1 forms a 16-meric ring structure of B825 subunits. B825 is a heterodimer of transmembrane α- and β-polypeptide chains, which non-covalently binds two bacteriochlorophyll a molecules. These pigment molecules were used as intrinsic spectroscopic sensors to follow the dissociation reaction. Our results demonstrate that the LH1 dissociates into B825 subunits through an intermediary tetrameric unit B845. The dissociation mechanism depends on pressure. At ∼200-500 MPa the dissociation corresponds to a pseudo-first-order reaction, characterised by the apparent reaction rate at atmospheric pressure k0 = 3.10-5 s-1, activation volume ΔV‡ = -4 mL/mol, and free energy of activation ΔG‡ = 26 kJ/mol. Below 200 MPa and above 500 MPa, the reaction is more complex, including further dissociation of B825 into monomers B777. This paper was presented at the LIIth European High Pressure Research Group (EHPRG 52) Meeting in Lyon (France), 7-12 September 2014.

  18. Insights into the species-specific TLR4 signaling mechanism in response to Rhodobacter sphaeroides lipid A detection

    NASA Astrophysics Data System (ADS)

    Anwar, Muhammad Ayaz; Panneerselvam, Suresh; Shah, Masaud; Choi, Sangdun

    2015-01-01

    TLR4 in complex with MD2 senses the presence of lipid A (LA) and initiates a signaling cascade that curb the infection. This complex is evolutionarily conserved and can initiate the immune system in response to a variety of LAs. In this study, molecular dynamics simulation (25 ns) was performed to elucidate the differential behavior of TLR4/MD2 complex in response to Rhodobacter sphaeroides lipid A (RsLA). Penta-acyl chain-containing RsLA is at the verge of agonist (6 acyl-chains) and antagonist (4 acyl-chains) structure, and activates the TLR4 pathway in horses and hamsters, while inhibiting in humans and murine. In the time-evolved coordinates, the promising factors that dictated the differential response included the local and global mobility pattern of complexes, solvent-accessible surface area of ligand, and surface charge distributions of TLR4 and MD2. We showed that the GlcN1-GlcN2 backbone acquires agonist (3FXI)-like configurations in horses and hamsters, while acquiring antagonist (2E59)-like configurations in humans and murine systems. Moreover, analysis of F126 behavior in the MD2 F126 loop (amino acids 123-129) and loop EF (81-89) suggested that certain sequence variations also contribute to species-specific response. This study underlines the TLR4 signaling mechanism and provides new therapeutic opportunities.

  19. Semi-continuous photo-fermentative H2 production by Rhodobacter sphaeroides: effect of decanting volume ratio.

    PubMed

    Kim, Dong-Hoon; Kim, Mi-Sun

    2012-01-01

    In this study, a semi-continuous operation of photo-fermentative H2-producing reactor was attempted at various decanting volume ratios (DVR, decanting volume per day/total working volume, %), ranging 30-70%, using Rhodobacter sphaeroides KD131. H2 production was not efficient with showing low H2 yields of 0.2 and 0.5 mol H2/mol succinate(added) at 30% and 40% DVR, respectively. The low performance ascribed to the fact that over 70% of substrate electrons were diverted towards cell growth under these conditions. Meanwhile, cell growth was limited at DVR≥50%; therefore, higher H2 yields (>2.0 mol H2/mol succinateadded) were observed. Both the highest H2 yield of 3.7 mol H2/mol succinateadded and production rate of 1494 mL H2/L-reactor/d were achieved at 60% DVR. The content of soluble microbial products (SMPs) was measured, which accounted for 3-15% of substrate electrons. It was found that the largest (65-75%) portion of SMPs comprised low molecular-weight (<3 kDa).

  20. Structural consequences of the replacement of glycine M203 with aspartic acid in the reaction center from Rhodobacter sphaeroides.

    PubMed

    Fyfe, P K; Ridge, J P; McAuley, K E; Cogdell, R J; Isaacs, N W; Jones, M R

    2000-05-23

    Reaction centers with the double mutation Phe M197 to Arg and Gly M203 to Asp (FM197R/GM203D) have been crystallized from an antenna-deficient strain of Rhodobacter sphaeroides, and the structure has been determined at 2.7 A resolution. Unlike in reaction centers with a single FM197R mutation, the Arg M197 residue in the FM197R/GM203D reaction center adopts a position similar to that of the native Phe residue in the wild-type reaction center. Asp M203 is packed in such a way that the gamma-carboxy group interacts with the backbone carbonyl of Arg M197. The Asp M203 residue takes up part of the volume that is occupied in the wild-type reaction center by a water molecule. This water has been proposed to form a hydrogen bond interaction with the 9-keto carbonyl group of the active branch accessory bacteriochlorophyll, particularly when the primary donor bacteriochlorophylls are oxidized. The GM203D mutation therefore appears to remove the possibility of this hydrogen bond interaction by exclusion of this water molecule, as well as altering the local dielectric environment of the 9-keto carbonyl group. We examine whether the observed structural changes can provide new or alternative explanations for the absorbance and electron-transfer properties of reaction centers with the FM197R and GM203D mutations.

  1. Modeling the light- and redox-dependent interaction of PpsR/AppA in Rhodobacter sphaeroides.

    PubMed

    Pandey, Rakesh; Flockerzi, Dietrich; Hauser, Marcus J B; Straube, Ronny

    2011-05-18

    Facultative photosynthetic bacteria switch their energy generation mechanism from respiration to photosynthesis depending on oxygen tension and light. Part of this transition is mediated by the aerobic transcriptional repressor PpsR. In Rhodobacter sphaeroides, the repressive action of PpsR is antagonized by the redox- and blue-light-sensitive flavoprotein AppA which results in a unique phenotype: the repression of photosynthesis genes at intermediate oxygen levels and high light intensity, which is believed to reduce the risk of photooxidative stress. To analyze the underlying mechanism we developed a simple mathematical model based on the AppA-dependent reduction of a disulfide bond in PpsR and the light-sensitive complex formation between the reduced forms of AppA and PpsR. A steady-state analysis shows that high light repression can indeed occur at intermediate oxygen levels if PpsR is reduced on a faster timescale than AppA and if the electron transfer from AppA to PpsR is effectively irreversible. The model further predicts that if AppA copy numbers exceed those of PpsR by at least a factor of two, the transition from aerobic to anaerobic growth mode can occur via a bistable regime. We provide necessary conditions for the emergence of bistability and discuss possible experimental verifications.

  2. Physiological Roles for Two Periplasmic Nitrate Reductases in Rhodobacter sphaeroides 2.4.3 (ATCC 17025)▿

    PubMed Central

    Hartsock, Angela; Shapleigh, James P.

    2011-01-01

    The metabolically versatile purple bacterium Rhodobacter sphaeroides 2.4.3 is a denitrifier whose genome contains two periplasmic nitrate reductase-encoding gene clusters. This work demonstrates nonredundant physiological roles for these two enzymes. One cluster is expressed aerobically and repressed under low oxygen while the second is maximally expressed under low oxygen. Insertional inactivation of the aerobically expressed nitrate reductase eliminated aerobic nitrate reduction, but cells of this strain could still respire nitrate anaerobically. In contrast, when the anaerobic nitrate reductase was absent, aerobic nitrate reduction was detectable, but anaerobic nitrate reduction was impaired. The aerobic nitrate reductase was expressed but not utilized in liquid culture but was utilized during growth on solid medium. Growth on a variety of carbon sources, with the exception of malate, the most oxidized substrate used, resulted in nitrite production on solid medium. This is consistent with a role for the aerobic nitrate reductase in redox homeostasis. These results show that one of the nitrate reductases is specific for respiration and denitrification while the other likely plays a role in redox homeostasis during aerobic growth. PMID:21949073

  3. Probing energy transfer events in the light harvesting complex 2 (LH2) of Rhodobacter sphaeroides with two-dimensional spectroscopy.

    PubMed

    Fidler, Andrew F; Singh, Ved P; Long, Phillip D; Dahlberg, Peter D; Engel, Gregory S

    2013-10-21

    Excitation energy transfer events in the photosynthetic light harvesting complex 2 (LH2) of Rhodobacter sphaeroides are investigated with polarization controlled two-dimensional electronic spectroscopy. A spectrally broadened pulse allows simultaneous measurement of the energy transfer within and between the two absorption bands at 800 nm and 850 nm. The phased all-parallel polarization two-dimensional spectra resolve the initial events of energy transfer by separating the intra-band and inter-band relaxation processes across the two-dimensional map. The internal dynamics of the 800 nm region of the spectra are resolved as a cross peak that grows in on an ultrafast time scale, reflecting energy transfer between higher lying excitations of the B850 chromophores into the B800 states. We utilize a polarization sequence designed to highlight the initial excited state dynamics which uncovers an ultrafast transfer component between the two bands that was not observed in the all-parallel polarization data. We attribute the ultrafast transfer component to energy transfer from higher energy exciton states to lower energy states of the strongly coupled B850 chromophores. Connecting the spectroscopic signature to the molecular structure, we reveal multiple relaxation pathways including a cyclic transfer of energy between the two rings of the complex.

  4. Concomitant biohydrogen and poly-β-hydroxybutyrate production from dark fermentation effluents by adapted Rhodobacter sphaeroides and mixed photofermentative cultures.

    PubMed

    Ghimire, Anish; Valentino, Serena; Frunzo, Luigi; Pirozzi, Francesco; Lens, Piet N L; Esposito, Giovanni

    2016-10-01

    This work aimed at investigating concomitant production of biohydrogen and poly-β-hydroxybutyrate (PHB) by photofermentation (PF) using dark fermentation effluents (DFE). An adapted culture of Rhodobacter sphaeroides AV1b (pH 6.5, 24±2°C) achieved H2 and PHB yields of 256 (±2) NmLH2/g Chemical Oxygen Demand (COD) and 273.8mgPHB/gCOD (32.5±3% of the dry cells weight (DCW)), respectively. When a diluted (1:2) DFE medium was applied to the adapted pure and mixed photofermentative culture, the respective H2 yields were 164.0 (±12) and 71.3 (±6) NmLH2/gCOD and the PHB yields were 212.1 (±105.2) and 50.7 (±2.7) mgPHB/gCOD added, corresponding to 24 (±0.7) and 6.3 (±0) % DCW, respectively. The concomitant H2 and PHB production from the PF process gave a good DFE post treatment achieving up to 80% COD removal from the initial DFE.

  5. Electronic Structure and Dynamics of Higher-Lying Excited States in Light Harvesting Complex 1 from Rhodobacter sphaeroides.

    PubMed

    Dahlberg, Peter D; Ting, Po-Chieh; Massey, Sara C; Martin, Elizabeth C; Hunter, C Neil; Engel, Gregory S

    2016-06-23

    Light harvesting in photosynthetic organisms involves efficient transfer of energy from peripheral antenna complexes to core antenna complexes, and ultimately to the reaction center where charge separation drives downstream photosynthetic processes. Antenna complexes contain many strongly coupled chromophores, which complicates analysis of their electronic structure. Two-dimensional electronic spectroscopy (2DES) provides information on energetic coupling and ultrafast energy transfer dynamics, making the technique well suited for the study of photosynthetic antennae. Here, we present 2DES results on excited state properties and dynamics of a core antenna complex, light harvesting complex 1 (LH1), embedded in the photosynthetic membrane of Rhodobacter sphaeroides. The experiment reveals weakly allowed higher-lying excited states in LH1 at 770 nm, which transfer energy to the strongly allowed states at 875 nm with a lifetime of 40 fs. The presence of higher-lying excited states is in agreement with effective Hamiltonians constructed using parameters from crystal structures and atomic force microscopy (AFM) studies. The energy transfer dynamics between the higher- and lower-lying excited states agree with Redfield theory calculations.

  6. Biodegradable polyurethanes for implants. II. In vitro degradation and calcification of materials from poly(epsilon-caprolactone)-poly(ethylene oxide) diols and various chain extenders.

    PubMed

    Gorna, Katarzyna; Gogolewski, Sylwester

    2002-06-15

    Linear, biodegradable, aliphatic polyurethanes with various degrees of hydrophilicity were synthesized in bulk at 50-100 degrees C. The ratios between the hydrophilic and hydrophobic segments were 0:100, 30:70, 40:60, 50:50, and 70:30, respectively. The hydrophilic segment consisted of poly(ethylene oxide) (PEO) diol (molecular weight = 600 or 2000) or the poly(ethylene-propylene-ethylene oxide) (PEO-PPO-PEO) diol Pluronic F-68 (molecular weight = 8000). The hydrophobic segment was made of poly(epsilon-caprolactone) diol (molecular weight = 530, 1250, or 2000). The chain extenders were 1,4-butane diol and 2-amino-1-butanol. The diisocyanate was aliphatic hexamethylene diisocyanate. The polymers absorbed water in an amount that increased with the increasing content of the PEO segment in the polymer chain. The total amount of absorbed water did not exceed 2% for the poly(ester urethane)s and was as high as 212% for some poly(ester ether urethane)s that behaved in water like hydrogels. The polymers were subjected to in vitro degradation at 37 +/- 0.1 degrees C in phosphate buffer solutions for up to 76 weeks. The poly(ester urethane)s showed 1-2% mass loss at 48 weeks and 1.1-3.8% mass loss at 76 weeks. The poly(ester ether urethane)s manifested 1.6-76% mass loss at 48 weeks and 1.6-96% mass loss at 76 weeks. The increasing content and molecular weight of the PEO segment enhanced the rate of mass loss. Similar relations were also observed for polyurethanes from PEO-PPO-PEO (Pluronic) diols. Materials obtained with 2-amino-1-butanol as the chain extender degraded at a slower rate than similar materials synthesized with 1,4-butane diol. All the materials already manifested a progressive decrease in the molecular weight in the first month of in vitro aging. The rate of molecular weight loss was higher for poly(ester ether urethane)s than for poly(ester urethane)s. For poly(ester ether urethane)s, the rate of molecular weight loss was higher for materials containing

  7. The extended ROSAT-ESO Flux-Limited X-ray Galaxy Cluster Survey (REFLEX II). VI. Effect of massive neutrinos on the cosmological constraints from clusters

    NASA Astrophysics Data System (ADS)

    Böhringer, Hans; Chon, Gayoung

    2015-02-01

    Clusters of galaxies are important probes for the large-scale structure that allow us to test cosmological models. With the REFLEX II galaxy cluster survey we previously derived tight constraints on the cosmological parameters for the matter density, Ωm, and the amplitude parameter of the matter density fluctuations, σ8. Whereas in these previous studies no effect of massive neutrinos was taken into account, we explore these effects in the present publication. We derive cosmological constraints for the sum of the neutrino masses of the conventional three neutrino families in the range Mν = ∑ imνi = 0 to 0.6 eV. The influence on the constraints of Ωm and σ8 for the expected mass range is weak. Interesting constraints on the neutrino properties can be derived by comparing the cluster data with those from the Planck cosmic microwave background observations. The current tension between the Planck results and clusters can formally be resolved with neutrino masses of about Mν = 0.45(±0.28,1σ) eV. While we caution not to consider this a firm measurement because it might also be the result of unresolved systematics, it is interesting that other measurements of the local large-scale structure fluctuation amplitude, like that of cosmic lensing shear, yield similar results and additionally confirm the effect of massive neutrinos. Among the indicators for massive neutrinos, galaxy clusters and in particular our large and well-controlled cluster survey currently provide the best potential for constraints of the total neutrino mass.

  8. Pharmacokinetics, safety, and efficacy of APF530 (extended-release granisetron) in patients receiving moderately or highly emetogenic chemotherapy: results of two Phase II trials

    PubMed Central

    Gabrail, Nashat; Yanagihara, Ronald; Spaczyński, Marek; Cooper, William; O’Boyle, Erin; Smith, Carrie; Boccia, Ralph

    2015-01-01

    Background Despite advances with new therapies, a significant proportion of patients (>30%) suffer delayed-onset chemotherapy-induced nausea and vomiting (CINV) despite use of antiemetics. APF530 is a sustained-release subcutaneous (SC) formulation of granisetron for preventing CINV. APF530 pharmacokinetics, safety, and efficacy were studied in two open-label, single-dose Phase II trials (C2005-01 and C2007-01, respectively) in patients receiving moderately emetogenic chemotherapy or highly emetogenic chemotherapy. Methods In C2005-01, 45 patients received APF530 250, 500, or 750 mg SC (granisetron 5, 10, or 15 mg, respectively). In C2007-01, 35 patients were randomized to APF530 250 or 500 mg SC. Injections were given 30 to 60 minutes before single-day moderately emetogenic chemotherapy or highly emetogenic chemotherapy. Plasma granisetron was measured from predose to 168 hours after study drug administration. Safety and efficacy were also evaluated. Results APF530 pharmacokinetics were dose proportional, with slow absorption and elimination of granisetron after a single SC dose. Median time to maximum plasma concentration and half-life were similar for APF530 250 and 500 mg in both trials, with no differences between the groups receiving moderately and highly emetogenic chemotherapy. Exposure to granisetron was maintained at a therapeutic level over the delayed-onset phase, at least 168 hours. Adverse events in both trials were as expected for granisetron; injection site reactions (eg, erythema and induration) were predominantly mild and seen in ≤20% of patients. Complete responses (no emesis, with no rescue medication) were obtained in the acute, delayed, and overall phases in ≥80% and ≥75% of patients in both trials with the 250 and 500 mg doses, respectively. Conclusion After a single injection of APF530, there were dose-proportional pharmacokinetics and sustained concentrations of granisetron over 168 hours. The 250 and 500 mg doses were well tolerated

  9. Magnetic Interactions in the Copper Complex (L-Aspartato)(1,10-phenanthroline)copper(II) Hydrate. An Exchange-Coupled Extended System with Two Dissimilar Copper Ions.

    PubMed

    Brondino, Carlos D.; Calvo, Rafael; Atria, Ana María; Spodine, Evgenia; Nascimento, Otaciro R.; Peña, Octavio

    1997-07-01

    We report EPR measurements in single-crystal samples at the microwave frequencies 9.8 and 34.3 GHz and magnetic susceptibility measurements in polycrystalline samples for the ternary complex of copper with aspartic acid and phenanthroline, (L-aspartato)(1,10-phenanthroline)copper(II) hydrate. The crystal lattice of this compound is composed of two dissimilar copper ions identified as Cu(A) and Cu(B), which are in two types of copper chains called A and B, respectively, running parallel to the b crystal axis. The copper ions in the A chains are connected by the aspartic acid molecule, and those in the B chains by a chemical path that involves a carboxylate bridge and a hydrogen bond. Both chains are held together by a complex network of hydrogen bonds and by hydrophobic interactions between aromatic amines. Magnetic susceptibility data indicate a Curie-Weiss behavior in the studied temperature range (2-300 K). The EPR spectra at 9.8 GHz display a single exchange collapsed resonance for any magnetic field orientation, in the so-called strong exchange regime. Those at 34.3 GHz are within the so-called weak exchange regime and display two resonances which belong to each type of copper ion chain. The decoupling of the spectra at 34.3 GHz using a theory based on Anderson's model for the case of two weakly exchange coupled spins S = (1)/(2) allows one to obtain the angular variation of the squares of the g-factor and the peak-to-peak line width of each resonance. This model also allows one to evaluate the exchange parameter |J(AB)/k| = 2.7(6) mK associated with the chemical path connecting dissimilar copper ions. The line width data obtained for each component of the spectra at 34.3 GHz are analyzed in terms of a model based on Kubo and Tomita's theory, to obtain the exchange parameters |J(A)/k| = 0.77(2) K and |J(B)/k| = 1.44(2) K associated with the chemical paths connecting the similar copper ions of types A and B, respectively.

  10. The extended ROSAT-ESO Flux-Limited X-ray Galaxy Cluster Survey (REFLEX II). V. Exploring a local underdensity in the southern sky

    NASA Astrophysics Data System (ADS)

    Böhringer, Hans; Chon, Gayoung; Bristow, Martyn; Collins, Chris A.

    2015-02-01

    Several claims have been made that we are located in a locally underdense region of the Universe based on observations of supernovae and galaxy density distributions. Two recent studies of K-band galaxy surveys have, in particular, provided new support for a local underdensity in the galaxy distribution out to distances of 200-300 Mpc. If confirmed, such local underdensities would have important implications interpreting local measurements of cosmological parameters. Galaxy clusters have been shown to be ideal probes for tracing the large-scale structure of the Universe. In this paper we study the local density distribution in the southern sky with the X-ray detected galaxy clusters from the REFLEX II cluster survey. From the normalised comoving number density of clusters, we find an average underdensity of ~30-40% in the redshift range out to z ~ 0.04 (~170 Mpc) in the southern extragalactic sky with a significance greater than 3.4σ. On larger scales from 300 Mpc to over 1 Gpc, the density distribution appears remarkably homogeneous. The local underdensity seems to be dominated by the south Galactic cap region. A comparison of the cluster distribution with that of galaxies in the K-band from a recent study shows that galaxies and clusters trace each other very closely in density. In the south Galactic cap region both surveys find a local underdensity in the redshift range z = 0 to 0.05 and no significant underdensity in the north Galactic cap at southern latitudes. Cosmological models that attempt to interpret the cosmic acceleration, deduced from observations of type Ia supernovae, by a large local void without the need for reacceleration, require that we are located close to the centre of a roughly spherical void with a minimum size of ~300 Mpc. In contrast our results show that the local underdensity is not isotropic and limited to a size significantly smaller than 300 Mpc radius. Based on observations at the European Southern Observatory La Silla, Chile.

  11. Use of extended curettage with osteotomy and fenestration followed by reconstruction with conservation of muscle insertion in the treatment of Enneking stage II locally aggressive bone tumor of the proximal extremities: resection and treatment of bone tumors

    PubMed Central

    2013-01-01

    Background The purpose of this study was to investigate the clinical efficacy of extended resection with osteotomy, fenestration and conservation of muscle (tendon) insertion in the treatment of bone tumors. Methods A total of 15 patients with locally aggressive bone tumors (Enneking stage II) in the adjacent muscle (tendon) insertion of the proximal extremity were enrolled in the present study (mean age of 29 years). Extended curettage of lesions with osteotomy, fenestration and/or conservation of muscle (tendon) insertion and internal fixation with a bone graft or bone cement was performed at stage I. Postsurgical brace protection was used for 4 to 12 weeks and the patients were periodically followed-up by X-ray and functional assessment. Recurrence, postsurgical Enneking score and outcome rating were assessed. Results Treated cases included 15 patients aged 29 ±7.75 years (range, 18 to 42) with a male to female ratio of 8:7. Six had a femoral tumor and nine had a humeral tumor. These tumors comprised three chondroblastomas, five giant-cell tumors and seven aneurysmal bone cysts. Follow-up for 48 ±12.95 months (range, 25 to 72) revealed that 13 of 15 (87%) patients exhibited no recurrence. Local recurrence was observed in a patient with an aneurysmal bone cyst (nine months) and one with a giant-cell tumor (12 months). Mean Enneking scores were 27 ±4.07 (range, 18 to 29). Except for the patient with the recurrent giant-cell tumor, all patients reported good (13%, 2 out of 15) or very good (80%, 12 out of 15) outcomes. Very good outcomes were reported in 92% of patients (12 out of 13) without recurrence. Conclusions The procedures used in this study achieved high clinical efficacy, complete lesion removal, reduced recurrence and good restoration of joint function in patients with primary locally aggressive Enneking stage II bone tumors of the proximal extremities. PMID:23497479

  12. Surface complexation and precipitate geometry for aqueous Zn(II) sorption on ferrihydrite I: X-ray absorption extended fine structure spectroscopy analysis

    USGS Publications Warehouse

    Waychunas, G.A.; Fuller, C.C.; Davis, J.A.

    2002-01-01

    "Two-line" ferrihydrite samples precipitated and then exposed to a range of aqueous Zn solutions (10-5 to 10-3 M), and also coprecipitated in similar Zn solutions (pH 6.5), have been examined by Zn and Fe K-edge X-ray absorption spectroscopy. Typical Zn complexes on the surface have Zn-O distances of 1.97(0.2) A?? and coordination numbers of about 4.0(0.5), consistent with tetrahedral oxygen coordination. This contrasts with Zn-O distances of 2.11(.02) A?? and coordination numbers of 6 to 7 in the aqueous Zn solutions used in sample preparation. X-ray absorption extended fine structure spectroscopy (EXAFS) fits to the second shell of cation neighbors indicate as many as 4 Zn-Fe neighbors at 3.44(.04) A?? in coprecipitated samples, and about two Zn-Fe neighbors at the same distance in adsorption samples. In both sets of samples, the fitted coordination number of second shell cations decreases as sorption density increases, indicating changes in the number and type of available complexing sites or the onset of competitive precipitation processes. Comparison of our results with the possible geometries for surface complexes and precipitates suggests that the Zn sorption complexes are inner sphere and at lowest adsorption densities are bidentate, sharing apical oxygens with adjacent edge-sharing Fe(O,OH)6 octahedra. Coprecipitation samples have complexes with similar geometry, but these are polydentate, sharing apices with more than two adjacent edge-sharing Fe(O,OH)6 polyhedra. The results are inconsistent with Zn entering the ferrihydrite structure (i.e., solid solution formation) or formation of other Zn-Fe precipitates. The fitted Zn-Fe coordination numbers drop with increasing Zn density with a minimum of about 0.8(.2) at Zn/(Zn + Fe) of 0.08 or more. This change appears to be attributable to the onset of precipitation of zinc hydroxide polymers with mainly tetrahedral Zn coordination. At the highest loadings studied, the nature of the complexes changes further

  13. PucC and LhaA direct efficient assembly of the light‐harvesting complexes in Rhodobacter sphaeroides

    PubMed Central

    Mothersole, David J.; Jackson, Philip J.; Vasilev, Cvetelin; Tucker, Jaimey D.; Brindley, Amanda A.; Dickman, Mark J.

    2015-01-01

    Summary The mature architecture of the photosynthetic membrane of the purple phototroph R hodobacter sphaeroides has been characterised to a level where an atomic‐level membrane model is available, but the roles of the putative assembly proteins LhaA and PucC in establishing this architecture are unknown. Here we investigate the assembly of light‐harvesting LH2 and reaction centre‐light‐harvesting1‐PufX (RC‐LH1‐PufX) photosystem complexes using spectroscopy, pull‐downs, native gel electrophoresis, quantitative mass spectrometry and fluorescence lifetime microscopy to characterise a series of lha A and puc C mutants. LhaA and PucC are important for specific assembly of LH1 or LH2 complexes, respectively, but they are not essential; the few LH1 subunits found in Δlha A mutants assemble to form normal RC‐LH1‐PufX core complexes showing that, once initiated, LH1 assembly round the RC is cooperative and proceeds to completion. LhaA and PucC form oligomers at sites of initiation of membrane invagination; LhaA associates with RCs, bacteriochlorophyll synthase (BchG), the protein translocase subunit YajC and the YidC membrane protein insertase. These associations within membrane nanodomains likely maximise interactions between pigments newly arriving from BchG and nascent proteins within the SecYEG‐SecDF‐YajC‐YidC assembly machinery, thereby co‐ordinating pigment delivery, the co‐translational insertion of LH polypeptides and their folding and assembly to form photosynthetic complexes. PMID:26419219

  14. prrA, a putative response regulator involved in oxygen regulation of photosynthesis gene expression in Rhodobacter sphaeroides.

    PubMed Central

    Eraso, J M; Kaplan, S

    1994-01-01

    A new locus, prrA, involved in the regulation of photosynthesis gene expression in response to oxygen, has been identified in Rhodobacter sphaeroides. Inactivation of prrA results in the absence of photosynthetic spectral complexes. The prrA gene product has strong homology to response regulators associated with signal transduction in other prokaryotes. When prrA is present in multiple copies, cells produce light-harvesting complexes under aerobic growth conditions, suggesting that prrA affects photosynthesis gene expression positively in response to oxygen deprivation. Analysis of the expression of puc::lacZ fusions in wild-type and PrrA- cells revealed a substantial decrease in LacZ expression in the absence of prrA under all conditions of growth, especially when cells were grown anaerobically in the dark in the presence of dimethyl sulfoxide. Northern (RNA) and slot blot hybridizations confirmed the beta-galactoside results for puc and revealed additional positive regulation of puf, puhA, and cycA by PrrA. The effect of truncated PrrA on photosynthesis gene expression in the presence of low oxygen levels can be explained by assuming that PrrA may be effective as a multimer. PrrA was found to act on the downstream regulatory sequences (J. K. Lee and S. Kaplan, J. Bacteriol. 174:1146-1157, 1992) of the puc operon regulatory region. Finally, two spontaneous prrA mutations that abolish prrA function by changing amino acids in the amino-terminal domain of the protein were isolated. Images PMID:8282708

  15. Control of hemA Expression in Rhodobacter sphaeroides 2.4.1: Effect of a Transposon Insertion in the hbdA Gene

    PubMed Central

    Fales, Linda; Kryszak, Luiza; Zeilstra-Ryalls, Jill

    2001-01-01

    The common precursor to all tetrapyrroles is 5-aminolevulinic acid (ALA), and in Rhodobacter sphaeroides its formation occurs via the Shemin pathway. ALA synthase activity is encoded by two differentially regulated genes in R. sphaeroides 2.4.1: hemA and hemT. In our investigations of hemA regulation, we applied transposon mutagenesis under aerobic conditions, followed by a selection that identified transposon insertion mutants in which hemA expression is elevated. One of these mutants has been characterized previously (J. Zeilstra-Ryalls and S. Kaplan, J. Bacteriol. 178:985–993, 1996), and here we describe our analysis of a second mutant strain. The transposon inserted into the coding sequences of hbdA, coding for S-(+)-β-hydroxybutyryl–coenzyme A dehydrogenase and catalyzing an NAD-dependent reaction. We provide evidence that the hbdA gene product participates in polyhydroxybutyrate (PHB) metabolism and, based on our findings, we discuss possibilities as to how defective PHB metabolism might alter the level of hemA expression. PMID:11160087

  16. Molecular genetic analysis of a dimethylsulfoniopropionate lyase that liberates the climate-changing gas dimethylsulfide in several marine alpha-proteobacteria and Rhodobacter sphaeroides.

    PubMed

    Curson, A R J; Rogers, R; Todd, J D; Brearley, C A; Johnston, A W B

    2008-03-01

    The alpha-proteobacterium Sulfitobacter EE-36 makes the gas dimethylsulfide (DMS) from dimethylsulfoniopropionate (DMSP), an abundant antistress molecule made by many marine phytoplankton. We screened a cosmid library of Sulfitobacter for clones that conferred to other bacteria the ability to make DMS. One gene, termed dddL, was sufficient for this phenotype when cloned in pET21a and introduced into Escherichia coli. Close DddL homologues exist in the marine alpha-proteobacteria Fulvimarina, Loktanella Oceanicola and Stappia, all of which made DMS when grown on DMSP. There was also a dddL homologue in Rhodobacter sphaeroides strain 2.4.1, but not in strain ATCC 17025; significantly, the former, but not the latter, emits DMS when grown with DMSP. Escherichia coli containing the cloned, overexpressed dddL genes of R. sphaeroides 2.4.1 and Sulfitobacter could convert DMSP to acrylate plus DMS. This is the first identification of such a 'DMSP lyase'. Thus, DMS can be made either by this DddL lyase or by a DMSP acyl CoA transferase, specified by dddD, a gene that we had identified in several other marine bacteria.

  17. Homogeneous Universes in Extended Inflation II

    NASA Astrophysics Data System (ADS)

    Guzmán, Enrique

    1997-04-01

    It is shown that the scalar field π of the Brans-Dicke theory in the Bianchi TypeVIo-VIh-VIIh-VIII and IX models has the same form that in the isotropic Robertson-Walker case. It is shown that the Universe will be isotropized very fast, permitting so that the approximation of an Universe Robertson-Walker isotropic to be a good approach in the early Universe.

  18. Structure-property relationship of extended π-conjugation of ancillary ligands with and without an electron donor of heteroleptic Ru(II) bipyridyl complexes for high efficiency dye-sensitized solar cells.

    PubMed

    Hussain, Maqbool; El-Shafei, Ahmed; Islam, Ashraful; Han, Liyuan

    2013-06-01

    Two new heteroleptic Ru(II) bipyridyl complexes MH06 and MH11 were designed, synthesized and characterized for DSSCs. While the ancillary ligand of MH06 was molecularly engineered with a strong electron donating group coupled with an extended π-conjugated system, the ancillary ligand of MH11 contained a longer π-conjugated system only. Molecular modeling, photophysical, and photovoltaic properties were compared under the same experimental conditions against the benchmark N719. In an effort to understand the structure-property relationship, their photovoltaic and photoelectrochemical properties including Jsc, Voc, ground and excited state oxidation potentials, UV-Vis absorption, and molar extinction coefficients were studied. The UV-Vis results showed intense MLCT absorption peaks of MH06 and MH11 in the visible region with a red shift of 12 and 18 nm, respectively, with significantly higher molar extinction coefficients compared to N719. Tetrabutylammonium (TBA) substituted MH11-TBA demonstrated the most efficient IPCE of over 90% in the plateau region covering the entire visible spectrum and extending into the near IR region (ca. 890 nm), which showed a solar-to-power conversion efficiency (η) of 10.06%, significantly higher than that of the benchmark N719 dye (9.32%). The superior performance in terms of the IPCE and Jsc of MH11 can be attributed to the bulky and highly hydrophobic nature of the pyrene-based ancillary ligand, which behaves as a shielding barrier for hole-transport recombination between TiO2 and the electrolyte. In addition, the IMPS results showed that the contribution of dyes to the conduction band shift of the TiO2 level is almost similar, regardless of different substitutions on the bipy-moiety. This implies that the open-circuit photovoltage (Voc) increases with reduced charge recombination in the presence of a thick layer of tetrabutyl ammonium ions (TBA) of the dye anchored on the surface of TiO2.

  19. A redox-responsive pathway for aerobic regulation of photosynthesis gene expression in Rhodobacter sphaeroides 2.4.1.

    PubMed

    O'Gara, J P; Eraso, J M; Kaplan, S

    1998-08-01

    To further understand the proposed signal transduction pathway involving the presumed redox proteins RdxBH and cbb3 cytochrome oxidase in Rhodobacter sphaeroides 2.4.1, a series of mutants lacking components of both the Prr two-component activation system and the cbb3-type cytochrome oxidase or RdxBH were constructed. We report that under highly aerobic conditions, aberrant photosynthesis gene expression and spectral complex formation typical of cbb3- or RdxBH-deficient mutants were no longer observed when either prrA (encoding the response regulator of the Prr system) or prrB (encoding the presumed sensor kinase) was also deleted. These double-mutant strains are phenotypically identical to single-mutant PrrA and PrrB strains, suggesting that the signal(s) originating from the cbb3 terminal oxidase affects downstream puc and puf operon expression by acting exclusively through the Prr system. When the same double-mutant strains were examined under anaerobic dark dimethyl sulfoxide growth conditions, photosynthesis gene expression was obligatorily linked to the two-component activation system. However, photosynthesis gene expression under the same growth conditions was significantly higher in the cbb3 mutant strain when compared to that in the wild type. Similarly, under anaerobic photosynthetic conditions the high levels of the oxidized carotenoid, spheroidenone, which accumulate in cbb3-deficient mutants were nearly restored to normal in a PrrB- CcoP- double mutant. This observation, together with previously published results, suggests that the regulation of the CrtA-catalyzed reaction possesses both transcriptional and posttranscriptional regulatory effectors. We propose that the cbb3 cytochrome oxidase, which by definition can interact with external oxygen, serves to control the activity of the Prr two-component activation system under both aerobic and anaerobic conditions. Although independent from the cbb3 oxidase, the RdxBH proteins are also required for

  20. Enhanced photo-fermentative H2 production using Rhodobacter sphaeroides by ethanol addition and analysis of soluble microbial products

    PubMed Central

    2014-01-01

    Background Biological fermentation routes can provide an environmentally friendly way of producing H2 since they use renewable biomass as feedstock and proceed under ambient temperature and pressure. In particular, photo-fermentation has superior properties in terms of achieving high H2 yield through complete degradation of substrates. However, long-term H2 production data with stable performance is limited, and this data is essential for practical applications. In the present work, continuous photo-fermentative H2 production from lactate was attempted using the purple non-sulfur bacterium, Rhodobacter sphaeroides KD131. As a gradual drop in H2 production was observed, we attempted to add ethanol (0.2% v/v) to the medium. Results As continuous operation went on, H2 production was not sustained and showed a negligible H2 yield (< 0.5 mol H2/mol lactateadded) within two weeks. Electron balance analysis showed that the reason for the gradual drop in H2 production was ascribed to the increase in production of soluble microbial products (SMPs). To see the possible effect of ethanol addition, a batch test was first conducted. The presence of ethanol significantly increased the H2 yield from 1.15 to 2.20 mol H2/mol lactateadded, by suppressing the production of SMPs. The analysis of SMPs by size exclusion chromatography showed that, in the later period of fermentation, more than half of the low molecular weight SMPs (< 1 kDa) were consumed and used for H2 production when ethanol had been added, while the concentration of SMPs continuously increased in the absence of ethanol. It was found that the addition of ethanol facilitated the utilization of reducing power, resulting in an increase in the cellular levels of NAD+ and NADP+. In continuous operation, ethanol addition was effective, such that stable H2 production was attained with an H2 yield of 2.5 mol H2/mol lactateadded. Less than 15% of substrate electrons were used for SMP production, whereas 35% were used in

  1. Isolation and characterization of photosynthetic reaction centers from Rhodopseudomonas capsulata and Rhodopseudomonas sphaeroides

    SciTech Connect

    Worland, S.T.

    1984-09-01

    Reaction centers were isolated by affinity chromatography on equine cytochrome C. Peripheral proteins were removed with 0.05% LDAO. Absorption and EPR spectra and bleaching assays indicate that the reaction centers retained their electron donors and acceptors in the native environment. Three reaction center polypeptides were isolated and submitted for amino-terminal sequence determination. By comparing these sequences to those deduced from DNA, it was established that the M and L subunits are post-translationally modified to remove the aminoterminal Met, whereas the H subunit is not. Inhibition of O/sub 2/ evolution in photosystem II particles from spinach by naphthoquinone derivatives show O/sub 2/ inhibition by bromomethyl and acetoxymethyl derivatives but not with hydroxymethyl derivatives. Inhibition by acetoxymethyl derivatives in irreversible and dependent on illumination suggesting that reduction of the quinone is necessary. Therefore acetoxymethyl derivatives may be useful as suicide reagents for labelling quinone binding sites. Procedures were developed to extract one or both of the quinones present in reaction centers and preserve the integrity of the co-factor binding sites. The H and M subunits were cleaned using furmic acid. Both fragments were isolated from the H subunit, while the larger fragment was isolated from the M subunit. Electrophoretic mobilities of the isolated fragments agrees well with the expected molecular weights. The L subunit was digested with Staphylococcus areus vs protease. The pattern obtained was consistant with the potential sites of cleavage, but it was not possible to assign cleavage sites unambiguously. 112 references, 37 figures, 2 tables.

  2. Structural and preliminary molecular dynamics studies of the Rhodobacter sphaeroides reaction center and its mutant form L(M196)H + H(M202)L

    NASA Astrophysics Data System (ADS)

    Klyashtorny, V. G.; Fufina, T. Yu.; Vasilieva, L. G.; Shuvalov, V. A.; Gabdulkhakov, A. G.

    2014-07-01

    Pigment-protein interactions are responsible for the high efficiency of the light-energy transfer and conversion in photosynthesis. The reaction center (RC) from the purple bacterium Rhodobacter sphaeroides is the most convenient model for studying the mechanisms of primary processes of photosynthesis. Site-directed mutagenesis can be used to study the effect of the protein environment of electron-transfer cofactors on the optical properties, stability, pigment composition, and functional activity of RC. The preliminary analysis of RC was performed by computer simulation of the amino acid substitutions L(M196)H + H(M202)L at the pigment-protein interface and by estimating the stability of the threedimensional structure of the mutant RC by the molecular dynamics method. The doubly mutated reaction center was overexpressed, purified, and crystallized. The three-dimensional structure of this mutant was determined by X-ray crystallography and compared with the molecular dynamics model.

  3. Expression, purification, crystallization and preliminary X-ray structure analysis of wild-type and L(M196)H-mutant Rhodobacter sphaeroides reaction centres

    PubMed Central

    Gabdulkhakov, A. G.; Fufina, T. Y.; Vasilieva, L. G.; Mueller, U.; Shuvalov, V. A.

    2013-01-01

    The electron and proton transport mediated by protein-bound cofactors in photosynthesis have been investigated by various methods in order to determine the energetics, the dynamics and the pathway of this process. In purple bacteria, primary photosynthetic charge separation and the build-up of a proton gradient across the periplasmic membrane are catalyzed by the photosynthetic reaction centre (RC). Here, the purification, crystallization and preliminary X-ray analysis of wild-type and L(M196)H-mutant RCs of Rhodobacter sphaeroides are presented, enabling study of the influence of the protein environment of the primary electron donor on the spectral properties and photochemical activity of the RC. PMID:23695564

  4. New tetragonal form of reaction centers from Rhodobacter sphaeroides and the involvement of a manganese ion at a crystal contact point

    PubMed Central

    Uyeda, G.; Cámara-Artigas, A.; Williams, J. C.; Allen, J. P.

    2005-01-01

    Crystals have been obtained of wild-type reaction centers from Rhodobacter sphaeroides using manganese chloride as a precipitating agent. The crystals belong to the tetragonal space group P4222, with unit-cell parameters a = b = 207.8, c = 107.5 Å. The crystal structure has been determined to a resolution limit of 4.6 Å using a previously determined structure of the reaction center as a molecular-replacement model. The calculated electron-density maps show the presence of a manganese ion at one of the crystal contact points bridging two symmetry-related histidine residues, suggesting that the metal plays a key role in facilitating the crystallization of the protein in this form. PMID:16511142

  5. 15N electron nuclear double resonance of the primary donor cation radical P+.865 in reaction centers of Rhodopseudomonas sphaeroides: additional evidence for the dimer model.

    PubMed Central

    Lubitz, W; Isaacson, R A; Abresch, E C; Feher, G

    1984-01-01

    Four 15N hyperfine coupling constants, including signs, have been measured by electron nuclear double resonance (ENDOR) and electron nuclear nuclear triple resonance (TRIPLE) for the bacteriochlorophyll a radical cation, BChla+., in vitro and for the light-induced primary donor radical cation, P+.865, in reaction centers of Rhodopseudomonas sphaeroides R-26. A comparison of the data shows that the hyperfine coupling constants have the same sign in both radicals and are, on the average, smaller by a factor of 2 in P+.865. These results provide additional evidence that P+.865 is a bacteriochlorophyll dimer and are in contradiction with the monomer structure of P+.865 recently proposed by O'Malley and Babcock. The reduction factors of the individual 15N couplings, together with the evidence from proton ENDOR data and molecular orbital calculations, indicate a dimer structure in which only two rings (either I and I or III and III) of the bacteriochlorophyll macrocycles overlap. PMID:6096857

  6. Absence of the cbb3 Terminal Oxidase Reveals an Active Oxygen-Dependent Cyclase Involved in Bacteriochlorophyll Biosynthesis in Rhodobacter sphaeroides

    PubMed Central

    Chen, Guangyu E.; Martin, Elizabeth C.; Hunter, C. Neil

    2016-01-01

    ABSTRACT The characteristic green color associated with chlorophyll pigments results from the formation of an isocyclic fifth ring on the tetrapyrrole macrocycle during the biosynthesis of these important molecules. This reaction is catalyzed by two unrelated cyclase enzymes employing different chemistries. Oxygenic phototrophs such as plants and cyanobacteria utilize an oxygen-dependent enzyme, the major component of which is a diiron protein named AcsF, while BchE, an oxygen-sensitive [4Fe-4S] cluster protein, dominates in phototrophs inhabiting anoxic environments, such as the purple phototrophic bacterium Rhodobacter sphaeroides. We identify a potential acsF in this organism and assay for activity of the encoded protein in a strain lacking bchE under various aeration regimes. Initially, cells lacking bchE did not demonstrate AcsF activity under any condition tested. However, on removal of a gene encoding a subunit of the cbb3-type respiratory terminal oxidase, cells cultured under regimes ranging from oxic to micro-oxic exhibited cyclase activity, confirming the activity of the oxygen-dependent enzyme in this model organism. Potential reasons for the utilization of an oxygen-dependent enzyme in anoxygenic phototrophs are discussed. IMPORTANCE The formation of the E ring of bacteriochlorophyll pigments is the least well characterized step in their biosynthesis, remaining enigmatic for over 60 years. Two unrelated enzymes catalyze this cyclization step; O2-dependent and O2-independent forms dominate in oxygenic and anoxygenic phototrophs, respectively. We uncover the activity of an O2-dependent enzyme in the anoxygenic purple phototrophic bacterium Rhodobacter sphaeroides, initially by inactivation of the high-affinity terminal respiratory oxidase, cytochrome cbb3. We propose that the O2-dependent form allows for the biosynthesis of a low level of bacteriochlorophyll under oxic conditions, so that a rapid initiation of photosynthetic processes is possible for

  7. Differences in the binding of the primary quinone receptor in Photosystem I and reaction centres of Rhodobacter sphaeroides-R26 studied with transient EPR spectroscopy

    NASA Astrophysics Data System (ADS)

    van der Est, A.; Sieckmann, I.; Lubitz, W.; Stehlik, D.

    1995-05-01

    The binding of the primary quinone acceptor, Q, in Photosystem I (PS I) and reaction centres (RC's) of Rhodobacter Sphaeroide-R26 in which, the non-heme iron has been replaced by zinc (Zn-bRC's) is studied using transient EPR spectroscopy. In PS I, Q is phylloquinone (vitamin K 1, VK 1) and is referred to as A 1. In Zn-bRC's, it is ubiquinone-10 (UQ 10) and called Q A. Native samples of the two RC's as well as those in which A 1 and Q A have been replaced by perdeuterated napthoquinone (NQ- d6) and duroquinone (DQ- d12) are compared. The spin polarized K-band (24 GHz) spectra of the charge separated state P +.Q -. (P = primary chlorophyll donor) in Zn-bRC's show that substitution of Q A, with NQ- d6 and DQ- d12 does not have a measurable effect on the quinone orientation in the Q A site. In contrast, large differences in the orientation of VK 1, NQ- d6 and DQ- d12 in the A 1 site in PS I are found. In addition, all three quinones in PS I are oriented differently than Q A in Zn-bRC's. Further, the x and y principal values of the g-tensors of VK 1-., NQ -. and DQ -. in PS I are shown to be significantly larger than in frozen alcohol and Zn-bRC's. It is suggested that the differences in the orientation and a g-values of the quinones in the two RC's arise from a weaker binding to the protein in PS I.

  8. The nature of the lower excited state of the special pair of bacterial photosynthetic reaction center of Rhodobacter Sphaeroides and the dynamics of primary charge separation

    NASA Astrophysics Data System (ADS)

    Ivashin, N. V.; Shchupak, E. E.

    2016-08-01

    Quantum-chemical calculations of the structure in the ground and lower singlet excited states and the vibrations (in the ground state) of special pair P of photosynthetic reaction center of purple bacteria (RCPb) Rhodobacter Sphaeroides, consisting of two bacteriochlorophyll molecules PA and PB, have been carried out. It is shown that excitation of the special pair is followed by fast relaxation dynamics, accompanied by the transformation of the initial P* state into the P A δ+ P B δ- state (δ ~ 0.5) with charge separation. This behavior is due to the presence of several nonplanar vibrations with participation of the acetyl group of macrocycle PB in the nuclear wave packet on the potential surface of the P* state; these vibrations facilitate destabilization of the lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) of the macrocycle PA and formation of the P A δ+ P B δ- state. The structural transformations in the P* state are due to its linking character in the contact region of the acetyl group-containing pyrrole rings of PA and PB. The transition from the P* state to specifically the P A δ+ P B δ- state is related to the fact that the acetyl group PA is involved in the intermolecular hydrogen bond with amino acid residue HisL168; for this reason, this group and the pyrrole ring linked with it can hardly participate in structural transformations. The electronic matrix element H12 of the electron transfer from the special pair in the P A δ+ P B δ- state to a molecule of accessory bacteriochlorophyll BA greatly exceeds that for the transfer to BB. This circumstance and the fact that the P A δ+ P B δ- state is energetically more favorable than the P* state facilitate the preferred directionality of the electron transfer in RCPb Rhodobacter Sphaeroides with participation of the cofactors located in its subunit L.

  9. Facile solid-phase synthesis of sulfated tyrosine-containing peptides: Part II. Total synthesis of human big gastrin-II and its C-terminal glycine-extended peptide (G34-Gly sulfate) by the solid-phase segment condensation approach.

    PubMed

    Kitagawa, K; Aida, C; Fujiwara, H; Yagami, T; Futaki, S

    2001-08-01

    Application of the fluoren-9-ylmethoxycarbonyl (Fmoc)-based solid-phase segment condensation approach to the preparation of sulfated peptides was investigated through the synthesis of human big gastrin-II, a 34-residue sulfated tyrosine [Tyr(SO3H)]-containing peptide. Highly acid-sensitive 2-chlorotrityl resin (Clt resin) was exclusively employed as an anchor-resin for the preparation of the three peptide segments having the C-terminal Pro residue as well as of the Tyr(SO3H)-containing resin-bound segment. By using the PyBOP-mediated coupling protocol [PyBOP=benzotriazolyloxytris(pyrrolidino)phosphonium hexafluorophosphatel, we successively condensed each segment and constructed the 34-residue peptide-resin without any difficulty. The final acid treatment of the fully protected peptide-resin at low temperature (90% aqueous TFA, 0 degree C for 8 h), which can detach a Tyr(SO3H)-containing peptide from the resin and remove the protecting groups concurrently with minimum deterioration of the sulfate, afforded a crude sulfated peptide. After one-step HPLC purification, a highly homogeneous human big gastrin-II was easily obtained in 14% yield from the protected peptide-resin. The sulfate form of the C-terminal glycine-extended gastrin (G34-Gly sulfate), a posttranslational processing intermediate of gastrin-II, was also successfully prepared with the segment condensation approach (11% yield). These results demonstrated the usefulness of the segment condensation protocol for preparing large Tyr(SO3H)-containing peptides.

  10. Relationship of proton motive force and the F(0)F (1)-ATPase with bio-hydrogen production activity of Rhodobacter sphaeroides: effects of diphenylene iodonium, hydrogenase inhibitor, and its solvent dimethylsulphoxide.

    PubMed

    Hakobyan, Lilit; Gabrielyan, Lilit; Trchounian, Armen

    2012-08-01

    Rhodobacter sphaeroides MDC 6521 was able to produce bio-hydrogen (H(2)) in anaerobic conditions under illumination. In this study the effects of the hydrogenase inhibitor-diphenylene iodonium (Ph(2)I) and its solvent dimethylsulphoxide (DMSO) on growth characteristics and H(2) production by R. sphaeroides were investigated. The results point out the concentration dependent DMSO effect: in the presence of 10 mM DMSO H(2) yield was ~6 fold lower than that of the control. The bacterium was unable to produce H(2) in the presence of Ph(2)I. In order to examine the mediatory role of proton motive force (∆p) or the F(0)F(1)-ATPase in H(2) production by R. sphaeroides, the effects of Ph(2)I and DMSO on ∆p and its components (membrane potential (∆ψ) and transmembrane pH gradient), and ATPase activity were determined. In these conditions ∆ψ was of -98 mV and the reversed ∆pH was +30 mV, resulting in ∆p of -68 mV. Ph(2)I decreased ∆ψ in concentrations of 20 μM and higher; lower concentrations of Ph(2)I as DMSO had no valuable effect on ∆ψ. The R. sphaeroides membrane vesicles demonstrated significant ATPase activity sensitive to N,N'-dicyclohexylcarbodiimide. The 10-20 μM Ph(2)I did not affect the ATPase activity, whereas 40 μM Ph(2)I caused a marked inhibition (~2 fold) in ATPase activity. The obtained results provide novel evidence on the involvement of hydrogenase and the F(0)F(1)-ATPase in H(2) production by R. sphaeroides. Moreover, these data indicate the role of hydrogenase and the F(0)F(1)-ATPase in ∆p generation. In addition, DMSO might increase an interaction of nitrogenase with CO(2), decreasing nitrogenase activity and affecting H(2) production.

  11. Effects of the Cryptochrome CryB from Rhodobacter sphaeroides on Global Gene Expression in the Dark or Blue Light or in the Presence of Singlet Oxygen

    PubMed Central

    Frühwirth, Sebastian; Teich, Kristin; Klug, Gabriele

    2012-01-01

    Several regulators are controlling the formation of the photosynthetic apparatus in the facultatively photosynthetic bacterium Rhodobacter sphaeroides. Among the proteins affecting photosynthesis gene expression is the blue light photoreceptor cryptochrome CryB. This study addresses the effect of CryB on global gene expression. The data reveal that CryB does not only influence photosynthesis gene expression but also genes for the non-photosynthetic energy metabolism like citric acid cycle and oxidative phosphorylation. In addition several genes involved in RNA processing and in transcriptional regulation are affected by a cryB deletion. Although CryB was shown to undergo a photocycle it does not only affect gene expression in response to blue light illumination but also in response to singlet oxygen stress conditions. While there is a large overlap in these responses, some CryB-dependent effects are specific for blue-light or photooxidative stress. In addition to protein-coding genes some genes for sRNAs show CryB-dependent expression. These findings give new insight into the function of bacterial cryptochromes and demonstrate for the first time a function in the oxidative stress response. PMID:22496766

  12. Chronic exposure to Rhodobacter sphaeroides extract Lycogen™ prevents UVA-induced malondialdehyde accumulation and procollagen I down-regulation in human dermal fibroblasts.

    PubMed

    Yang, Tsai-Hsiu; Lai, Ying-Hsiu; Lin, Tsuey-Pin; Liu, Wen-Sheng; Kuan, Li-Chun; Liu, Chia-Chyuan

    2014-01-01

    UVA contributes to the pathogenesis of skin aging by downregulation of procollagen I content and induction of matrix metalloproteinase (MMP)-associated responses. Application of antioxidants such as lycopene has been demonstrated as a convenient way to achieve protection against skin aging. Lycogen™, derived from the extracts of Rhodobacter sphaeroides, exerts several biological effects similar to that of lycopene whereas most of its anti-aging efficacy remains uncertain. In this study, we attempted to examine whether Lycogen™ could suppress malondialdehyde (MDA) accumulation and restore downregulated procollagen I expression induced by UVA exposure. In human dermal fibroblasts Hs68 cells, UVA repressed cell viability and decreased procollagen I protein content accompanied with the induction of MMP-1 and MDA accumulation. Remarkably, incubation with 50 µM Lycogen™ for 24 h ameliorated UVA-induced cell death and restored UVA-induced downregulation of procollagen in a dose-related manner. Lycogen™ treatment also prevented the UVA-induced MMP-1 upregulation and intracellular MDA generation in Hs68 cells. Activation of NFκB levels, one of the downstream events induced by UVA irradiation and MMP-1 induction, were also prevented by Lycogen™ administration. Taken together, our findings demonstrate that Lycogen™ may be an alternative agent that prevents UVA-induced skin aging and could be used in cosmetic and pharmaceutical applications. PMID:24463291

  13. In vitro and in vivo safety assessment of edible blue-green algae, Nostoc commune var. sphaeroides Kützing and Spirulina plantensis

    PubMed Central

    Yang, Yue; Park, Youngki; Cassada, David A.; Snow, Daniel D.; Rogers, Douglas G.; Lee, Jiyoung

    2011-01-01

    Blue-green algae (BGA) have been consumed as food and herbal medicine for centuries. However, safety for their consumption has not been well investigated. This study was undertaken to evaluate in vitro and in vivo toxicity of cultivated Nostoc commune var. sphaeroides Kützing (NO) and Spirulina platensis (SP). Neither NO nor SP contained detectable levels of microcystin (MC)-LA, MC-RR, MC-LW and MC-LR by LC/MS/MS. Cell viability remained ~70-80% when HepG2 cells were incubated with 0-500 μg/ml of hexane, chloroform, methanol and water-extractable fractions of NO and SP. Four-week-old male and female C57BL/6J mice were fed an AIN-93G/M diet supplemented with 0, 2.5% or 5% of NO and SP (wt/wt) for 6 months. For both genders, BGA-rich diets did not induce noticeable abnormality in weight gain and plasma alanine aminotransferase (ALT) and aspartate aminotransferase concentrations except a significant increase in plasma ALT levels by 2.5% NO supplementation in male mice at 6 month. Histopathological analysis of livers, however, indicated that BGA did not cause significant liver damage compared with controls. In conclusion, our results suggest that NO and SP are free of MC and the long-term dietary supplementation of up to 5% of the BGA may be consumed without evident toxic side-effects. PMID:21473896

  14. Extending the extended V-Y flap.

    PubMed

    Prowse, Phoebe; Morton, Jonathan

    2012-06-01

    This case report demonstrates a modification of the so-called 'Extended V-Y Flap' used to simultaneously reconstruct a defect involving the upper lip, floor of nose and alar rim following tumour excision. We hope that this case serves as a reminder of the versatility of the V-Y flap in the nasolabial region, and its considerable capacity for augmentation. PMID:22018837

  15. Optical Modeling Activities for the James Webb Space Telescope (JWST) Project. II; Determining Image Motion and Wavefront Error Over an Extended Field of View with a Segmented Optical System

    NASA Technical Reports Server (NTRS)

    Howard, Joseph M.; Ha, Kong Q.

    2004-01-01

    This is part two of a series on the optical modeling activities for JWST. Starting with the linear optical model discussed in part one, we develop centroid and wavefront error sensitivities for the special case of a segmented optical system such as JWST, where the primary mirror consists of 18 individual segments. Our approach extends standard sensitivity matrix methods used for systems consisting of monolithic optics, where the image motion is approximated by averaging ray coordinates at the image and residual wavefront error is determined with global tip/tilt removed. We develop an exact formulation using the linear optical model, and extend it to cover multiple field points for performance prediction at each instrument aboard JWST. This optical model is then driven by thermal and dynamic structural perturbations in an integrated modeling environment. Results are presented.

  16. Functional Extended Redundancy Analysis

    ERIC Educational Resources Information Center

    Hwang, Heungsun; Suk, Hye Won; Lee, Jang-Han; Moskowitz, D. S.; Lim, Jooseop

    2012-01-01

    We propose a functional version of extended redundancy analysis that examines directional relationships among several sets of multivariate variables. As in extended redundancy analysis, the proposed method posits that a weighed composite of each set of exogenous variables influences a set of endogenous variables. It further considers endogenous…

  17. Extended or Restricted Childhood?

    ERIC Educational Resources Information Center

    Richards, Colin

    2005-01-01

    This article discusses the Government's proposals for "extended" primary schools, an important element in the recently-published five-year plan for education. The author expresses concern that extended primary schools will not provide a variety of experiences, including "play" experiences for young children.

  18. Extended conformal field theories

    NASA Astrophysics Data System (ADS)

    Taormina, Anne

    1990-08-01

    Some extended conformal field theories are briefly reviewed. They illustrate how non minimal models of the Virasoro algebra (c≥1) can become minimal with respect to a larger algebra. The accent is put on N-extended superconformal algebras, which are relevant in superstring compactification.

  19. Role of the global transcriptional regulator PrrA in Rhodobacter sphaeroides 2.4.1: combined transcriptome and proteome analysis

    SciTech Connect

    Eraso, Jesus M.; Roh, Jung Hyeob; Zeng, Xiaohua; Callister, Stephen J.; Lipton, Mary S.; Kaplan, Samuel

    2008-07-01

    The PrrBA two-component regulatory system is a major global regulator in Rhodobacter sphaeroides 2.4.1. In this study we have compared the transcriptome and proteome profiles of the wild type (WT) and mutant PrrA2 cells grown anaerobically, in the dark, with DMSO as electron acceptor. Approximately 25% of the genes present in the genome are PrrA-regulated, at the transcriptional level, either directly or indirectly, by ≥ 2-fold relative to wild type. The genes affected are widespread throughout all COG functional categories, with previously unsuspected “metabolic” genes affected when in the PrrA mutant background. PrrA was found to act both as an activator and a repressor of transcription, with more genes being repressed in the presence of PrrA (9:5 ratio). An analysis of the genes encoding the 1,536 peptides detected through our chromatographic study, which corresponds to 36% coverage of the genome, revealed that approximately 20% of the genes encoding these proteins were positively regulated, whereas approximately 32% were negatively regulated by PrrA, which is in excellent agreement with the percentages obtained for the whole genomic transcriptome profile. In addition, comparison of the transcriptome and proteome mean parameter values chosen between WT and PrrA2 showed good qualitative agreement, indicating that transcript regulation paralleled the corresponding protein abundance, although not one for one. The microarray analysis was validated by direct mRNA measurement of randomly selected, both positively and negatively regulated genes. lacZ transcriptional and kan translational fusions enabled us to map putative PrrA binding sites, as well as revealing potential gene targets for indirect regulation by PrrA.

  20. Interaction between Cytochrome c2 and Photosynthetic Reaction Center from Rhodobacter sphaeroides: Role of Inter- Protein Hydrogen Bonds in Binding and Electron Transfer †

    PubMed Central

    Abresch, Edward C.; Paddock, Mark L.; Villalobos, Miguel; Chang, Charlene; Okamura, Melvin Y.

    2008-01-01

    The role of short-range hydrogen bond interactions at the interface between electron transfer proteins cytochrome c2 (cyt) and reaction center (RC) from Rb. sphaeroides was studied by mutation (to Ala) of RC residues Asn M187, Asn M188 and Gln L258 which form inter-protein hydrogen bonds to cyt in the cyt:RC complex. The largest decrease in binding constant KA (8-fold) for single mutation was observed for Asn M187, which forms an intra-protein hydrogen bond to the key residue Tyr L162 in the center of the contact region having low solvent accessibility. Interaction between Asn M187 and Tyr L162 was also implicated in binding by double mutation of the two residues. The hydrogen bond mutations did not significantly change the second order rate constant, k2 , indicating the mutations did not change the association rate for forming the cyt:RC complex, but increased the dissociation rate. The first order electron transfer rate, ke, for the cyt:RC complex was reduced by up to a factor of 4 (for Asn M187). The changes in ke were correlated with the changes in binding affinity but were not accompanied by increases in activation energy. We conclude that short-range hydrogen bond interactions contribute to the close packing of residues in the central contact region between the cyt and RC near Asn M187 and Tyr L162. The close packing contributes to fast electron transfer by increasing the electronic coupling and contributes to the binding energy holding the cyt in position for times long enough for electron transfer to occur. PMID:19053264

  1. Examination of stability of mutant photosynthetic reaction center of Rhodobacter sphaeroides I(L177)H and determination of location of bacteriochlorophyll covalently bound to the protein.

    PubMed

    Fufina, T Y; Vasilieva, L G; Shuvalov, V A

    2010-02-01

    We demonstrated earlier that as a result of the I(L177)H mutation in the photosynthetic reaction center (RC) of the bacterium Rhodobacter sphaeroides, one of the bacteriochlorophylls (BChl) binds with the L-subunit, simultaneously raising coordination stability of the central magnesium atom of the bacteriochlorophyll associated with the protein. In this study, spectral properties of wild type RC and I(L177)H in the presence of urea and SDS as well as at 48 degrees C were examined. It is shown that the I(L177)H mutation decreases the RC stability. Under denaturing conditions, some changes indicating breakdown of oligomeric structure of the complex and loss of interaction between pigments and their protein environment are observed in I(L177)H RC spectra. In addition, pheophytinization of bacteriochlorophylls occurs in both types of RC in the presence of SDS. However, an 811-nm band is observed in the spectrum of the mutant RC under these conditions, which indicates retention of one of the BChl molecules in the protein binding site and stable coordination of its central magnesium atom. It is shown that in both types of RC, monomeric BChl B(B) can be modified by sodium borohydride treatment and then extracted by acetone-methanol mixture. Spectral properties of the BChl covalently bound with the protein in I(L177)H RC do not change. The results demonstrate that BChl P(A) is the molecule of BChl tightly bound with the L-subunit in mutant RC as it was supposed earlier. PMID:20367608

  2. Electron-Transfer Secondary Reaction Matrices for MALDI MS Analysis of Bacteriochlorophyll a in Rhodobacter sphaeroides and Its Zinc and Copper Analogue Pigments

    NASA Astrophysics Data System (ADS)

    Calvano, Cosima Damiana; Ventura, Giovanni; Trotta, Massimo; Bianco, Giuliana; Cataldi, Tommaso R. I.; Palmisano, Francesco

    2016-10-01

    Bacteriochlorophyll a (BChl a), a photosynthetic pigment performing the same functions of chlorophylls in plants, features a bacteriochlorin macrocycle ring (18 π electrons) with two reduced pyrrole rings along with a hydrophobic terpenoid side chain (i.e., the phytol residue). Chlorophylls analysis by matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) is not so straightforward since pheophytinization (i.e., release of the central metal ion) and cleavage of the phytol-ester linkage are invariably observed by employing protonating matrices such as 2,5-dihydroxybenzoic acid, sinapinic acid, and α-cyano-4-hydroxycinnamic acid. Using BChl a from Rhodobacter sphaeroides R26 strain as a model system, different electron-transfer (ET) secondary reaction matrices, leading to the formation of almost stable radical ions in both positive ([M]+•) and negative ([M]-•) ionization modes at m/z 910.55, were evaluated. Compared with ET matrices such as trans-2-[3-(4-t-butyl-phenyl)-2-methyl-2-propenylidene]malononitrile (DCTB), 2,2':5',2''-terthiophene (TER), anthracene (ANT), and 9,10-diphenylanthracene (DP-ANT), 1,5-diaminonaphthalene (DAN) was found to provide the highest ionization yield with a negligible fragmentation. DAN also displayed excellent ionization properties for two metal ion-substituted bacteriochlorophylls, (i.e., Zn- and Cu-BChl a at m/z 950.49 and 949.49), respectively. MALDI MS/MS of both radical charged molecular species provide complementary information, thus making analyte identification more straightforward.

  3. Mutation-Induced Changes in the Protein Environment and Site Energies in the (M)L214G Mutant of the Rhodobacter sphaeroides Bacterial Reaction Center.

    PubMed

    Jankowiak, Ryszard; Rancova, Olga; Chen, Jinhai; Kell, Adam; Saer, Rafael G; Beatty, J Thomas; Abramavicius, Darius

    2016-08-18

    This work focuses on the low-temperature (5 K) photochemical (transient) hole-burned (HB) spectra within the P870 absorption band, and their theoretical analysis, for the (M)L214G mutant of the photosynthetic Rhodobacter sphaeroides bacterial reaction center (bRC). To provide insight into system-bath interactions of the bacteriochlorophyll a (BChl a) special pair, i.e., P870, in the mutated bRC, the optical line shape function for the P870 band is calculated numerically. On the basis of the modeling studies, we demonstrate that (M)L214G mutation leads to a heterogeneous population of bRCs with modified (increased) total electron-phonon coupling strength of the special pair BChl a and larger inhomogeneous broadening. Specifically, we show that after mutation in the (M)L214G bRC a large fraction (∼50%) of the bacteriopheophytin (HA) chromophores shifts red and the 800 nm absorption band broadens, while the remaining fraction of HA cofactors retains nearly the same site energy as HA in the wild-type bRC. Modeling using these two subpopulations allowed for fits of the absorption and nonresonant (transient) HB spectra of the mutant bRC in the charge neutral, oxidized, and charge-separated states using the Frenkel exciton Hamiltonian, providing new insight into the mutant's complex electronic structure. Although the average (M)L214G mutant quantum efficiency of P(+)QA(-) state formation seems to be altered in comparison with the wild-type bRC, the average electron transfer time (measured via resonant transient HB spectra within the P870 band) was not affected. Thus, mutation in the vicinity of the electron acceptor (HA) does not tune the charge separation dynamics. Finally, quenching of the (M)L214G mutant excited states by P(+) is addressed by persistent HB spectra burned within the B band in chemically oxidized samples.

  4. Kinetic phases in the electron transfer from P+QA-QB to P+QAQB- and the associated processes in Rhodobacter sphaeroides R-26 reaction centers.

    PubMed

    Li, J; Gilroy, D; Tiede, D M; Gunner, M R

    1998-03-01

    Electron transfer from P+QA-QB to form P+QAQB- was measured in Rhodobacter sphaeroides R-26 reaction centers (RCs) where the native primary quinone, ubiquinone-10 (UQA), was replaced by 2-methyl-3-phytyl-1,4-naphthoquinone (MQA). The native secondary quinone, UQ-10, was retained as UQB. The difference spectrum of the semiquinone MQA- minus UQB- absorption is very similar to that of MQ- minus UQ- in solution (398-480 nm). Thus, the absorption change provides a direct monitor of the electron transfer from MQA- to UQB. In contrast, when both QA and QB are UQ-10 the spectral difference between UQA- and UQB- arises from electrochromic responses of RC chromophores. Three kinetic processes are seen in the near UV (390-480 nm) and near-IR (740-820 nm). Analysis of the time-correlated spectra support the conclusion that the changes at tau1 approximately 3 micros are mostly due to electron transfer, electron transfer and charge compensation are mixed in tau2 approximately 80 micros, while little or no electron transfer occurs at 200-600 micros (tau3) in MQAUQB RCs. The 80-micros rate has been previously observed, while the fast component has not. The fast phase represents 60% of the electron-transfer reaction (398 nm). The activation energy for electron transfer is DeltaG approximately 3.5 kcal/mol for both tau1 and tau2 between 0 and 30 degrees C. In isolated RCs with UQA, if there is any fast component, it appears to be faster and less important than in the MQA reconstituted RCs.

  5. The role of an extra fragment of cytochrome b (residues 309-326) in the cytochrome bc1 complex from Rhodobacter sphaeroides.

    PubMed

    Gong, Xing; Yu, Linda; Yu, Chang-An

    2006-09-19

    In bacterial cytochrome b of the cytochrome bc(1) complex, there is an extra fragment located between the amphipathic helix ef and the transmembrane helix F compared to the mitochondrial counterparts. In this work, mutants at various positions of this extra fragment were generated in Rhodobacter sphaeroides in an effort to investigate its specific role in the bacterial bc(1) complex. The total deletion [cytb-Delta(309-326)] and alanine substitution [cytb-(309-326)A] mutant complexes have about 20% of the bc(1) activity found in the wild-type complex. Mutant complexes of cytb-(309-311)A, cytb-(312-314)A, cytb-(315-317)A, cytb-(318-321)A, cytb-(322-323)A, cytb-(324-326)A, cytb-(F323A), and cytb-(S322A) have respectively 87%, 85%, 89%, 100%, 32%, 90%, 100%, and 32% of the bc(1) activity, indicating that the S322 of cytochrome b is important. EPR spectral analysis reveals that the [2Fe-2S] cluster in the cytb-(S322A) mutant complex has a broadened and shifted g(x)() signal (g = 1.76). The rate of superoxide anion (O(2)(*)(-)) generation is 4 times higher in the cytb-(S322A) mutant complex than in the wild-type or mutant complexes of S322T, S322Y, or S322C. These results support the idea that alanine substitution at S322 of cytochrome b causes conformational changes at the Q(o) site by weakening the binding between cytochrome b and ISP through hydrogen bonding provided by the hydroxyl group of this residue. This change facilitates electron leakage from the Q(o) site for reaction with molecular oxygen to form superoxide anion, thus decreasing bc(1) activity.

  6. Extending mine life

    SciTech Connect

    Not Available

    1984-06-01

    Mine layouts, new machines and techniques, research into problem areas of ground control and so on, are highlighted in this report on extending mine life. The main resources taken into account are coal mining, uranium mining, molybdenum and gold mining.

  7. Dicyanometallates as Model Extended Frameworks

    PubMed Central

    2016-01-01

    We report the structures of eight new dicyanometallate frameworks containing molecular extra-framework cations. These systems include a number of hybrid inorganic–organic analogues of conventional ceramics, such as Ruddlesden–Popper phases and perovskites. The structure types adopted are rationalized in the broader context of all known dicyanometallate framework structures. We show that the structural diversity of this family can be understood in terms of (i) the charge and coordination preferences of the particular metal cation acting as framework node, and (ii) the size, shape, and extent of incorporation of extra-framework cations. In this way, we suggest that dicyanometallates form a particularly attractive model family of extended frameworks in which to explore the interplay between molecular degrees of freedom, framework topology, and supramolecular interactions. PMID:27057759

  8. Light-dependent regulation of photosynthesis genes in Rhodobacter sphaeroides 2.4.1 is coordinately controlled by photosynthetic electron transport via the PrrBA two-component system and the photoreceptor AppA.

    PubMed

    Happ, Hendrik N; Braatsch, Stephan; Broschek, Vera; Osterloh, Lisa; Klug, Gabriele

    2005-11-01

    Formation of the photosynthetic apparatus in Rhodobacter is regulated by oxygen tension and light intensity. Here we show that in anaerobically grown Rhodobacter cells a light-dependent increase in expression of the puc and puf operons encoding structural proteins of the photosynthetic complexes requires an active photosynthetic electron transport. The redox-sensitive CrtJ/PpsR repressor of photosynthesis genes, which was suggested to mediate electron transport-dependent signals, is not involved in this light-dependent signal chain. Our data reveal that the signal initiated in the photosynthetic reaction centre is transmitted via components of the electron transport chain and the PrrB/PrrA two-component system in Rhodobacter sphaeroides. Under blue light illumination in the absence of oxygen this signal leads to activation of photosynthesis genes and interferes with a blue-light repression mediated by the AppA photoreceptor and the PpsR transcriptional repressor in R. sphaeroides. Thus, light either sensed by a photoreceptor or initiating photosynthetic electron transport has opposite effects on the transcription of photosynthesis genes. Both signalling pathways involve redox-dependent steps that finally determine the effect of light on gene expression.

  9. Extended lifetime railgap switch

    SciTech Connect

    Cohn, D.B.; Mendoza, P.J.

    1988-02-02

    In a railgap switch of the type having an elongate blade electrode made of conductive material, an elongate housing made of insulating material for supporting the blade electrode and plate electrode in opposed relation extending in the same direction with the blade centered over the plate and separated therefrom by a gap, and a gas filling the housing and the gap, the gas being selected to breakdown and switch from a highly insulative state to a highly conductive state upon application of a high voltage across the blade and plate electrodes, the improvement is described comprising: forming the blade with laterally extending transverse wing portions at the edge of the blade and adjacent the gap so as to extend in spaced parallel relation to the surface of the plate, the blade generally following the contour thereof to form an inverted T-shape structure with the wing portions extending transversely of the elongate dimension of the blade. The wing portions terminating in a pair of spaced parallel edges extending along the elongate direction of the blade to thereby create two spaced elongate edges along which arcs form serving to divide the erosion effects of discharge between them, the current through each edge being one-half of that in single-edge devices with ablation wear reduced accordingly to give significantly larger switch lifetime. The blade and wing portions limiting ablation erosion of the edges in a direction generally align with the plate contour so that the edge-to-plate separation remains substantially constant.

  10. Extending quantum mechanics entails extending special relativity

    NASA Astrophysics Data System (ADS)

    Aravinda, S.; Srikanth, R.

    2016-05-01

    The complementarity between signaling and randomness in any communicated resource that can simulate singlet statistics is generalized by relaxing the assumption of free will in the choice of measurement settings. We show how to construct an ontological extension for quantum mechanics (QMs) through the oblivious embedding of a sound simulation protocol in a Newtonian spacetime. Minkowski or other intermediate spacetimes are ruled out as the locus of the embedding by virtue of hidden influence inequalities. The complementarity transferred from a simulation to the extension unifies a number of results about quantum non-locality, and implies that special relativity has a different significance for the ontological model and for the operational theory it reproduces. Only the latter, being experimentally accessible, is required to be Lorentz covariant. There may be certain Lorentz non-covariant elements at the ontological level, but they will be inaccessible at the operational level in a valid extension. Certain arguments against the extendability of QM, due to Conway and Kochen (2009) and Colbeck and Renner (2012), are attributed to their assumption that the spacetime at the ontological level has Minkowski causal structure.

  11. Physical properties of galaxies and their evolution in the VIMOS VLT Deep Survey. II. Extending the mass-metallicity relation to the range z ≈ 0.89-1.24

    NASA Astrophysics Data System (ADS)

    Pérez-Montero, E.; Contini, T.; Lamareille, F.; Brinchmann, J.; Walcher, C. J.; Charlot, S.; Bolzonella, M.; Pozzetti, L.; Bottini, D.; Garilli, B.; Le Brun, V.; Le Fèvre, O.; Maccagni, D.; Scaramella, R.; Scodeggio, M.; Tresse, L.; Vettolani, G.; Zanichelli, A.; Adami, C.; Arnouts, S.; Bardelli, S.; Cappi, A.; Ciliegi, P.; Foucaud, S.; Franzetti, P.; Gavignaud, I.; Guzzo, L.; Ilbert, O.; Iovino, A.; McCracken, H. J.; Marano, B.; Marinoni, C.; Mazure, A.; Meneux, B.; Merighi, R.; Paltani, S.; Pellò, R.; Pollo, A.; Radovich, M.; Vergani, D.; Zamorani, G.; Zucca, E.

    2009-02-01

    Aims: We present a continuation of our study about the relation between stellar mass and gas-phase metallicity in the VIMOS VLT Deep Survey (VVDS). In this work we extend the determination of metallicities up to redshift ≈1.24 for a sample of 42 star-forming galaxies with a mean redshift value of 0.99. Methods: For a selected sample of emission-line galaxies, we use both diagnostic diagrams and empirical calibrations based on [Oii] emission lines along with the empirical relation between the intensities of the [Oiii] and [Neiii] emission lines and the theoretical ratios between Balmer recombination emission lines to identify star-forming galaxies and to derive their metallicities. We derive stellar masses by fitting the whole spectral energy distribution with a set of stellar population synthesis models. Results: These new methods allow us to extend the mass-metallicity relation to higher redshift. We show that the metallicity determinations are consistent with more established strong-line methods. Taken together this allows us to study the evolution of the mass-metallicity relation up to z ≈ 1.24 with good control of systematic uncertainties. We find an evolution with redshift of the average metallicity of galaxies very similar to those reported in the literature: for a given stellar mass, galaxies at z ~ 1 have, on average, a metallicity ~ 0.3 dex lower than galaxies in the local universe. However we do not see any significant metallicity evolution between redshifts z ~ 0.7 (Paper I) and z ~ 1.0 (this paper). We find also the same flattening of the mass-metallicity relation for the most massive galaxies as reported in Paper I at lower redshifts, but again no apparent evolution of the slope is seen between z ~ 0.7 and z ~ 1.0. Based on data obtained with the European Southern Observatory Very Large Telescope, Paranal, Chile, program 070.A-9007, and on data obtained at the Canada-France-Hawaii Telescope, operated by the CNRS in France, CNRC in Canada and the

  12. Extendable pipe crawler

    DOEpatents

    Hapstack, Mark

    1991-01-01

    A pipe crawler having a front leg assembly and a back leg assembly connected together by two air cylinders, each leg assembly having four extendable legs and a pair of actuators for sliding the extendable legs radially outward to increase the range of the legs when the pipe crawler enters a section of a pipe having a larger diameter. The crawler crawls by "inchworm"-like motion, the front leg assembly and back leg assembly alternately engaging and disengaging the wall of the pipe to hold the pipe crawler as the air cylinders alternately advance the front leg assembly and bring up the rear leg assembly. The pair of actuators of each leg assembly are parallel, adjacent and opposing acting so that each slides two adjacent extendable legs radially outward.

  13. Extendable pipe crawler

    DOEpatents

    Hapstack, M.

    1991-05-28

    A pipe crawler is described having a front leg assembly and a back leg assembly connected together by two air cylinders, each leg assembly having four extendable legs and a pair of actuators for sliding the extendable legs radially outward to increase the range of the legs when the pipe crawler enters a section of a pipe having a larger diameter. The crawler crawls by inchworm'-like motion, the front leg assembly and back leg assembly alternately engaging and disengaging the wall of the pipe to hold the pipe crawler as the air cylinders alternately advance the front leg assembly and bring up the rear leg assembly. The pair of actuators of each leg assembly are parallel, adjacent and opposing acting so that each slides two adjacent extendable legs radially outward. 5 figures.

  14. An Extended Duopoly Game.

    ERIC Educational Resources Information Center

    Eckalbar, John C.

    2002-01-01

    Illustrates how principles and intermediate microeconomic students can gain an understanding for strategic price setting by playing a relatively large oligopoly game. Explains that the game extends to a continuous price space and outlines appropriate applications. Offers the Mathematica code to instructors so that the assumptions of the game can…

  15. Towards Extended Vantage Theory

    ERIC Educational Resources Information Center

    Glaz, Adam

    2010-01-01

    The applicability of Vantage Theory (VT), a model of (colour) categorization, to linguistic data largely depends on the modifications and adaptations of the model for the purpose. An attempt to do so proposed here, called Extended Vantage Theory (EVT), slightly reformulates the VT conception of vantage by capitalizing on some of the entailments of…

  16. Extended artistic appreciation.

    PubMed

    Wilson, Robert A

    2013-04-01

    I propose that in at least some cases, objects of artistic appreciation are best thought of not simply as causes of artistic appreciation, but as parts of the cognitive machinery that drives aesthetic appreciation. In effect, this is to say that aesthetic appreciation operates via extended cognitive systems.

  17. Partial Steps of Charge Translocation in the Non-Pumping Mutant N139L of Rhodobacter Sphaeroides Cytochrome C Oxidase with a Blocked D-Channel

    PubMed Central

    Siletsky, Sergey A.; Zhu, Jiapeng; Gennis, Robert B.; Konstantinov, Alexander A.

    2010-01-01

    N139L substitution in D-channel of cytochrome oxidase from Rhodobacter sphaeroides results in a ∼15-fold decrease of turnover number and in loss of proton pumping. Time-resolved absorption and electrometric assays of the F→O transition in the N139L mutant oxidase result in 3 major findings. (1) Oxidation of the reduced enzyme by O2 shows ∼200-fold inhibition of the F→O step (k ∼ 2 s-1 at pH 8) which is not compatible with the enzyme turnover (∼30 s-1). Presumably, an abnormal intermediate Fdeprotonated is formed under these conditions, one proton-deficient relative to a normal F-state. In contrast, the F→O transition in N139L oxidase induced by single-electron photoreduction of intermediate F, generated by reaction of the oxidized enzyme with H2O2, decelerates to an extent compatible with enzyme turnover. (2) In the N139L, the protonic phase of Δψ-generation coupled to the flash-induced F→O transition greatly decreases in rate and magnitude and can be assigned to proton movement from E286 to the binuclear site, required for reduction of heme a3 from Fe4+=O2- to Fe3+-OH- state. Electrogenic reprotonation of E286 from the inner aqueous phase is missing from the F→O step in the mutant. (3) In the N139L, the KCN-insensitive rapid electrogenic phase may be actually composed of two components with lifetimes of ∼10 and ∼40 μs and the magnitude ratio of ∼3:2, respectively. The 10 μs phase matches vectorial electron transfer from CuA to heme a, whereas the 40 μs component is assigned to intraprotein proton displacement across ∼20% of the membrane dielectric thickness. This proton displacement might be triggered by rotation of the charged K362 side-chain coupled to heme a reduction. The two components of the rapid electrogenic phase have been resolved subsequently with other D-channel mutants as well as with cyanide-inhibited wild-type oxidase. The finding helps to reconcile the unusually high relative contribution of the microsecond

  18. Propelling Extended Objects

    ERIC Educational Resources Information Center

    Humbert, Richard

    2010-01-01

    A force acting on just part of an extended object (either a solid or a volume of a liquid) can cause all of it to move. That motion is due to the transmission of the force through the object by its material. This paper discusses how the force is distributed to all of the object by a gradient of stress or pressure in it, which creates the local…

  19. Binuclear Complexes and Extended Chains Featuring Pt(II)-Tl(I) Bonds: Influence of the Pyridine-2-Thiolate and Cyclometalated Ligands on the Self-Assembly and Luminescent Behavior.

    PubMed

    Berenguer, Jesús R; Lalinde, Elena; Martín, Antonio; Moreno, M Teresa; Sánchez, Sergio; Shahsavari, Hamid R

    2016-08-15

    Platinum solvate complexes [Pt(C6F5)(C^N)(S)] [C^N = phenylpyridinyl (ppy), S = dimethyl sulfoxide (DMSO) (A); C^N = benzoquinolinyl (bzq), S = CH3COCH3 (B)] react with [Tl(Spy)] (Spy = 2-pyridinethiolate) to afford binuclear [{Pt(C6F5)(C^N)}Tl(Spy)] [C^N = ppy (1) and bzq (2)] species containing a Pt-Tl bonding interaction, supported by a μ-Spy-κN,S bridging ligand, as confirmed by X-ray diffraction. However, the related reactions with [Tl(SpyCF3-5)] [SpyCF3-5 = 5-(trifluoromethyl)-2-pyridinethiolate] give neutral extended chains [{Pt(C6F5)(C^N)}Tl(SpyCF3-5)]n [C^N = ppy (3) and bzq (4)]. 3 features a zigzag -Pt-Tl···S-Pt- chain, generated by Pt-Tl and Tl···S bonds, with the SpyCF3 acting as a μ-κN:κ(2)S bridging ligand, whereas 4 displays an unsupported ···Tl-Pt···Tl-Pt··· backbone (angle of ca. 158.7°). The lowest-energy absorption bands in the UV-vis spectra in CH2Cl2, associated with (1)L'LCT transitions with minor (1)LC/(1)MLCT (L' = Spy or SpyCF3-5; L = C^N) character, are similar for all complexes 1-4, demonstrating that for 3 and 4 the chains break down in solution to yield similar bimetallic Pt-Tl units. For 2, two different forms, 2-o (orange) and 2-y (yellow), exhibiting different colors and emissions were found depending on the isolation conditions. Slow crystallization favors formation of the thermodynamically more stable yellow form (2-y), which exhibits a high-energy (HE) structured emission band, whereas fast crystallization gives rise to the orange form (2-o), with a remarkably lower energy structureless emission. Complexes 1 and 3 exhibit dual luminescence in the solid state at 298 K: an unstructured low-energy band associated with (3)ππ* excimeric emission due to π···π (C^N) interactions and a more structured HE band, assigned, with support of density functional theory calculations, to an intraligand (3)LC (C^N) excited state mixed with some ligand (SPy)/platinum-to-ligand (C^N)(3)[(L' + M)LCT] charge transfer. Chain

  20. Binuclear Complexes and Extended Chains Featuring Pt(II)-Tl(I) Bonds: Influence of the Pyridine-2-Thiolate and Cyclometalated Ligands on the Self-Assembly and Luminescent Behavior.

    PubMed

    Berenguer, Jesús R; Lalinde, Elena; Martín, Antonio; Moreno, M Teresa; Sánchez, Sergio; Shahsavari, Hamid R

    2016-08-15

    Platinum solvate complexes [Pt(C6F5)(C^N)(S)] [C^N = phenylpyridinyl (ppy), S = dimethyl sulfoxide (DMSO) (A); C^N = benzoquinolinyl (bzq), S = CH3COCH3 (B)] react with [Tl(Spy)] (Spy = 2-pyridinethiolate) to afford binuclear [{Pt(C6F5)(C^N)}Tl(Spy)] [C^N = ppy (1) and bzq (2)] species containing a Pt-Tl bonding interaction, supported by a μ-Spy-κN,S bridging ligand, as confirmed by X-ray diffraction. However, the related reactions with [Tl(SpyCF3-5)] [SpyCF3-5 = 5-(trifluoromethyl)-2-pyridinethiolate] give neutral extended chains [{Pt(C6F5)(C^N)}Tl(SpyCF3-5)]n [C^N = ppy (3) and bzq (4)]. 3 features a zigzag -Pt-Tl···S-Pt- chain, generated by Pt-Tl and Tl···S bonds, with the SpyCF3 acting as a μ-κN:κ(2)S bridging ligand, whereas 4 displays an unsupported ···Tl-Pt···Tl-Pt··· backbone (angle of ca. 158.7°). The lowest-energy absorption bands in the UV-vis spectra in CH2Cl2, associated with (1)L'LCT transitions with minor (1)LC/(1)MLCT (L' = Spy or SpyCF3-5; L = C^N) character, are similar for all complexes 1-4, demonstrating that for 3 and 4 the chains break down in solution to yield similar bimetallic Pt-Tl units. For 2, two different forms, 2-o (orange) and 2-y (yellow), exhibiting different colors and emissions were found depending on the isolation conditions. Slow crystallization favors formation of the thermodynamically more stable yellow form (2-y), which exhibits a high-energy (HE) structured emission band, whereas fast crystallization gives rise to the orange form (2-o), with a remarkably lower energy structureless emission. Complexes 1 and 3 exhibit dual luminescence in the solid state at 298 K: an unstructured low-energy band associated with (3)ππ* excimeric emission due to π···π (C^N) interactions and a more structured HE band, assigned, with support of density functional theory calculations, to an intraligand (3)LC (C^N) excited state mixed with some ligand (SPy)/platinum-to-ligand (C^N)(3)[(L' + M)LCT] charge transfer. Chain

  1. Extended optical model for fission

    DOE PAGESBeta

    Sin, M.; Capote, R.; Herman, M. W.; Trkov, A.

    2016-03-07

    A comprehensive formalism to calculate fission cross sections based on the extension of the optical model for fission is presented. It can be used for description of nuclear reactions on actinides featuring multi-humped fission barriers with partial absorption in the wells and direct transmission through discrete and continuum fission channels. The formalism describes the gross fluctuations observed in the fission probability due to vibrational resonances, and can be easily implemented in existing statistical reaction model codes. The extended optical model for fission is applied for neutron induced fission cross-section calculations on 234,235,238U and 239Pu targets. A triple-humped fission barrier ismore » used for 234,235U(n,f), while a double-humped fission barrier is used for 238U(n,f) and 239Pu(n,f) reactions as predicted by theoretical barrier calculations. The impact of partial damping of class-II/III states, and of direct transmission through discrete and continuum fission channels, is shown to be critical for a proper description of the measured fission cross sections for 234,235,238U(n,f) reactions. The 239Pu(n,f) reaction can be calculated in the complete damping approximation. Calculated cross sections for 235,238U(n,f) and 239Pu(n,f) reactions agree within 3% with the corresponding cross sections derived within the Neutron Standards least-squares fit of available experimental data. Lastly, the extended optical model for fission can be used for both theoretical fission studies and nuclear data evaluation.« less

  2. Extended Testability Analysis Tool

    NASA Technical Reports Server (NTRS)

    Melcher, Kevin; Maul, William A.; Fulton, Christopher

    2012-01-01

    The Extended Testability Analysis (ETA) Tool is a software application that supports fault management (FM) by performing testability analyses on the fault propagation model of a given system. Fault management includes the prevention of faults through robust design margins and quality assurance methods, or the mitigation of system failures. Fault management requires an understanding of the system design and operation, potential failure mechanisms within the system, and the propagation of those potential failures through the system. The purpose of the ETA Tool software is to process the testability analysis results from a commercial software program called TEAMS Designer in order to provide a detailed set of diagnostic assessment reports. The ETA Tool is a command-line process with several user-selectable report output options. The ETA Tool also extends the COTS testability analysis and enables variation studies with sensor sensitivity impacts on system diagnostics and component isolation using a single testability output. The ETA Tool can also provide extended analyses from a single set of testability output files. The following analysis reports are available to the user: (1) the Detectability Report provides a breakdown of how each tested failure mode was detected, (2) the Test Utilization Report identifies all the failure modes that each test detects, (3) the Failure Mode Isolation Report demonstrates the system s ability to discriminate between failure modes, (4) the Component Isolation Report demonstrates the system s ability to discriminate between failure modes relative to the components containing the failure modes, (5) the Sensor Sensor Sensitivity Analysis Report shows the diagnostic impact due to loss of sensor information, and (6) the Effect Mapping Report identifies failure modes that result in specified system-level effects.

  3. Extended Wordsearches in Chemistry

    NASA Astrophysics Data System (ADS)

    Cotton, Simon

    1998-04-01

    Students can be encouraged to develop their factual knowledge by use of puzzles. One strategy described here is the extended wordsearch, where the wordsearch element generates a number of words or phrases from which the answers to a series of questions are selected. The wordsearch can be generated with the aid of computer programs, though in order to make them suitable for students with dyslexia or other learning difficulties, a simpler form is more appropriate. These problems can be employed in a variety of contexts, for example, as topic tests and classroom end-of-lesson fillers. An example is provided in the area of calcium chemistry. Sources of suitable software are listed.

  4. Low-temperature interquinone electron transfer in photosynthetic reaction centers from Rhodobacter sphaeroides and Blastochloris viridis: characterization of Q(B)- states by high-frequency electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR).

    PubMed

    Utschig, Lisa M; Thurnauer, Marion C; Tiede, David M; Poluektov, Oleg G

    2005-11-01

    High-frequency electron paramagnetic resonance (HF EPR) techniques have been employed to look for localized light-induced conformational changes in the protein environments around the reduced secondary quinone acceptor (Q(B)(-)) in Rhodobacter sphaeroides and Blastochloris viridis RCs. The Q(A)(-) and Q(B)(-) radical species in Fe-removed/Zn-replaced protonated RCs substituted with deuterated quinones are distinguishable with pulsed D-band (130 GHz) EPR and provide native probes of both the low-temperature Q(A)(-)Q(B) --> Q(A)Q(B)(-) electron-transfer event and the structure of trapped conformational substates. We report here the first spectroscopic evidence that cryogenically trapped, light-induced changes enable low-temperature Q(A)(-)Q(B) --> Q(A)Q(B)(-) electron transfer in the B. viridis RC and the first observation of an inactive, trapped P(+)Q(B)(-) state in both R. sphaeroides and B. viridis RCs that does not recombine at 20 K. The high resolution and orientational selectivity of HF electron-nuclear double resonance (ENDOR) allows us to directly probe protein environments around Q(B)(-) for distinct P(+)Q(B)(-) kinetic RC states by spectrally selecting specific nuclei in isotopically labeled samples. No structural differences in the protein structure near Q(B)(-) or reorientation (within 5 degrees ) of Q(B)(-) was observed with HF ENDOR spectra of two states of P(+)Q(B)(-): "active" and "inactive" states with regards to low-temperature electron transfer. These results reveal a remarkably enforced local protein environment for Q(B) in its reduced semiquinone state and suggest that the conformational change that controls reactivity resides beyond the Q(B) local environment.

  5. Reduced Extended MHD

    NASA Astrophysics Data System (ADS)

    Morrison, P. J.; Abdelhamid, H. M.; Grasso, D.; Hazeltine, R. D.; Lingam, M.; Tassi, E.

    2015-11-01

    Over the years various reduced fluid models have been obtained for modeling plasmas, with the goal of capturing important physics while maintaining computability. Such models have included the physics contained in various generalizations of Ohm's law, including Hall drift and electron inertia. In a recent publication it was shown that full 3D extended MHD is a Hamiltonian system by finding its noncanonical Poisson bracket. Subsequently, this bracket was shown to be derivable from that for Hall MHD by a series of remarkable transformations, which greatly simplifies the proof of the Jacobi identity and allows one to immediately obtain generalizations of the helicity and cross helicity. In this poster we use this structure to obtain exact reduced fluid models with the effects of full two-fluid theory. Results of numerical computations of collisionless reconnection using an exact reduced 4-field model will be presented and analytical comparisons of mode structure of previous reduced models will be made.

  6. Extended Ewald summation technique

    NASA Astrophysics Data System (ADS)

    Kylänpää, Ilkka; Räsänen, Esa

    2016-09-01

    We present a technique to improve the accuracy and to reduce the computational labor in the calculation of long-range interactions in systems with periodic boundary conditions. We extend the well-known Ewald method by using a linear combination of screening Gaussian charge distributions instead of only one. This enables us to find faster converging real-space and reciprocal space summations. The combined simplicity and efficiency of our method is demonstrated, and the scheme is readily applicable to large-scale periodic simulations, classical as well as quantum. Moreover, apart from the required a priori optimization the method is straightforward to include in most routines based on the Ewald method within, e.g., density-functional, molecular dynamics, and quantum Monte Carlo calculations.

  7. Stars with Extended Atmospheres

    NASA Astrophysics Data System (ADS)

    Sterken, C.

    2002-12-01

    This Workshop consisted of a full-day meeting of the Working Group "Sterren met Uitgebreide Atmosferen" (SUA, Working Group Stars with Extended Atmospheres), a discussion group founded in 1979 by Kees de Jager, Karel van der Hucht and Pik Sin The. This loose association of astronomers and astronomy students working in the Dutch-speaking part of the Low Countries (The Netherlands and Flanders) organised at regular intervals one-day meetings at the Universities of Utrecht, Leiden, Amsterdam and Brussels. These meetings consisted of the presentation of scientific results by junior as well as senior members of the group, and by discussions between the participants. As such, the SUA meetings became a forum for the exchange of ideas, and for asking questions and advice in an informal atmosphere. Kees de Jager has been chairman of the WG SUA from the beginning in 1979 till today, as the leading source of inspiration. At the occasion of Prof. Kees de Jager's 80th birthday, we decided to collect the presented talks in written form as a Festschrift in honour of this well-respected and much beloved scientist, teacher and friend. The first three papers deal with the personality of Kees de Jager, more specifically with his role as a supervisor and mentor of young researchers and as a catalyst in the research work of his colleagues. And also about his remarkable role in the establishment of astronomy education and research at the University of Brussels. The next presentation is a very detailed review of solar research, a field in which Cees was prominently active for many years. Then follow several papers dealing with stars about which Kees is a true expert: massive stars and extended atmospheres.

  8. Extended chameleon models

    NASA Astrophysics Data System (ADS)

    Brax, Philippe; Tamanini, Nicola

    2016-05-01

    We extend the chameleon models by considering scalar-fluid theories where the coupling between matter and the scalar field can be represented by a quadratic effective potential with density-dependent minimum and mass. In this context, we study the effects of the scalar field on Solar System tests of gravity and show that models passing these stringent constraints can still induce large modifications of Newton's law on galactic scales. On these scales we analyze models which could lead to a percent deviation of Newton's law outside the virial radius. We then model the dark matter halo as a Navarro-Frenk-White profile and explicitly find that the fifth force can give large contributions around the galactic core in a particular model where the scalar field mass is constant and the minimum of its potential varies linearly with the matter density. At cosmological distances, we find that this model does not alter the growth of large scale structures and therefore would be best tested on galactic scales, where interesting signatures might arise in the galaxy rotation curves.

  9. Giotto Extended Mission (GEM)

    NASA Technical Reports Server (NTRS)

    Wilkins, D. E. B.; Grensemann, M.

    1991-01-01

    The primary objectives of the Giotto Extended Mission (GEM), are to determine the composition and physical state of the Grigg Skjellerup Comet's nucleus; to determine the processes that govern the composition and distribution of neutral and ionized species in the cometary atmosphere. Giotto consists of a single European Space Agency (ESA) spacecraft that was launched in 1985 from Center Spatial Guyanis in French Guiana on an Ariane launch vehicle. After a successful launch into geostationary orbit and a heliocentric transfer trajectory, the spacecraft successfully encountered Halley's Comet in 1986. One month after encountering Halley's Comet, Mar. 1986, the spacecraft was placed in hibernation in a heliocentric orbit slightly less than 1 AU. Between Feb. and Jul. 1990 the spacecraft was successfully reactivated, checked out, and placed on a trajectory course to intercept comet Grigg Skjellerup. The spacecraft has been in hibernation since Jul. 1990. Information is presented in tabular form in the following areas: coverage goals, Deep Space Network Support, frequency assignments, telemetry, command, and tracking support responsibility.

  10. An Extended Lagrangian Method

    NASA Technical Reports Server (NTRS)

    Liou, Meng-Sing

    1995-01-01

    A unique formulation of describing fluid motion is presented. The method, referred to as 'extended Lagrangian method,' is interesting from both theoretical and numerical points of view. The formulation offers accuracy in numerical solution by avoiding numerical diffusion resulting from mixing of fluxes in the Eulerian description. The present method and the Arbitrary Lagrangian-Eulerian (ALE) method have a similarity in spirit-eliminating the cross-streamline numerical diffusion. For this purpose, we suggest a simple grid constraint condition and utilize an accurate discretization procedure. This grid constraint is only applied to the transverse cell face parallel to the local stream velocity, and hence our method for the steady state problems naturally reduces to the streamline-curvature method, without explicitly solving the steady stream-coordinate equations formulated a priori. Unlike the Lagrangian method proposed by Loh and Hui which is valid only for steady supersonic flows, the present method is general and capable of treating subsonic flows and supersonic flows as well as unsteady flows, simply by invoking in the same code an appropriate grid constraint suggested in this paper. The approach is found to be robust and stable. It automatically adapts to flow features without resorting to clustering, thereby maintaining rather uniform grid spacing throughout and large time step. Moreover, the method is shown to resolve multi-dimensional discontinuities with a high level of accuracy, similar to that found in one-dimensional problems.

  11. Interferon α kinoid induces neutralizing anti-interferon α antibodies that decrease the expression of interferon-induced and B cell activation associated transcripts: analysis of extended follow-up data from the interferon α kinoid phase I/II study

    PubMed Central

    Ducreux, Julie; Houssiau, Frédéric A.; Vandepapelière, Pierre; Jorgensen, Christian; Lazaro, Estibaliz; Spertini, François; Colaone, Fabien; Roucairol, Camille; Laborie, Marion; Croughs, Thérèse; Lauwerys, Bernard R.

    2016-01-01

    Objective. IFN α Kinoid (IFN-K) is a therapeutic vaccine composed of IFNα2b coupled to a carrier protein. In a phase I/II placebo-controlled trial, we observed that IFN-K significantly decreases the IFN gene signature in whole blood RNA samples from SLE patients. Here, we analysed extended follow-up data from IFN-K-treated patients, in order to evaluate persistence of neutralizing anti-IFNα Abs antibodies (Abs), and gene expression profiling. Methods. Serum and whole blood RNA samples were obtained in IFN-K-treated patients included in the follow-up study, in order to determine binding and neutralizing anti-IFNα Ab titres, and perform high-throughput transcriptomic studies. Results. Neutralization studies of 13 IFNα subtypes demonstrated the polyclonal nature of the Ab response induced by IFN-K. Follow-up analyses in six patients confirmed a significant correlation between neutralizing anti-IFNα Ab titres and decrease in IFN scores compared to baseline. These analyses also revealed an inhibitory effect of IFNα blockade on the expression of B cell associated transcripts. Conclusions. IFN-K induces a polyclonal anti-IFNα response that decreases IFN- and B cell-associated transcripts. Trial registration: ClinicalTrials.gov, clinicaltrials.gov, NCT01058343 PMID:27354683

  12. Reconstruction of the Core and Extended Regulons of Global Transcription Factors

    PubMed Central

    Dufour, Yann S.; Kiley, Patricia J.; Donohue, Timothy J.

    2010-01-01

    The processes underlying the evolution of regulatory networks are unclear. To address this question, we used a comparative genomics approach that takes advantage of the large number of sequenced bacterial genomes to predict conserved and variable members of transcriptional regulatory networks across phylogenetically related organisms. Specifically, we developed a computational method to predict the conserved regulons of transcription factors across α-proteobacteria. We focused on the CRP/FNR super-family of transcription factors because it contains several well-characterized members, such as FNR, FixK, and DNR. While FNR, FixK, and DNR are each proposed to regulate different aspects of anaerobic metabolism, they are predicted to recognize very similar DNA target sequences, and they occur in various combinations among individual α-proteobacterial species. In this study, the composition of the respective FNR, FixK, or DNR conserved regulons across 87 α-proteobacterial species was predicted by comparing the phylogenetic profiles of the regulators with the profiles of putative target genes. The utility of our predictions was evaluated by experimentally characterizing the FnrL regulon (a FNR-type regulator) in the α-proteobacterium Rhodobacter sphaeroides. Our results show that this approach correctly predicted many regulon members, provided new insights into the biological functions of the respective regulons for these regulators, and suggested models for the evolution of the corresponding transcriptional networks. Our findings also predict that, at least for the FNR-type regulators, there is a core set of target genes conserved across many species. In addition, the members of the so-called extended regulons for the FNR-type regulators vary even among closely related species, possibly reflecting species-specific adaptation to environmental and other factors. The comparative genomics approach we developed is readily applicable to other regulatory networks. PMID

  13. Levomilnacipran extended release: first global approval.

    PubMed

    Hair, Philip; Cameron, Fiona; Garnock-Jones, Karly P

    2013-09-01

    Pierre Fabre and Forest Laboratories are developing levomilnacipran extended release (ER) [FETZIMA™], an enantiomer of milnacipran, for the treatment of major depressive disorder (MDD). In addition, Pierre Fabre (the originator of the compound) is developing the drug to improve recovery in patients with ischaemic stroke. Levomilnacipran ER exerts its effects by selectively inhibiting the reuptake of norepinephrine and serotonin (two neurotransmitters known to play an essential role in regulating mood) without directly affecting the uptake of dopamine or other neurotransmitters. The agent is being developed as an extended-release capsule formulation for once-daily dosing. Levomilnacipran ER is approved and launched in the US for the treatment of MDD; phase III development in this indication was completed in the US and Canada. In Europe, a phase II trial for MDD was completed, and development is in progress for improving functional recovery of patients with ischaemic stroke. A completed phase II trial in the US investigated levomilnacipran ER for the treatment of fatigue associated with MDD. This article summarizes the milestones in the development of levomilnacipran ER leading to the first approval for major depressive disorder.

  14. Levomilnacipran extended release: first global approval.

    PubMed

    Hair, Philip; Cameron, Fiona; Garnock-Jones, Karly P

    2013-09-01

    Pierre Fabre and Forest Laboratories are developing levomilnacipran extended release (ER) [FETZIMA™], an enantiomer of milnacipran, for the treatment of major depressive disorder (MDD). In addition, Pierre Fabre (the originator of the compound) is developing the drug to improve recovery in patients with ischaemic stroke. Levomilnacipran ER exerts its effects by selectively inhibiting the reuptake of norepinephrine and serotonin (two neurotransmitters known to play an essential role in regulating mood) without directly affecting the uptake of dopamine or other neurotransmitters. The agent is being developed as an extended-release capsule formulation for once-daily dosing. Levomilnacipran ER is approved and launched in the US for the treatment of MDD; phase III development in this indication was completed in the US and Canada. In Europe, a phase II trial for MDD was completed, and development is in progress for improving functional recovery of patients with ischaemic stroke. A completed phase II trial in the US investigated levomilnacipran ER for the treatment of fatigue associated with MDD. This article summarizes the milestones in the development of levomilnacipran ER leading to the first approval for major depressive disorder. PMID:24000002

  15. 38 CFR 21.7051 - Extended period of eligibility.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... consider a veteran who is disabled for a period of 30 days or less as having been prevented from initiating... the day the veteran's training became medically infeasible, (ii) The last date of the veteran's... 38 Pensions, Bonuses, and Veterans' Relief 2 2010-07-01 2010-07-01 false Extended period...

  16. Extended Active Disturbance Rejection Controller

    NASA Technical Reports Server (NTRS)

    Gao, Zhiqiang (Inventor); Tian, Gang (Inventor)

    2014-01-01

    Multiple designs, systems, methods and processes for controlling a system or plant using an extended active disturbance rejection control (ADRC) based controller are presented. The extended ADRC controller accepts sensor information from the plant. The sensor information is used in conjunction with an extended state observer in combination with a predictor that estimates and predicts the current state of the plant and a co-joined estimate of the system disturbances and system dynamics. The extended state observer estimates and predictions are used in conjunction with a control law that generates an input to the system based in part on the extended state observer estimates and predictions as well as a desired trajectory for the plant to follow.

  17. Extended Active Disturbance Rejection Controller

    NASA Technical Reports Server (NTRS)

    Gao, Zhiqiang (Inventor); Tian, Gang (Inventor)

    2016-01-01

    Multiple designs, systems, methods and processes for controlling a system or plant using an extended active disturbance rejection control (ADRC) based controller are presented. The extended ADRC controller accepts sensor information from the plant. The sensor information is used in conjunction with an extended state observer in combination with a predictor that estimates and predicts the current state of the plant and a co-joined estimate of the system disturbances and system dynamics. The extended state observer estimates and predictions are used in conjunction with a control law that generates an input to the system based in part on the extended state observer estimates and predictions as well as a desired trajectory for the plant to follow.

  18. Extended active disturbance rejection controller

    NASA Technical Reports Server (NTRS)

    Gao, Zhiqiang (Inventor); Tian, Gang (Inventor)

    2012-01-01

    Multiple designs, systems, methods and processes for controlling a system or plant using an extended active disturbance rejection control (ADRC) based controller are presented. The extended ADRC controller accepts sensor information from the plant. The sensor information is used in conjunction with an extended state observer in combination with a predictor that estimates and predicts the current state of the plant and a co-joined estimate of the system disturbances and system dynamics. The extended state observer estimates and predictions are used in conjunction with a control law that generates an input to the system based in part on the extended state observer estimates and predictions as well as a desired trajectory for the plant to follow.

  19. Detection of an Extended Outflow in NGC 4102

    NASA Astrophysics Data System (ADS)

    Trent Braun, Timothy; van Zee, Liese; Richards, Emily E.; McQuinn, Kristen B.; Skillman, Evan D.; Edges

    2015-01-01

    We report the detection of an extended galactic outflow in narrowband H alpha imaging of NGC 4102, a nearby spiral galaxy that hosts a low ionization nuclear emission region (LINER) and a circumnuclear H II region. NGC 4102 is a moderate luminosity galaxy, M_B = -19.3, in the Ursa Major Cluster. The outflow protrudes out to 60' (5 kpc at an adopted distance of 17.4 Mpc) to the northwest of the galactic center and may extend as much as 75' (6.3 kpc.) Follow-up integral field spectroscopic observations reveal split line profiles over the outflow region, indicative of both blue and red shifted emission-line components. Based on [N II] / H alpha and [S II] flux ratios of this region, the line emission appears to be nonthermal. We discuss possible origins of the outflow, including both nuclear and/or starburst activity.

  20. Protein-Cofactor Interactions in Bacterial Reaction Centers from Rhodobacter sphaeroides R-26: I. Identification of the ENDOR Lines Associated with the Hydrogen Bonds to the Primary Quinone QA⋅−

    PubMed Central

    Flores, M.; Isaacson, R.; Abresch, E.; Calvo, R.; Lubitz, W.; Feher, G.

    2006-01-01

    Hydrogen bonds are important in determining the structure and function of biomolecules. Of particular interest are hydrogen bonds to quinones, which play an important role in the bioenergetics of respiration and photosynthesis. In this work we investigated the hydrogen bonds to the two carbonyl oxygens of the semiquinone \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}{\\mathrm{Q}}_{{\\mathrm{A}}}^{{\\cdot}-}\\end{equation*}\\end{document} in the well-characterized reaction center from the photosynthetic bacterium Rhodobacter sphaeroides R-26. We used electron paramagnetic resonance and electron nuclear double resonance techniques at 35 GHz at a temperature of 80 K. The goal of this study was to identify and assign sets of 1H-ENDOR lines to protons hydrogen bonded to each of the two oxygens. This was accomplished by preferentially exchanging the hydrogen bond on one of the oxygens with deuterium while concomitantly monitoring the changes in the amplitudes of the 1H-ENDOR lines. The preferential deuteration of one of the oxygens was made possible by the different 1H → 2H exchange times of the protons bonded to the two oxygens. The assignment of the 1H-ENDOR lines sets the stage for the determination of the geometries of the H-bonds by a detailed field selection ENDOR study to be presented in a future article. PMID:16473904

  1. From Self-Organized to Extended Criticality

    PubMed Central

    Lovecchio, Elisa; Allegrini, Paolo; Geneston, Elvis; West, Bruce J.; Grigolini, Paolo

    2012-01-01

    We address the issue of criticality that is attracting the attention of an increasing number of neurophysiologists. Our main purpose is to establish the specific nature of some dynamical processes that although physically different, are usually termed as “critical,” and we focus on those characterized by the cooperative interaction of many units. We notice that the term “criticality” has been adopted to denote both noise-induced phase transitions and Self-Organized Criticality (SOC) with no clear connection with the traditional phase transitions, namely the transformation of a thermodynamic system from one state of matter to another. We notice the recent attractive proposal of extended criticality advocated by Bailly and Longo, which is realized through a wide set of critical points rather than emerging as a singularity from a unique value of the control parameter. We study a set of cooperatively firing neurons and we show that for an extended set of interaction couplings the system exhibits a form of temporal complexity similar to that emerging at criticality from ordinary phase transitions. This extended criticality regime is characterized by three main properties: (i) In the ideal limiting case of infinitely large time period, temporal complexity corresponds to Mittag-Leffler complexity; (ii) For large values of the interaction coupling the periodic nature of the process becomes predominant while maintaining to some extent, in the intermediate time asymptotic region, the signature of complexity; (iii) Focusing our attention on firing neuron avalanches, we find two of the popular SOC properties, namely the power indexes 2 and 1.5 respectively for time length and for the intensity of the avalanches. We derive the main conclusion that SOC emerges from extended criticality, thereby explaining the experimental observation of Plenz and Beggs: avalanches occur in time with surprisingly regularity, in apparent conflict with the temporal complexity of physical

  2. Relevance of the photosynthetic reaction center from purple bacteria to the structure of photosystem II

    SciTech Connect

    Michel, H.; Deisenhofer, J.

    1988-01-12

    Photosynthetic organisms are able to oxidize organic or inorganic compounds upon the absorption of light, and they use the extracted electron for the fixation of carbon dioxide. The most important oxidation product is oxygen due to the splitting of water. In eukaryotes these processes occur in photosystem II of chloroplasts. Among prokaryotes photosynthetic oxygen evolution is restricted to cyanobacteria and prochloron-type organisms. How water is split in the oxygen-evolving complex of photosystem II belongs to the most important question to be answered. The primary charge separation occurs in the reaction center of photosystem II. This reaction center is a complex consisting of peripheral and integral membrane proteins, several chlorophyll A molecules, two pheophytin A molecules, two and three plastoquinone molecules, and one non-heme iron atom. The location of the photosystem II reaction center is still a matter of debate. Nakatani et al. (l984) concluded from fluorescence measurements that a protein of apparent molecular weight 47,000 (CP47) is the apoprotein of the photosystem II reaction center. A different view emerged from work with the photosynthetic reaction centers from the purple bacteria. The amino acid sequence of the M subunit of the reaction center from Phodopseudomonas (Rps.) sphaeroides has sequence homologies with the D1 protein from spinach. A substantial amount of structural information can be obtained with the reaction center from Rhodopseudomonas viridis, which can be crystallized. Here the authors discuss the structure of the photosynthetic reaction center from the purple bacterium Rps. viridis and describe the role of those amino acids that are conserved between the bacterial and photosystem II reaction center.

  3. Cognitive Transformations and Extended Expertise

    ERIC Educational Resources Information Center

    Menary, Richard; Kirchhoff, Michael

    2014-01-01

    Expertise is extended by becoming immersed in cultural practices. We look at an example of mathematical expertise in which immersion in cognitive practices results in the transformation of expert performance.

  4. Tyrosinaemia II.

    PubMed

    Colditz, P B; Yu, J S; Billson, F A; Rogers, M; Molloy, H F; O'Halloran, M; Wilcken, B

    1984-08-18

    Four cases of tyrosinaemia type II (Richner-Hanhart syndrome) are reported. This syndrome consists of corneal erosions, palmar and plantar hyperkeratoses, and sometimes mental retardation. Presentation with photophobia and dendritic corneal ulceration or circumscribed palmoplantar keratoderma should alert the physician to the possible diagnosis of tyrosinaemia II. Early diagnosis is important, as the clinical picture can be modified by dietary restriction.

  5. Topological defects in extended inflation

    NASA Technical Reports Server (NTRS)

    Copeland, Edmund J.; Kolb, Edward W.; Liddle, Andrew R.

    1990-01-01

    The production of topological defects, especially cosmic strings, in extended inflation models was considered. In extended inflation, the Universe passes through a first-order phase transition via bubble percolation, which naturally allows defects to form at the end of inflation. The correlation length, which determines the number density of the defects, is related to the mean size of bubbles when they collide. This mechanism allows a natural combination of inflation and large scale structure via cosmic strings.

  6. Slow-roll extended quintessence

    SciTech Connect

    Chiba, Takeshi; Siino, Masaru; Yamaguchi, Masahide

    2010-04-15

    We derive the slow-roll conditions for a nonminimally coupled scalar field (extended quintessence) during the radiation/matter dominated era extending our previous results for thawing quintessence. We find that the ratio {phi}e/3H{phi} becomes constant but negative, in sharp contrast to the ratio for the minimally coupled scalar field. We also find that the functional form of the equation of state of the scalar field asymptotically approaches that of the minimally coupled thawing quintessence.

  7. Extender for securing a closure

    SciTech Connect

    Thomas, II, Patrick A.

    2012-10-02

    An apparatus for securing a closure such as door or a window that opens and closes by movement relative to a fixed structure such as a wall or a floor. Many embodiments provide a device for relocating a padlock from its normal location where it secures a fastener (such as a hasp) to a location for the padlock that is more accessible for locking and unlocking the padlock. Typically an extender is provided, where the extender has a hook at a first end that is disposed through the eye of the staple of the hasp, and at an opposing second end the extender has an annulus, such as a hole in the extender or a loop or ring affixed to the extender. The shackle of the padlock may be disposed through the annulus and may be disposed through the eye of a second staple to secure the door or window in a closed or open position. Some embodiments employ a rigid sheath to enclose at least a portion of the extender. Typically the rigid sheath has an open state where the hook is exposed outside the sheath and a closed state where the hook is disposed within the sheath.

  8. [Practical experience of endotelon application in patients with cervix uteri cancer after extended panhysterectomy].

    PubMed

    Dolyk, S S

    2004-06-01

    Application of endotelon in early period after extended panhysterectomy in patients with cervix uteri cancer of I-II stages promotes reduction of the occurrence frequency of retroperitoneal lymphatic cyst and lymphostasis in parametrium and lower extremities.

  9. Extended treatment of older cigarette smokers

    PubMed Central

    Hall, Sharon M.; Humfleet, Gary L.; Muñoz, Ricardo F.; Reus, Victor I.; Robbins, Julie A.; Prochaska, Judith J.

    2009-01-01

    Aims Tobacco dependence treatments achieve abstinence rates of 25–30% at 1 year. Low rates may reflect failure to conceptualize tobacco dependence as a chronic disorder. The aims of the present study were to determine the efficacy of extended cognitive behavioral and pharmacological interventions in smokers ≥ 50 years of age, and to determine if gender differences in efficacy existed. Design Open randomized clinical trial. Setting A free-standing, smoking treatment research clinic. Participants A total of 402 smokers of ≥ 10 cigarettes per day, all 50 years of age or older. Intervention Participants completed a 12-week treatment that included group counseling, nicotine replacement therapy (NRT) and bupropion. Participants, independent of smoking status, were then assigned randomly to follow-up conditions: (i) standard treatment (ST; no further treatment); (ii) extended NRT (E-NRT; 40 weeks of nicotine gum availability); (iii) extended cognitive behavioral therapy (E-CBT; 11 cognitive behavioral sessions over a 40-week period); or (iv) E-CBT plus E-NRT (E-combined; 11 cognitive behavioral sessions plus 40 weeks nicotine gum availability). Measurements Primary outcome variable was 7-day point prevalence cigarette abstinence verified biochemically at weeks 24, 52, 64 and 104. Findings The most clinically important findings were significant main effects for treatment condition, time and the treatment × time interaction. The E-CBT condition produced high cigarette abstinence rates that were maintained throughout the 2-year study period [(week 24 (58%), 52 (55%), 64 (55%) and 104 (55%)], and was significantly more effective than E-NRT and ST across that period. No other treatment condition was significantly different to ST. No effects for gender were found. Conclusions Extended cognitive behavioral treatments can produce high and stable cigarette abstinence rates for both men and women. NRT does not add to the efficacy of extended CBT, and may hamper its efficacy

  10. The prognostic value of concurrent Horner syndrome in extended Erb obstetric brachial plexus palsy.

    PubMed

    El-Sayed, Amel A F

    2014-10-01

    Horner syndrome may be seen in infants with extended Erb obstetric brachial plexus palsy. However, its prognostic value in these infants has not been previously investigated. A total of 220 infants with extended Erb palsy were included and divided into 2 groups: group I (n = 209) were infants with extended Erb palsy without Horner syndrome, and group II (n = 11) were infants with extended Erb palsy and concurrent Horner syndrome. The rate of good spontaneous recovery of elbow flexion was 59% in group I and 27% in group II, and the difference was significant (P = .038). The rate of good spontaneous recovery of wrist extension was 61% in group I and 0% in group II, and the difference as highly significant (P < .0001). Concurrent Horner syndrome in infants with extended Erb palsy may be considered as a poor prognostic sign for recovery of the sixth and seventh cervical roots.

  11. Extended cognition in science communication.

    PubMed

    Ludwig, David

    2014-11-01

    The aim of this article is to propose a methodological externalism that takes knowledge about science to be partly constituted by the environment. My starting point is the debate about extended cognition in contemporary philosophy and cognitive science. Externalists claim that human cognition extends beyond the brain and can be partly constituted by external devices. First, I show that most studies of public knowledge about science are based on an internalist framework that excludes the environment we usually utilize to make sense of science and does not allow the possibility of extended knowledge. In a second step, I argue that science communication studies should adopt a methodological externalism and accept that knowledge about science can be partly realized by external information resources such as Wikipedia.

  12. An Extended Keyword Extraction Method

    NASA Astrophysics Data System (ADS)

    Hong, Bao; Zhen, Deng

    Among numerous Chinese keyword extraction methods, Chinese characteristics were shortly considered. This phenomenon going against the precision enhancement of the Chinese keyword extraction. An extended term frequency based method(Extended TF) is proposed in this paper which combined Chinese linguistic characteristics with basic TF method. Unary, binary and ternary grammars for the candidate keyword extraction as well as other linguistic features were all taken into account. The method establishes classification model using support vector machine. Tests show that the proposed extraction method improved key words precision and recall rate significantly. We applied the key words extracted by the extended TF method into the text file classification. Results show that the key words extracted by the proposed method contributed greatly to raising the precision of text file classification.

  13. Complex-extended Bohmian mechanics.

    PubMed

    Chou, Chia-Chun; Wyatt, Robert E

    2010-04-01

    Complex-extended Bohmian mechanics is investigated by analytically continuing the wave function in polar form into the complex plane. We derive the complex-extended version of the quantum Hamilton-Jacobi equation and the continuity equation in Bohmian mechanics. Complex-extended Bohmian mechanics recovers the standard real-valued Bohmian mechanics on the real axis. The trajectories on the real axis are in accord with the standard real-valued Bohmian trajectories. The trajectories launched away from the real axis never intersect the real axis, and they display symmetry with respect to the real axis. Trajectories display hyperbolic deflection around nodes of the wave function in the complex plane. PMID:20387916

  14. A novel extended state observer.

    PubMed

    Xiong, Shaofeng; Wang, Weihong; Liu, Xiaodong; Chen, Zengqiang; Wang, Sen

    2015-09-01

    A novel extended state observer, which feeds back the output estimation error via both nonlinear and switching terms, is put forward for the first time in this paper. No longer neglecting the lumped uncertainty׳s first time derivative, the problem of disturbance observer design is transformed into the problem of state observer design in the presence of external disturbance. The switching term of the output estimation error is employed to counteract the adverse effect of external disturbance. The newly developed extended state observer provides an attractive solution to the issue of high precision motion control system. Both numerical simulation and experimentation on a speed turntable with temperature box are implemented to verify the performance of the proposed newly developed extended state observer. PMID:26275404

  15. Photosystem II

    ScienceCinema

    James Barber

    2016-07-12

    James Barber, Ernst Chain Professor of Biochemistry at Imperial College, London, gives a BSA Distinguished Lecture titled, "The Structure and Function of Photosystem II: The Water-Splitting Enzyme of Photosynthesis."

  16. Constrained Stochastic Extended Redundancy Analysis.

    PubMed

    DeSarbo, Wayne S; Hwang, Heungsun; Stadler Blank, Ashley; Kappe, Eelco

    2015-06-01

    We devise a new statistical methodology called constrained stochastic extended redundancy analysis (CSERA) to examine the comparative impact of various conceptual factors, or drivers, as well as the specific predictor variables that contribute to each driver on designated dependent variable(s). The technical details of the proposed methodology, the maximum likelihood estimation algorithm, and model selection heuristics are discussed. A sports marketing consumer psychology application is provided in a Major League Baseball (MLB) context where the effects of six conceptual drivers of game attendance and their defining predictor variables are estimated. Results compare favorably to those obtained using traditional extended redundancy analysis (ERA). PMID:24327066

  17. Adjustable extender for instrument module

    DOEpatents

    Sevec, J.B.; Stein, A.D.

    1975-11-01

    A blank extender module used to mount an instrument module in front of its console for repair or test purposes has been equipped with a rotatable mount and means for locking the mount at various angles of rotation for easy accessibility. The rotatable mount includes a horizontal conduit supported by bearings within the blank module. The conduit is spring-biased in a retracted position within the blank module and in this position a small gear mounted on the conduit periphery is locked by a fixed pawl. The conduit and instrument mount can be pulled into an extended position with the gear clearing the pawl to permit rotation and adjustment of the instrument.

  18. Constrained Stochastic Extended Redundancy Analysis.

    PubMed

    DeSarbo, Wayne S; Hwang, Heungsun; Stadler Blank, Ashley; Kappe, Eelco

    2015-06-01

    We devise a new statistical methodology called constrained stochastic extended redundancy analysis (CSERA) to examine the comparative impact of various conceptual factors, or drivers, as well as the specific predictor variables that contribute to each driver on designated dependent variable(s). The technical details of the proposed methodology, the maximum likelihood estimation algorithm, and model selection heuristics are discussed. A sports marketing consumer psychology application is provided in a Major League Baseball (MLB) context where the effects of six conceptual drivers of game attendance and their defining predictor variables are estimated. Results compare favorably to those obtained using traditional extended redundancy analysis (ERA).

  19. WFRC patrners: our extended family

    USGS Publications Warehouse

    Thorsteinson, Lyman

    2007-01-01

    For more than five decades the Western Fisheries Research Center (WFRC) has worked with partners to provide research findings to managers of aquatic resources. Those partners form an extended family, a network of clients, colleagues, co-investigators, and customers. Our partners include numerous clients in other Department of Interior bureaus such as the U.S. Fish and Wildlife Service, the U.S. Bureau of Reclamation, and the National Park Service. But there is much more--we have partners in other federal agencies, state agencies, and universities. The extended family includes tribal governments, and non-government organizations such as the Nature Conservancy and the Lower Columbia River Estuary Program.

  20. Catalytically-relevant electron transfer between two hemes bL in the hybrid cytochrome bc1-like complex containing a fusion of Rhodobacter sphaeroides and capsulatus cytochromes b.

    PubMed

    Czapla, Monika; Cieluch, Ewelina; Borek, Arkadiusz; Sarewicz, Marcin; Osyczka, Artur

    2013-06-01

    To address mechanistic questions about the functioning of dimeric cytochrome bc1 new genetic approaches have recently been developed. They were specifically designed to enable construction of asymmetrically-mutated variants suitable for functional studies. One approach exploited a fusion of two cytochromes b that replaced the separate subunits in the dimer. The fusion protein, built from two copies of the same cytochrome b of purple bacterium Rhodobacter capsulatus, served as a template to create a series of asymmetrically-mutated cytochrome bc1-like complexes (B-B) which, through kinetic studies, disclosed several important principles of dimer engineering. Here, we report on construction of another fusion protein complex that adds a new tool to investigate dimeric function of the enzyme through the asymmetrically mutated forms of the protein. This complex (BS-B) contains a hybrid protein that combines two different cytochromes b: one coming from R. capsulatus and the other - from a closely related species, R. sphaeroides. With this new fusion we addressed a still controversial issue of electron transfer between the two hemes bL in the core of dimer. Kinetic data obtained with a series of BS-B variants provided new evidence confirming the previously reported observations that electron transfer between those two hemes occurs on a millisecond timescale, thus is a catalytically-relevant event. Both types of the fusion complexes (B-B and BS-B) consistently implicate that the heme-bL-bL bridge forms an electronic connection available for inter-monomer electron transfer in cytochrome bc1.

  1. The role of arginine-127 at the proximal NO-binding site in determining the electronic structure and function of 5-coordinate NO-heme in cytochrome c' of Rhodobacter sphaeroides.

    PubMed

    Lee, Byunghoon; Usov, Oleg M; Grigoryants, Vladimir M; Myers, William K; Shapleigh, James P; Scholes, Charles P

    2009-09-29

    Cytochrome c' is a heme protein from a denitrifying variant of Rhodobacter sphaeroides which may serve to store and transport metabolic NO while protecting against NO toxicity. Its heme site bears resemblance through its 5-coordinate NO-binding capability to the regulatory site in soluble guanylate cyclase. A conserved arginine (Arg-127) abuts the 5-coordinate NO-heme binding site, and the alanine mutant R127A provided insight into the role of the Arg-127 in establishing the electronic structure of the heme-NO complex and in modifying the heme-centered redox potential and NO-binding affinity. By comparison to R127A, the wild-type Arg-127 was determined to increase the heme redox potential, diminish the NO-binding affinity, perturb and diminish the 14NO hyperfine coupling determined by ENDOR (electron nuclear double resonance), and increase the maximal electronic g-value. The larger isotropic NO hyperfine and the smaller maximal g-value of the R127A mutant together predicted that the Fe-N-O bond angle in the mutant is larger than that of the Arg-127-containing wild-type protein. Deuterium ENDOR provided evidence for exchangeable H/D consistent with hydrogen bonding of Arg-127, but not Ala-127, to the O of the NO. Proton ENDOR features previously assigned to Phe-14 on the distal side of the heme were unperturbed by the proximal side R127A mutation, implying the localized nature of that mutational perturbation at the proximal, NO-binding side of the heme. From this work two functions of positively charged Arg-127 emerged: the first was to maintain the KD of the cytochrome c' in the 1 microM range, and the second was to provide a redox potential that enhances the stability of the ferrous heme.

  2. Lightweight extendable and retractable pole

    DOEpatents

    Warren, J.L.; Brandt, J.E.

    1994-08-02

    A lightweight extendable and retractable telescopic pole is disclosed comprising a plurality of non-metallic telescoping cylinders with sliding and sealing surfaces between the cylinders, a first plug member on the upper end of the smallest cylinder, and a second plug member on the lower end of the largest cylinder, whereby fluid pressure admitted to the largest cylinder will cause the telescoping cylinders to slide relative to one another causing the pole to extend. An elastomeric member connects the first plug member with one of the intermediate cylinders to urge the cylinders back into a collapsed position when the fluid pressure in the cylinders is vented. Annular elastomer members are provided which seal one cylinder to another when the pole is fully extended and further serve to provide a cushion to prevent damage to the cylinders when the pole is urged back into its retractable position by the elastomeric members and the venting of the pressure. A value mechanism associated with the pole is provided to admit a fluid under pressure to the interior of the telescoping cylinders of the pole while pressurizing a pressure relief port having an opening larger than the inlet port in a closed position whereby removal of the pressure on the relief port will cause the relief port to open to quickly lower the pressure in the interior of the telescoping cylinders to thereby assist in the rapid retraction of the extended pole. 18 figs.

  3. Lightweight extendable and retractable pole

    DOEpatents

    Warren, John L.; Brandt, James E.

    1994-01-01

    A lightweight extendable and retractable telescopic pole is disclosed comprising a plurality of non-metallic telescoping cylinders with sliding and sealing surfaces between the cylinders, a first plug member on the upper end of the smallest cylinder, and a second plug member on the lower end of the largest cylinder, whereby fluid pressure admitted to the largest cylinder will cause the telescoping cylinders to slide relative to one another causing the pole to extend. An elastomeric member connects the first plug member with one of the intermediate cylinders to urge the cylinders back into a collapsed position when the fluid pressure in the cylinders is vented. Annular elastomer members are provided which seal one cylinder to another when the pole is fully extended and further serve to provide a cushion to prevent damage to the cylinders when the pole is urged back into its retractable position by the elastomeric members and the venting of the pressure. A value mechanism associated with the pole is provided to admit a fluid under pressure to the interior of the telescoping cylinders of the pole while pressurizing a pressure relief port having an opening larger than the inlet port in a closed position whereby removal of the pressure on the relief port will cause the relief port to open to quickly lower the pressure in the interior of the telescoping cylinders to thereby assist in the rapid retraction of the extended pole.

  4. Engage, Enhance, and Extend Learning!

    ERIC Educational Resources Information Center

    Keren-Kolb, Liz

    2013-01-01

    Educators often say that technology is more than a gimmick or add-on, and that it should engage, enhance, or extend learning in ways that traditional tools do not. Yet they seldom stop to define these terms, and they can be confusing, especially for teachers and preservice teachers. Recently, while collaborating on an English language arts and…

  5. Extended Duration Orbiter Medical Project

    NASA Technical Reports Server (NTRS)

    Leach, C. S.; Pool, S. L.; Sawin, C. F.; Nicogossian, A. E.

    1990-01-01

    The Extended Duration Orbiter (EDO) program addresses a need for more time to perform experiments and other tasks during Space Shuttle missions. As a part of this program, the Extended Duration Orbiter Medical Project (EDOMP) has been instituted to obtain information about physiologic effects of extending mission duration and the effectiveness of countermeasures against factors that might compromise crew health, safety, or performance on extended-duration missions. Only those investigations that address and characterize operational problems, develop countermeasures, or evaluate the effectiveness of countermeasures will be pursued. The EDOMP investigations will include flight-associated Detailed Supplementary Objectives as well as ground-based studies simulating the influence of microgravity. Investigator teams have been formed in the following areas: biomedical physiology, cardiovascular and fluid/electrolyte physiology, environmental health, muscle and exercise physiology, and neurophysiology. Major operational questions must be answered in each of these areas, and investigations have been designed to answer them. The EDO program will proceed only after countermeasures have been shown to be effective in preventing or mitigating the adverse changes they have been designed to attenuate. The program is underway and will continue on each Shuttle flight as the manifest builds toward a 16-day orbital flight.

  6. Extended range chemical sensing apparatus

    DOEpatents

    Hughes, Robert C.; Schubert, W. Kent

    1994-01-01

    An apparatus for sensing chemicals over extended range of concentrations. In particular, first and second sensors each having separate, but overlapping ranges for sensing concentrations of hydrogen are provided. Preferably, the first sensor is a MOS solid state device wherein the metal electrode or gate is a nickel alloy. The second sensor is a chemiresistor comprising a nickel alloy.

  7. Extended recency effect extended: blocking, presentation mode, and retention interval.

    PubMed

    Glidden, L M; Pawelski, C; Mar, H; Zigman, W

    1979-07-01

    The effect of blocking of stimulus items on the free recall of EMR adolescents was examined. In Experiment 1 a multitrial free-recall list of 15 pictures was presented either simultaneously in groups of 3, or sequentially, one at a time. Consistent ordering was used in both conditions, so that on each trial, each item in each set of 3 pictures was presented contiguously with the other 2 items from that set. In addition, recall came immediately or after a filled or unfilled delay of 24.5 seconds. Results showed that simultaneous presentation led to higher recall, subjective organization, and clustering than did sequential presentation, but analysis of serial-position curves showed a much reduced extended recency effect in comparison with previous studies. Experiment 2 was designed to determine whether the cause of the reduced extended recency was the use of pictures rather than words as stimuli. Stimuli were presented either as pictures, as pictures with auditory labels, or as words with auditory labels, with both simultaneous and consistent ordering for all conditions. Results indicated a strong extended recency effect for all groups, eliminating presentation mode as a causal factor in the data of Experiment 1. We concluded that blocking leads to increased organization and recall over a variety of presentation modes, rates, and block sizes.

  8. FIRE I - Extended Time Observations Data Sets

    Atmospheric Science Data Center

    2013-08-01

    FIRE I - Extended Time Observations Data Sets First ISCCP Regional Experiment (FIRE) I - Extended Time Observations were conducted in Utah. Relevant Documents:  FIRE Project Guide FIRE I - Extended Time Observations Home Page SCAR-B Block:  ...

  9. Extended-Synaptotagmins (E-Syts); the extended story.

    PubMed

    Herdman, Chelsea; Moss, Tom

    2016-05-01

    The Extended-Synaptotagmin (E-Syt) membrane proteins were only recently discovered, but have already been implicated in a range of interrelated cellular functions, including calcium and receptor signaling, and membrane lipid transport. However, despite their evolutionary conservation and detailed studies of their molecular actions, we still have little idea of how and when these proteins are required in cellular and organism physiology. Here we review our present understanding of the E-Syts and discuss the molecular functions and in vivo requirements for these proteins. PMID:26926095

  10. SAGE II

    Atmospheric Science Data Center

    2016-02-16

    ... of stratospheric aerosols, ozone, nitrogen dioxide, water vapor and cloud occurrence by mapping vertical profiles and calculating ... (i.e. MLS and SAGE III versus HALOE) Fixed various bugs Details are in the  SAGE II V7.00 Release Notes .   ...

  11. Electromagnetic interactions of extended nucleons

    SciTech Connect

    Ohta, K. )

    1989-09-01

    An electromagnetic current operator is deduced from the most general form of the extended pion-nucleon vertex function using the minimal substitution prescription. It is proved that the sum of the obtained current operator and the isolated-pole contribution satisfies the Ward-Takahashi identity derived for the pion photoproduction. The minimal-coupling interaction is applied to the calculation of the one-pion exchange current regularized by the pion-nucleon form factors. It is found that the one-pion exchange current operator including hadronic and electromagnetic form factors satisfies the Ward-Takahashi equation for the nucleon-nucleon interaction.

  12. Renormalization of Extended QCD2

    NASA Astrophysics Data System (ADS)

    Fukaya, Hidenori; Yamamura, Ryo

    2015-10-01

    Extended QCD (XQCD), proposed by Kaplan [D. B. Kaplan, arXiv:1306.5818], is an interesting reformulation of QCD with additional bosonic auxiliary fields. While its partition function is kept exactly the same as that of original QCD, XQCD naturally contains properties of low-energy hadronic models. We analyze the renormalization group flow of 2D (X)QCD, which is solvable in the limit of a large number of colors N_c, to understand what kind of roles the auxiliary degrees of freedom play and how the hadronic picture emerges in the low-energy region.

  13. Extending earthquakes' reach through cascading.

    PubMed

    Marsan, David; Lengliné, Olivier

    2008-02-22

    Earthquakes, whatever their size, can trigger other earthquakes. Mainshocks cause aftershocks to occur, which in turn activate their own local aftershock sequences, resulting in a cascade of triggering that extends the reach of the initial mainshock. A long-lasting difficulty is to determine which earthquakes are connected, either directly or indirectly. Here we show that this causal structure can be found probabilistically, with no a priori model nor parameterization. Large regional earthquakes are found to have a short direct influence in comparison to the overall aftershock sequence duration. Relative to these large mainshocks, small earthquakes collectively have a greater effect on triggering. Hence, cascade triggering is a key component in earthquake interactions.

  14. 38 CFR 21.57 - Extended evaluation.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2012-07-01 2012-07-01 false Extended evaluation. 21... Initial and Extended Evaluation § 21.57 Extended evaluation. (a) Purpose. The purpose of an extended evaluation for a veteran with a serious employment handicap is to determine the current feasibility of...

  15. Decoupling mutations in the D-channel of the aa(3)-type cytochrome c oxidase from Rhodobacter sphaeroides suggest that a continuous hydrogen-bonded chain of waters is essential for proton pumping.

    PubMed

    Zhu, Jiapeng; Han, Huazhi; Pawate, Ashtamurthy; Gennis, Robert B

    2010-06-01

    The aa(3)-type cytochrome c oxidase from Rhodobacter sphaeroides utilizes two proton-input channels to provide all the protons for chemistry (water formation) and proton pumping. The D-channel is responsible for the uptake of all pumped protons, four protons per O(2). Several substitutions of either N139 or N207, near the entrance of the D-channel, were previously reported to decouple the proton pump from oxidase activity. In this work, the characteristics of additional mutations in this region of the protein (N139, N207, N121, and S142) are determined to elucidate the mechanism of decoupling. With the exception of the substitution of a large, hydrophobic residue (N139L), all the mutations of N139 resulted in an enzyme with high oxidase activity but with a severely diminished proton pumping stoichiometry. Whereas N207D was previously shown to be decoupled, N207A and N207T exhibit nearly wild-type behavior. The new data display a pattern. Small, nonionizable substitutions of N139 or N121 result in decoupling of the proton pump but maintain high turnover rates. These residues are directly hydrogen bonded to two water molecules (Water6574 and Water6584) that are part of the single-file chain of water molecules within the D-channel leading to E286 at the top of the channel. The data suggest that the integrity of this water chain within the D-channel is critical for rapid proton transfer. The mechanism of decoupling is most likely due to the slowing of the rate of proton delivery below a threshold that is required for protonation of the putative proton loading site. Protons delivered outside this time window are delivered to the active site where they are consumed in the formation of water. The rate of proton delivery required to protonate the pump site must be significantly faster than the rate of delivery of protons to the catalytic site. For this reason, mutations can result in decoupling of the proton pump without slowing the catalytic turnover by the enzyme.

  16. PORT II

    NASA Technical Reports Server (NTRS)

    Muniz, Beau

    2009-01-01

    One unique project that the Prototype lab worked on was PORT I (Post-landing Orion Recovery Test). PORT is designed to test and develop the system and components needed to recover the Orion capsule once it splashes down in the ocean. PORT II is designated as a follow up to PORT I that will utilize a mock up pressure vessel that is spatially compar able to the final Orion capsule.

  17. Extended suicide with a pet.

    PubMed

    Cooke, Brian K

    2013-01-01

    The combination of the killing of a pet and a suicide is a perplexing scenario that is largely unexplored in the literature. Many forensic psychiatrists and psychologists may be unaccustomed to considering the significance of the killing of a pet. The subject is important, however, because many people regard their pets as members of their family. A case is presented of a woman who killed her pet dog and herself by carbon monoxide poisoning. The purpose of this article is to provide an initial exploration of the topic of extended suicide with a pet. Forensic mental health evaluations may have a role in understanding the etiology of this event and in opining as to the culpability of individuals who attempt to or successfully kill a pet and then commit suicide. Because the scientific literature is lacking, there is a need to understand this act from a variety of perspectives. First, a social and anthropological perspective will be presented that summarizes the history of the practice of killing of one's pet, with a focus on the ancient Egyptians. A clinical context will examine what relationship animals have to mental illness. A vast body of existing scientific data showing the relevance of human attachment to pets suggests that conclusions from the phenomena of homicide-suicide and filicide-suicide are applicable to extended suicide with a pet. Finally, recommendations will be proposed for both clinical and forensic psychiatrists faced with similar cases. PMID:24051598

  18. Extended Duration Orbiter Medical Project

    NASA Technical Reports Server (NTRS)

    Sawin, Charles F. (Editor); Taylor, Gerald R. (Editor); Smith, Wanda L. (Editor); Brown, J. Travis (Technical Monitor)

    1999-01-01

    Biomedical issues have presented a challenge to flight physicians, scientists, and engineers ever since the advent of high-speed, high-altitude airplane flight in the 1940s. In 1958, preparations began for the first manned space flights of Project Mercury. The medical data and flight experience gained through Mercury's six flights and the Gemini, Apollo, and Skylab projects, as well as subsequent space flights, comprised the knowledge base that was used to develop and implement the Extended Duration Orbiter Medical Project (EDOMP). The EDOMP yielded substantial amounts of data in six areas of space biomedical research. In addition, a significant amount of hardware was developed and tested under the EDOMP. This hardware was designed to improve data gathering capabilities and maintain crew physical fitness, while minimizing the overall impact to the microgravity environment. The biomedical findings as well as the hardware development results realized from the EDOMP have been important to the continuing success of extended Space Shuttle flights and have formed the basis for medical studies of crew members living for three to five months aboard the Russian space station, Mir. EDOMP data and hardware are also being used in preparation for the construction and habitation of International Space Station. All data sets were grouped to be non-attributable to individuals, and submitted to NASA s Life Sciences Data Archive.

  19. Implications of Extended Solar Minima

    NASA Technical Reports Server (NTRS)

    Adams, Mitzi L.; Davis, J. M.

    2009-01-01

    Since the discovery of periodicity in the solar cycle, the historical record of sunspot number has been carefully examined, attempting to make predictions about the next cycle. Much emphasis has been on predicting the maximum amplitude and length of the next cycle. Because current space-based and suborbital instruments are designed to study active phenomena, there is considerable interest in estimating the length and depth of the current minimum. We have developed criteria for the definition of a minimum and applied it to the historical sunspot record starting in 1749. In doing so, we find that 1) the current minimum is not yet unusually long and 2) there is no obvious way of predicting when, using our definition, the current minimum may end. However, by grouping the data into 22- year cycles there is an interesting pattern of extended minima that recurs every fourth or fifth 22-year cycle. A preliminary comparison of this pattern with other records, suggests the possibility of a correlation between extended minima and lower levels of solar irradiance.

  20. Extended Operation of Stirling Convertors

    NASA Technical Reports Server (NTRS)

    Roth, Mary Ellen; Schreiber, Jeffery G.; Pepper, Stephen V.

    2004-01-01

    A high-efficiency 110 W Stirling Radioisotope Generator 110 (SRG110) is being developed for potential NASA exploration missions. The SRG system efficiency is greater than 20%, making it an attractive candidate power system for deep space missions and unmanned rovers. The Department of Energy SRG110 Project team consists of the System Integrator, Lockheed Martin (LM), Stirling Technology Company (STC), and NASA Glenn Research Center (GRC). One of the GRC roles is to provide Independent Verification and Validation of the Stirling TDC s. At the request of LM, a part of this effort includes the Extended Operation of the TDC s in the dynamically balanced dual-opposed configuration. Performance data of Stirling Convertors over time is required to demonstrate that an SRG110 can meet long-duration mission requirements. A test plan and test system were developed to evaluate TDC s #13 and #14 steady-state performance for a minimum of 5000 hours. Hardware, software and TDC preparation processes were developed to support this test and insure safe, round-the-clock operation of the TDC s. This paper will discuss the design and development, and status of the Extended Operation Test.

  1. Extended Operation of Stirling Convertors

    NASA Technical Reports Server (NTRS)

    Roth, Mary Ellen; Schreiber, Jeffrey G.; Pepper, Stephen V.

    2004-01-01

    A high-efficiency 110 watt Stirling Radioisotope Generator 110 (SRG110) is being developed for potential NASA exploration missions. The SRG system efficiency is greater than 20%, making it an attractive candidate power system for deep space missions and unmanned rovers. The Department of Energy SRG110 Project team consists of the System Integrator, Lockheed Martin (LM), Stirling Technology Company (STC), and NASA Glenn Research Center (GRC). One of the GRC roles is to provide Independent Verification and Validation of the Stirling TDC's. At the request of LM, a part of this effort includes the extended operation of the TDC's in the dynamically balanced dual-opposed configuration. Performance data of the Stirling Converters over time is required to demonstrate that an SRG110 can meet long-duration mission requirements. A test plan and test system were developed to evaluate TDC's #13 and #14 steady-state performance for a minimum of 5000 hours and insure safe, round-the-clock operation of the TDC's. This paper will discuss the design and development, and status of the Extended Operation Test.

  2. Reasoning over Extended ER Models

    NASA Astrophysics Data System (ADS)

    Artale, A.; Calvanese, D.; Kontchakov, R.; Ryzhikov, V.; Zakharyaschev, M.

    We investigate the computational complexity of reasoning over various fragments of the Extended Entity-Relationship (EER) language, which includes a number of constructs: isa between entities and relationships, disjointness and covering of entities and relationships, cardinality constraints for entities in relationships and their refinements as well as multiplicity constraints for attributes. We extend the known ExpTime-completeness result for UML class diagrams [5] and show that reasoning over EER diagrams with isa between relationships is ExpTime-complete even without relationship covering. Surprisingly, reasoning becomes NP-complete when we drop isa between relationships (while still allowing all types of constraints on entities). If we further omit disjointness and covering over entities, reasoning becomes polynomial. Our lower complexity bound results are proved by direct reductions, while the upper bounds follow from the correspondences with expressive variants of the description logic DL-Lite, which we establish in this paper. These correspondences also show the usefulness of DL-Lite as a language for reasoning over conceptual models and ontologies.

  3. Pipe crawler with extendable legs

    DOEpatents

    Zollinger, W.T.

    1992-06-16

    A pipe crawler for moving through a pipe in inchworm fashion having front and rear leg assemblies separated by air cylinders to increase and decrease the spacing between assemblies. Each leg of the four legs of an assembly is moved between a wall-engaging, extended position and a retracted position by a separate air cylinder. The air cylinders of the leg assemblies are preferably arranged in pairs of oppositely directed cylinders with no pair lying in the same axial plane as another pair. Therefore, the cylinders can be as long as a leg assembly is wide and the crawler can crawl through sections of pipes where the diameter is twice that of other sections. The crawler carries a valving system, a manifold to distribute air supplied by a single umbilical air hose to the various air cylinders in a sequence controlled electrically by a controller. The crawler also utilizes a rolling mechanism, casters in this case, to reduce friction between the crawler and pipe wall thereby further extending the range of the pipe crawler. 8 figs.

  4. Pipe crawler with extendable legs

    DOEpatents

    Zollinger, William T.

    1992-01-01

    A pipe crawler for moving through a pipe in inchworm fashion having front and rear leg assemblies separated by air cylinders to increase and decrease the spacing between assemblies. Each leg of the four legs of an assembly is moved between a wall-engaging, extended position and a retracted position by a separate air cylinder. The air cylinders of the leg assemblies are preferably arranged in pairs of oppositely directed cylinders with no pair lying in the same axial plane as another pair. Therefore, the cylinders can be as long a leg assembly is wide and the crawler can crawl through sections of pipes where the diameter is twice that of other sections. The crawler carries a valving system, a manifold to distribute air supplied by a single umbilical air hose to the various air cylinders in a sequence controlled electrically by a controller. The crawler also utilizes a rolling mechanism, casters in this case, to reduce friction between the crawler and pipe wall thereby further extending the range of the pipe crawler.

  5. BORE II

    2015-08-01

    Bore II, co-developed by Berkeley Lab researchers Frank Hale, Chin-Fu Tsang, and Christine Doughty, provides vital information for solving water quality and supply problems and for improving remediation of contaminated sites. Termed "hydrophysical logging," this technology is based on the concept of measuring repeated depth profiles of fluid electric conductivity in a borehole that is pumping. As fluid enters the wellbore, its distinct electric conductivity causes peaks in the conductivity log that grow and migratemore » upward with time. Analysis of the evolution of the peaks enables characterization of groundwater flow distribution more quickly, more cost effectively, and with higher resolution than ever before. Combining the unique interpretation software Bore II with advanced downhole instrumentation (the hydrophysical logging tool), the method quantifies inflow and outflow locations, their associated flow rates, and the basic water quality parameters of the associated formation waters (e.g., pH, oxidation-reduction potential, temperature). In addition, when applied in conjunction with downhole fluid sampling, Bore II makes possible a complete assessment of contaminant concentration within groundwater.« less

  6. BORE II

    SciTech Connect

    2015-08-01

    Bore II, co-developed by Berkeley Lab researchers Frank Hale, Chin-Fu Tsang, and Christine Doughty, provides vital information for solving water quality and supply problems and for improving remediation of contaminated sites. Termed "hydrophysical logging," this technology is based on the concept of measuring repeated depth profiles of fluid electric conductivity in a borehole that is pumping. As fluid enters the wellbore, its distinct electric conductivity causes peaks in the conductivity log that grow and migrate upward with time. Analysis of the evolution of the peaks enables characterization of groundwater flow distribution more quickly, more cost effectively, and with higher resolution than ever before. Combining the unique interpretation software Bore II with advanced downhole instrumentation (the hydrophysical logging tool), the method quantifies inflow and outflow locations, their associated flow rates, and the basic water quality parameters of the associated formation waters (e.g., pH, oxidation-reduction potential, temperature). In addition, when applied in conjunction with downhole fluid sampling, Bore II makes possible a complete assessment of contaminant concentration within groundwater.

  7. Extended HLA-D region haplotype associated with celiac disease

    SciTech Connect

    Howell, M.D.; Smith, J.R.; Austin, R.K.; Kelleher, D.; Nepom, G.T.; Volk, B.; Kagnoff, M.F.

    1988-01-01

    Celiac disease has one of the strongest associations with HLA (human leukocyte antigen) class II markers of the known HLA-linked diseases. This association is primarily with the class II serologic specificities HLA-DR3 and -DQw2. The authors previously described a restriction fragment length polymorphism (RFLP) characterized by the presence of a 4.0-kilobase Rsa I fragment derived from an HLA class II ..beta..-chain gene, which distinguishes the class II HLA haplotype of celiac disease patients from those of many serologically matched controls. They now report the isolation of this ..beta..-chain gene from a bacteriophage genomic library constructed from the DNA of a celiac disease patient. Based on restriction mapping and differential hybridization with class II cDNA and oligonucleotide probes, this gene was identified as one encoding an HLA-DP ..beta..-chain. This celiac disease-associated HLA-DP ..beta..-chain gene was flanked by HLA-DP ..cap alpha..-chain genes and, therefore, was probably in its normal chromosomal location. The HLA-DP..cap alpha..-chain genes of celiac disease patients also were studied by RFLP analysis. Celiac disease is associated with a subset of HLA-DR3, -DQw2 haplotypes characterized by HLA-DP ..cap alpha..- and ..beta..-chain gene RFLPs. Within the celiac-disease patient population, the joint segregation of these HLA-DP genes with those encoding the serologic specificities HLA-DR3 and -DQw2 indicates: (i) that the class II HLA haplotype associated with celiac disease is extended throughout the entire HLA-D region, and (ii) that celiac-disease susceptibility genes may reside as far centromeric on this haplotype as the HLA-DP subregion.

  8. Hamiltonian dynamics of extended objects

    NASA Astrophysics Data System (ADS)

    Capovilla, R.; Guven, J.; Rojas, E.

    2004-12-01

    We consider relativistic extended objects described by a reparametrization-invariant local action that depends on the extrinsic curvature of the worldvolume swept out by the object as it evolves. We provide a Hamiltonian formulation of the dynamics of such higher derivative models which is motivated by the ADM formulation of general relativity. The canonical momenta are identified by looking at boundary behaviour under small deformations of the action; the relationship between the momentum conjugate to the embedding functions and the conserved momentum density is established. The canonical Hamiltonian is constructed explicitly; the constraints on the phase space, both primary and secondary, are identified and the role they play in the theory is described. The multipliers implementing the primary constraints are identified in terms of the ADM lapse and shift variables and Hamilton's equations are shown to be consistent with the Euler Lagrange equations.

  9. Extending Medicare immunosuppressive medication coverage.

    PubMed

    Beaubrun, Anne Christine

    2012-02-01

    African Americans and the poor are at a high risk of suffering from kidney disease and are at an extreme disadvantage when it comes to obtaining the resources needed to maintain a functioning kidney post-transplant. Medicare currently covers 80% of the cost of immunosuppressive therapy for up to three years following a Medicare-covered transplant for patients whose Medicare entitlement was based solely on their end-stage renal disease diagnosis. Adequate insurance coverage has the potential to prevent graft failure and retransplantation resulting from cost-related immunosuppressive medication nonadherence. Given the multifactorial nature of medication nonadherence, extending insurance coverage in an attempt to reduce graft failures should be coupled with intensive interventions to prevent the socioeconomic and various other factors associated with medication nonadherence. Lifetime Medicare coverage for all kidney-transplant recipients, coupled with medication adherence promotion, has the potential to minimize poor outcomes associated with graft failure, especially among minorities and the impoverished.

  10. Extended uncertainty from first principles

    NASA Astrophysics Data System (ADS)

    Costa Filho, Raimundo N.; Braga, João P. M.; Lira, Jorge H. S.; Andrade, José S.

    2016-04-01

    A translation operator acting in a space with a diagonal metric is introduced to describe the motion of a particle in a quantum system. We show that the momentum operator and, as a consequence, the uncertainty relation now depend on the metric. It is also shown that, for any metric expanded up to second order, this formalism naturally leads to an extended uncertainty principle (EUP) with a minimum momentum dispersion. The Ehrenfest theorem is modified to include an additional term related to a tidal force arriving from the space curvature introduced by the metric. For one-dimensional systems, we show how to map a harmonic potential to an effective potential in Euclidean space using different metrics.

  11. Extended mission life support systems

    NASA Technical Reports Server (NTRS)

    Quattrone, P. D.

    1985-01-01

    Extended manned space missions which include interplanetary missions require regenerative life support systems. Manned mission life support considerations are placed in perspective and previous manned space life support system technology, activities and accomplishments in current supporting research and technology (SR&T) programs are reviewed. The life support subsystem/system technologies required for an enhanced duration orbiter (EDO) and a space operations center (SOC), regenerative life support functions and technology required for manned interplanetary flight vehicles, and future development requirements are outlined. The Space Shuttle Orbiters (space transportation system) is space cabin atmosphere is maintained at Earth ambient pressure of 14.7 psia (20% O2 and 80% N2). The early Shuttle flights will be seven-day flights, and the life support system flight hardware will still utilize expendables.

  12. Learning Extended Finite State Machines

    NASA Technical Reports Server (NTRS)

    Cassel, Sofia; Howar, Falk; Jonsson, Bengt; Steffen, Bernhard

    2014-01-01

    We present an active learning algorithm for inferring extended finite state machines (EFSM)s, combining data flow and control behavior. Key to our learning technique is a novel learning model based on so-called tree queries. The learning algorithm uses the tree queries to infer symbolic data constraints on parameters, e.g., sequence numbers, time stamps, identifiers, or even simple arithmetic. We describe sufficient conditions for the properties that the symbolic constraints provided by a tree query in general must have to be usable in our learning model. We have evaluated our algorithm in a black-box scenario, where tree queries are realized through (black-box) testing. Our case studies include connection establishment in TCP and a priority queue from the Java Class Library.

  13. Extended MHD Simulations of Spheromaks

    NASA Astrophysics Data System (ADS)

    Howell, E. C.; Sovinec, C. R.

    2012-10-01

    Nonlinear extended MHD simulations of a spheromak in a cylindrical flux conserver are performed using the NIMROD code (JCP 195, 2004). An idealized series of simulations starting from a Grad-Shafranov equilibrium and small non-axisymmetric perturbations are performed to model the sustained decay phase. The resulting confinement leads to steep resistivity gradients. Strong current gradients develop, driving tearing modes that dominate the evolution of the spheromak. Absent in these simulations are the remains of n=1 fluctuations created during the formation process. A second series of simulations start from vacuum fields and model the full spheromak evolution, including the formation process where the n=1 fluctuations dominate. To understand the role of pressure driven instabilities in the evolution of the spheromak, a numerical diagnostic is developed to calculate the Mercier stability criterion from the axisymmetric fields.

  14. Stellar structures in Extended Gravity

    NASA Astrophysics Data System (ADS)

    Capozziello, S.; De Laurentis, M.

    2016-09-01

    Stellar structures are investigated by considering the modified Lané-Emden equation coming out from Extended Gravity. In particular, this equation is obtained in the Newtonian limit of f ( R) -gravity by introducing a polytropic relation between the pressure and the density into the modified Poisson equation. The result is an integro-differential equation, which, in the limit f ( R) → R , becomes the standard Lané-Emden equation usually adopted in the stellar theory. We find the radial profiles of gravitational potential by solving for some values of the polytropic index. The solutions are compatible with those coming from General Relativity and could be physically relevant in order to address peculiar and extremely massive objects.

  15. Extended Klein edges in graphene.

    PubMed

    He, Kuang; Robertson, Alex W; Lee, Sungwoo; Yoon, Euijoon; Lee, Gun-Do; Warner, Jamie H

    2014-12-23

    Graphene has three experimentally confirmed periodic edge terminations, zigzag, reconstructed 5-7, and arm-chair. Theory predicts a fourth periodic edge of graphene called the extended Klein (EK) edge, which consists of a series of single C atoms protruding from a zigzag edge. Here, we confirm the existence of EK edges in both graphene nanoribbons and on the edge of bulk graphene using atomic resolution imaging by aberration-corrected transmission electron microscopy. The formation of the EK edge stems from sputtering and reconstruction of the zigzag edge. Density functional theory reveals minimal energy for EK edge reconstruction and bond distortion both in and out of plane, supporting our TEM observations. The EK edge can now be included as the fourth member of observed periodic edge structures in graphene.

  16. THE EXTENDED VIRGO CLUSTER CATALOG

    SciTech Connect

    Kim, Suk; Rey, Soo-Chang; Lee, Youngdae; Chung, Jiwon; Pak, Mina; Yi, Wonhyeong; Lee, Woong; Jerjen, Helmut; Lisker, Thorsten; Sung, Eon-Chang

    2015-01-01

    We present a new catalog of galaxies in the wider region of the Virgo cluster, based on the Sloan Digital Sky Survey (SDSS) Data Release 7. The Extended Virgo Cluster Catalog (EVCC) covers an area of 725 deg{sup 2} or 60.1 Mpc{sup 2}. It is 5.2 times larger than the footprint of the classical Virgo Cluster Catalog (VCC) and reaches out to 3.5 times the virial radius of the Virgo cluster. We selected 1324 spectroscopically targeted galaxies with radial velocities less than 3000 km s{sup –1}. In addition, 265 galaxies that have been overlooked in the SDSS spectroscopic survey but have available redshifts in the NASA Extragalactic Database are also included. Our selection process secured a total of 1589 galaxies, 676 of which are not included in the VCC. The certain and possible cluster members are defined by means of redshift comparison with a cluster infall model. We employed two independent and complementary galaxy classification schemes: the traditional morphological classification based on the visual inspection of optical images and a characterization of galaxies from their spectroscopic features. SDSS u, g, r, i, and z passband photometry of all EVCC galaxies was performed using Source Extractor. We compare the EVCC galaxies with the VCC in terms of morphology, spatial distribution, and luminosity function. The EVCC defines a comprehensive galaxy sample covering a wider range in galaxy density that is significantly different from the inner region of the Virgo cluster. It will be the foundation for forthcoming galaxy evolution studies in the extended Virgo cluster region, complementing ongoing and planned Virgo cluster surveys at various wavelengths.

  17. Movement of elongation factor G between compact and extended conformations.

    PubMed

    Salsi, Enea; Farah, Elie; Netter, Zoe; Dann, Jillian; Ermolenko, Dmitri N

    2015-01-30

    Previous structural studies suggested that ribosomal translocation is accompanied by large interdomain rearrangements of elongation factor G (EF-G). Here, we follow the movement of domain IV of EF-G relative to domain II of EF-G using ensemble and single-molecule Förster resonance energy transfer. Our results indicate that ribosome-free EF-G predominantly adopts a compact conformation that can also, albeit infrequently, transition into a more extended conformation in which domain IV moves away from domain II. By contrast, ribosome-bound EF-G predominantly adopts an extended conformation regardless of whether it is interacting with pretranslocation ribosomes or with posttranslocation ribosomes. Our data suggest that ribosome-bound EF-G may also occasionally sample at least one more compact conformation. GTP hydrolysis catalyzed by EF-G does not affect the relative stability of the observed conformations in ribosome-free and ribosome-bound EF-G. Our data support a model suggesting that, upon binding to a pretranslocation ribosome, EF-G moves from a compact to a more extended conformation. This transition is not coupled to but likely precedes both GTP hydrolysis and mRNA/tRNA translocation.

  18. Movement of Elongation Factor G between Compact and Extended Conformations

    PubMed Central

    Salsi, Enea; Farah, Elie; Netter, Zoe; Dann, Jillian; Ermolenko, Dmitri N.

    2014-01-01

    Previous structural studies suggested that ribosomal translocation is accompanied by large interdomain rearrangements of elongation factor G (EF-G). Here, we follow the movement of domain IV of EF-G relative to domain II of EF-G using ensemble and single-molecule Förster resonance energy transfer (smFRET). Our results indicate that ribosome-free EF-G predominantly adopts a compact conformation that can also, albeit infrequently, transition into a more extended conformation in which domain IV moves away from domain II. By contrast, ribosome-bound EF-G predominantly adopts an extended conformation regardless of whether it is interacting with pre- or posttranslocation ribosomes. Our data suggest that ribosome-bound EF-G may also occasionally sample at least one more compact conformation. GTP hydrolysis catalyzed by EF-G does not affect the relative stability of the observed conformations in ribosome-free and ribosome-bound EF-G. Our data support a model suggesting that, upon binding to a pretranslocation ribosome, EF-G moves from a compact to a more extended conformation. This transition is not coupled to, but likely precedes both GTP hydrolysis and mRNA/tRNA translocation. PMID:25463439

  19. Extended Deterrence, Nuclear Proliferation, and START III

    SciTech Connect

    Speed, R.D.

    2000-06-20

    Early in the Cold War, the United States adopted a policy of ''extended nuclear deterrence'' to protect its allies by threatening a nuclear strike against any state that attacks these allies. This threat can (in principle) be used to try to deter an enemy attack using conventional weapons or one using nuclear, chemical, or biological weapons. The credibility of a nuclear threat has long been subject to debate and is dependent on many complex geopolitical factors, not the least of which is the military capabilities of the opposing sides. The ending of the Cold War has led to a significant decrease in the number of strategic nuclear weapons deployed by the United States and Russia. START II, which was recently ratified by the Russian Duma, will (if implemented) reduce the number deployed strategic nuclear weapons on each side to 3500, compared to a level of over 11,000 at the end of the Cold War in 1991. The tentative limit established by Presidents Clinton and Yeltsin for START III would reduce the strategic force level to 2000-2500. However, the Russians (along with a number of arms control advocates) now argue that the level should be reduced even further--to 1500 warheads or less. The conventional view is that ''deep cuts'' in nuclear weapons are necessary to discourage nuclear proliferation. Thus, as part of the bargain to get the non-nuclear states to agree to the renewal of the Nuclear Non-Proliferation Treaty, the United States pledged to work towards greater reductions in strategic forces. Without movement in the direction of deep cuts, it is thought by many analysts that some countries may decide to build their own nuclear weapons. Indeed, this was part of the rationale India used to justify its own nuclear weapons program. However, there is also some concern that deep cuts (to 1500 or lower) in the U.S. strategic nuclear arsenal could have the opposite effect. The fear is that such cuts might undermine extended deterrence and cause a crisis in confidence

  20. Probing outflows in z = 1 ∼ 2 galaxies through Fe II/Fe II* multiplets

    SciTech Connect

    Tang, Yuping; Giavalisco, Mauro; Guo, Yicheng

    2014-10-01

    We report on a study of the 2300-2600 Å Fe II/Fe II* multiplets in the rest-UV spectra of star-forming galaxies at 1.0 < z < 2.6 as probes of galactic-scale outflows. We extracted a mass-limited sample of 97 galaxies at z ∼ 1.0-2.6 from ultra-deep spectra obtained during the GMASS spectroscopic survey in the GOODS South field with the Very Large Telescope and FORS2. We obtain robust measures of the rest equivalent width of the Fe II absorption lines down to a limit of W{sub r} > 1.5 Å and of the Fe II* emission lines to W{sub r} > 0.5 Å. Whenever we can measure the systemic redshift of the galaxies from the [O II] emission line, we find that both the Fe II and Mg II absorption lines are blueshifted, indicating that both species trace gaseous outflows. We also find, however, that the Fe II gas has generally lower outflow velocity relative to that of Mg II. We investigate the variation of Fe II line profiles as a function of the radiative transfer properties of the lines, and find that transitions with higher oscillator strengths are more blueshifted in terms of both line centroids and line wings. We discuss the possibility that Fe II lines are suppressed by stellar absorptions. The lower velocities of the Fe II lines relative to the Mg II doublet, as well as the absence of spatially extended Fe II* emission in two-dimensional stacked spectra, suggest that most clouds responsible for Fe II absorption lie close (3 ∼ 4 kpc) to the disks of galaxies. We show that the Fe II/Fe II* multiplets offer unique probes of the kinematic structure of galactic outflows.

  1. Bioconvection in spatially extended domains

    NASA Astrophysics Data System (ADS)

    Karimi, A.; Paul, M. R.

    2013-05-01

    We numerically explore gyrotactic bioconvection in large spatially extended domains of finite depth using parameter values from available experiments with the unicellular alga Chlamydomonas nivalis. We numerically integrate the three-dimensional, time-dependent continuum model of Pedley [J. Fluid Mech.10.1017/S0022112088002393 195, 223 (1988)] using a high-order, parallel, spectral-element approach. We explore the long-time nonlinear patterns and dynamics found for layers with an aspect ratio of 10 over a range of Rayleigh numbers. Our results yield the pattern wavelength and pattern dynamics which we compare with available theory and experimental measurement. There is good agreement for the pattern wavelength at short times between numerics, experiment, and a linear stability analysis. At long times we find that the general sequence of patterns given by the nonlinear evolution of the governing equations correspond qualitatively to what has been described experimentally. However, at long times the patterns in numerics grow to larger wavelengths, in contrast to what is observed in experiment where the wavelength is found to decrease with time.

  2. Earth Observing-1 Extended Mission

    USGS Publications Warehouse

    ,

    2005-01-01

    Since November 2000, the National Aeronautics and Space Administration (NASA) Earth Observing-1 (EO-1) mission has demonstrated the capabilities of a dozen spacecraft sensor and communication innovations. Onboard the EO-1 spacecraft are two land remote sensing instruments. The Advanced Land Imager (ALI) acquires data in spectral bands and at resolutions similar to Landsat. The Hyperion instrument, which is the first civilian spaceborne hyperspectral imager, acquires data in 220 10-nanometer bands covering the visible, near, and shortwave-infrared bands. The initial one-year technology demonstration phase of the mission included a detailed comparison of ALI with the Landsat Enhanced Thematic Mapper Plus (ETM+) instrument. Specifications for the Operational Land Imager (OLI), the planned successor to ETM+, were formulated in part from performance characteristics of ALI. Recognizing the remarkable performance of the satellite's instruments and the exceptional value of the data, the U.S. Geological Survey (USGS) and NASA agreed in December 2001 to share responsibility for operating EO-1. The extended mission continues, on a cost-reimbursable basis, as long as customer sales fully recover flight and ground operations costs. As of May 2005, more than 17,800 scenes from each instrument have been acquired, indexed, archived, and made available to the public.

  3. Pair extended coupled cluster doubles

    SciTech Connect

    Henderson, Thomas M.; Scuseria, Gustavo E.; Bulik, Ireneusz W.

    2015-06-07

    The accurate and efficient description of strongly correlated systems remains an important challenge for computational methods. Doubly occupied configuration interaction (DOCI), in which all electrons are paired and no correlations which break these pairs are permitted, can in many cases provide an accurate account of strong correlations, albeit at combinatorial computational cost. Recently, there has been significant interest in a method we refer to as pair coupled cluster doubles (pCCD), a variant of coupled cluster doubles in which the electrons are paired. This is simply because pCCD provides energies nearly identical to those of DOCI, but at mean-field computational cost (disregarding the cost of the two-electron integral transformation). Here, we introduce the more complete pair extended coupled cluster doubles (pECCD) approach which, like pCCD, has mean-field cost and reproduces DOCI energetically. We show that unlike pCCD, pECCD also reproduces the DOCI wave function with high accuracy. Moreover, pECCD yields sensible albeit inexact results even for attractive interactions where pCCD breaks down.

  4. Earth Observing-1 Extended Mission

    USGS Publications Warehouse

    ,

    2003-01-01

    From its beginning in November 2000, the NASA Earth Observing-1 (EO-1) mission demonstrated the feasibility and performance of a dozen innovative sensor, spacecraft, and operational technologies. The 1-year mission tested a variety of technologies, some of which may be included on the planned 2007 Landsat Data Continuity Mission. Onboard the spacecraft are two land remote sensing instruments: the Advanced Land Imager (ALI), which acquires data in spectral bands and at resolutions similar to Landsat, and Hyperion, which acquires data in 220 10-nanometer-wide bands covering the visible, near-, and shortwave-infrared bands. Recognizing the remarkable performance of the satellite's instruments and the exceptional value of the data, the U.S. Geological Survey (USGS) and NASA agreed in December 2001 to share responsibility for operating EO-1 on a cost-reimbursable basis as long as customer sales are sufficient to recover flight and ground operations costs. The EO-1 extended mission operates within constraints imposed by its technology-pioneering origins, but it also provides unique and valuable capabilities. The spacecraft can acquire a target scene three times in a 16-day period. The ALI instrument has additional spectral coverage and greater radiometric dynamic range compared with the sensors on Landsat 7. Hyperion is the first civilian spaceborne hyperspectral imager. As of January 2003, more than 5,000 scenes had been acquired, indexed, and archived.

  5. The Extended Mission Rover (EMR)

    NASA Astrophysics Data System (ADS)

    Shields, W.; Halecki, Anthony; Chung, Manh; Clarke, Ken; Frankle, Kevin; Kassemkhani, Fariba; Kuhlhoff, John; Lenzini, Josh; Lobdell, David; Morgan, Sam

    A key component in ensuring America's status as a leader in the global community is its active pursuit of space exploration. On the twentieth anniversary of Apollo 11, President George Bush challenged the nation to place a man on the moon permanently and to conduct human exploration of Mars in the 21st century. The students of the FAMU/FSU College of Engineering hope to make a significant contribution to this challenge, America's Space Exploration Initiative (SEI), with their participation in the NASA/USRA Advanced Design Program. The project selected by the 1991/1992 Aerospace Design group is the design of an Extended Mission Rover (EMR) for use on the lunar surface. This vehicle will serve as a mobile base to provide future astronauts with a 'shirt-sleeve' living and working environment. Some of the proposed missions are planetary surface exploration, construction and maintenance, hardware setup, and in situ resource experimentation. This vehicle will be put into use in the 2010-2030 time frame.

  6. Extended attention span training system

    NASA Technical Reports Server (NTRS)

    Pope, Alan T.; Bogart, Edward H.

    1991-01-01

    Attention Deficit Disorder (ADD) is a behavioral disorder characterized by the inability to sustain attention long enough to perform activities such as schoolwork or organized play. Treatments for this disorder include medication and brainwave biofeedback training. Brainwave biofeedback training systems feed back information to the trainee showing him how well he is producing the brainwave pattern that indicates attention. The Extended Attention Span Training (EAST) system takes the concept a step further by making a video game more difficult as the player's brainwaves indicate that attention is waning. The trainee can succeed at the game only by maintaining an adequate level of attention. The EAST system is a modification of a biocybernetic system that is currently being used to assess the extent to which automated flight management systems maintain pilot engagement. This biocybernetic system is a product of a program aimed at developing methods to evaluate automated flight deck designs for compatibility with human capabilities. The EAST technology can make a contribution in the fields of medical neuropsychology and neurology, where the emphasis is on cautious, conservative treatment of youngsters with attention disorders.

  7. The Extended Mission Rover (EMR)

    NASA Technical Reports Server (NTRS)

    Shields, W.; Halecki, Anthony; Chung, Manh; Clarke, Ken; Frankle, Kevin; Kassemkhani, Fariba; Kuhlhoff, John; Lenzini, Josh; Lobdell, David; Morgan, Sam

    1992-01-01

    A key component in ensuring America's status as a leader in the global community is its active pursuit of space exploration. On the twentieth anniversary of Apollo 11, President George Bush challenged the nation to place a man on the moon permanently and to conduct human exploration of Mars in the 21st century. The students of the FAMU/FSU College of Engineering hope to make a significant contribution to this challenge, America's Space Exploration Initiative (SEI), with their participation in the NASA/USRA Advanced Design Program. The project selected by the 1991/1992 Aerospace Design group is the design of an Extended Mission Rover (EMR) for use on the lunar surface. This vehicle will serve as a mobile base to provide future astronauts with a 'shirt-sleeve' living and working environment. Some of the proposed missions are planetary surface exploration, construction and maintenance, hardware setup, and in situ resource experimentation. This vehicle will be put into use in the 2010-2030 time frame.

  8. Bose-Einstein Condensation in Extended Microgravity

    NASA Astrophysics Data System (ADS)

    Scharringhausen, Marco; Quantus Team; Rasel, Ernst Maria

    2012-07-01

    The setup and the envisaged experiment timeline of the QUANTUS-III experiment onboard a sounding rocket to be started in the near future are presented. The major intention of QUANTUS-III is the stable generation of a number of Bose-Einstein condensates as a source for atom interferometry during several minutes of microgravity onboard the sounding rocket. Later missions aim at the realization of atom interferoemeters as precursor satellite missions. These condesates will be generated serially, allowing a large number of repeatable tests. Within such Bose-Einstein condensates, millions of atoms lose their identity and can be described by a single macroscopic wave function. During the expansion over several seconds, the atoms form a giant coherent matter wave that is delocalized on a millimeter scale, which represents a promising source for matter-wave interferometry to test the universality of free fall with quantum matter. Cold quantum gases and, in particular, Bose-Einstein condensates represent a new state of matter which is nowadays established in many laboratories. They offer unique insights into a broad range of fundamental physics as well as prospects for novel quantum sensors. Microgravity will substantially extend the science of quantum gases towards nowadays inaccessible regimes at lowest temperatures, to macroscopic dimensions, and to unequalled durations of unperturbed evolution of these distinguished quantum objects. Right now, the QUANTUS-III experiment is in the development phase, taking heritage from QUANTUS-I and QUANTUS-II. Major components of the engineering model are available. Boundary conditions of the rocket, requirements of the experiment and interface considerations are presented. This include laser stabilization, vacuum technology and magnetic shielding. The planned trajectory of the rocket will have an apogee of 200 - 300 km and a total microgravity time of 4 - 7 minutes, both depending on the total experiment mass.

  9. 38 CFR 21.74 - Extended evaluation.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2012-07-01 2012-07-01 false Extended evaluation. 21... Duration of Rehabilitation Programs § 21.74 Extended evaluation. (a) General. An extended evaluation may be... evaluation are listed in § 21.57(b) of this part. (Authority: 38 U.S.C. 3105(a), 3106(a)) (b) Duration....

  10. Competitive Fe(II)-Zn(II) uptake on a synthetic montmorillonite.

    PubMed

    Soltermann, Daniela; Marques Fernandes, Maria; Baeyens, Bart; Miehé-Brendlé, Jocelyne; Dähn, Rainer

    2014-01-01

    The interaction of Fe(II) with clay minerals is of particular relevance in global geochemical processes controlling metal and nutrient cycles and the fate of contaminants. In this context, the influence of competitive sorption effects between Fe(II) and other relevant transition metals on their uptake characteristics and mobility remains an important issue. Macroscopic sorption experiments combined with surface complexation modeling and extended X-ray absorption fine structure (EXAFS) spectroscopy were applied to elucidate competitive sorption processes between divalent Fe and Zn at the clay mineral-water interface. Sorption isotherms were measured on a synthetic iron-free montmorillonite (IFM) under anoxic conditions (O2 <0.1 ppm) for the combinations of Zn(II)/Fe(II) and Fe(II)/Zn(II), where the former metal in each pair represents the trace metal (<10(-7) M) and the latter the competing metal at higher concentrations (10(-7) to 10(-3) M). Results of the batch sorption and EXAFS measurements indicated that Fe(II) is competing with trace Zn(II) for the same type of strong sites if Fe(II) is present in excess, whereas no competition between trace Fe(II) and Zn(II) was observed if Zn(II) is present at high concentrations. The noncompetitive behavior suggests the existence of sorption sites which have a higher affinity for Fe(III), where surface-induced oxidation of the sorbed Fe(II) to Fe(III) occurred, and which are not accessible for Zn(II). The understanding of this competitive uptake mechanism between Fe(II) and Zn(II) is of great importance to assess the bioavailability and mobility of transition metals in the natural environment. PMID:24289476

  11. THE EXTENDED ENVIRONMENT OF M17: A STAR FORMATION HISTORY

    SciTech Connect

    Povich, Matthew S.; Churchwell, Ed; Babler, Brian L.; Meade, Marilyn R.; Bieging, John H.; Kang, Miju; Kulesa, Craig A.; Whitney, Barbara A.; Brogan, Crystal L.; Cohen, Martin; Indebetouw, Remy; Robitaille, Thomas P.

    2009-05-10

    M17 is one of the youngest and most massive nearby star-formation regions in the Galaxy. It features a bright H II region erupting as a blister from the side of a giant molecular cloud (GMC). Combining photometry from the Spitzer Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) with complementary infrared (IR) surveys, we identify candidate young stellar objects (YSOs) throughout a 1.{sup 0}5 x 1{sup 0} field that includes the M17 complex. The long sightline through the Galaxy behind M17 creates significant contamination in our YSO sample from unassociated sources with similar IR colors. Removing contaminants, we produce a highly reliable catalog of 96 candidate YSOs with a high probability of association with the M17 complex. We fit model spectral energy distributions to these sources and constrain their physical properties. Extrapolating the mass function of 62 intermediate-mass YSOs (M {sub *} > 3 M {sub sun}), we estimate that >1000 stars are in the process of forming in the extended outer regions of M17. The remaining 34 candidate YSOs are found in a 0.17 deg{sup 2} field containing the well-studied M17 H II region and photodissociation region (PDR), where bright diffuse mid-IR emission drastically reduces the sensitivity of the GLIMPSE point-source detections. By inspecting IR survey images from IRAS and GLIMPSE, we find that M17 lies on the rim of a large shell structure {approx}0.{sup 0}5 in diameter ({approx}20 pc at 2.1 kpc). We present maps of {sup 12}CO and {sup 13}CO (J = 2 {yields} 1) emission observed with the Heinrich Hertz Telescope. The CO emission shows that the shell is a coherent, kinematic structure associated with M17, centered at v = 19 km s{sup -1}. The shell is an extended bubble outlining the PDR of a faint, diffuse H II region several Myr old. We identify a group of candidate ionizing stars within the bubble. YSOs in our catalog are concentrated around the bubble rim, providing evidence that massive star formation has

  12. The Extended Environment of M17: A Star Formation History

    NASA Astrophysics Data System (ADS)

    Povich, Matthew S.; Churchwell, Ed; Bieging, John H.; Kang, Miju; Whitney, Barbara A.; Brogan, Crystal L.; Kulesa, Craig A.; Cohen, Martin; Babler, Brian L.; Indebetouw, Rémy; Meade, Marilyn R.; Robitaille, Thomas P.

    2009-05-01

    M17 is one of the youngest and most massive nearby star-formation regions in the Galaxy. It features a bright H II region erupting as a blister from the side of a giant molecular cloud (GMC). Combining photometry from the Spitzer Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) with complementary infrared (IR) surveys, we identify candidate young stellar objects (YSOs) throughout a 1fdg5 × 1° field that includes the M17 complex. The long sightline through the Galaxy behind M17 creates significant contamination in our YSO sample from unassociated sources with similar IR colors. Removing contaminants, we produce a highly reliable catalog of 96 candidate YSOs with a high probability of association with the M17 complex. We fit model spectral energy distributions to these sources and constrain their physical properties. Extrapolating the mass function of 62 intermediate-mass YSOs (M sstarf > 3 M sun), we estimate that >1000 stars are in the process of forming in the extended outer regions of M17. The remaining 34 candidate YSOs are found in a 0.17 deg2 field containing the well-studied M17 H II region and photodissociation region (PDR), where bright diffuse mid-IR emission drastically reduces the sensitivity of the GLIMPSE point-source detections. By inspecting IR survey images from IRAS and GLIMPSE, we find that M17 lies on the rim of a large shell structure ~0fdg5 in diameter (~20 pc at 2.1 kpc). We present maps of 12CO and 13CO (J = 2 → 1) emission observed with the Heinrich Hertz Telescope. The CO emission shows that the shell is a coherent, kinematic structure associated with M17, centered at v = 19 km s-1. The shell is an extended bubble outlining the PDR of a faint, diffuse H II region several Myr old. We identify a group of candidate ionizing stars within the bubble. YSOs in our catalog are concentrated around the bubble rim, providing evidence that massive star formation has been triggered by the expansion of the bubble. The formation of

  13. Extend{trademark} customization -- Experiences and issues

    SciTech Connect

    Parker, R.Y.

    1997-12-09

    Extend{trademark} simulation software is a dynamic modeling package developed by Imagine That Incorporated. The Technology Modeling and Analysis group (TSA-7) at Los Alamos National Laboratory has used Extend extensively over the past few years as one of various tools employed to perform simulation modeling and analysis. Development efforts over much of this period have made Extend a more effective and efficient tool through block customization. TSA-7 has taken advantage of the built-in capability in Extend to allow users to create new or modify existing functional blocks from which simulation models are constructed. As a result, Extend is much more effective and efficient for the group`s applications. This paper summarizes block customization and simulation model development that markedly improved the utilization of the Extend software package. The material covered herein includes some background information on Extend, which is necessary for understanding the balance of the paper. Following the background, the paper addresses Extend block customization efforts, including advantages and disadvantages to customizing, and the impact customization has had on Extend modeling efforts in TSA-7. Brief descriptions of many customized blocks developed by the author are presented in the appendix.

  14. 41 CFR 101-27.207-3 - Marking material to show extended shelf life.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 41 Public Contracts and Property Management 2 2012-07-01 2012-07-01 false Marking material to show...-INVENTORY MANAGEMENT 27.2-Management of Shelf-Life Materials § 101-27.207-3 Marking material to show extended shelf life. When the shelf-life period of Type II material (except for critical end-use items...

  15. 41 CFR 101-27.207-3 - Marking material to show extended shelf life.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 41 Public Contracts and Property Management 2 2011-07-01 2007-07-01 true Marking material to show...-INVENTORY MANAGEMENT 27.2-Management of Shelf-Life Materials § 101-27.207-3 Marking material to show extended shelf life. When the shelf-life period of Type II material (except for critical end-use items...

  16. 41 CFR 101-27.207-3 - Marking material to show extended shelf life.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 41 Public Contracts and Property Management 2 2013-07-01 2012-07-01 true Marking material to show...-INVENTORY MANAGEMENT 27.2-Management of Shelf-Life Materials § 101-27.207-3 Marking material to show extended shelf life. When the shelf-life period of Type II material (except for critical end-use items...

  17. 41 CFR 101-27.207-3 - Marking material to show extended shelf life.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 41 Public Contracts and Property Management 2 2014-07-01 2012-07-01 true Marking material to show...-INVENTORY MANAGEMENT 27.2-Management of Shelf-Life Materials § 101-27.207-3 Marking material to show extended shelf life. When the shelf-life period of Type II material (except for critical end-use items...

  18. Extended Family Integration among Euro and Mexican Americans: Ethnicity, Gender, and Class

    ERIC Educational Resources Information Center

    Sarkisian, Natalia; Gerena, Mariana; Gerstel, Naomi

    2007-01-01

    This article compares the extended family integration of Euro and Mexican American women and men and assesses the importance of class and culture in explaining ethnic differences. Using National Survey of Families and Households II data (N = 7,929), we find that ethnic differences depend on the dimension of integration. Mexican Americans exhibit…

  19. 78 FR 2256 - Extension of the Extended Missing Parts Pilot Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-10

    ... Reply to a Notice to File Missing Parts of Nonprovisional Application, 75 FR 76401 (Dec. 8, 2010), 1362... until December 31, 2012. See Extension of the Extended Missing Parts Pilot Program, 76 FR 78246 (Dec. 16... (EFS-Web), 74 FR 55200 (Oct. 27, 2009), 1348 Off. Gaz. Pat. Office 394 (Nov. 24, 2009). II....

  20. 78 FR 34099 - FCC Extends Pleading Cycle for Indecency Cases Policy

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-06

    ... Electronic Comment Filing System (ECFS). See Electronic Filing of Documents in Rulemaking Proceedings, 63 FR... COMMISSION FCC Extends Pleading Cycle for Indecency Cases Policy AGENCY: Federal Communications Commission.... until 11:30 a.m. on Friday at the FCC Reference Information Center, Portals II, Room CY- A257, 445...

  1. Evaluation of Kentucky's Extended School Services Program.

    ERIC Educational Resources Information Center

    Meehan, Merrill L.; Cowley, Kimberly S.; Schumacher, Debbie; Hauser, Brenda

    The Extended School Services (ESS) program was established in 1990 as part of the Kentucky Education Reform Act. The program extends the school day, week, or year for students at risk of academic failure, providing them with additional instructional time to help them meet academic goals. An evaluation of ESS in 2001 utilized statewide surveys and…

  2. 38 CFR 21.74 - Extended evaluation.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) VOCATIONAL REHABILITATION AND EDUCATION Vocational Rehabilitation and Employment Under 38 U.S.C. Chapter 31 Duration of Rehabilitation Programs § 21.74 Extended evaluation. (a) General. An extended evaluation may be... concurrence of the Vocational Rehabilitation and Employment (VR&E) Officer before approving the extension of...

  3. ADD, LD and Extended Information Processing.

    ERIC Educational Resources Information Center

    Stolzenberg, J. B.; Cherkes-Julkowski, M.

    This study examines executive function and its relationship to attention dysfunction and working memory. It attempts to document the manifestations of executive function problems in school-related extended processing tasks, such as verbal problem-solving in math and reading of extended passages. Subjects (in grades 1-12) included 49 children with…

  4. Extended, Embodied Cognition and Second Language Acquisition

    ERIC Educational Resources Information Center

    Atkinson, Dwight

    2010-01-01

    A "cognitivist" approach to cognition has traditionally dominated second language acquisition (SLA) studies. In this article, I examine two alternative approaches--"extended cognition" and "embodied cognition"--for how they might help us conceptualize SLA. More specifically, I present: (i) summaries of extended and embodied cognition, followed by…

  5. Report on Extended Campus Library Services.

    ERIC Educational Resources Information Center

    Strickler, Sally Ann; And Others

    This report presents the results of a study of the Extended Campus Library Services program at Western Kentucky University (WKU), which was conducted by a committee appointed by the Director of University Libraries. A description of the program's goals and objectives is followed by a review of the extended campus programs in relation to similar…

  6. 42 CFR 488.720 - Extended surveys.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 5 2014-10-01 2014-10-01 false Extended surveys. 488.720 Section 488.720 Public...) STANDARDS AND CERTIFICATION SURVEY, CERTIFICATION, AND ENFORCEMENT PROCEDURES Survey and Certification of Home Health Agencies § 488.720 Extended surveys. (a) Purpose of survey. The purpose of an...

  7. 42 CFR 488.720 - Extended surveys.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 5 2013-10-01 2013-10-01 false Extended surveys. 488.720 Section 488.720 Public...) STANDARDS AND CERTIFICATION SURVEY, CERTIFICATION, AND ENFORCEMENT PROCEDURES Survey and Certification of Home Health Agencies § 488.720 Extended surveys. (a) Purpose of survey. The purpose of an...

  8. 42 CFR 488.310 - Extended survey.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 5 2010-10-01 2010-10-01 false Extended survey. 488.310 Section 488.310 Public...) STANDARDS AND CERTIFICATION SURVEY, CERTIFICATION, AND ENFORCEMENT PROCEDURES Survey and Certification of Long-Term Care Facilities § 488.310 Extended survey. (a) Purpose of survey. The purpose of an...

  9. 42 CFR 488.310 - Extended survey.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 5 2014-10-01 2014-10-01 false Extended survey. 488.310 Section 488.310 Public...) STANDARDS AND CERTIFICATION SURVEY, CERTIFICATION, AND ENFORCEMENT PROCEDURES Survey and Certification of Long-Term Care Facilities § 488.310 Extended survey. (a) Purpose of survey. The purpose of an...

  10. 42 CFR 488.310 - Extended survey.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 5 2012-10-01 2012-10-01 false Extended survey. 488.310 Section 488.310 Public...) STANDARDS AND CERTIFICATION SURVEY, CERTIFICATION, AND ENFORCEMENT PROCEDURES Survey and Certification of Long-Term Care Facilities § 488.310 Extended survey. (a) Purpose of survey. The purpose of an...

  11. 42 CFR 488.310 - Extended survey.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 5 2013-10-01 2013-10-01 false Extended survey. 488.310 Section 488.310 Public...) STANDARDS AND CERTIFICATION SURVEY, CERTIFICATION, AND ENFORCEMENT PROCEDURES Survey and Certification of Long-Term Care Facilities § 488.310 Extended survey. (a) Purpose of survey. The purpose of an...

  12. 42 CFR 488.310 - Extended survey.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 5 2011-10-01 2011-10-01 false Extended survey. 488.310 Section 488.310 Public...) STANDARDS AND CERTIFICATION SURVEY, CERTIFICATION, AND ENFORCEMENT PROCEDURES Survey and Certification of Long-Term Care Facilities § 488.310 Extended survey. (a) Purpose of survey. The purpose of an...

  13. Extend School Day and Year for NCLB?

    ERIC Educational Resources Information Center

    Chmelynski, Carol

    2006-01-01

    This article highlights the extended-day program adopted by many schools. With so much material being crammed into the curriculum--and with so much time during the school day being devoted to the matter of test preparation--many schools have been looking at the possibility of extending the school day. Several schools are experimenting with longer…

  14. Teaching the Extended Modifier: A Transformational Approach.

    ERIC Educational Resources Information Center

    Mann, G. Thomas

    1985-01-01

    Offers a practical model for teaching the extended modifier that is economical and linguistically sound, based on the insights and methodology of transformational generative grammar. Five transformational rules are given for generating extended modifiers from relative clauses. Examples of transformations and two class exercises in German are also…

  15. Competitive adsorption of copper(II), cadmium(II), lead(II) and zinc(II) onto basic oxygen furnace slag.

    PubMed

    Xue, Yongjie; Hou, Haobo; Zhu, Shujing

    2009-02-15

    Polluted and contaminated water can often contain more than one heavy metal species. It is possible that the behavior of a particular metal species in a solution system will be affected by the presence of other metals. In this study, we have investigated the adsorption of Cd(II), Cu(II), Pb(II), and Zn(II) onto basic oxygen furnace slag (BOF slag) in single- and multi-element solution systems as a function of pH and concentration, in a background solution of 0.01M NaNO(3). In adsorption edge experiments, the pH was varied from 2.0 to 13.0 with total metal concentration 0.84mM in the single element system and 0.21mM each of Cd(II), Cu(II), Pb(II), and Zn(II) in the multi-element system. The value of pH(50) (the pH at which 50% adsorption occurs) was found to follow the sequence Zn>Cu>Pb>Cd in single-element systems, but Pb>Cu>Zn>Cd in the multi-element system. Adsorption isotherms at pH 6.0 in the multi-element systems showed that there is competition among various metals for adsorption sites on BOF slag. The adsorption and potentiometric titrations data for various slag-metal systems were modeled using an extended constant-capacitance surface complexation model that assumed an ion-exchange process below pH 6.5 and the formation of inner-sphere surface complexes at higher pH. Inner-sphere complexation was more dominant for the Cu(II), Pb(II) and Zn(II) systems.

  16. The symmetric extendibility of quantum states

    NASA Astrophysics Data System (ADS)

    Nowakowski, Marcin L.

    2016-09-01

    Studies on the symmetric extendibility of quantum states have become particularly important in the context of the analysis of one-way quantum measures of entanglement, and the distillability and security of quantum protocols. In this paper we analyze composite systems containing a symmetric extendible part, with particular attention devoted to the one-way security of such systems. Further, we introduce a new one-way entanglement monotone based on the best symmetric approximation of a quantum state and the extendible number of a quantum state. We underpin these results with geometric observations about the structures of multi-party settings which posses substantial symmetric extendible components in their subspaces. The impossibility of reducing the maximal symmetric extendibility by means of the one-way local operations and classical communication method is pointed out on multiple copies. Finally, we state a conjecture linking symmetric extendibility with the one-way distillability and security of all quantum states, analyzing the behavior of a private key in the neighborhood of symmetric extendible states.

  17. [C II] and [N II] from dense ionized regions in the Galaxy

    NASA Astrophysics Data System (ADS)

    Langer, W. D.; Goldsmith, P. F.; Pineda, J. L.

    2016-05-01

    Context. The interstellar medium (ISM) consists of highly ionized and neutral atomic, as well as molecular, components. Knowledge of their distribution is important for tracing the structure and lifecycle of the ISM. Aims: To determine the properties of the highly ionized gas and neutral weakly ionized gas in the Galaxy traced by the fine-structure lines of ionized nitrogen, [N ii], and ionized carbon, [C ii]. Methods: We utilize observations of the [C ii] 158 μm and [N ii] 205 μm fine-structure lines taken with the high spectral resolution Heterodyne Instrument in the Far-Infrared (HIFI) on the Herschel Space Observatory along ten lines of sight towards the inner Galaxy to analyze the ionized ISM. The [N ii] emission can be used to estimate the contribution of the highly ionized gas to the [C ii] emission and separate the contributions from highly ionized and weakly ionized neutral gas. Results: We find that [N ii] has strong emission in distinct spectral features along all lines of sight associated with strong [C ii] emission. The [N ii] arises from moderate density extended H ii regions or ionized boundary layers of clouds. Comparison of the [N ii] and [C ii] spectra in 31 separate kinematic features shows that many of the [C ii] spectra are affected by absorption from low excitation gas associated with molecular clouds, sometimes strongly so. The apparent fraction of the [C ii] associated with the [N ii] gas is unrealistically large in many cases, most likely due to the reduction of [C ii] by absorption. In a few cases the foreground absorption can be modeled to determine the true source intensity. In these sources we find that the foreground absorbing gas layer has C+ column densities of order 1018 cm-2. Conclusions: [C ii] emission arising from strong sources of [N ii] emission is frequently absorbed by low excitation foreground gas complicating the interpretation of the properties of the ionized and neutral gas components that give rise to [C ii] emission.

  18. Physical nature of interactions in Zn(II) complexes with 2,2'-bipyridyl: quantum theory of atoms in molecules (QTAIM), interacting quantum atoms (IQA), noncovalent interactions (NCI), and extended transition state coupled with natural orbitals for chemical valence (ETS-NOCV) comparative studies.

    PubMed

    Cukrowski, Ignacy; de Lange, Jurgens H; Mitoraj, Mariusz

    2014-01-23

    In the present account factors determining the stability of ZnL, ZnL2, and ZnL3 complexes (L = bpy, 2,2′-bipyridyl) were characterized on the basis of various techniques: the quantum theory of atoms in molecules (QTAIM), energy decomposition schemes based on interacting quantum atoms (IQA), and extended transition state coupled with natural orbitals for chemical valence (ETS-NOCV). Finally, the noncovalent interactions (NCI) index was also applied. All methods consistently indicated that the strength of the coordination bonds, Zn–O and Zn–N, decreases from ZnL to ZnL3. Importantly, it has been identified that the strength of secondary intramolecular heteropolar hydrogen bonding interactions, CH···O and CH···N, increases when going from ZnL to ZnL3. A similar trend appeared to be valid for the π-bonding as well as electrostatic stabilization. In addition to the above leading bonding contributions, all techniques suggested the existence of very subtle, but non-negligible additional stabilization from the CH···HC electronic exchange channel; these interactions are the weakest among all considered here. From IQA it was found that the local diatomic interaction energy, Eint(H,H), amounts at HF to −2.5, −2.7, and −2.9 kcal mol(–1) for ZnL, ZnL2, and ZnL3, respectively (−2.1 kcal mol(–1) for ZnL at MP2). NOCV-based deformation density channels showed that formation of CH--HC contacts in Zn complexes causes significant polarization of σ(C–H) bonds, which accordingly leads to charge accumulation in the CH···HC bay region. Charge depletion from σ(C–H) bonds was also reflected in the calculated spin–spin (1)J(C–H) coupling constants, which decrease from 177.06 Hz (ZnL) to 173.87 Hz (ZnL3). This last result supports our findings of an increase in the local electronic CH···HC stabilization from ZnL to ZnL3 found from QTAIM, IQA, and ETS-NOCV. Finally, this work unites for the first time the results from four methods that are widely

  19. Very extended cold gas, star formation and outflows in the halo of a bright quasar at z > 6

    NASA Astrophysics Data System (ADS)

    Cicone, C.; Maiolino, R.; Gallerani, S.; Neri, R.; Ferrara, A.; Sturm, E.; Fiore, F.; Piconcelli, E.; Feruglio, C.

    2015-02-01

    Past observations of quasar host galaxies at z> 6 have found cold gas and star formation on compact scales of a few kiloparsecs. We present new high sensitivity IRAM Plateau de Bure Interferometer follow-up observations of the [C ii] 158 μm emission line and far-infrared (FIR) continuum in the host galaxy of SDSS J1148+5251, a luminous quasar at redshift 6.4189. We find that a large portion of the gas traced by [C ii] is at high velocities, up to ~1400 km s-1relative to the systemic velocity, confirming the presence of a major outflow as indicated by previous observations. The outflow has a complex morphology and reaches a maximum projected radius of ≃30 kpc. The extreme spatial extent of the outflow allows us, for the first time in an external galaxy, to estimate mass-loss rate, kinetic power, and momentum rate of the outflow as a function of the projected distance from the nucleus and the dynamical time scale. These trends reveal multiple outflow events during the past 100 Myr, although the bulk of the mass, energy, and momentum appear to have been released more recently within the past ~20 Myr. Surprisingly, we discover that the quiescent gas at systemic velocity is also extremely extended. More specifically, we find that, while 30% of the [C ii] within v ∈(-200, 200) km s-1 traces a compact component that is not resolved by our observations, 70% of the [C ii] emission in this velocity range is extended with a projected full width at half maximum (FWHM) size of 17.4 ± 1.4 kpc. We detect FIR continuum emission associated with both the compact and the extended [C ii] components, although the extended FIR emission has a FWHM of 11 ± 3 kpc, thus smaller than the extended [C ii] source. Overall, our results indicate that the cold gas traced by [C ii] is distributed up to r ~ 30 kpc in the host galaxy of SDSS J1148+5251. A large amount of extended [C ii] is likely to be associated with star formation occurring on large scales, but the [C ii] source extends well

  20. Phosphate effects on copper(II) and lead(II) sorption to ferrihydrite

    NASA Astrophysics Data System (ADS)

    Tiberg, Charlotta; Sjöstedt, Carin; Persson, Ingmar; Gustafsson, Jon Petter

    2013-11-01

    Transport of lead(II) and copper(II) ions in soil is affected by the soil phosphorus status. Part of the explanation may be that phosphate increases the adsorption of copper(II) and lead(II) to iron (hydr)oxides in soil, but the details of these interactions are poorly known. Knowledge about such mechanisms is important, for example, in risk assessments of contaminated sites and development of remediation methods. We used a combination of batch experiments, extended X-ray absorption fine structure (EXAFS) spectroscopy and surface complexation modeling with the three-plane CD-MUSIC model to study the effect of phosphate on sorption of copper(II) and lead(II) to ferrihydrite. The aim was to identify the surface complexes formed and to derive constants for the surface complexation reactions. In the batch experiments phosphate greatly enhanced the adsorption of copper(II) and lead(II) to ferrihydrite at pH < 6. The largest effects were seen for lead(II).

  1. Apparatus and methods for a human extender

    DOEpatents

    Jansen, John F.

    2001-01-01

    A human extender controller for interface between a human operator and a physical object through a physical plant. The human extender controller uses an inner-feedback loop to increase the equivalent damping of the operating system to stabilize the system when it contacts with the environment and reduces the impact of the environment variation by utilizing a high feedback gain, determined by a root locus sketch. Because the stability of the human extender controller of the present invention is greatly enhanced over that of the prior art, the present invention is able to achieve a force reflection ratio 500 to 1 and capable of handling loads above the two (2) ton range.

  2. Extended Hamiltonian approach to continuous tempering

    NASA Astrophysics Data System (ADS)

    Gobbo, Gianpaolo; Leimkuhler, Benedict J.

    2015-06-01

    We introduce an enhanced sampling simulation technique based on continuous tempering, i.e., on continuously varying the temperature of the system under investigation. Our approach is mathematically straightforward, being based on an extended Hamiltonian formulation in which an auxiliary degree of freedom, determining the effective temperature, is coupled to the physical system. The physical system and its temperature evolve continuously in time according to the equations of motion derived from the extended Hamiltonian. Due to the Hamiltonian structure, it is easy to show that a particular subset of the configurations of the extended system is distributed according to the canonical ensemble for the physical system at the correct physical temperature.

  3. Extended core for motor/generator

    DOEpatents

    Shoykhet, Boris A.

    2006-08-22

    An extended stator core in a motor/generator can be utilized to mitigate losses in end regions of the core and a frame of the motor/generator. To mitigate the losses, the stator core can be extended to a length substantially equivalent to or greater than a length of a magnetically active portion in the rotor. Alternatively, a conventional length stator core can be utilized with a shortened magnetically active portion to mitigate losses in the motor/generator. To mitigate the losses in the core caused by stator winding, the core can be extended to a length substantially equivalent or greater than a length of stator winding.

  4. Extended core for motor/generator

    DOEpatents

    Shoykhet, Boris A.

    2005-05-10

    An extended stator core in a motor/generator can be utilized to mitigate losses in end regions of the core and a frame of the motor/generator. To mitigate the losses, the stator core can be extended to a length substantially equivalent to or greater than a length of a magnetically active portion in the rotor. Alternatively, a conventional length stator core can be utilized with a shortened magnetically active portion to mitigate losses in the motor/generator. To mitigate the losses in the core caused by stator winding, the core can be extended to a length substantially equivalent or greater than a length of stator winding.

  5. Generalized Laplace Transforms and Extended Heaviside Calculus

    ERIC Educational Resources Information Center

    Deakin, Michael A. B.

    2008-01-01

    An extended Heaviside calculus proposed by Peraire in a recent paper is similar to a generalization of the Laplace transform proposed by the present author. This similarity will be illustrated by analysis of an example supplied by Peraire.

  6. Extended Adjuvant Therapy for Breast Cancer

    Cancer.gov

    An NCI Cancer Currents blog on findings from a recent clinical trial which showed that extending adjuvant therapy with an aromatase inhibitor can have important benefits for some women with early-stage cancer.

  7. Extended service 5w-40 motor oil

    SciTech Connect

    Schiemen, R.D.

    1983-09-06

    An extended drain 5W-40 motor oil composition for internal combustion engines comprises a base oil component of one or more solvent extracted mineral oils and a high refractory mineral oil, a V.I. improver, and preferably other suitable lube oil additives. The finished oil formulation has characteristics of minimal viscosity at low temperatures, low volatility at higher temperatures, and stable viscosity over extended use.

  8. eXtended MetaData Registry

    2006-10-25

    The purpose of the eXtended MetaData Registry (XMDR) prototype is to demonstrate the feasibility and utility of constructing an extended metadata registry, i.e., one which encompasses richer classification support, facilities for including terminologies, and better support for formal specification of semantics. The prototype registry will also serve as a reference implementation for the revised versions of ISO 11179, Parts 2 and 3 to help guide production implementations.

  9. An extended duration hybrid powered hexcopter

    NASA Astrophysics Data System (ADS)

    Winningham, Jason D.

    This work attempts to extend the flight time of a UAS to allow for longer ranges, extended time on station, and larger payloads by adding lift capacity for an auxiliary power unit that generates electrical power using an internal combustion engine. The UAS is instrumented to examine power consumption during flights with various payload masses. Safety aspects of the larger UAS are examined, including a safety analysis of the flight control software.

  10. Supradiaphragmatic bronchogenic cyst extending into the retroperitoneum.

    PubMed

    Jo, Won-Min; Shin, Jae Seung; Lee, In Sung

    2006-01-01

    We experienced a case of bronchogenic cyst located on the left lower pleural space extending into the retroperitoneum in a 33-year-old man with left chest pain. Preoperative imaging studies and operative findings showed a broad-based cystic mass on the left lower posterior pleura and diaphragmatic pleura extending into the retroperitoneal region across the diaphragm. Histologic studies proved this mass to be a bronchogenic cyst.

  11. Structure of the extended emission in the infrared celestial background

    SciTech Connect

    Price, S.D.

    1988-01-01

    The extended infrared celestial emission is due to three main sources: zodiacal dust, large discrete objects in the galaxy, and interstellar dust. As viewed from earth orbit, the thermal reradiation of sunlight absorbed by dust in the solar system produces a pervasive IR background that peaks roughly along the ecliptic plane, where the density of dust is highest. Much-smaller-scale structure was also observed in both the visual and infrared. Between 7 and 30 micrometers, H II regions are the brightest discrete objects in the galaxy. An additional emission mechanism is needed, however, to account for the shorter-wavelength observations. The galactic sources combine along the line of sight to produce an intense band of emission, centered on the galactic plane. Structure in all of these backgrounds creates a clutter problem for an orbiting IR telescope.

  12. Positive deconvolution for superimposed extended source and point sources

    NASA Astrophysics Data System (ADS)

    Giovannelli, J.-F.; Coulais, A.

    2005-08-01

    The paper deals with the construction of images from visibilities acquired using aperture synthesis instruments: Fourier synthesis, deconvolution, and spectral interpolation/extrapolation. Its intended application is to specific situations in which the imaged object possesses two superimposed components: (i) an extended component together with (ii) a set of point sources. It is also specifically designed to the case of positive maps, and accounts for a known support. Its originality lies within joint estimation of the two components, coherently with data, properties of each component, positivity and possible support. We approach the subject as an inverse problem within a regularization framework: a regularized least-squares criterion is specifically proposed and the estimated maps are defined as its minimizer. We have investigated several options for the numerical minimization and we propose a new efficient algorithm based on augmented Lagrangian. Evaluation is carried out using simulated and real data (from radio interferometry) demonstrating the capability to accurately separate the two components.

  13. Extended-release methylphenidate (Ritalin LA).

    PubMed

    Lyseng-Williamson, Katherine A; Keating, Gillian M

    2002-01-01

    An extended-release formulation of methylphenidate (Ritalin LA), a CNS stimulant that inhibits dopamine and noradrenaline (norepinephrine) reuptake into presynaptic neurons, has been developed for use in patients with attention deficit/hyperactivity disorder (ADHD). In children with ADHD and healthy male adults, extended-release methylphenidate 20mg was rapidly absorbed and demonstrated two distinct peak plasma concentrations approximately 4 hours apart. The absorption pharmacokinetics of extended-release methylphenidate 20mg, which closely mimics those of immediate-release methylphenidate 10mg given in two doses 4 hours apart, permits once-daily administration. In a 2-week randomised, double-blind, placebo-controlled trial in 134 evaluable children aged 6 to 12 years with ADHD, symptoms improved to a significantly greater extent with extended-release methylphenidate 10 to 40mg once daily than with placebo. Extended-release methylphenidate improved both inattention and hyperactivity symptoms and was effective in children with combined- (inattentive and hyperactive/impulsive) type or predominantly inattentive-type ADHD. In clinical trials, the safety and tolerability profiles of extended-release methylphenidate were consistent with that of the immediate-release formulation.

  14. Potential future applications for the tracking and data relay satellite II (TDRS II) system

    NASA Technical Reports Server (NTRS)

    Gibbons, Richard C.

    1995-01-01

    During the conceptual design phases of the tracking and data relay satellite (TDRS) II system provision was made for a future service growth (FSG) payload with an undefined mission. The intent of the FSG was to provide a resource for TDRS II applications which would be available to meet a change in requirements for the operational TDRS II system. This paper summarizes the effect of the consideration of potential FSG applications imposed on the tracking and data relay satellite (TDRS) II system. The following applications were considered as FSG candidates: An optical 650 Mbps space-to-space link (SSL) coupled to an optical or RF downlink, an RF or optical crosslink to extend the baseline TDRS II system coverage, -zone of exclusion (ZOE) closure, relay for lunar communications either RF or optically, and relay for Martian communications either RF or optically. This paper summarizes work done in the 1990 time frame on the above stated applications. Since then, NASA has sponsored several studies (during phase B of the TDRS II development cycle) of the ZOE closure application of the FSG. The purpose of this paper is to report on the efforts previously considered for the FSG. A previous paper was presented at the 1991 Congress related to the second application above. This paper extends this effort to the four stated applications.

  15. A survey of extended H2 emission from massive YSOs

    NASA Astrophysics Data System (ADS)

    Navarete, F.; Damineli, A.; Barbosa, C. L.; Blum, R. D.

    2015-07-01

    We present the results from a survey, designed to investigate the accretion process of massive young stellar objects (MYSOs) through near-infrared narrow-band imaging using the H2 ν=1-0 S(1) transition filter. A sample of 353 MYSO candidates was selected from the Red MSX Source survey using photometric criteria at longer wavelengths (infrared and submillimetre) and chosen with positions throughout the Galactic plane. Our survey was carried out at the Southern Astrophysical Research Telescope Telescope in Chile and Canada-France-Hawaii Telescope in Hawaii covering both hemispheres. The data reveal that extended H2 emission is a good tracer of outflow activity, which is a signpost of accretion process on young massive stars. Almost half of the sample exhibit extended H2 emission and 74 sources (21 per cent) have polar morphology, suggesting collimated outflows. The polar-like structures are more likely to appear on radio-quiet sources, indicating these structures occur during the pre-UCH II phase. We also found an important fraction of sources associated with fluorescent H2 diffuse emission that could be due to a more evolved phase. The images also indicate only ˜23 per cent (80) of the sample is associated with extant (young) stellar clusters. These results support the scenario in which massive stars are formed by accretion discs, since the merging of low-mass stars would not produce outflow structures.

  16. WILSON-BAPPU EFFECT: EXTENDED TO SURFACE GRAVITY

    SciTech Connect

    Park, Sunkyung; Kang, Wonseok; Lee, Jeong-Eun; Lee, Sang-Gak E-mail: wskang@khu.ac.kr E-mail: sanggak@snu.ac.kr

    2013-10-01

    In 1957, Wilson and Bappu found a tight correlation between the stellar absolute visual magnitude (M{sub V} ) and the width of the Ca II K emission line for late-type stars. Here, we revisit the Wilson-Bappu relationship (WBR) to claim that the WBR can be an excellent indicator of stellar surface gravity of late-type stars as well as a distance indicator. We have measured the width (W) of the Ca II K emission line in high-resolution spectra of 125 late-type stars obtained with the Bohyunsan Optical Echelle Spectrograph and adopted from the Ultraviolet and Visual Echelle Spectrograph archive. Based on our measurement of the emission line width (W), we have obtained a WBR of M{sub V} = 33.76 - 18.08 log W. In order to extend the WBR to being a surface gravity indicator, stellar atmospheric parameters such as effective temperature (T{sub eff}), surface gravity (log g), metallicity ([Fe/H]), and micro-turbulence ({xi}{sub tur}) have been derived from self-consistent detailed analysis using the Kurucz stellar atmospheric model and the abundance analysis code, MOOG. Using these stellar parameters and log W, we found that log g = -5.85 log W+9.97 log T{sub eff} - 23.48 for late-type stars.

  17. Type II achondrogenesis-hypochondrogenesis: identification of abnormal type II collagen.

    PubMed

    Godfrey, M; Hollister, D W

    1988-12-01

    We have extended the study of a mild case of type II achondrogenesis-hypochondrogenesis to include biochemical analyses of cartilage, bone, and the collagens produced by dermal fibroblasts. Type I collagen extracted from bone and types I and III collagen produced by dermal fibroblasts were normal, as was the hexosamine ratio of cartilage proteoglycans. Hyaline cartilage, however, contained approximately equal amounts of types I and II collagen and decreased amounts of type XI collagen. Unlike the normal SDS-PAGE mobility. Two-dimensional SDS-PAGE revealed extensive overmodification of all type II cyanogen bromide peptides in a pattern consistent with heterozygosity for an abnormal pro alpha 1(II) chain which impaired the assembly and/or folding of type II collagen. This interpretation implies that dominant mutations of the COL2A1 gene may cause type II achondrogenesis-hypochondrogenesis. More generally, emerging data implicating defects of type II collagen in the type II achondrogenesis-hypochondrogenesis-spondyloepiphyseal dysplasia congenita spectrum and in the Kniest-Stickler syndrome spectrum suggest that diverse mutations of this gene may be associated with widely differing phenotypic outcome. PMID:3195588

  18. Solute drag on perfect and extended dislocations

    NASA Astrophysics Data System (ADS)

    Sills, R. B.; Cai, W.

    2016-04-01

    The drag force exerted on a moving dislocation by a field of mobile solutes is studied in the steady state. The drag force is numerically calculated as a function of the dislocation velocity for both perfect and extended dislocations. The sensitivity of the non-dimensionalized force-velocity curve to the various controlling parameters is assessed, and an approximate analytical force-velocity expression is given. A non-dimensional parameter S characterizing the strength of the solute-dislocation interaction, the background solute fraction ?, and the dislocation character angle ?, are found to have the strongest influence on the force-velocity curve. Within the model considered here, a perfect screw dislocation experiences no solute drag, but an extended screw dislocation experiences a non-zero drag force that is about 10 to 30% of the drag on an extended edge dislocation. The solutes can change the spacing between the Shockley partials in both stationary and moving extended dislocations, even when the stacking fault energy remains unaltered. Under certain conditions, the solutes destabilize an extended dislocation by either collapsing it into a perfect dislocation or causing the partials to separate unboundedly. It is proposed that the latter instability may lead to the formation of large faulted areas and deformation twins in low stacking fault energy materials containing solutes, consistent with experimental observations of copper and stainless steel containing hydrogen.

  19. Electron spin echo envelope modulation spectroscopy supports the suggested coordination of two histidine ligands to the Rieske Fe-S centers of the cytochrome b sub 6 f complex of spinach and the cytochrome bc sub 1 complexes of Rhodospirillum rubrum, Rhodobacter sphaeroides R-26, and bovine heart mitochondria

    SciTech Connect

    Britt, R.D.; Sauer, K.; Klein, M.P. ); Knaff, D.B.; Kriauciunas, A. ); Yu, Changan; Yu, Linda ); Malkin, R. )

    1991-02-19

    Electron spin echo envelope modulation (ESEEM) experiments performed on the Rieske Fe-S clusters of the cytochrome b{sub 6}f complex of spinach chloroplasts and of the cytochrome bc{sub 1} complexes of Rhodospirillum rubrum, Rhodobacter sphaeroides R-26, and bovine heart mitochondria show modulation components resulting from two distinct classes of {sup 14}N ligands. At the g = 1.92 region of the Rieske EPR spectrum of the cytochrome b{sub 6}f complex, the measured hyperfine couplings for the two classes of coupled nitrogens are A{sub 1} = 4.6 MHz and A{sub 2} = 3.8 MHz. Similar couplings are observed for the Rieske centers in the three cytochrome bc{sub 1} complexes. These ESEEM results indicate a nitrogen coordination environment for these Rieske Fe-S centers that is similar to that of the Fe-S cluster of a bacterial dioxygenase enzyme with two coordinated histidine ligands. The Rieske Fe-S cluster lacks modulation components from a weakly coupled peptide nitrogen observed in water-soluble spinach ferredoxin. Treatment with the quinone analogue inhibitor DBMIB causes a shift in the Rieske EPR spectrum to g = 1.95 with no alteration in the magnetic couplings to the two nitrogen atoms. However, the ESEEM pattern of the DBMIB-altered Rieske EPR signal shows evidence of an additional weakly coupled nitrogen similar to that observed in the spinach ferrodoxin ESEEM patterns.

  20. Extended nebular emission in CALIFA early-type galaxies

    NASA Astrophysics Data System (ADS)

    Gomes, J. M.; Papaderos, P.; Kehrig, C.; Vílchez, J. M.; Lehnert, M. D.

    2015-02-01

    The morphological, spectroscopic and kinematical properties of the warm interstellar medium ( wim ) in early-type galaxies (ETGs) hold key observational constraints to nuclear activity and the buildup history of these massive quiescent systems. High-quality integral field spectroscopy (IFS) data with a wide spectral and spatial coverage, such as those from the CALIFA survey, offer a precious opportunity for advancing our understanding in this respect. We use deep IFS data from CALIFA (califa.caha.es) to study the wim over the entire extent and optical spectral range of 32 nearby ETGs. We find that all ETGs in our sample show faint (Hα equivalent width EW(Hα)~0.5 ... 2 Å) extranuclear nebular emission extending out to >=2 Petrosian50 radii. Confirming and strengthening our conclusions in Papaderos et al. (2013, hereafter P13) we argue that ETGs span a broad continuous sequence with regard to the properties of their wim , and they can be roughly subdivided into two characteristic classes. The first one (type i) comprises ETGs with a nearly constant EW(Hα)~1-3 Å in their extranuclear component, in quantitative agreement with (even though, no proof for) the hypothesis of photoionization by the post-AGB stellar component being the main driver of extended wim emission. The second class (type ii) consists of virtually wim -evacuated ETGs with a large Lyman continuum (Ly c) photon escape fraction and a very low (<=0.5 Å) EW(Hα) in their nuclear zone. These two ETG classes appear indistinguishable from one another by their LINER-specific emission-line ratios. Additionally, here we extend the classification by P13 by the class i+ which stands for a subset of type i ETGs with low-level star-forming activity in contiguous spiral-arm like features in their outermost periphery. These faint features, together with traces of localized star formation in several type i&i+ systems point to a non-negligible contribution from young massive stars to the global ionizing photon

  1. [Ischemic cholangiopathy induced by extended burns].

    PubMed

    Cohen, Laurence; Angot, Emilie; Goria, Odile; Koning, Edith; François, Arnaud; Sabourin, Jean-Christophe

    2013-04-01

    Ischemic cholangiopathy is a recently described entity occurring mainly after hepatic grafts. Very few cases after intensive care unit (ICU) for extended burn injury were reported. We report the case of a 73-year-old woman consulting in an hepatology unit, for a jaundice appearing during a hospitalisation in an intensive care unit and increasing from her leaving from ICU, where she was treated for an extended burn injury. She had no pre-existing biological features of biliary disease. Biological tests were normal. Magnetic resonance imaging acquisitions of biliary tracts pointed out severe stenosing lesions of diffuse cholangiopathy concerning intrahepatic biliary tract, mainly peri-hilar. Biopsie from the liver confirmed the diagnosis, showing a biliary cirrhosis with bile infarcts. This case is the fourth case of ischemic cholangiopathy after extended burn injury, concerning a patient without a prior history of hepatic or biliary illness and appearing after hospitalisation in intensive care unit.

  2. Remarkable connections between extended magnetohydrodynamics models

    SciTech Connect

    Lingam, M. Morrison, P. J. Miloshevich, G.

    2015-07-15

    Through the use of suitable variable transformations, the commonality of all extended magnetohydrodynamics (MHD) models is established. Remarkable correspondences between the Poisson brackets of inertialess Hall MHD and inertial MHD (which has electron inertia, but not the Hall drift) and extended MHD (which has both effects) are established. The helicities (two in all) for each of these models are obtained through these correspondences. The commonality of all the extended MHD models is traced to the existence of two Lie-dragged 2-forms, which are closely associated with the canonical momenta of the two underlying species. The Lie-dragging of these 2-forms by suitable velocities also leads to the correct equations of motion. The Hall MHD Poisson bracket is analyzed in detail, the Jacobi identity is verified through a detailed proof, and this proof ensures the Jacobi identity for the Poisson brackets of all the models.

  3. Extended inflation from higher dimensional theories

    SciTech Connect

    Holman, R.; Kolb, E.W.; Vadas, S.L.; Wang, Yun.

    1990-04-01

    The possibility is considered that higher dimensional theories may, upon reduction to four dimensions, allow extended inflation to occur. Two separate models are analayzed. One is a very simple toy model consisting of higher dimensional gravity coupled to a scalar field whose potential allows for a first-order phase transition. The other is a more sophisticated model incorporating the effects of non-trivial field configurations (monopole, Casimir, and fermion bilinear condensate effects) that yield a non-trivial potential for the radius of the internal space. It was found that extended inflation does not occur in these models. It was also found that the bubble nucleation rate in these theories is time dependent unlike the case in the original version of extended inflation.

  4. Extended inflation from higher-dimensional theories

    NASA Astrophysics Data System (ADS)

    Holman, Richard; Kolb, Edward W.; Vadas, Sharon L.; Wang, Yun

    1991-02-01

    We consider the possibility that higher-dimensional theories may, upon reduction to four dimensions, allow extended inflation to occur. We analyze two separate models. One is a very simple toy model consisting of higher-dimensional gravity coupled to a scalar field whose potential allows for a first-order phase transition. The other is a more sophisticated model incorporating the effects of nontrivial field configurations (monopole, Casimir, and fermion bilinear condensate effects) that yield a nontrivial potential for the radius of the internal space. We find that extended inflation does not occur in these models. We also find that the bubble nucleation rate in these theories is time dependent unlike the case in the original version of extended inflation.

  5. Overview of the Cassini Extended Mission Trajectory

    NASA Technical Reports Server (NTRS)

    Buffington, Brent; Strange, Nathan; Smith, John

    2008-01-01

    Due to the highly successful execution of the Cassini-Huygens prime mission and the estimated propellant remaining at the conclusion of the prime mission, NASA Headquarters allocated funding for the development of a 2-year long Cassini extended mission. The resultant extended mission, stemming from 1.5 years of development, includes an additional 26 targeted Titan flybys, 9 close flybys of icy satellites, and 60 orbits about Saturn. This paper describes, in detail, the different phases of the Cassini extended mission and the associated design methodology, which attempted to maximize the number and quality of high-priority scientific objectives while minimizing the total delta v expenditure and adhering to mission-imposed constraints.

  6. Extended inflation from higher dimensional theories

    NASA Technical Reports Server (NTRS)

    Holman, Richard; Kolb, Edward W.; Vadas, Sharon L.; Wang, Yun

    1990-01-01

    The possibility is considered that higher dimensional theories may, upon reduction to four dimensions, allow extended inflation to occur. Two separate models are analayzed. One is a very simple toy model consisting of higher dimensional gravity coupled to a scalar field whose potential allows for a first-order phase transition. The other is a more sophisticated model incorporating the effects of non-trivial field configurations (monopole, Casimir, and fermion bilinear condensate effects) that yield a non-trivial potential for the radius of the internal space. It was found that extended inflation does not occur in these models. It was also found that the bubble nucleation rate in these theories is time dependent unlike the case in the original version of extended inflation.

  7. Extended range radiation dose-rate monitor

    DOEpatents

    Valentine, Kenneth H.

    1988-01-01

    An extended range dose-rate monitor is provided which utilizes the pulse pileup phenomenon that occurs in conventional counting systems to alter the dynamic response of the system to extend the dose-rate counting range. The current pulses from a solid-state detector generated by radiation events are amplified and shaped prior to applying the pulses to the input of a comparator. The comparator generates one logic pulse for each input pulse which exceeds the comparator reference threshold. These pulses are integrated and applied to a meter calibrated to indicate the measured dose-rate in response to the integrator output. A portion of the output signal from the integrator is fed back to vary the comparator reference threshold in proportion to the output count rate to extend the sensitive dynamic detection range by delaying the asymptotic approach of the integrator output toward full scale as measured by the meter.

  8. Extending Double Optical Gating to the Midinfrared

    NASA Astrophysics Data System (ADS)

    Gorman, Timothy; Camper, Antoine; Agostini, Pierre; Dimauro, Louis

    2015-05-01

    In the past decade there has been great interest in creating broadband isolated attosecond pulses (IAPs). Primarily these IAPs have been generated using Ti:Sapphire 800nm short pulses, namely through spatiotemporal gating with the attosecond lighthouse technique, amplitude gating, polarization gating, and double optical gating (DOG). Here we present theoretical calculations and experimental investigations into extending DOG to using a 2 μm driving wavelength, the benefits of which include extended harmonic cutoff and longer input driving pulse durations. It is proposed that broadband IAPs with cutoffs extending up to 250 eV can be generated in Argon by using >30 fs pulses from the passively-CEP stabilized 2 μm idler out of an optical parametric amplifier combined with a collinear DOG experimental setup.

  9. Extending the ADM formalism to Weyl geometry

    NASA Astrophysics Data System (ADS)

    Barreto, A. B.; Almeida, T. S.; Romero, C.

    2015-03-01

    In order to treat quantum cosmology in the framework of Weyl spacetimes we take the first step of extending the Arnowitt-Deser-Misner formalism to Weyl geometry. We then obtain an expression of the curvature tensor in terms of spatial quantities by splitting spacetime in (3+l)-dimensional form. We next write the Lagrangian of the gravitation field based in Weyl-type gravity theory. We extend the general relativistic formalism in such a way that it can be applied to investigate the quantum cosmology of models whose spacetimes are endowed with a Weyl geometrical structure.

  10. NASA Orbiter Extended Nose Landing Gear

    NASA Technical Reports Server (NTRS)

    King, Steven R.; Jensen, Scott A.; Hansen, Christopher P.

    1999-01-01

    This paper discusses the design, development, test, and evaluation of a prototype Extended Nose Landing Gear (ENLG) for NASA's Space Shuttle orbiters. The ENLG is a proposed orbiter modification developed in-house at NASA's Johnson Space Center (JSC) by a joint government/industry team. It increases the orbiter's nose landing gear (NLG) length, thereby changing the vehicle's angle of attack during rollout, which lowers the aerodynamic forces on the vehicle. This, in combination with a dynamic elevon change, will lower the loads on the orbiter's main landing gear (MLG). The extension is accomplished by adding a telescoping section to the current NLG strut that will be pneumatically extended during NLG deployment.

  11. The Extended Mind: Coupling Environment and Brain

    NASA Astrophysics Data System (ADS)

    Vrobel, Susie

    2010-11-01

    This paper describes embodiment and cognitive extension as examples of strong anticipation as defined by Dubois. Clark and Chalmers formulated a thesis which states that parts of the environment, if coupled successfully, can become part of the extended mind. This coupling, be it deliberate or unintentional, shifts the observer-world boundary outwards when the observer encompasses parts of his environment. The resulting extended observer forms a new systemic whole, which consists of both the assimilated context and the recalibrated version of the original observer. Recalibration occurs when conditioning and adaptation lead to corresponding changes on the neural level, for instance, when an agent compensates for delays in a control loop. Plasticity is a prerequisite for any successful incorporation of external structures. However, uncoupled parts of the observer must remain inviolate in order to preserve the boundary. Neither the extended mind nor the core observer are absolute concepts. Depending on whether we focus on local-scale interactions or on large-scale behaviour, boundaries are formed at different interfacial cuts, which lead to either an endo- or an exo-perspective or endo- or exo-anticipation, respectively. For biological extended agents which undergo a transition from exo- to endo-states, a tell-tale sign of a successful exo-endo transition is invisibility. This invisibility occurs when the agent is no longer aware of the delay originally introduced into the control loop by the assimilated part of the environment. Explaining the world in terms of effective causality is not sufficient to account for extended minds. The latter require explanations in terms of final causation. For extended minds, this ordering principle comes in the shape of nested hierarchical layers. The interfaces of these layers may have merged for an endo-observer, whereas an exo-observer can make out the detailed structure, including artificially introduced delays. A sufficient

  12. Weak Lie symmetry and extended Lie algebra

    SciTech Connect

    Goenner, Hubert

    2013-04-15

    The concept of weak Lie motion (weak Lie symmetry) is introduced. Applications given exhibit a reduction of the usual symmetry, e.g., in the case of the rotation group. In this context, a particular generalization of Lie algebras is found ('extended Lie algebras') which turns out to be an involutive distribution or a simple example for a tangent Lie algebroid. Riemannian and Lorentz metrics can be introduced on such an algebroid through an extended Cartan-Killing form. Transformation groups from non-relativistic mechanics and quantum mechanics lead to such tangent Lie algebroids and to Lorentz geometries constructed on them (1-dimensional gravitational fields).

  13. Extending the ADM formalism to Weyl geometry

    SciTech Connect

    Barreto, A. B.; Almeida, T. S.; Romero, C.

    2015-03-26

    In order to treat quantum cosmology in the framework of Weyl spacetimes we take the first step of extending the Arnowitt-Deser-Misner formalism to Weyl geometry. We then obtain an expression of the curvature tensor in terms of spatial quantities by splitting spacetime in (3+l)-dimensional form. We next write the Lagrangian of the gravitation field based in Weyl-type gravity theory. We extend the general relativistic formalism in such a way that it can be applied to investigate the quantum cosmology of models whose spacetimes are endowed with a Weyl geometrical structure.

  14. Extending Program Resources: Meeting Necessity with Invention.

    ERIC Educational Resources Information Center

    Fuston, Judith; Hargens, Mark

    This document describes collaborative strategies used by one school guidance department that allow counselors to complete their designated work without extending their school day. One strategy involves pairing mentors with first-year counselors to help answer their questions. Another uses retired counselors as "substitutes" when regular counselors…

  15. Extended Learning Institute. Policies and Procedures Manual.

    ERIC Educational Resources Information Center

    Adams, Larry

    This manual describes the Extended Learning Institute (ELI) at John Tyler Community College in Virginia. The ELI is a comprehensive program of instruction using alternative delivery systems (e.g., television, print-based, radio, and newspapers). General procedures and policies are delineated in section I, including registration and student and…

  16. Some Remarks on the Extended Galilean Transformation.

    ERIC Educational Resources Information Center

    Greenberger, Daniel M.

    1979-01-01

    The extended Galilean transformation carries an inertial frame into a rigid frame with uniform spatial, but arbitrary translational acceleration. Besides being useful in discussing the equivalence principle, this transformation provides a physical interpretation for the theorem in nonrelativistic quantum mechanics, that we cannot coherently…

  17. Robotic extended pyelolithotomy for complete staghorn calculus.

    PubMed

    Sotelo, Rene; Astigueta, Juan Carlos; Giedelman, Camilo; de Andrade, Robert; Carmona, Oswaldo; Ramirez, Daniel; Clavijo, Rafael

    2010-08-01

    Staghorn stones represent a therapeutic challenge to urologists. We present our experience with laparoscopic extended pyelolithotomy for treatment of staghorn and complex renal calculi in highly selected cases. This approach provides the principles of open surgery with the advantages of minimally invasive surgery. We describe our experience with robot-assisted extended pyelolithotomy for complex coralliform calculi. Since January 2007, robotic extended pyelolithotomy has been performed by transperitoneal approach in two patients with complete coralliform lithiasis (calculi average size 8 cm). One patient had history of percutaneous nephrolithotomy. Demographic and operative data were collected. All procedures were technically successful without need for open conversion. Mean estimated blood loss was 175 ml (range 50-300 ml), and mean operative time was 150 min (range 120-150 min). A perinephric drain was employed in one patient with duration of 5 days. Postoperative imaging confirmed complete stone clearance. Robotic extended pyelolithotomy is a feasible and reproducible procedure for removal of complete and partial staghorn calculi in selected patients with complex nephrolithiasis. This approach might limit the role of open surgery for these calculi, but further publications with more cases are necessary to further define its utility.

  18. On energy conservation in extended magnetohydrodynamics

    SciTech Connect

    Kimura, Keiji; Morrison, P. J.

    2014-08-15

    A systematic study of energy conservation for extended magnetohydrodynamic models that include Hall terms and electron inertia is performed. It is observed that commonly used models do not conserve energy in the ideal limit, i.e., when viscosity and resistivity are neglected. In particular, a term in the momentum equation that is often neglected is seen to be needed for conservation of energy.

  19. Extended School Year. Information Capsule. Volume 0910

    ERIC Educational Resources Information Center

    Blazer, Christie

    2010-01-01

    Extended school years are being considered by districts around the country as educators search for new ways to raise student achievement. The addition of time to the school calendar is also supported by President Barack Obama, who recently stated that American students do not spend enough time in school. This Information Capsule addresses research…

  20. The Extended Family and Children's Educational Success

    ERIC Educational Resources Information Center

    Jaeger, Mads Meier

    2012-01-01

    Research on family background and educational success focuses almost exclusively on two generations: parents and children. This study argues that the extended family contributes significantly to the total effect of family background on educational success. Analyses using the Wisconsin Longitudinal Study show that, net of family factors shared by…

  1. Sulfur extended asphalt pavement evaluation: Executive summary

    NASA Astrophysics Data System (ADS)

    Mahoney, J. P.

    1982-09-01

    This summary report overviews two previously issued study reports. One report assesses The availability and pricing of sulfur with respect to sulfur extended asphalt (SEA) paving mixture is assessed. A laboratory oriented testing program which was principally used to examine the durability and aging characteristics of SEA paving mixtures is reported.

  2. Extending School Hours: A Capital Idea.

    ERIC Educational Resources Information Center

    Jones, John Hodge

    1995-01-01

    The Murfreesboro, Tennessee, City Schools have doubled the amount of time schools are open without raising taxes. Instead of going home to empty houses, kids participate in an extended school program offering over 100 courses in recreation, academics, arts, and life skills. Parents and organizations foot the costs; no child is excluded for…

  3. Extended Learning: What Are the States Doing?

    ERIC Educational Resources Information Center

    Brown, Cynthia G.

    2001-01-01

    The standards movement and family work schedules are major factors underpinning the expansion of extended learning opportunities. A recent report by the Council of Chief State School Officials details the development of afterschool and other programs in California, Illinois, Kentucky, Massachusetts, Minnesota, and Texas. (MLH)

  4. Extending Transitional Services to Former Foster Children

    ERIC Educational Resources Information Center

    Kerman, Ben; Barth, Richard P.; Wildfire, Judy

    2004-01-01

    This article describes what a private agency expended while addressing the transitional needs of former long-term foster youth and examines the association between expenditures and adult outcomes. Not all young adults accepted supports extended to them. In the sample, 41% of the young adults incurred expenses after age 19. Of those using supports,…

  5. Extendible column can be stowed on drum

    NASA Technical Reports Server (NTRS)

    Holtz, G. M.; Howard, E. A.

    1965-01-01

    Column formed from a series of segments held together by an internal spring or cable can be coiled on a drum or extended into a rigid structure. This storable coil is useful in boring for soil samples and supporting electrical and optical sensors.

  6. Fullerton Junior College Extended-Day Program.

    ERIC Educational Resources Information Center

    Meservy, Royal R.

    This paper describes in detail the administrative and operational organization of a program for 4,000 night students and 2,000 extended-day students. It outlines the duties of the Administrative Assistant in Instruction, who is responsible to the Dean of Instruction, Liberal Arts and to the Dean of Instruction, Technical Arts. It also gives a…

  7. Extended Learning Time: Research and Resources

    ERIC Educational Resources Information Center

    Stelow, Shawn; Holland, Jenifer Gager; Jackson, Rebecca

    2012-01-01

    In recent years policymakers have increasingly looked to Extended Learning Time (ELT) as a means of improving student outcomes. As a result, some school districts have increased academic time for students by adding time to the school day or days to the school year. In other communities, schools and community-based organizations have partnered to…

  8. Integrable extended van der Waals model

    NASA Astrophysics Data System (ADS)

    Giglio, Francesco; Landolfi, Giulio; Moro, Antonio

    2016-10-01

    Inspired by the recent developments in the study of the thermodynamics of van der Waals fluids via the theory of nonlinear conservation laws and the description of phase transitions in terms of classical (dissipative) shock waves, we propose a novel approach to the construction of multi-parameter generalisations of the van der Waals model. The theory of integrable nonlinear conservation laws still represents the inspiring framework. Starting from a macroscopic approach, a four parameter family of integrable extended van der Waals models is indeed constructed in such a way that the equation of state is a solution to an integrable nonlinear conservation law linearisable by a Cole-Hopf transformation. This family is further specified by the request that, in regime of high temperature, far from the critical region, the extended model reproduces asymptotically the standard van der Waals equation of state. We provide a detailed comparison of our extended model with two notable empirical models such as Peng-Robinson and Soave's modification of the Redlich-Kwong equations of state. We show that our extended van der Waals equation of state is compatible with both empirical models for a suitable choice of the free parameters and can be viewed as a master interpolating equation. The present approach also suggests that further generalisations can be obtained by including the class of dispersive and viscous-dispersive nonlinear conservation laws and could lead to a new type of thermodynamic phase transitions associated to nonclassical and dispersive shock waves.

  9. The inflation sector of extended inflation

    SciTech Connect

    Kolb, E.W. Chicago Univ., IL )

    1990-11-01

    In extended inflation the inflationary era is brought to a close by the process of percolation of true vacuum bubbles produced in a first-order phase transition. In this paper I discuss several effects that might obtain if the Universe undergoes an inflationary first-order phase transition. 17 refs.

  10. The inflation sector of extended inflation

    NASA Technical Reports Server (NTRS)

    Kolb, Edward W.

    1991-01-01

    In extended inflation, the inflationary era is brought to a close by the process of percolation of true vacuum bubbles produced in a first-order phase transition. This paper discusses several effects that might obtain if the universe undergoes an inflationary first-order phase transition.

  11. Adult Day Care--Extended Family.

    ERIC Educational Resources Information Center

    Smith, Bert Kruger

    This pamphlet describes a multi-purpose day-care center for the elderly in Abilene, Texas which is intended to fill the "extended family" role of offering companionship, medical attention, and other aspects of concern to older persons in the community. The goals of the program are as follows: (1) to keep individuals out of institutions as long as…

  12. Robotic extended pyelolithotomy for complete staghorn calculus.

    PubMed

    Sotelo, Rene; Astigueta, Juan Carlos; Giedelman, Camilo; de Andrade, Robert; Carmona, Oswaldo; Ramirez, Daniel; Clavijo, Rafael

    2010-08-01

    Staghorn stones represent a therapeutic challenge to urologists. We present our experience with laparoscopic extended pyelolithotomy for treatment of staghorn and complex renal calculi in highly selected cases. This approach provides the principles of open surgery with the advantages of minimally invasive surgery. We describe our experience with robot-assisted extended pyelolithotomy for complex coralliform calculi. Since January 2007, robotic extended pyelolithotomy has been performed by transperitoneal approach in two patients with complete coralliform lithiasis (calculi average size 8 cm). One patient had history of percutaneous nephrolithotomy. Demographic and operative data were collected. All procedures were technically successful without need for open conversion. Mean estimated blood loss was 175 ml (range 50-300 ml), and mean operative time was 150 min (range 120-150 min). A perinephric drain was employed in one patient with duration of 5 days. Postoperative imaging confirmed complete stone clearance. Robotic extended pyelolithotomy is a feasible and reproducible procedure for removal of complete and partial staghorn calculi in selected patients with complex nephrolithiasis. This approach might limit the role of open surgery for these calculi, but further publications with more cases are necessary to further define its utility. PMID:27628774

  13. Q-Method Extended Kalman Filter

    NASA Technical Reports Server (NTRS)

    Zanetti, Renato; Ainscough, Thomas; Christian, John; Spanos, Pol D.

    2012-01-01

    A new algorithm is proposed that smoothly integrates non-linear estimation of the attitude quaternion using Davenport s q-method and estimation of non-attitude states through an extended Kalman filter. The new method is compared to a similar existing algorithm showing its similarities and differences. The validity of the proposed approach is confirmed through numerical simulations.

  14. Extended Generalized Linear Latent and Mixed Model

    ERIC Educational Resources Information Center

    Segawa, Eisuke; Emery, Sherry; Curry, Susan J.

    2008-01-01

    The generalized linear latent and mixed modeling (GLLAMM framework) includes many models such as hierarchical and structural equation models. However, GLLAMM cannot currently accommodate some models because it does not allow some parameters to be random. GLLAMM is extended to overcome the limitation by adding a submodel that specifies a…

  15. 14 CFR 1274.207 - Extended agreements.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 5 2010-01-01 2010-01-01 false Extended agreements. 1274.207 Section 1274.207 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION COOPERATIVE AGREEMENTS WITH..., period of performance and funding levels; therefore, new proposals, certifications, and...

  16. 14 CFR 1274.207 - Extended agreements.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 5 2012-01-01 2012-01-01 false Extended agreements. 1274.207 Section 1274.207 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION COOPERATIVE AGREEMENTS WITH..., period of performance and funding levels; therefore, new proposals, certifications, and...

  17. 14 CFR 1274.207 - Extended agreements.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 5 2011-01-01 2010-01-01 true Extended agreements. 1274.207 Section 1274.207 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION COOPERATIVE AGREEMENTS WITH..., period of performance and funding levels; therefore, new proposals, certifications, and...

  18. Interpolation of the Extended Boolean Retrieval Model.

    ERIC Educational Resources Information Center

    Zanger, Daniel Z.

    2002-01-01

    Presents an interpolation theorem for an extended Boolean information retrieval model. Results show that whenever two or more documents are similarly ranked at any two points for a query containing exactly two terms, then they are similarly ranked at all points in between; and that results can fail for queries with more than two terms. (Author/LRW)

  19. Trigeminal schwannoma extending into the parapharyngeal space.

    PubMed

    Yumuşakhuylu, Ali Cemal; Sari, Murat; Topuz, Muhammet Fatih; Bağlam, Tekin; Binnetoğlu, Adem

    2014-07-01

    Parapharyngeal space tumors are very rarely seen, and surgical approach to these tumors has not been well established. Most of these tumors are benign and originated from salivary glands and neurogenic in nature. In this case, we report a patient who has a trigeminal schwannoma extending into the deep parapharyngeal space and explain our surgical approach.

  20. A Model for E-Education: Extended Teaching Spaces and Extended Learning Spaces

    ERIC Educational Resources Information Center

    Jung, Insung; Latchem, Colin

    2011-01-01

    The paper proposes a model for e-education in instruction, training, initiation and induction based upon the concept of extended teaching spaces involving execution, facilitation and liberation, and extended learning spaces used for acquisition, application and construction cemented by dialogue and reflection. The proposed model is based upon…

  1. Elaborated Odor Test for Extended Exposure

    NASA Technical Reports Server (NTRS)

    Buchanan, Vanessa D.; Henry, Emily J.; Mast, Dion J.; Harper, Susana A.; Beeson, Harold D.; Tapia, Alma S.

    2016-01-01

    Concerns were raised when incidental exposure to a proprietary bonding material revealed the material had an irritating odor. The NASA-STD-6001B document describes a supplemental test method option for programs to evaluate materials with odor concerns (Test 6, Odor Assessment). In addition to the supplemental standard odor assessment with less than 10 seconds of exposure, the NASA White Sands Test Facility (WSTF) Materials Flight Acceptance Testing section was requested to perform an odor test with an extended duration to evaluate effects of an extended exposure and to more closely simulate realistic exposure scenarios. With approval from the NASA Johnson Space Center Industrial Hygienist, WSTF developed a 15-minute odor test method. WSTF performed this extended-duration odor test to evaluate the odor and physical effects of the bonding material configured between two aluminum plates, after the safety of the gas was verified via toxicity analysis per NASA-STD-6001B Test 7, Determination of Offgassed Products. During extended-duration testing, odor panel members were arranged near the test material in a small room with the air handlers and doors closed to minimize dilution. The odor panel members wafted gas toward themselves and recorded their individual assessments of odor and physical effects at various intervals during the 15-minute exposure and posttest. A posttest interview was conducted to obtain further information. Testing was effective in providing data for comparison and selection of an optimal offgassing and odor containment configuration. The developed test method for extended exposure is proposed as a useful tool for further evaluating materials with identified odors of concern if continued use of the material is anticipated.

  2. FIRE II - Cirrus Data Sets

    Atmospheric Science Data Center

    2013-07-26

    FIRE II - Cirrus Data Sets First ISCCP Regional Experiment (FIRE) II ... stratocumulus systems, the radiative properties of these clouds and their interactions. Relevant Documents:  FIRE Project Guide FIRE II - Cirrus Home Page FIRE II - Cirrus Mission Summaries ...

  3. VELOCITY-RESOLVED [C ii] EMISSION AND [C ii]/FIR MAPPING ALONG ORION WITH HERSCHEL *,**

    PubMed Central

    Goicoechea, Javier R.; Teyssier, D.; Etxaluze, M.; Goldsmith, P.F.; Ossenkopf, V.; Gerin, M.; Bergin, E.A.; Black, J.H.; Cernicharo, J.; Cuadrado, S.; Encrenaz, P.; Falgarone, E.; Fuente, A.; Hacar, A.; Lis, D.C.; Marcelino, N.; Melnick, G.J.; Müller, H.S.P.; Persson, C.; Pety, J.; Röllig, M.; Schilke, P.; Simon, R.; Snell, R.L.; Stutzki, J.

    2015-01-01

    We present the first ~7.5′×11.5′ velocity-resolved (~0.2 km s−1) map of the [C ii] 158 μm line toward the Orion molecular cloud 1 (OMC 1) taken with the Herschel/HIFI instrument. In combination with far-infrared (FIR) photometric images and velocity-resolved maps of the H41α hydrogen recombination and CO J=2-1 lines, this data set provides an unprecedented view of the intricate small-scale kinematics of the ionized/PDR/molecular gas interfaces and of the radiative feedback from massive stars. The main contribution to the [C ii] luminosity (~85 %) is from the extended, FUV-illuminated face of the cloud (G0>500, nH>5×103 cm−3) and from dense PDRs (G≳104, nH≳105 cm−3) at the interface between OMC 1 and the H ii region surrounding the Trapezium cluster. Around ~15 % of the [C ii] emission arises from a different gas component without CO counterpart. The [C ii] excitation, PDR gas turbulence, line opacity (from [13C ii]) and role of the geometry of the illuminating stars with respect to the cloud are investigated. We construct maps of the L[C ii]/LFIR and LFIR/MGas ratios and show that L[C ii]/LFIR decreases from the extended cloud component (~10−2–10−3) to the more opaque star-forming cores (~10−3–10−4). The lowest values are reminiscent of the “[C ii] deficit” seen in local ultra-luminous IR galaxies hosting vigorous star formation. Spatial correlation analysis shows that the decreasing L[C ii]/LFIR ratio correlates better with the column density of dust through the molecular cloud than with LFIR/MGas. We conclude that the [C ii] emitting column relative to the total dust column along each line of sight is responsible for the observed L[C ii]/LFIR variations through the cloud. PMID:26568638

  4. Extending the rapeseed gene pool with resynthesized Brassica napus II: Heterosis.

    PubMed

    Girke, Andreas; Schierholt, Antje; Becker, Heiko C

    2012-04-01

    Hybrid breeding relies on the combination of parents from two differing heterotic groups. However, the genetic diversity in adapted oilseed rape breeding material is rather limited. Therefore, the use of resynthesized Brassica napus as a distant gene pool was investigated. Hybrids were derived from crosses between 44 resynthesized lines with a diverse genetic background and two male sterile winter oilseed rape tester lines. The hybrids were evaluated together with their parents and check cultivars in 2 years and five locations in Germany. Yield, plant height, seed oil, and protein content were monitored, and genetic distances were estimated with molecular markers (127 polymorphic RFLP fragments). Resynthesized lines varied in yield between 40.9 dt/ha and 21.5 dt/ha, or between 85.1 and 44.6% of check cultivar yields. Relative to check cultivars, hybrids varied from 91.6 to 116.6% in yield and from 94.5 to 103.3% in seed oil content. Mid-parent heterosis varied from -3.5 to 47.2% for yield. The genetic distance of parental lines was not significantly correlated with heterosis or hybrid yield. Although resynthesized lines do not meet the elite rapeseed standards, they are a valuable source for hybrid breeding due to their large distance from present breeding material and their high heterosis when combined with European winter oilseed rape.

  5. 0.6 GHz mapping of extended radio galaxies. II - Edge-darkened double sources

    NASA Astrophysics Data System (ADS)

    Jaegers, W. J.

    1987-10-01

    Radio observations made with the Westerbork telescope at 0.6 GHz are presented for 8 edge-darkened double sources: NGC 315, NGC 326, 3C 31, 3C 130, B 0915+320, HB 13, NGC 6251 and 3C 449. Previously observed Westerbork data at 1.4 GHz are convolved for comparison with the 0.6 GHz observational data. Besides maps of the total intensity and linear polarization structure, the distributions of the spectral index, the depolarization and the rotation of the polarization position angle between 0.6 GHz and 1.4 GHz have been derived. Integrated values for the total intensity and the polarization are also given.

  6. Rate of reduction of ore-carbon composites: Part II. Modeling of reduction in extended composites

    SciTech Connect

    Fortini, O.M.; Fruehan, R.J.

    2005-12-01

    A new process for ironmaking was proposed using a rotary hearth furnace and an iron bath smelter to produce iron employing wood charcoal as an energy source and reductant. This paper examines reactions in composite pellet samples with sizes close to sizes used in industrial practice (10 to 16 min in diameter). A model was constructed using the combined kinetic mechanism developed in Part I of this series of articles along with equations for the computation of pellet temperature and shrinkage during the reaction. The analysis of reaction rates measured for pellets with wood charcoal showed that heat transfer plays a significant role in their overall rate of reaction at elevated temperatures. The slower rates measured in pellets containing coal char show that the intrinsic kinetics of carbon oxidation is more significant than heat transfer. Model calculations suggest that the rates are highly sensitive to the thermal conductivity of pellets containing wood charcoal and are less sensitive to the external conditions of heat transfer. It was seen that the changes in pellet surface area and diameter due to shrinkage introduce little change on reaction rates. The model developed provides an adequate description of pellets of wood charcoal up to circa 90% of reduction. Experimentally determined rates of reduction of iron oxide by wood charcoal were approximately 5 to 10 times faster than rates measured in pellets with coal char.

  7. Extending the Capabilities of Single Particle Mass Spectrometry: II. Measurements of Aerosol Particle Density without DMA

    SciTech Connect

    Vaden, Timothy D.; Imre, D.; Beranek, Josef; Zelenyuk, Alla

    2011-01-04

    Particle density is an important and useful property that is difficult to measure because it usually 5 requires separate instruments to measure two particle attributes. As density measurements are 6 often performed on size-classified particles, they are hampered by low particle numbers, and 7 hence poor temporal resolution. We present here a new method for measuring particle densities 8 using our single particle mass spectrometer, SPLAT. This method takes advantage of the fact 9 that the detection efficiency in our single particle mass spectrometer drops off very rapidly as the 10 particle size decreases below ~125 nm creating a distinct sharp feature on the small particle side 11 of the vacuum aerodynamic size distribution. Thus, the two quantities needed to determine 12 particle density, the particle diameter and vacuum aerodynamic diameter, are known. We first 13 test this method on particles of known composition and find that the densities it yields are 14 sufficiently accurate. We then apply the method to obtain the densities of particles that were 15 characterized during an airborne field campaign. In addition, we show that the distinctive 16 features of the vacuum aerodynamic size distribution can be used to characterize the instrument 17 detection efficiency as a function of particle size. In general, the method presented here reduces 18 complexity and yields information with high temporal resolution while the instrument is 19 collecting routine data on particle size and composition.

  8. Planning for Extended Hours: A Survey of Practice.

    ERIC Educational Resources Information Center

    Despines, Janine

    2001-01-01

    Discusses extended hours of operation for school library media centers and describes how to plan for them. Considers benefits of extended hours; planning questions; staffing, including volunteers; costs and funding; security; and patron use of extended hours. (LRW)

  9. Extending resolution limits of EUV resist materials

    NASA Astrophysics Data System (ADS)

    Krysak, Marie; Leeson, Michael; Han, Eungnak; Blackwell, James; Harlson, Shane

    2015-03-01

    Extreme ultraviolet lithography (EUVL) technology continues to progress and remains a viable candidate for next generation lithography1, which drives the need for EUV resists capable of high resolution with high sensitivity and low LWR. While chemically amplified resists (CARs) have demonstrated the ability to pattern 12nm half-pitch features2, pattern collapse continues to limit their ultimate resolution. We have taken multiple approaches to extend resist capabilities past these limits. Recent results in pattern collapse mitigation using a resist encapsulation and etch back strategy will be discussed. We continue to investigate EUV patterning of semi-inorganic resists to simultaneously increase EUV photon absorption and extend mechanical strength beyond CAR capabilities. The limitations of metal oxide-based nanoparticle photoresists have been investigated, and have provided key insights to further understanding the mechanism of this class of materials.

  10. Synchronization in networks of spatially extended systems

    SciTech Connect

    Filatova, Anastasiya E.; Hramov, Alexander E.; Koronovskii, Alexey A.; Boccaletti, Stefano

    2008-06-15

    Synchronization processes in networks of spatially extended dynamical systems are analytically and numerically studied. We focus on the relevant case of networks whose elements (or nodes) are spatially extended dynamical systems, with the nodes being connected with each other by scalar signals. The stability of the synchronous spatio-temporal state for a generic network is analytically assessed by means of an extension of the master stability function approach. We find an excellent agreement between the theoretical predictions and the data obtained by means of numerical calculations. The efficiency and reliability of this method is illustrated numerically with networks of beam-plasma chaotic systems (Pierce diodes). We discuss also how the revealed regularities are expected to take place in other relevant physical and biological circumstances.

  11. Extended target recognition in cognitive radar networks.

    PubMed

    Wei, Yimin; Meng, Huadong; Liu, Yimin; Wang, Xiqin

    2010-01-01

    We address the problem of adaptive waveform design for extended target recognition in cognitive radar networks. A closed-loop active target recognition radar system is extended to the case of a centralized cognitive radar network, in which a generalized likelihood ratio (GLR) based sequential hypothesis testing (SHT) framework is employed. Using Doppler velocities measured by multiple radars, the target aspect angle for each radar is calculated. The joint probability of each target hypothesis is then updated using observations from different radar line of sights (LOS). Based on these probabilities, a minimum correlation algorithm is proposed to adaptively design the transmit waveform for each radar in an amplitude fluctuation situation. Simulation results demonstrate performance improvements due to the cognitive radar network and adaptive waveform design. Our minimum correlation algorithm outperforms the eigen-waveform solution and other non-cognitive waveform design approaches.

  12. Junction conditions in extended Teleparallel gravities

    SciTech Connect

    De la Cruz-Dombriz, Álvaro; Dunsby, Peter K.S.; Sáez-Gómez, Diego E-mail: peter.dunsby@uct.ac.za

    2014-12-01

    In the context of extended Teleparallel gravity theories, we address the issue of junction conditions required to guarantee the correct matching of different regions of spacetime. In the absence of shells/branes, these conditions turn out to be more restrictive than their counterparts in General Relativity as in other extended theories of gravity. In fact, the general junction conditions on the matching hypersurfaces depend on the underlying theory and a new condition on the induced tetrads in order to avoid delta-like distributions in the field equations. This result imposes strict consequences on the viability of standard solutions such as the Einstein-Straus-like construction. We find that the continuity of the scalar torsion is required in order to recover the usual General Relativity results.

  13. Extended Source/Galaxy All Sky 2

    NASA Technical Reports Server (NTRS)

    2003-01-01

    This panoramic view encompasses the entire sky and reveals the distribution of galaxies beyond the Milky Way galaxy, which astronomers call extended sources, as observed by Two Micron All-Sky Survey. The image is assembled from a database of over 1.6 million galaxies listed in the survey's All-Sky Survey Extended Source Catalog,; more than half of the galaxies have never before been catalogued. The colors represent how the many galaxies appear at three distinct wavelengths of infrared light (blue at 1.2 microns, green at 1.6 microns, and red at 2.2 microns). Quite evident are the many galactic clusters and superclusters, as well as some streamers composing the large-scale structure of the nearby universe. The blue overlay represents the very close and bright stars from our own Milky Way galaxy. In this projection, the bluish Milky Way lies predominantly toward the upper middle and edges of the image.

  14. Extended Lagrangian free energy molecular dynamics.

    PubMed

    Niklasson, Anders M N; Steneteg, Peter; Bock, Nicolas

    2011-10-28

    Extended free energy Lagrangians are proposed for first principles molecular dynamics simulations at finite electronic temperatures for plane-wave pseudopotential and local orbital density matrix-based calculations. Thanks to the extended Lagrangian description, the electronic degrees of freedom can be integrated by stable geometric schemes that conserve the free energy. For the local orbital representations both the nuclear and electronic forces have simple and numerically efficient expressions that are well suited for reduced complexity calculations. A rapidly converging recursive Fermi operator expansion method that does not require the calculation of eigenvalues and eigenfunctions for the construction of the fractionally occupied density matrix is discussed. An efficient expression for the Pulay force that is valid also for density matrices with fractional occupation occurring at finite electronic temperatures is also demonstrated.

  15. Spectral Mapping Reconstruction of Extended Sources

    NASA Astrophysics Data System (ADS)

    Smith, J. D. T.; Armus, L.; Dale, D. A.; Roussel, H.; Sheth, K.; Buckalew, B. A.; Jarrett, T. H.; Helou, G.; Kennicutt, R. C., Jr.

    2007-10-01

    Three-dimensional spectroscopy of extended sources is typically performed with dedicated integral field spectrographs. We describe a method of reconstructing full spectral cubes, with two spatial and one spectral dimension, from rastered spectral mapping observations employing a single slit in a traditional slit spectrograph. When the background and image characteristics are stable, as is often achieved in space, the use of traditional long slits for integral field spectroscopy can substantially reduce instrument complexity over dedicated integral field designs, without loss of mapping efficiency-particularly compelling when a long-slit mode for single unresolved source follow-up is separately required. We detail a custom flux-conserving cube reconstruction algorithm, discuss issues of extended-source flux calibration, and describe CUBISM, a tool that implements these methods for spectral maps obtained with the Spitzer Space Telescope's Infrared Spectrograph.

  16. Charged local defects in extended systems

    NASA Astrophysics Data System (ADS)

    Schultz, Peter A.

    2000-03-01

    The conventional approach to treating charged defects in extended systems in first principles calculations is via the supercell approximation using a neutralizing jellium background charge. I explicitly demonstrate shortcomings of this standard appoach and show that the resulting errors in the electrostatic potential energy surface are comparable to band gaps energies, for supercell sizes typically used in defect calculations. I present an alternate scheme, generalized from the local moment counter-charge method [P.A. Schultz, Phys. Rev. B 60, 1551 (1999)], that gives the correct electrostatic potential in the vicinity of a defect, via a mixed boundary condition approach. As examples, I present results of first principles calculations for charged defects in extended systems.

  17. Extended ion pumped vacuum friction test

    NASA Technical Reports Server (NTRS)

    Hammel, R. L.

    1971-01-01

    Boundary layer friction data under ion pumped vacuum was taken for sixteen material couples. The test series was an extension of a previous study of the effects of modified ion pumped environments. Sliding distances imposed in the present effort greatly exceeded any studied in the previous contiguous, flight or ground tests. Wear out of specific couples, in particular, thin film lubricants was noted. The behavior of the test hardware including wear out of the mechanisms was noted. As a result, the impact of test interruption was observed for several test couples. Recovery of the friction upon re-establishing sliding in vacuum was generally rapid. The results of the extended sliding study reinforce the previous conclusion that sliding distance (mechanical history) is the primary factor in establishing the force limiting boundary layer friction. General friction value under the extended sliding confirm those observed in previous orbital and the related ground test studies.

  18. Optimizing Extender Code for NCSX Analyses

    SciTech Connect

    M. Richman, S. Ethier, and N. Pomphrey

    2008-01-22

    Extender is a parallel C++ code for calculating the magnetic field in the vacuum region of a stellarator. The code was optimized for speed and augmented with tools to maintain a specialized NetCDF database. Two parallel algorithms were examined. An even-block work-distribution scheme was comparable in performance to a master-slave scheme. Large speedup factors were achieved by representing the plasma surface with a spline rather than Fourier series. The accuracy of this representation and the resulting calculations relied on the density of the spline mesh. The Fortran 90 module db access was written to make it easy to store Extender output in a manageable database. New or updated data can be added to existing databases. A generalized PBS job script handles the generation of a database from scratch

  19. Extended hydrogen-bonded structures of phosphatidylethanolamine.

    PubMed

    Sen, A; Yang, P W; Mantsch, H H; Hui, S W

    1988-06-01

    The structure of phosphatidylethanolamine in pure dry hexane was studied. Viscosity measurements show that the hexane solution of PE has a very high viscosity, while freeze fracture electron microscopy revealed extensive fibre-like structures. These extended structures are disrupted by the addition of small amounts of water or organic solvents which are capable of hydrogen-bonding. The Fourier transform infrared spectra of the lipid solutions in dry and hydrated hexane show considerable differences in the phosphate and ethanolamine absorption bands, and demonstrate that the viscous fibre-like structures formed by phosphatidylethanolamine in dry hexane consist of extended intermolecular hydrogen-bonds, similar to those found in the solid lipid, with the ammonium group as the hydrogen-donor and the phosphate group as the hydrogen-acceptor. The high viscosity is not observed in hexane solution of phosphatidylcholine.

  20. Extended source model for diffusive coupling.

    PubMed

    González-Ochoa, Héctor O; Flores-Moreno, Roberto; Reyes, Luz M; Femat, Ricardo

    2016-01-01

    Motivated by the prevailing approach to diffusion coupling phenomena which considers point-like diffusing sources, we derived an analogous expression for the concentration rate of change of diffusively coupled extended containers. The proposed equation, together with expressions based on solutions to the diffusion equation, is intended to be applied to the numerical solution of systems exclusively composed of ordinary differential equations, however is able to account for effects due the finite size of the coupled sources.

  1. Extending The Shelf Life Of Blood Platelets

    NASA Technical Reports Server (NTRS)

    Surgenor, Douglas M.

    1988-01-01

    New method of storing human blood platelets extends vitality for transfusions. Packaged as suspension in sterile liquid in plastic blood bags. Each bag placed between pair of plastic grids, and rubberbands placed around sandwich thus formed to hold together. Stored upright in open air or in container through which air pumped at rate of at least 45 L/min. Ensures that platelets receive ample oxygen and expiratory carbon dioxide form platelets removed before pH drops to harmful levels.

  2. Analytical satellite theory in extended phase space

    NASA Technical Reports Server (NTRS)

    Bond, V.; Broucke, R.

    1980-01-01

    It is noted that a satellite theory, based on extended phase space and on the true anomaly, was introduced by Scheifele (1970). In the present paper a simple canonical transformation is shown that makes the transition from the classical Delaunay elements to the Scheifele variables. It is stressed that neither spherical coordinates nor Hamilton-Jacobi theory is used. Finally, attention is given to the meaning of the new variables, especially the use of the true anomaly as one of the variables.

  3. Analytical satellite theory in extended phase space

    NASA Astrophysics Data System (ADS)

    Bond, V.; Broucke, R.

    1980-05-01

    It is noted that a satellite theory, based on extended phase space and on the true anomaly, was introduced by Scheifele (1970). In the present paper a simple canonical transformation is shown that makes the transition from the classical Delaunay elements to the Scheifele variables. It is stressed that neither spherical coordinates nor Hamilton-Jacobi theory is used. Finally, attention is given to the meaning of the new variables, especially the use of the true anomaly as one of the variables.

  4. Rugged, Tunable Extended-Cavity Diode Laser

    NASA Technical Reports Server (NTRS)

    Moore, Donald; Brinza, David; Seidel, David; Klipstein, William; Choi, Dong Ho; Le, Lam; Zhang, Guangzhi; Iniguez, Roberto; Tang, Wade

    2007-01-01

    A rugged, tunable extended-cavity diode laser (ECDL) has been developed to satisfy stringent requirements for frequency stability, notably including low sensitivity to vibration. This laser is designed specifically for use in an atomic-clock experiment to be performed aboard the International Space Station (ISS). Lasers of similar design would be suitable for use in terrestrial laboratories engaged in atomic-clock and atomic-physics research.

  5. Astrophysical constraints on extended gravity models

    SciTech Connect

    Lambiase, Gaetano; Stabile, Antonio; Sakellariadou, Mairi; Stabile, Arturo E-mail: mairi.sakellariadou@kcl.ac.uk E-mail: arturo.stabile@gmail.com

    2015-07-01

    We investigate the propagation of gravitational waves in the context of fourth order gravity nonminimally coupled to a massive scalar field. Using the damping of the orbital period of coalescing stellar binary systems, we impose constraints on the free parameters of extended gravity models. In particular, we find that the variation of the orbital period is a function of three mass scales which depend on the free parameters of the model under consideration; we can constrain these mass scales from current observational data.

  6. THE EXTENDED OPTICAL DISK OF M101

    SciTech Connect

    Mihos, J. Christopher; Harding, Paul; Spengler, Chelsea E.; Rudick, Craig S.; Feldmeier, John J. E-mail: paul.harding@case.edu E-mail: craig.rudick@phys.ethz.ch

    2013-01-10

    We have used deep, wide-field optical imaging to study the faint outskirts of the luminous spiral galaxy M101 (NGC 5457) as well as its surrounding environment. Over 6 deg{sup 2}, our imaging has a limiting surface brightness of {mu} {sub B} {approx} 29.5 mag arcsec{sup -2}, and has revealed the stellar structure of M101's disk out to nearly 25' (50 kpc), 3 times our measured R {sub 25} isophotal size of the optical disk. At these radii, the well-known asymmetry of the inner disk slews 180 Degree-Sign , resulting in an asymmetric plume of light at large radius which follows the very extended H I disk to the northeast of M101. This plume has very blue colors (B - V {approx} 0.2), suggesting that it is the somewhat more evolved (few hundred Myr to {approx}1 Gyr) counterpart of the young far-ultraviolet emitting population traced by Galaxy Evolution Explorer imaging. We also detect another, redder spur of extended light to the east of the disk, and both structures are reminiscent of features produced during fly-by galaxy interactions. However, we see no evidence of very extended tidal tails around M101 or any of its companions which might be expected from a recent encounter with a massive companion. We consider the properties of M101's outer disk in light of possible past interactions with the nearby companion galaxies NGC 5477 and NGC 5474. The detection of optical starlight at such large radii gives us the ability to study star formation histories and stellar populations in outer disks over longer timescales than those traced by the UV or H{alpha} emitting populations. Our data suggest an ongoing buildup of M101's outer disk due to encounters in the group environment triggering extended star formation and tidal heating of existing disk populations.

  7. Extended Corannulenes: Aromatic Bowl/Sheet Hybridization.

    PubMed

    Dutta, Amit K; Linden, Anthony; Zoppi, Laura; Baldridge, Kim K; Siegel, Jay S

    2015-09-01

    Among sheet/sheet polynuclear aromatic hydrocarbon (PAH) hybrids, a buckybowl-graphene hybrid has been used as a model to explore the effects of physical properties of PAHs with distinct planar and bowl regions. Activation of a C(Ar)-F bond was used to synthesize this corannulene/graphenic hybrid. Photophysical and voltammetric studies together with high-level computations revealed curvature and extended π-effects on the properties of these materials. PMID:26216746

  8. Extended source model for diffusive coupling.

    PubMed

    González-Ochoa, Héctor O; Flores-Moreno, Roberto; Reyes, Luz M; Femat, Ricardo

    2016-01-01

    Motivated by the prevailing approach to diffusion coupling phenomena which considers point-like diffusing sources, we derived an analogous expression for the concentration rate of change of diffusively coupled extended containers. The proposed equation, together with expressions based on solutions to the diffusion equation, is intended to be applied to the numerical solution of systems exclusively composed of ordinary differential equations, however is able to account for effects due the finite size of the coupled sources. PMID:26802012

  9. Extended Temperature Solar Cell Technology Development

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.; Jenkins, Phillip; Scheiman, David; Rafaelle, Ryne

    2004-01-01

    Future NASA missions will require solar cells to operate both in regimes closer to the sun, and farther from the sun, where the operating temperatures will be higher and lower than standard operational conditions. NASA Glenn is engaged in testing solar cells under extended temperature ranges, developing theoretical models of cell operation as a function of temperature, and in developing technology for improving the performance of solar cells for both high and low temperature operation.

  10. Hybrid functionals applied to extended systems

    NASA Astrophysics Data System (ADS)

    Marsman, M.; Paier, J.; Stroppa, A.; Kresse, G.

    2008-02-01

    We present an overview of the description of structural, thermochemical, and electronic properties of extended systems using several well known hybrid Hartree-Fock/density-functional-theory functionals (PBE0, HSE03, and B3LYP). In addition we address a few aspects of the evaluation of the Hartree-Fock exchange interactions in reciprocal space, relevant to all methods that employ a plane wave basis set and periodic boundary conditions.

  11. Photovoltaic device having an extended PN junction

    NASA Technical Reports Server (NTRS)

    D'Aiello, Robert Vincent (Inventor)

    1978-01-01

    A photovoltaic device having essentially only a body of semiconductor material having a first region of one conductivity type in contact with a second region of the opposite conductivity type, forming a portion of the device PN junction therebetween. A plurality of pocket regions of the same conductivity type as the first region extend into the second region thereby further defining a portion of the PN junction in the second region.

  12. Extended Decentralized Linear-Quadratic-Gaussian Control

    NASA Technical Reports Server (NTRS)

    Carpenter, J. Russell

    2000-01-01

    A straightforward extension of a solution to the decentralized linear-Quadratic-Gaussian problem is proposed that allows its use for commonly encountered classes of problems that are currently solved with the extended Kalman filter. This extension allows the system to be partitioned in such a way as to exclude the nonlinearities from the essential algebraic relationships that allow the estimation and control to be optimally decentralized.

  13. Relic gravitational waves and extended inflation

    NASA Technical Reports Server (NTRS)

    Turner, Michael S.; Wilczek, Frank

    1990-01-01

    In extended inflation, a new version of inflation where the transition from an inflationary to a radiation-dominated universe is accomplished by bubble nucleation, bubble collisions supply a potent - and potentially detectable - source of gravitational waves. The energy density in relic gravitons from bubble collisions is expected to be about 0.00005 of closure density. Their characteristic wavelength depends on the reheating temperature. If black holes are produced by bubble collisions, they will evaporate, producing shorter-wavelength gravitons.

  14. Origin of density fluctuations in extended inflation

    NASA Technical Reports Server (NTRS)

    Kolb, Edward W.; Salopek, David S.; Turner, Michael S.

    1990-01-01

    The density fluctuations (both curvature and isocurvature) that arise due to quantum fluctuations in a simple model of extended inflation based upon the Jordan-Brans-Dicke theory are calculated. Curvature fluctuations arise due to quantum fluctuations in the Brans-Dicke field, in general have a nonscale-invariant spectrum, and can have an amplitude that is cosmologically acceptable and interesting without having to tune any coupling constant to a very small value. The density perturbations that arise due to the inflation field are subdominant. If there are other massless fields in the theory, e.g., an axion or an ilion, then isocurvature fluctuations arise in these fields too. Production of gravitational waves and the massless particles associated with excitations of the Brans-Dicke field are also discussed. Several attempts at more realistic models of extended inflation are also analyzed. The importance of the Einstein conformal frame in calculating curvature fluctuations is emphasized. When viewed in this frame, extended inflation closely resembles slow-rollover inflation with an exponential potential and the usual formula for the amplitude of curvature perturbations applies.

  15. Extending the ICRF to Higher Radio Frequencies

    NASA Technical Reports Server (NTRS)

    Jacobs, C. S.; Jones, D. L.; Lanyi, G. E.; Lowe, S. T.; Naudet, C. J.; Resch, G. M.; Steppe, J. A.; Zhang, L. D.; Ulvestad, J. S.; Taylor, G. B.

    2002-01-01

    The ICRF forms the basis for all astrometry including use as the inertial coordinate system for navigating deep space missions. This frame was defined using S/X-band observations over the past 20+ years. In January 2002, the VLBA approved our proposal for observing time to extend the ICRF to K-band (24 GHz) and Q-band (43 GHz). The first step will be observations at K- and Q-bands on a subset of ICRF sources. Eventually, K- and Q-band multi-epoch observations will be used to estimate positions, flux density and source structure for a large fraction of the current S/X-band ICRF source list. This work will benefit the radio astronomy community by extending the VLBA calibrator list at these bands. In the longer term, we would also like to extend the ICRF to Ka-band (32 GHz). A celestial reference frame will be needed at this frequency to support deep space navigation. A navigation demonstration is being considered for NASA's Mars 2005 mission. The initial K- and Q-band work will serve to identify candidate sources at Ka-band for use with that mission.

  16. On extended thermonuclear functions through pathway model

    NASA Astrophysics Data System (ADS)

    Kumar, Dilip

    when α → 1. The beauty of the result is that these different families of three different functional forms are covered through the pathway parameter α. In a physical set up if f (x) in (3) is the stable or limiting form, the Maxwell-Boltzmann approach to thermonuclear functions, then f (x) in (1) and (2) will contain a large variety of unstable or chaotic situations which will all tend to (3) in the limit. Thus we get a clear idea of all the stable and unstable situations around the Maxwell-Boltzmann approach. Thus the current theory is given a mathematical extension and physical interpretations can be found to situations in (1) and (2). Incidently Tsallis statistics is a special case of (1) for γ = 0, a = 1, δ = 1, η = 1. The Beck-Cohen superstatistics, discussed in current statistical mechanics literature is a special case of (2) for a = 1, η = 1, α > 1. The main purpose of the present paper is to investigate in some more detail, mathematically, the extended thermonuclear functions for Maxwell-Boltzmann statistics and in the cut-off case. The extended thermonuclear functions will be evaluated in closed form for all convenient values of the parameter by means of residue calculus. A comparison of the standard thermonuclear functions with the extended thermonuclear functions is also done. The results and derivations in this paper are new and these will be of interest to physicists, mathematicians, probabilists, and statisticians.

  17. Inviscid Analysis of Extended Formation Flight

    NASA Technical Reports Server (NTRS)

    Kless, James; Aftosmis, Michael J.; Ning, Simeon Andrew; Nemec, Marian

    2012-01-01

    Flying airplanes in extended formations, with separation distances of tens of wingspans, significantly improves safety while maintaining most of the fuel savings achieved in close formations. The present study investigates the impact of roll trim and compressibility at fixed lift coefficient on the benefits of extended formation flight. An Euler solver with adjoint-based mesh refinement combined with a wake propagation model is used to analyze a two-body echelon formation at a separation distance of 30 spans. Two geometries are examined: a simple wing and a wing-body geometry. Energy savings, quantified by both formation drag fraction and span efficiency factor, are investigated at subsonic and transonic speeds for a matrix of vortex locations. The results show that at fixed lift and trimmed for roll, the optimal location of vortex impingement is about 10% inboard of the trailing airplane s wing-tip. Interestingly, early results show the variation in drag fraction reduction is small in the neighborhood of the optimal position. Over 90% of energy benefits can be obtained with a 5% variation in transverse and 10% variation in crossflow directions. Early results suggest control surface deflections required to achieve trim reduce the benefits of formation flight by 3-5% at subsonic speeds. The final paper will include transonic effects and trim on extended formation flight drag benefits.

  18. Extended Empirical Orthogonal Teleconnection (EEOT) Analysis

    NASA Astrophysics Data System (ADS)

    Eastman, R.; Wu, Q.

    2012-12-01

    Earth System Science (ESS) is particularly concerned with understanding coupled earth systems. With the advent of the Earth Observing System, empirical analysis of coupled systems is now greatly facilitated. However, the conventional means of spectral decomposition through Extended EOF (EEOF) is highly susceptible to the determination of components that mix the character of underlying factors. In this paper we present Extended Empirical Orthogonal Teleconnection (EEOT) analysis as a means to address this issue. EEOT is an extension of Empirical Orthogonal Teleconnection analysis - a regression-based form of spectral decomposition that offers the advantage of a natural and automatic form of rotation. In this extended form where multiple image times series are analyzed simultaneously, EEOT provides an opportunity to search for coupled sources of variability. The technique is illustrated through an analysis of the relationship between anomalies in detrended sea surface temperature, middle tropospheric temperature and lower stratospheric temperature for the 30-year period from 1982-2011. One of the predominant patterns found is a pan-tropical Atmospheric Bridge effect whereby ENSO ocean forcing is propagated throughout the tropical troposphere with feedbacks to the Atlantic and Indian ocean basins.

  19. The influence of quorum sensing in compartment II of the MELiSSA loop

    NASA Astrophysics Data System (ADS)

    Condori, Sandra; Mastroleo, Felice; Wattiez, Ruddy; Leys, Natalie

    MELiSSA (Micro-Ecological Life Support System Alternative) has been conceived as a 5 compartments microorganisms and higher plants recycling system for long haul space flights. Rhodospirillum rubrum S1H colonizes compartment II. Previous work reported that continuous culture of the bacterium in a photobioreactor could lead to thick biofilm formation, leading to bioreactor arrest. Our aim is to investigate the unknown quorum sensing (QS) system of R. rubrum S1H, specifically under MELiSSA relevant culture conditions meaning light anaerobic (LAN) and using acetate as carbon source. In that purpose an autoinducer synthase gene (Rru_A3396) knockout mutant was constructed by allelic exchange generating strain M68. In addition phenotypic comparison between wild type (WT) and M68 was performed. Results of thin layer chromatography assay where Agrobacterium tumefaciens NT1 have been used as reporter strain showed that WT produces acyl-homoserine lactones (AHLs) from C4 to C12 acyl carbon chain length; however, in M68 no AHLs were detected confirming that gene Rru_A3396 (named rruI) encodes an autoinducer synthase. Interestingly under a low shear or static environment M68 showed cell aggregation similar as reported in a closely related bacterium Rhodobacter sphaeroides (cerI mutant). In contrast to WT, M68 did not form biofilm and exhibited a decreased motility and pigment content. M68 vs wild type transcriptomics results showed that 326 genes were statistically significant differentially expressed. Downregulation of genes related to photosynthesis e.g., reaction center subunits, light harvesting complex and photosynthetic assembly proteins was observed. Similar results were obtained for preliminary proteomic analysis. Results obtained showed that in R. rubrum S1H the AHL-based QS system regulates almost 8% of the genome which is linked to biofilm formation among other biological processes described above. Since strain M68 could not be used in compartment II due to its less

  20. Simultaneous observations of Ca II K and Mg II k in T Tauri stars

    NASA Technical Reports Server (NTRS)

    Calvet, N.; Basri, G.; Imhoff, C. L.; Giampapa, M. S.

    1985-01-01

    The first simultaneous, calibrated observations of the Ca II K and Mg II k resonance lines in T Tauri stars are presented. It is found that for T Tauri stars with mass greater than 1.5 solar mass, which have radiative cores and tend to be fast rotators, the k line seems to arise in an extended region (probably also responsible for the H-alpha emission), whereas the K line apparently originates closer to the highly inhomogeneous stellar surface. The lower mass stars, which are fully convective and tend to be slow rotators, are more easily described by a largely chromospheric model, consistent with main-sequence activity structures but at greater values of the nonradiative flux. The strongest emission-line stars in the low-mass group, however, are also likely to have extended k line regions.

  1. Type II universal spacetimes

    NASA Astrophysics Data System (ADS)

    Hervik, S.; Málek, T.; Pravda, V.; Pravdová, A.

    2015-12-01

    We study type II universal metrics of the Lorentzian signature. These metrics simultaneously solve vacuum field equations of all theories of gravitation with the Lagrangian being a polynomial curvature invariant constructed from the metric, the Riemann tensor and its covariant derivatives of an arbitrary order. We provide examples of type II universal metrics for all composite number dimensions. On the other hand, we have no examples for prime number dimensions and we prove the non-existence of type II universal spacetimes in five dimensions. We also present type II vacuum solutions of selected classes of gravitational theories, such as Lovelock, quadratic and L({{Riemann}}) gravities.

  2. Angiotensin II receptor signalling.

    PubMed

    Daniels, Derek; Yee, Daniel K; Fluharty, Steven J

    2007-05-01

    Angiotensin II plays a key role in the regulation of body fluid homeostasis. To correct body fluid deficits that occur during hypovolaemia, an animal needs to ingest both water and electrolytes. Thus, it is not surprising that angiotensin II, which is synthesized in response to hypovolaemia, acts centrally to increase both water and NaCl intake. Here, we review findings relating to the properties of angiotensin II receptors that give rise to changes in behaviour. Data are described to suggest that divergent signal transduction pathways are responsible for separable behavioural responses to angiotensin II, and a hypothesis is proposed to explain how this divergence may map onto neural circuits in the brain.

  3. Malate and Fumarate Extend Lifespan in Caenorhabditis elegans

    PubMed Central

    Edwards, Clare B.; Copes, Neil; Brito, Andres G.; Canfield, John; Bradshaw, Patrick C.

    2013-01-01

    Malate, the tricarboxylic acid (TCA) cycle metabolite, increased lifespan and thermotolerance in the nematode C. elegans. Malate can be synthesized from fumarate by the enzyme fumarase and further oxidized to oxaloacetate by malate dehydrogenase with the accompanying reduction of NAD. Addition of fumarate also extended lifespan, but succinate addition did not, although all three intermediates activated nuclear translocation of the cytoprotective DAF-16/FOXO transcription factor and protected from paraquat-induced oxidative stress. The glyoxylate shunt, an anabolic pathway linked to lifespan extension in C. elegans, reversibly converts isocitrate and acetyl-CoA to succinate, malate, and CoA. The increased longevity provided by malate addition did not occur in fumarase (fum-1), glyoxylate shunt (gei-7), succinate dehydrogenase flavoprotein (sdha-2), or soluble fumarate reductase F48E8.3 RNAi knockdown worms. Therefore, to increase lifespan, malate must be first converted to fumarate, then fumarate must be reduced to succinate by soluble fumarate reductase and the mitochondrial electron transport chain complex II. Reduction of fumarate to succinate is coupled with the oxidation of FADH2 to FAD. Lifespan extension induced by malate depended upon the longevity regulators DAF-16 and SIR-2.1. Malate supplementation did not extend the lifespan of long-lived eat-2 mutant worms, a model of dietary restriction. Malate and fumarate addition increased oxygen consumption, but decreased ATP levels and mitochondrial membrane potential suggesting a mild uncoupling of oxidative phosphorylation. Malate also increased NADPH, NAD, and the NAD/NADH ratio. Fumarate reduction, glyoxylate shunt activity, and mild mitochondrial uncoupling likely contribute to the lifespan extension induced by malate and fumarate by increasing the amount of oxidized NAD and FAD cofactors. PMID:23472183

  4. Dark energy and extended dark matter halos

    NASA Astrophysics Data System (ADS)

    Chernin, A. D.; Teerikorpi, P.; Valtonen, M. J.; Dolgachev, V. P.; Domozhilova, L. M.; Byrd, G. G.

    2012-03-01

    The cosmological mean matter (dark and baryonic) density measured in the units of the critical density is Ωm = 0.27. Independently, the local mean density is estimated to be Ωloc = 0.08-0.23 from recent data on galaxy groups at redshifts up to z = 0.01-0.03 (as published by Crook et al. 2007, ApJ, 655, 790 and Makarov & Karachentsev 2011, MNRAS, 412, 2498). If the lower values of Ωloc are reliable, as Makarov & Karachentsev and some other observers prefer, does this mean that the Local Universe of 100-300 Mpc across is an underdensity in the cosmic matter distribution? Or could it nevertheless be representative of the mean cosmic density or even be an overdensity due to the Local Supercluster therein. We focus on dark matter halos of groups of galaxies and check how much dark mass the invisible outer layers of the halos are able to host. The outer layers are usually devoid of bright galaxies and cannot be seen at large distances. The key factor which bounds the size of an isolated halo is the local antigravity produced by the omnipresent background of dark energy. A gravitationally bound halo does not extend beyond the zero-gravity surface where the gravity of matter and the antigravity of dark energy balance, thus defining a natural upper size of a system. We use our theory of local dynamical effects of dark energy to estimate the maximal sizes and masses of the extended dark halos. Using data from three recent catalogs of galaxy groups, we show that the calculated mass bounds conform with the assumption that a significant amount of dark matter is located in the invisible outer parts of the extended halos, sufficient to fill the gap between the observed and expected local matter density. Nearby groups of galaxies and the Virgo cluster have dark halos which seem to extend up to their zero-gravity surfaces. If the extended halo is a common feature of gravitationally bound systems on scales of galaxy groups and clusters, the Local Universe could be typical or even

  5. Implantation induced extended defects and transient enhanced diffusion in silicon

    SciTech Connect

    Chen, J.; Liu, J.; Listebarger, J.; Krishnamoorthy, W.; Zhang, L.; Jones, K.S.

    1995-08-01

    Transient enhanced diffusion (TED) of dopant in silicon caused by point defects during annealing of implanted. Si has become one of the essential concerns in miniaturization of silicon device technology. In order to control and minimize the TED effect, a fundamental understanding of the evolution of the point defects upon annealing and the interaction between point defects and extended defects and their effects on dopant diffusion is necessary. Our studies were carried out by two parts; (1) For understanding the evolution of <311> and <110> defects, B{sup +} and Si{sup +} implantation at energies (from 5 keV to 40 keV) and doses in the range from 5 x 10{sup 12} to 1 x 10{sup 14}/cm{sup 2} were used. The annealing kinetics were investigated using a N{sub 2} ambient with temperatures for time ranging from 500{degrees}C to 1100{degrees}C for time ranging from 3 min to 3 hours. A matrix of implant energy vs. dose on formation threshold of <311> and <110> defect, interstitials napped and dissolved condition were obtained. (2) For Understanding the interaction between Type II dislocation loop and point defect a B doped buried marker layer was used. The oxidation of silicon surface used as a interstitials injection source and a buried type II loop layer as a point defect detector used to quantify the flux of interstitials injected. Combining the flux measured by loops and dopant diffusion the D{sub I} C{sub I} was determined. The diffusion limited kinetics was concluded. The TED from <311> and EOR (End of Range) <110> defect was studied using 8keV B{sup +} implanted Si to a dose of the le14 and 190keV Ge{sub +} implanted to a dose of le15. Subsequent anneals are done for 5 min and 30 min, respectively, These defects affect dopant diffusion by trapping and releasing point defects.

  6. Practical Approach for Detection and Identification of OXA-10-Derived Ceftazidime-Hydrolyzing Extended-Spectrum β-Lactamases

    PubMed Central

    Vahaboglu, Haluk; Ozturk, Recep; Akbal, Huriye; Saribas, Suat; Tansel, Ozlem; Coşkunkan, Figen

    1998-01-01

    A practical approach to detect and identify ceftazidime-hydrolyzing extended-spectrum mutants of OXA-10 β-lactamase is presented. Large numbers of bacteria were screened by colony hybridization, a 720-bp part of blaOXA was amplified by PCR from the hybridization-positive isolates, and the products were digested by PvuII and HaeIII. PMID:9508324

  7. Ovarian Cancer Stage II

    MedlinePlus

    ... hyphen, e.g. -historical Searches are case-insensitive Ovarian Cancer Stage II Add to My Pictures View /Download : ... 1650x675 View Download Large: 3300x1350 View Download Title: Ovarian Cancer Stage II Description: Three-panel drawing of stage ...

  8. World War II Homefront.

    ERIC Educational Resources Information Center

    Garcia, Rachel

    2002-01-01

    Presents an annotated bibliography that provides Web sites focusing on the U.S. homefront during World War II. Covers various topics such as the homefront, Japanese Americans, women during World War II, posters, and African Americans. Includes lesson plan sources and a list of additional resources. (CMK)

  9. Extended space charge in concentration polarization.

    PubMed

    Rubinstein, Isaak; Zaltzman, Boris

    2010-09-15

    This paper is concerned with ionic currents from an electrolyte solution into a charge-selective solid, such as, an electrode, an ion-exchange membrane or an array of nano-channels in a micro-fluidic system, and the related viscous fluid flows on the length scales varying from nanometers to millimeters. All systems of this kind have characteristic voltage-current curves with segments in which current nearly saturates at some plateau values due to concentration polarization--formation of solute concentration gradients under the passage of a DC current. A number of seemingly different phenomena occurring in that range, such as anomalous rectification in cathodic copper deposition from a copper sulfate solution, super-fast vortexes near an ion-exchange granule, overlimiting conductance in electrodialysis and the recently observed non-equilibrium electroosmotic instability, result from the formation of an additional extended space charge layer next to that of a classical electrical double layer at the solid/liquid interface. In this paper we review the peculiar features of the non-equilibrium electric double layer and extended space charge and the possibility of their direct probing by harmonic voltage/current perturbations through a linear and non-linear system's response, by the methods of electrical impedance spectroscopy and via the anomalous rectification effect. On the relevant microscopic scales the ionic transport in the direction normal to the interface is dominated by drift-diffusion; hence, the extended space charge related viscous flows remain beyond the scope of this paper. PMID:20619824

  10. Fixed provisional restorations for extended prosthodontic treatment.

    PubMed

    Amet, E M; Phinney, T L

    1995-01-01

    During extensive and extended prosthodontic treatment, there is need for a durable esthetic fixed provisional restoration that can be easily modified as treatment is completed and that is cost-effective. The needed strength of provisional restorations can be underestimated, and the management of complex treatment is then more difficult and the prosthetic results less predictable. Knowledge of the criteria for treatment restorations and the adequacies of their construction is essential for the prevention of catastrophic failures, patient management problems, and compromised results. Many times in complex prosthodontic treatment, changes are needed in esthetics, the plane of occlusion, incisal edge position, lip support, and type of occlusion, or the soft and/or hard tissues need to be altered or grafted surgically. In addition, after first- and second-stage implant surgery and extractions, there is a need for immediate tooth replacement with extended time between prosthodontic treatments. These prosthodontic changes and challenges can be addressed with reinforced acrylic provisional restorations that are adequately cemented and retained during the interim stage of healing and treatment. In addition, the provisional restoration should serve as a guide for the final restoration while esthetics and phonetics are evaluated for patient acceptance. This article describes the materials used with an indirect technique for fabrication of an extended-treatment acrylic provisional restoration that uses an internal cast metal support system for strength. This support system consists of metal bands or copings with extensions into edentulous areas and that have been opaqued to neutralize the metallic color. A matrix of vinyl polysiloxane made from the diagnostic wax-up simplifies construction of the acrylic, resulting in a strong, ridged, yet esthetic result.

  11. Implementing extended observing at the JCMT

    NASA Astrophysics Data System (ADS)

    Walther, Craig; Dempsey, Jessica; Campbell, Ian

    2014-08-01

    The James Clerk Maxwell Telescope (JCMT) is the largest single dish submillimetre telescope in the world. Recently the Joint Astronomy Centre (JAC) has learned that the JCMT will no longer receive financial support from its original supporting agencies after September 2014. There is significant pressure to complete some surveys that have been in progress at the JCMT for many years now. With the goal of completing a higher percentage of these surveys it was decided to take advantage of the hours between when the telescope operator leaves the telescope and when the day crew arrives. These hours generally have reasonable seeing and low column integrated water vapor, so they are good for observing. This observing is being performed remotely, in Hilo, without staff at the telescope, by staff members who do not have telescope operation as part of their job descriptions. This paper describes the hardware changes necessary to implement remote observing at JCMT. It also describes the software needed for remote, fail safe, operation of the telescope. The protocols and rules for passing the control of the telescope between the various groups are discussed. Since these Extended Operators are not expert telescope operators, the system was simplified as much as possible, but some training was necessary and proper checklists are essential. Due to the success of the first phase of Extending Observing at the JCMT, the hours when the weather is good and no one is at the telescope, but no day crew is on the way, are also now being utilized. Extended Observing has already yielded a considerable amount of science observing time.

  12. Extending "color constancy" outside the visible region.

    PubMed

    Ratnasingam, Sivalogeswaran; Collins, Steve; Hernández-Andrés, Javier

    2011-04-01

    In this paper, the results of an investigation of the possibility of extending "color constancy" to obtain illuminant-invariant reflectance features from data in the near-ultraviolet (UV) and near-infrared (IR) wavelength regions are reported. These features are obtained by extending a blackbody-model-based color constancy algorithm proposed by Ratnasingam and Collins [J. Opt. Soc. Am. A27, 286 (2010)] to these additional wavelengths. Ratnasingam and Collins applied the model-based algorithm in the visible region to extract two illuminant-invariant features related to the wavelength-dependent reflectance of a surface from the responses of four sensors. In this paper, this model-based algorithm is extended to extract two illuminant-invariant reflectance features from the responses of sensors that cover the visible and either the near-UV or near-IR wavelength. In this investigation, test reflectance data sets are generated using the goodness-fitness coefficient (GFC). The appropriateness of the GFC for generating the test data sets is demonstrated by comparing the results obtained with these data with those obtained from data sets generated using the CIELab distance. Results based upon the GFC are then presented that suggest that the model-based algorithm can extract useful features from data from the visible and near-IR wavelengths. Finally, results are presented that show that, although the spectrum of daylight in the near UV is very different from a blackbody spectrum, the algorithm can be modified to extract useful features from visible and near-UV wavelengths. PMID:21478947

  13. Improving epidemic control strategies by extended detection

    NASA Astrophysics Data System (ADS)

    Karp, Paweł; Dybiec, Bartłomiej; Kleczkowski, Adam

    2014-11-01

    Majority of epidemics eradication programs work in preventive responsive way. The lack of exact information about epidemiological status of individuals makes responsive actions less efficient. Here, we demonstrate that additional tests can significantly increase the efficiency of "blind" treatment (vaccination or culling). Eradication strategy consisting of "blind" treatment in very limited local neighborhood supplemented by extra tests in a little bit larger neighborhood is able to prevent invasion of even highly infectious diseases and to achieve this at a cost lower than for the "blind" strategy. The effectiveness of the extended strategy depends on such parameters as the test efficiency and test cost.

  14. Extended moment arm anti-spin device

    NASA Technical Reports Server (NTRS)

    Whipple, R. D. (Inventor)

    1985-01-01

    A device which corrects aerodynamic spin is provided in which a collapsible boom extends an aircraft moment arm and an anti-spin parachute force is exerted upon the end of the moment arm to correct intentional or inadvertent aerodynamic spin. This configuration effects spin recovery by means of a parachute whose required diameter decreases as an inverse function of the increasing length of the moment arm. The collapsible boom enables the parachute to avoid the aircraft wake without mechanical assistance, retracts to permit steep takeoff, and permits a parachute to correct spin while minimizing associated aerodynamic, structural and in-flight complications.

  15. Extending quantum coherence of superconducting flux

    NASA Astrophysics Data System (ADS)

    Yan, Fei; Kamal, Archana; Orlando, Terry; Gustavsson, Simon; Oliver, William; Engineering Quantum Systems, MIT Team

    We present the design of a superconducting qubit with multiple Josephson junctions. The design starts with a capacitively shunted flux qubit, and it incorporates particular junction parameter choices for the purpose of simultaneously optimizing over transition frequency, anharmonicity, flux- and charge-noise sensitivity around flux degeneracy. By studying the scaling properties with design parameters, we identify directions to extend coherence substantially. This research was funded by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Projects Activity (IARPA) via MIT Lincoln Laboratory under Air Force Contract No. FA8721-05-C-0002.

  16. The extended SMAS approach to neck rejuvenation.

    PubMed

    Perkins, Stephen W; Waters, Heather H

    2014-05-01

    Jowling, submental lipoptosis, and platysmal banding can affect self-image and reduce quality of life, leading one to seek facial and neck rejuvenation. With realistic expectations, a facelift can provide the desired improvement in appearance and sense of well-being. Before any intervention, a detailed history, focused examination, communication of expected outcomes with the assistance of preoperative digital imaging, and discussion of perioperative instructions are of utmost importance. Although many techniques exist, the modified deep plane extended superficial muscular aponeurotic system rhytidectomy with submentoplasty reliably delivers a significant improvement with lasting results. PMID:24745387

  17. Praxair extending hydrogen pipeline in Southeast Texas

    SciTech Connect

    Not Available

    1992-08-24

    This paper reports that Praxair Inc., an independent corporation created by the spinoff of Union Carbide Corp.'s Linde division, is extending its high purity hydrogen pipeline system from Channelview, Tex., to Port Arthur, Tex. The 70 mile, 10 in. extension begins at a new pressure swing adsorption (PSA) purification unit next to Lyondell Petrochemical Co.'s Channelview plant. The PSA unit will upgrade hydrogen offgas from Lyondell's methanol plant to 99.99% purity hydrogen. The new line, advancing at a rate of about 1 mile/day, will reach its first customer, Star Enterprise's 250,000 b/d Port Arthur refinery, in September.

  18. Extended Scaling Relations for Planar Lattice Models

    NASA Astrophysics Data System (ADS)

    Benfatto, G.; Falco, P.; Mastropietro, V.

    2009-12-01

    It is widely believed that the critical properties of several planar lattice systems, like the Eight Vertex or the Ashkin-Teller models, are well described by an effective continuum fermionic theory obtained as a formal scaling limit. On the basis of this assumption several extended scaling relations among their indices were conjectured. We prove the validity of some of them, among which the ones predicted by Kadanoff (Phys Rev Lett 39:903-905, 1977) and by Luther and Peschel (Phys Rev B 12:3908-3917, 1975).

  19. Extending the applicability of multigrid methods

    SciTech Connect

    Brannick, J; Brezina, M; Falgout, R; Manteuffel, T; McCormick, S; Ruge, J; Sheehan, B; Xu, J; Zikatanov, L

    2006-09-25

    Multigrid methods are ideal for solving the increasingly large-scale problems that arise in numerical simulations of physical phenomena because of their potential for computational costs and memory requirements that scale linearly with the degrees of freedom. Unfortunately, they have been historically limited by their applicability to elliptic-type problems and the need for special handling in their implementation. In this paper, we present an overview of several recent theoretical and algorithmic advances made by the TOPS multigrid partners and their collaborators in extending applicability of multigrid methods. Specific examples that are presented include quantum chromodynamics, radiation transport, and electromagnetics.

  20. Three-Dimensional Extended Bargmann Supergravity

    NASA Astrophysics Data System (ADS)

    Bergshoeff, Eric; Rosseel, Jan

    2016-06-01

    We show that three-dimensional general relativity, augmented with two vector fields, allows for a nonrelativistic limit, different from the standard limit leading to Newtonian gravity, that results in a well-defined action which is of the Chern-Simons type. We show that this three-dimensional "extended Bargmann gravity," after coupling to matter, leads to equations of motion allowing a wider class of background geometries than the ones that one encounters in Newtonian gravity. We give the supersymmetric generalization of these results and point out an important application in the context of calculating partition functions of nonrelativistic field theories using localization techniques.

  1. Extended ultrahigh-Q-cavity diode laser.

    PubMed

    Xie, Zhenda; Liang, Wei; Savchenkov, Anatoliy A; Lim, Jinkang; Burkhart, Jan; McDonald, Mickey; Zelevinsky, Tanya; Ilchenko, Vladimir S; Matsko, Andrey B; Maleki, Lute; Wong, Chee Wei

    2015-06-01

    We report on a study of a 698 nm extended cavity semiconductor laser with intracavity narrowband optical feedback from a whispering gallery mode resonator. This laser comprises an ultrahigh-Q (>10(10)) resonator supporting stimulated Rayleigh scattering, a diffraction grating wavelength preselector, and a reflective semiconductor amplifier. Single longitudinal mode lasing is characterized with sub-kilohertz linewidth and a 9 nm coarse tuning range. The laser has a potential application for integration with the 1S0-3P0 strontium transition to create compact precision atomic clocks. PMID:26030566

  2. Three-Dimensional Extended Bargmann Supergravity.

    PubMed

    Bergshoeff, Eric; Rosseel, Jan

    2016-06-24

    We show that three-dimensional general relativity, augmented with two vector fields, allows for a nonrelativistic limit, different from the standard limit leading to Newtonian gravity, that results in a well-defined action which is of the Chern-Simons type. We show that this three-dimensional "extended Bargmann gravity," after coupling to matter, leads to equations of motion allowing a wider class of background geometries than the ones that one encounters in Newtonian gravity. We give the supersymmetric generalization of these results and point out an important application in the context of calculating partition functions of nonrelativistic field theories using localization techniques. PMID:27391712

  3. Topologically massive gravity with extended supersymmetry

    NASA Astrophysics Data System (ADS)

    Lauf, Frederik; Sachs, Ivo

    2016-09-01

    We describe the construction of 2 +1 -dimensional toplogically massive anti-de Sitter gravity with N -extended supersymmetry in superspace by means of introducing a compensating hypermultiplet for the super-Weyl invariance. For N ≥3 , the scalar multiplet must be on shell and the potential for the scalar compensator is completely determined by the geometry. As a consequence, the resulting massive theory has no free parameter for N ≥4 . For N =4 , we show that this leads to topologically massive gravity at the chiral point and construct the corresponding off-shell component action.

  4. Proving refinement transformations using extended denotational semantics

    SciTech Connect

    Winter, V.L.; Boyle, J.M.

    1996-04-01

    TAMPR is a fully automatic transformation system based on syntactic rewrites. Our approach in a correctness proof is to map the transformation into an axiomatized mathematical domain where formal (and automated) reasoning can be performed. This mapping is accomplished via an extended denotational semantic paradigm. In this approach, the abstract notion of a program state is distributed between an environment function and a store function. Such a distribution introduces properties that go beyond the abstract state that is being modeled. The reasoning framework needs to be aware of these properties in order to successfully complete a correctness proof. This paper discusses some of our experiences in proving the correctness of TAMPR transformations.

  5. Extendable retractable telescopic mast for deployable structures

    NASA Technical Reports Server (NTRS)

    Schmid, M.; Aguirre, M.

    1986-01-01

    The Extendable and Retractable Mast (ERM) which is presently developed by Dornier in the frame of an ESA-contract, will be used to deploy and retract large foldable structures. The design is based on a telescopic carbon-fiber structure with high stiffness, strength and pointing accuracy. To verify the chosen design, a breadboard model of an ERM was built and tested under thermal vacuum (TV)-conditions. It is planned as a follow-on development to manufacture and test an Engineering Model Mast. The Engineering Model will be used to establish the basis for an ERM-family covering a wide range of requirements.

  6. Thermal stabilized vegetable oil extended diesel fuels

    SciTech Connect

    Sweeney, W.M.; Lachowicz, D.R.

    1986-03-11

    A middle distillate fuel composition is described comprising: (a) a major portion of a middle distillate containing a hydrocarbon boiling in the middle distillate boiling range; (b) an extending portion of a vegetable oil; and (c) an effective thermal-stabilizing amount of a nitrogen-containing polymer prepared by reacting an ethylene/propylene copolymer with maleic anhydride, thereby forming a succinic anhydride, reacting the succinic anhydride, with an alcohol, thereby forming a succinate ester while leaving a portion of the succinic anhydride unreacted, and, reacting the succinate ester and the unreacted succinic anhydride with dimethylaminopropylamine, thereby forming a nitrogen-containing polymer.

  7. Simulating futures in extended common LISP

    NASA Technical Reports Server (NTRS)

    Nachtsheim, Philip R.

    1988-01-01

    Stack-groups comprise the mechanism underlying implementation of multiprocessing in Extended Common LISP, i.e., running multiple quasi-simultaneous processes within a single LISP address space. On the other hand, the future construct of MULTILISP, an extension of the LISP dialect scheme, deals with parallel execution. The source of concurrency that future exploits is the overlap between computation of a value and use of the value. Described is a simulation of the future construct by an interpreter utilizing stack-group extensions to common LISP.

  8. Preparation and Spectrophotometric Analysis of Hexaamminenickel(II) Chloride.

    ERIC Educational Resources Information Center

    Wieder, Grace M.

    1986-01-01

    Describes an experiment developed at Brooklyn College (New York) in which the preparation and ammonia analysis of an amminenickel(II) chloride is extended to include a spectrophotometric analysis for nickel. Discusses the materials needed and the procedure for the experiment which takes nine hours of laboratory work. (TW)

  9. Alberta Education Energy Conservation Project. Phase II: Internal Evaluation.

    ERIC Educational Resources Information Center

    Sundmark, Dana

    This report is based on the Alberta Education Energy Conservation Project - Phase II. The project was a follow-up to an earlier study, extending from June 1980 to June 1983, in which government funding and engineering manpower were used to conduct an energy management program in 52 selected pilot schools in 5 areas of the province. The report…

  10. Structure of the extended emission in the infrared celestial background

    SciTech Connect

    Price, S.D.

    1986-09-30

    The extended emission in the infrared celestial background may be divided into three main components: the zodiacal background, the large discrete sources in the galaxy, and the interstellar dust. The zodiacal background is due to the thermal reradiation of sunlight absorbed by the dust in the solar system. An earth-orbiting infrared telescope will detect the diffuse emission from this dust in all directions with maximum intensity lying roughly along the ecliptic plane where the density of dust is highest. Structure with scale lengths of 10/sup 0/ was measured in both the visual and infrared; finer structure was detected in the infrared by the Infrared Astronomy Satellite. H II regions, areas of ionized gas mixed with and surrounded by dust, are the brightest discrete objects in the galaxy in the long wavelength infrared re-emitted in the infrared with a range of temperatures characteristic of the thermal equilibrium for the surroundings of the dust. The emission from the interstellar dust produces a filimentary structured background, the infrared cirrus. The observed far-infrared color temperature of about 20-35K for the cirrus is consistent with emission-form graphite and silicate grains which absorb the interstellar radiation field. The much-larger LWIR color temperature is likely due to a greater abundance of sub-micron particles in the interstellar medium and, perhaps, from band emission due to polycyclic aromatic hydrocarbons. These galactic planes have full width at half maxima of about 2/sup 0/.

  11. Design considerations for extending ADMX to temperatures below 1K

    NASA Astrophysics Data System (ADS)

    Gonzalez, Miguel

    2014-03-01

    Phase II of the ADMX experiment is a large-scale upgrade with the objective of integrating the state-of-the-art in microwave detection and in cryogenic technologies. From its initial operations with pumped liquid 4He at ~1.5 K, a further reduction in physical temperature to the targeted 100 mK would improve its sensitivity more than twentyfold, extending the search below the DFSZ limit. But the cooling of a large microwave cavity to millikelvin temperatures in a high magnetic field poses some new challenges with no turnkey solutions from commercial cryogenic technologies. In this talk, we address the issue of incorporating current commercial technologies within our custom made insert to construct a dilution refrigeration system with a cooling power of 800 μW at 100 mK. Additionally, we describe a separate homemade pumped liquid 3He system with a 2-3 mW cooling power at 0.5 K, which will be used as a bridge between the current 4He system at 1.5 K and the planned 100 mK dilution system. Supported by DOE Grants DE-FG02-97ER41029, DE-FG02-96ER40956, DE-AC52-07NA27344, DE-AC03-76SF00098, NSF grants PHY-1067242 and PHY-1306729, and the Livermore LDRD program.

  12. Oscillating laminar electrokinetic flow in infinitely extended circular microchannels.

    PubMed

    Bhattacharyya, A; Masliyah, J H; Yang, J

    2003-05-01

    This article addresses the problem of oscillating laminar electrokinetic liquid flow in an infinitely extended circular microchannel. Based on the Debye-Huckel approximation for low surface potential at the channel wall, a complex variable approach is used to obtain an analytical solution for the flow. The complex counterparts of the flow rate and the current are linearly dependent on the pressure gradient and the external electric field. This property is used to show that Onsager's principle of reciprocity continues to be valid (involving the complex quantities) for the stated problem. During oscillating pressure-driven flow, the electroviscous effect for a given value of the normalized reciprocal electrical double-layer (EDL) thickness is observed to attain a maximum at a certain normalized frequency. In general, an increasing normalized frequency results in a reduction of EDL effects, leading to (i). a volumetric flow rate in the case of streaming potential approaching that predicted by the theory without EDL effects, and (ii). a reduction in the volumetric flow rate in the case of electroosmosis. PMID:12725819

  13. STS-39 SPAS-II IBSS is grappled by remote manipulator system (RMS)

    NASA Technical Reports Server (NTRS)

    1991-01-01

    STS-39 Shuttle Pallet Satellite II (SPAS-II) / Infrared Background Signature Survey (IBSS) spacecraft is grappled by remote manipulator system (RMS) end effector. Backdropped against the cloud-covered surface of the Earth, SPAS-II/IBSS spacecraft is extended outside Discovery's, Orbiter Vehicle (OV) 103's, payload bay (PLB). Components visible on the SPAS-II/IBSS spacecraft include the Cryostat, antennas, NFOV TV camera, WFOV TV camera, Arizona Imager/Spectrograph (AIS), and the handling trunnions. SPAS-II is a Strategic Defense Initiative Organization (SDIO) payload.

  14. Extended arrays for nonlinear susceptibility magnitude imaging

    PubMed Central

    Ficko, Bradley W.; Giacometti, Paolo; Diamond, Solomon G.

    2016-01-01

    This study implements nonlinear susceptibility magnitude imaging (SMI) with multifrequency intermodulation and phase encoding. An imaging grid was constructed of cylindrical wells of 3.5-mm diameter and 4.2-mm height on a hexagonal two-dimensional 61-voxel pattern with 5-mm spacing. Patterns of sample wells were filled with 40-μl volumes of Fe3O4 starch-coated magnetic nanoparticles (mNPs) with a hydrodynamic diameter of 100 nm and a concentration of 25 mg/ml. The imaging hardware was configured with three excitation coils and three detection coils in anticipation that a larger imaging system will have arrays of excitation and detection coils. Hexagonal and bar patterns of mNP were successfully imaged (R2 > 0.9) at several orientations. This SMI demonstration extends our prior work to feature a larger coil array, enlarged field-of-view, effective phase encoding scheme, reduced mNP sample size, and more complex imaging patterns to test the feasibility of extending the method beyond the pilot scale. The results presented in this study show that nonlinear SMI holds promise for further development into a practical imaging system for medical applications. PMID:26124044

  15. Choice mechanisms for past, temporally extended outcomes.

    PubMed

    Vestergaard, Martin D; Schultz, Wolfram

    2015-07-01

    Accurate retrospection is critical in many decision scenarios ranging from investment banking to hedonic psychology. A notoriously difficult case is to integrate previously perceived values over the duration of an experience. Failure in retrospective evaluation leads to suboptimal outcome when previous experiences are under consideration for revisit. A biologically plausible mechanism underlying evaluation of temporally extended outcomes is leaky integration of evidence. The leaky integrator favours positive temporal contrasts, in turn leading to undue emphasis on recency. To investigate choice mechanisms underlying suboptimal outcome based on retrospective evaluation, we used computational and behavioural techniques to model choice between perceived extended outcomes with different temporal profiles. Second-price auctions served to establish the perceived values of virtual coins offered sequentially to humans in a rapid monetary gambling task. Results show that lesser-valued options involving successive growth were systematically preferred to better options with declining temporal profiles. The disadvantageous inclination towards persistent growth was mitigated in some individuals in whom a longer time constant of the leaky integrator resulted in fewer violations of dominance. These results demonstrate how focusing on immediate gains is less beneficial than considering longer perspectives. PMID:26063841

  16. Spatially Extended Memory Models of Cardiac Tissue

    NASA Astrophysics Data System (ADS)

    Fox, Jeffrey; Riccio, Mark; Hua, Fei; Bodenschatz, Eberhard; Gilmour, Robert

    2002-03-01

    Beat-to-beat alternation of cardiac electrical properties (alternans) commonly occurs during rapid periodic pacing. Although alternans is generally associated with a resititution curve with slope >=1, recent studies by Gauthier and co-workers reported the absence of alternans in frog heart tissue with a restitution curve of slope >=1. These experimental findings were understood in terms of a memory model in which the duration D of an action potential depends on the preceding rest interval I as well as a memory variable M that accumulates during D and dissipates during I. We study the spatiotemporal dynamics of a spatially extended 1-d fiber using an ionic model that exhibits memory effects. We find that while a single cell can have a restitution slope >=1 and not show alternans (because of memory), the spatially extended system exhibits alternans. To understand the dynamical mechanism of this behavior, we study a coupled maps memory model both numerically and analytically. These results illustrate that spatial effects and memory effects can play a significant role in determining the dynamics of wave propagation in cardiac tissue.

  17. Enhancing protein stability with extended disulfide bonds.

    PubMed

    Liu, Tao; Wang, Yan; Luo, Xiaozhou; Li, Jack; Reed, Sean A; Xiao, Han; Young, Travis S; Schultz, Peter G

    2016-05-24

    Disulfide bonds play an important role in protein folding and stability. However, the cross-linking of sites within proteins by cysteine disulfides has significant distance and dihedral angle constraints. Here we report the genetic encoding of noncanonical amino acids containing long side-chain thiols that are readily incorporated into both bacterial and mammalian proteins in good yields and with excellent fidelity. These amino acids can pair with cysteines to afford extended disulfide bonds and allow cross-linking of more distant sites and distinct domains of proteins. To demonstrate this notion, we preformed growth-based selection experiments at nonpermissive temperatures using a library of random β-lactamase mutants containing these noncanonical amino acids. A mutant enzyme that is cross-linked by one such extended disulfide bond and is stabilized by ∼9 °C was identified. This result indicates that an expanded set of building blocks beyond the canonical 20 amino acids can lead to proteins with improved properties by unique mechanisms, distinct from those possible through conventional mutagenesis schemes.

  18. NASA's extended duration orbiter medical program

    NASA Technical Reports Server (NTRS)

    Pool, Sam Lee; Sawin, Charles F.

    1992-01-01

    The physiological issues involved in safely extending Shuttle flights from 10 to 16 days have been viewed by some as academic. After all, they reasoned, humans already have lived and worked in space for periods exceeding even 28 days in the United States Skylab Program and onboard the Russian space stations. The difference in the Shuttle program is in the physical position of the astronauts as they reenter the Earth's atmosphere. Crewmembers in the earlier Apollo, Skylab, and Russian programs were returned to Earth in the supine position. Space Shuttle crewmembers, in contrast, are seated upright during reentry and landing; reexperiencing the Earth's g forces in this position has far more pronounced effects on the crewmember's physiological functions. The goal of the Extended Duration Orbiter (EDO) Medical Project (EDOMP) has been to ensure that crewmembers maintain physiological reserves sufficient to perform entry, landing, and egress safely. Early in the Shuttle Program, it became clear that physiological deconditioning during space flight could produce significant symptoms upon return to Earth. The signs and symptoms observed during the entry, landing, and egress after Shuttle missions have included very high heart rates and low blood pressures upon standing. Dizziness, 'graying out,' and fainting have occurred on ambulation or shortly thereafter. Other symptoms at landing have included headache, light-headedness, nausea and vomitting, leg cramping, inability to stand for several minutes after wheel-stop, and unsteadiness of gait.

  19. Thermoplastic Polyurethanes with Isosorbide Chain Extender

    SciTech Connect

    Javni, Ivan; Bilic, Olivera; Bilic, Nikola; Petrovic, Zoran; Eastwood, Eric; Zhang, Fan; Ilavsky, Jan

    2015-12-15

    Isosorbide, a renewable diol derived from starch, was used alone or in combination with butane diol (BD) as the chain extender in two series of thermoplastic polyurethanes (TPU) with 50 and 70% polytetramethylene ether glycol (PTMEG) soft segment concentration (SSC), respectively. In the synthesized TPUs, the hard segment composition was systematically varied in both series following BD/isosorbide molar ratios of 100 : 0; 75 : 25; 50 : 50; 25 : 75, and 0 : 100 to examine in detail the effect of chain extenders on properties of segmented polyurethane elastomers with different morphologies. We found that polyurethanes with 50% SSC were hard elastomers with Shore D hardness of around 50, which is consistent with assumed co-continuous morphology. Polymers with 70% SSC displayed lower Shore A hardness of 74–79 (Shore D around 25) as a result of globular hard domains dispersed in the soft matrix. Insertion of isosorbide increased rigidity, melting point and glass transition temperature of hard segments and tensile strength of elastomers with 50% SSC. These effects were weaker or non-existent in 70% SSC series due to the short hard segments and low content of isosorbide. We also found that the thermal stability was lowered by increasing isosorbide content in both series.

  20. An extended synthesis for evolutionary biology.

    PubMed

    Pigliucci, Massimo

    2009-06-01

    Evolutionary theory is undergoing an intense period of discussion and reevaluation. This, contrary to the misleading claims of creationists and other pseudoscientists, is no harbinger of a crisis but rather the opposite: the field is expanding dramatically in terms of both empirical discoveries and new ideas. In this essay I briefly trace the conceptual history of evolutionary theory from Darwinism to neo-Darwinism, and from the Modern Synthesis to what I refer to as the Extended Synthesis, a more inclusive conceptual framework containing among others evo-devo, an expanded theory of heredity, elements of complexity theory, ideas about evolvability, and a reevaluation of levels of selection. I argue that evolutionary biology has never seen a paradigm shift, in the philosophical sense of the term, except when it moved from natural theology to empirical science in the middle of the 19th century. The Extended Synthesis, accordingly, is an expansion of the Modern Synthesis of the 1930s and 1940s, and one that--like its predecessor--will probably take decades to complete.