55 research outputs found
Search for a Solution of the Pioneer Anomaly
In 1972 and 1973 the Pioneer 10 and 11 missions were launched. They were the
first to explore the outer solar system and achieved stunning breakthroughs in
deep-space exploration. But beginning in about 1980 an unmodeled force of \sim
8 \times 10^{-8} cm/s^2, directed approximately towards the Sun, appeared in
the tracking data. It later was unambiguously verified as being in the data and
not an artifact. The cause remains unknown (although radiant heat remains a
likely origin). With time more and more effort has gone into understanding this
anomaly (and also possibly related effects). We review the situation and
describe ongoing programs to resolve the issue.Comment: 24 pages 8 figure
Photon and Graviton Mass Limits
Efforts to place limits on deviations from canonical formulations of
electromagnetism and gravity have probed length scales increasing dramatically
over time.Historically, these studies have passed through three stages: (1)
Testing the power in the inverse-square laws of Newton and Coulomb, (2) Seeking
a nonzero value for the rest mass of photon or graviton, (3) Considering more
degrees of freedom, allowing mass while preserving explicit gauge or
general-coordinate invariance. Since our previous review the lower limit on the
photon Compton wavelength has improved by four orders of magnitude, to about
one astronomical unit, and rapid current progress in astronomy makes further
advance likely. For gravity there have been vigorous debates about even the
concept of graviton rest mass. Meanwhile there are striking observations of
astronomical motions that do not fit Einstein gravity with visible sources.
"Cold dark matter" (slow, invisible classical particles) fits well at large
scales. "Modified Newtonian dynamics" provides the best phenomenology at
galactic scales. Satisfying this phenomenology is a requirement if dark matter,
perhaps as invisible classical fields, could be correct here too. "Dark energy"
{\it might} be explained by a graviton-mass-like effect, with associated
Compton wavelength comparable to the radius of the visible universe. We
summarize significant mass limits in a table.Comment: 42 pages Revtex4. This version contains corrections and changes
contained in the published version, Rev. Mod. Phys. 82, 939-979 (2010), with
a few addition
Yeast Screens Identify the RNA Polymerase II CTD and SPT5 as Relevant Targets of BRCA1 Interaction
BRCA1 has been implicated in numerous DNA repair pathways that maintain genome integrity, however the function responsible for its tumor suppressor activity in breast cancer remains obscure. To identify the most highly conserved of the many BRCA1 functions, we screened the evolutionarily distant eukaryote Saccharomyces cerevisiae for mutants that suppressed the G1 checkpoint arrest and lethality induced following heterologous BRCA1 expression. A genome-wide screen in the diploid deletion collection combined with a screen of ionizing radiation sensitive gene deletions identified mutants that permit growth in the presence of BRCA1. These genes delineate a metabolic mRNA pathway that temporally links transcription elongation (SPT4, SPT5, CTK1, DEF1) to nucleopore-mediated mRNA export (ASM4, MLP1, MLP2, NUP2, NUP53, NUP120, NUP133, NUP170, NUP188, POM34) and cytoplasmic mRNA decay at P-bodies (CCR4, DHH1). Strikingly, BRCA1 interacted with the phosphorylated RNA polymerase II (RNAPII) carboxy terminal domain (P-CTD), phosphorylated in the pattern specified by the CTDK-I kinase, to induce DEF1-dependent cleavage and accumulation of a RNAPII fragment containing the P-CTD. Significantly, breast cancer associated BRCT domain defects in BRCA1 that suppressed P-CTD cleavage and lethality in yeast also suppressed the physical interaction of BRCA1 with human SPT5 in breast epithelial cells, thus confirming SPT5 as a relevant target of BRCA1 interaction. Furthermore, enhanced P-CTD cleavage was observed in both yeast and human breast cells following UV-irradiation indicating a conserved eukaryotic damage response. Moreover, P-CTD cleavage in breast epithelial cells was BRCA1-dependent since damage-induced P-CTD cleavage was only observed in the mutant BRCA1 cell line HCC1937 following ectopic expression of wild type BRCA1. Finally, BRCA1, SPT5 and hyperphosphorylated RPB1 form a complex that was rapidly degraded following MMS treatment in wild type but not BRCA1 mutant breast cells. These results extend the mechanistic links between BRCA1 and transcriptional consequences in response to DNA damage and suggest an important role for RNAPII P-CTD cleavage in BRCA1-mediated cancer suppression
A Membrane Fusion Protein αSNAP Is a Novel Regulator of Epithelial Apical Junctions
Tight junctions (TJs) and adherens junctions (AJs) are key determinants of the structure and permeability of epithelial barriers. Although exocytic delivery to the cell surface is crucial for junctional assembly, little is known about the mechanisms controlling TJ and AJ exocytosis. This study was aimed at investigating whether a key mediator of exocytosis, soluble N-ethylmaleimide sensitive factor (NSF) attachment protein alpha (αSNAP), regulates epithelial junctions. αSNAP was enriched at apical junctions in SK-CO15 and T84 colonic epithelial cells and in normal human intestinal mucosa. siRNA-mediated knockdown of αSNAP inhibited AJ/TJ assembly and establishment of the paracellular barrier in SK-CO15 cells, which was accompanied by a significant down-regulation of p120-catenin and E-cadherin expression. A selective depletion of p120 catenin effectively disrupted AJ and TJ structure and compromised the epithelial barrier. However, overexpression of p120 catenin did not rescue the defects of junctional structure and permeability caused by αSNAP knockdown thereby suggesting the involvement of additional mechanisms. Such mechanisms did not depend on NSF functions or induction of cell death, but were associated with disruption of the Golgi complex and down-regulation of a Golgi-associated guanidine nucleotide exchange factor, GBF1. These findings suggest novel roles for αSNAP in promoting the formation of epithelial AJs and TJs by controlling Golgi-dependent expression and trafficking of junctional proteins
Anomalous accelerations in spacecraft flybys of the Earth
[EN] The flyby anomaly is a persistent riddle in astrodynamics.
Orbital analysis in several flybys of the Earth
since the Galileo spacecraft flyby of the Earth in 1990 have
shown that the asymptotic post-encounter velocity exhibits
a difference with the initial velocity that cannot be attributed
to conventional effects. To elucidate its origin, we have developed
an orbital program for analyzing the trajectory of
the spacecraft in the vicinity of the perigee, including both
the Sun and the Moon¿s tidal perturbations and the geopotential
zonal, tesseral and sectorial harmonics provided by
the EGM96 model. The magnitude and direction of the
anomalous acceleration acting upon the spacecraft can be
estimated from the orbital determination program by comparing
with the trajectories fitted to telemetry data as provided
by the mission teams. This acceleration amounts to a
fraction of a mm/s2 and decays very fast with altitude. The
possibility of some new physics of gravity in the altitude
range for spacecraft flybys is discussed.Acedo Rodríguez, L. (2017). Anomalous accelerations in spacecraft flybys of the Earth. Astrophysics and Space Science. 362(12):1-15. doi:10.1007/s10509-017-3205-xS11536212Acedo, L.: Galaxies 3, 113 (2015)Acedo, L.: Mon. Not. R. Astron. Soc. 463(2), 2119 (2016)Acedo, L.: Adv. Space Res. 59(7), 1715 (2017). 1701.06939Acedo, L., Bel, L.: Astron. Nachr. 338(1), 117 (2017). 1602.03669Adler, S.L.: Int. J. Mod. Phys. A 25, 4577 (2010). 0908.2414 . doi: 10.1142/S0217751X10050706Adler, S.L.: In: Proceedings of the Conference in Honour of Murray Gellimann’s 80th Birthday, p. 352 (2011). doi: 10.1142/9789814335614_0032Anderson, J.D., Nieto, M.M.: In: Klioner, S.A., Seidelmann, P.K., Soffel, M.H. (eds.) Relativity in Fundamental Astronomy: Dynamics, Reference Frames, and Data Analysis. IAU Symposium, vol. 261, p. 189 (2010). doi: 10.1017/S1743921309990378Anderson, J.D., Laing, P.A., Lau, E.L., Liu, A.S., Nieto, M.M., Turyshev, S.G.: Phys. Rev. Lett. 81(14), 2858 (1998). gr-qc/0104064 . doi: 10.1103/PhysRevLett.81.2858Anderson, J.D., Laing, P.A., Lau, E.L., Liu, A.S., Nieto, M.M., Turyshev, S.G.: Phys. Rev. D 65(8), 082004 (2002). gr-qc/0104064 . doi: 10.1103/PhysRevD.65.082004Anderson, J.D., Campbell, J.K., Ekelund, J.E., Ellis, J., Jordan, J.F.: Phys. Rev. Lett. 100(9), 091102 (2008). doi: 10.1103/PhysRevLett.100.091102Atchison, J.A., Peck, M.A.: J. Guid. Control Dyn. 33, 1115 (2010). doi: 10.2514/1.47413Bertolami, O., Francisco, F., Gil, P.J.S.: Class. Quantum Gravity 33(12), 125021 (2016). 1507.08457 . doi: 10.1088/0264-9381/33/12/125021Bolton, S.J., Adriani, A., Adumitroaie, V., Allison, M., Anderson, J., Atreya, S., Bloxham, J., Brown, S., Connerney, J.E.P., DeJong, E., Folkner, W., Gautier, D., Grassi, D., Gulkis, S., Guillot, T., Hansen, C., Hubbard, W.B., Iess, L., Ingersoll, A., Janssen, M., Jorgensen, J., Kaspi, Y., Levin, S.M., Li, C., Lunine, J., Miguel, Y., Mura, A., Orton, G., Owen, T., Ravine, M., Smith, E., Steffes, P., Stone, E., Stevenson, D., Thorne, R., Waite, J., Durante, D., Ebert, R.W., Greathouse, T.K., Hue, V., Parisi, M., Szalay, J.R., Wilson, R.: Science 356, 821 (2017). doi: 10.1126/science.aal2108Cahill, R.T.: ArXiv e-prints (2008). 0804.0039Chamberlin, A., Yeomans, D., Giorgini, J., Chodas, P.: Horizons Ephemeris System (2016). http://ssd.jpl.nasa.gov/horizons.cgi . Accessed: 2016-10-27Chao, B.F.: C. R. Géosci. 338, 1123 (2006). doi: 10.1016/j.crte.2006.09.014Coddington, E., Levinson, N.: McGraw-Hill, New York (1955)Debono, I., Smoot, G.F.: Universe 2(4), 23 (2016). doi: 10.3390/universe2040023Desai, S.D.: J. Geophys. Res., Oceans 107(C11), 7 (2002). 3186. doi: 10.1029/2001JC001224Dickey, J.O., Bender, P.L., Faller, J.E., Newhall, X.X., Ricklefs, R.L., Ries, J.G., Shelus, P.J., Veillet, C., Whipple, A.L., Wiant, J.R., Williams, J.G., Yoder, C.F.: Science 265, 482 (1994). doi: 10.1126/science.265.5171.482Dyson, F.W., Eddington, A.S., Davidson, C.: Philos. Trans. R. Soc. Lond., Ser. A 220, 291 (1920). doi: 10.1098/rsta.1920.0009Everitt, C.W.F., et al.: Phys. Rev. Lett. 221101(106) (2011)Feng, J.L., Fornal, B., Galon, I., Gardner, S., Smolinsky, J., Tait, T.M.P., Tanedo, P.: Phys. Rev. Lett. 117, 071803 (2016). 1604.07411 . doi: 10.1103/PhysRevLett.117.071803Folkner, W.M., Williams, J.G., Boggs, D.H., Park, R.S., Kuchynka, P.: IPN Prog. Rep. 42(196) (2014)Fornberg, B.: Math. Comput. 51(184), 699 (1988). doi: 10.1090/S0025-5718-1988-0935077-0Franklin, A., Fischback, E.: The Rise and Fall of the Fifth Force. Discovery, Pursuit, and Justification in Modern Physics, second edition. Springer, New York (2016)Giorgini, J.D.: Personal communication (2015)Hackmann, E., Laemmerzahl, C.: In: 38th COSPAR Scientific Assembly. COSPAR Meeting, vol. 38, p. 3 (2010)Hafele, J.C.: ArXiv e-prints (2009). 0904.0383ICGEM: International Center for Global Gravity Field Models. http://icgem.gfz-potsdam.de/tom_longtimeIERS: In: Petit, G., Luzum, B. (eds.) IERS Conventions (2010), p. 1. Verlag des Bundesamts für Kartographie und Geodäsie, Frankfurt am Main (2010)Iess, L., Asmar, S.: Int. J. Mod. Phys. D 16, 2117 (2007). doi: 10.1142/S0218271807011449Iess, L., Asmar, S., Tortora, P.: Acta Astronaut. 65, 666 (2009). doi: 10.1016/j.actaastro.2009.01.049Iess, L., Di Benedetto, M., James, M., Mercolino, M., Simone, L., Tortora, P.: Acta Astronaut. 94, 699 (2014). doi: 10.1016/j.actaastro.2013.06.011Iorio, L.: Sch. Res. Exch. (2009). 0811.3924 . doi: 10.3814/2009/807695Iorio, L.: Astron. J. 142, 68 (2011a). 1102.4572 . doi: 10.1088/0004-6256/142/3/68Iorio, L.: Mon. Not. R. Astron. Soc. 415, 1266 (2011b). 1102.0212Iorio, L.: Europhys. Lett. (2011c). 1105.4145 . doi: 10.1209/0295-5075/96/30001Iorio, L.: Adv. Space Res. 54(11), 2441 (2014a). 1311.4218 . doi: 10.1016/j.asr.2014.06.035Iorio, L.: Galaxies 2, 259 (2014b). 1404.6537 . doi: 10.3390/galaxies2020259Iorio, L.: Universe 1(1), 38 (2015a). doi: 10.3390/universe1010038Iorio, L.: Int. J. Mod. Phys. D 24, 1530015 (2015b). 1412.7673Iorio, L., Giudice, G.: New Astron. 11, 600 (2006). gr-qc/0601055Iorio, L., Lichtenegger, H.I.M., Ruggiero, M.L., Corda, C.: Astrophys. Space Sci. 331, 351 (2011). 1009.3225 . doi: 10.1007/s10509-010-0489-5Jouannic, B., Noomen, R., van den IJSel, J.A.A.: In: Proceedings of the 25th International Symposium on Space Flight Dynamics ISSFD, Munich, Germany (2015)Kennefick, D.: Phys. Today 62, 37 (2009). doi: 10.1063/1.3099578King-Hele, D.: Satellite Orbits in an Atmosphere. Theory and Applications. Blackie and Son Ltd., Glasgow (1987)Lämmerzahl, C., Preuss, O., Dittus, H.: In: Dittus, H., Lammerzahl, C., Turyshev, S.G. (eds.) Lasers, Clocks and Drag-Free Control: Exploration of Relativistic Gravity in Space. Astrophysics and Space Science Library, vol. 349, p. 75 (2008). doi: 10.1007/978-3-540-34377-6_3Le Verrier, U.: C. R. Hebd. Acad. Sci. 49, 379 (1859)Lemoine, F.G.E.A.: NASA/TP-1998-206861 (1998)Lewis, R.A.: In: Robertson, G.A. (ed.) American Institute of Physics Conference Series. American Institute of Physics Conference Series, vol. 1103, p. 226 (2009). doi: 10.1063/1.3115499Longair, M.: Philos. Trans. R. Soc., Math. Phys. Eng. Sci. (2015). doi: 10.1098/rsta.2014.0287McCulloch, M.E.: Mon. Not. R. Astron. Soc. 389, 57 (2008). 0806.4159 . doi: 10.1111/j.1745-3933.2008.00523.xMoe, M.M., Wallace, S.D., Moe, K.: In: Washington DC American Geophysical Union Geophysical Monograph Series, vol. 87, p. 349 (1995). doi: 10.1029/GM087p0349Murphy, E.M.: Phys. Rev. Lett. 83, 1890 (1998). doi: 10.1103/PhysRevLett.83.1890Naval Observatory: Dept. of the Navy, USA (2009)Newcomb, S.: Tables of the Four Inner Planets. Government Printing Office, Washington (1895)Nyambuya, G.G.: ArXiv e-prints (2008). 0803.1370Nyambuya, G.G.: New Astron. 57, 22 (2017). doi: 10.1016/j.newast.2017.06.001Páramos, J., Hechenblaikner, G.: Adv. Space Res. 79–80(7), 76 (2013). 1210.7333v1Peskin, M.E., Schroeder, D.V.: An Introduction to Quantum Field Theory. Westview Press, Perseus Books Group, London (1995)Pinheiro, M.J.: Phys. Lett. A 378, 3007 (2014). 1404.1101Pinheiro, M.J.: Mon. Not. R. Astron. Soc. 461(4), 3948 (2016)Renzetti, G.: Cent. Eur. J. Phys. 11, 531 (2013). doi: 10.2478/s11534-013-0189-1Rievers, B., Lämmerzahl, C.: Ann. Phys. 523, 439 (2011). 1104.3985 . doi: 10.1002/andp.201100081Roseveare, N.T.: Mercury’s Perihelion, from Le Verrier to Einstein. Clarendon Press, Wotton-under-Edge (1982)Rubincam, D.P.: Icarus 148, 2 (2000). doi: 10.1006/icar.2000.6485Standish, E.M.: In: Macias, A., Lämmerzahl, C., Camacho, A. (eds.) Recent Developments in Gravitation and Cosmology. American Institute of Physics Conference Series, vol. 977, p. 254 (2008). doi: 10.1063/1.2902789Standish, E.M.: In: Klioner, S.A., Seidelmann, P.K., Soffel, M.H. (eds.) Relativity in Fundamental Astronomy: Dynamics, Reference Frames, and Data Analysis. IAU Symposium, vol. 261, p. 179 (2010). doi: 10.1017/S1743921309990354Thompson, P.F., Abrahamson, M., Ardalan, S., Bordi, J.: In: 24th AAS/AIAA Space Flight Mechanics Meeting, Santa Fe, New Mexico, January 26–30, 2014 (2014). http://hdl.handle.net/2014/45519Turyshev, S.G., Toth, V.T.: Living Rev. Relativ. (2010). 1001.3686 . doi: 10.12942/lrr-2010-4Turyshev, S.G., Toth, V.T., Kinsella, G., Lee, S.-C., Lok, S.M., Ellis, J.: Phys. Rev. Lett. 108(24), 241101 (2012). 1204.2507 . doi: 10.1103/PhysRevLett.108.241101Varieschi, G.U.: Gen. Relativ. Gravit. 46, 1741 (2014). 1401.6503 . doi: 10.1007/s10714-014-1741-zWilhelm, K., Dwivedi, B.N.: Astrophys. Space Sci. 358, 18 (2015). doi: 10.1007/s10509-015-2413-5Will, C.M.: Living Rev. Relativ. 3(9) (2006)Will, C.M.: Class. Quantum Gravity (2015). doi: 10.1098/rsta.2014.0287Will, C.M.: In: Peron, R., Colpi, M., Gorini, V., Moschella, U. (eds.) Gravity: Where Do We Stand? Astrophysics and Space Science Library, vol. 349, p. 9 (2016). doi: 10.1007/978-3-319-20224-2_2Williams, J.G., Boggs, D.H.: Celest. Mech. Dyn. Astron. 126, 89 (2016). doi: 10.1007/s10569-016-9702-3Williams, J.G., Dickey, J.O.: In: Noomen, R., Klosko, S., Noll, C., Pearlman, M. (eds.) Proceedings of 13th International Workshop on Laser Ranging, p. 75 (2003). http://cddisa.gsfc.nasa.gov/lw13/lw_proceedings.htmlWilliams, J.G., Newhall, X.X., Dickey, J.O.: Phys. Rev. D 53, 6730 (1996). doi: 10.1103/PhysRevD.53.6730Williams, J.G., Turyshev, S.G., Boggs, D.H.: Phys. Rev. Lett. 93(26), 261101 (2004). gr-qc/0411113 . doi: 10.1103/PhysRevLett.93.261101Williams, J.G., Turyshev, S.G., Boggs, D.H.: Planet. Sci. 3, 2 (2014). doi: 10.1186/s13535-014-0002-5Williams, J.G., Boggs, D.H., Yoder, C.F., Ratcliff, J.T., Dickey, J.O.: J. Geophys. Res. 106, 27933 (2001). doi: 10.1029/2000JE001396Wolfram, S.: The Mathematica Book, fifth edition. Wolfram Media, Champaign (2003
Approaches in biotechnological applications of natural polymers
Natural polymers, such as gums and mucilage, are biocompatible, cheap, easily available and non-toxic materials of native origin. These polymers are increasingly preferred over synthetic materials for industrial applications due to their intrinsic properties, as well as they are considered alternative sources of raw materials since they present characteristics of sustainability, biodegradability and biosafety. As definition, gums and mucilages are polysaccharides or complex carbohydrates consisting of one or more monosaccharides or their derivatives linked in bewildering variety of linkages and structures. Natural gums are considered polysaccharides naturally occurring in varieties of plant seeds and exudates, tree or shrub exudates, seaweed extracts, fungi, bacteria, and animal sources. Water-soluble gums, also known as hydrocolloids, are considered exudates and are pathological products; therefore, they do not form a part of cell wall. On the other hand, mucilages are part of cell and physiological products. It is important to highlight that gums represent the largest amounts of polymer materials derived from plants. Gums have enormously large and broad applications in both food and non-food industries, being commonly used as thickening, binding, emulsifying, suspending, stabilizing agents and matrices for drug release in pharmaceutical and cosmetic industries. In the food industry, their gelling properties and the ability to mold edible films and coatings are extensively studied. The use of gums depends on the intrinsic properties that they provide, often at costs below those of synthetic polymers. For upgrading the value of gums, they are being processed into various forms, including the most recent nanomaterials, for various biotechnological applications. Thus, the main natural polymers including galactomannans, cellulose, chitin, agar, carrageenan, alginate, cashew gum, pectin and starch, in addition to the current researches about them are reviewed in this article.. }To the Conselho Nacional de Desenvolvimento Cientfíico e Tecnológico (CNPq) for fellowships (LCBBC and MGCC) and the Coordenação de Aperfeiçoamento de Pessoal de Nvíel Superior (CAPES) (PBSA). This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit, the Project RECI/BBB-EBI/0179/2012 (FCOMP-01-0124-FEDER-027462) and COMPETE 2020 (POCI-01-0145-FEDER-006684) (JAT)
Nurses' perceptions of aids and obstacles to the provision of optimal end of life care in ICU
Contains fulltext :
172380.pdf (publisher's version ) (Open Access
- …