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Physics

2011

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Articles 1 - 30 of 54

Full-Text Articles in Physics

A Cultured Greigite-Producing Magnetotactic Bacterium In A Novel Group Of Sulfate-Reducing Bacteria, Christopher T. Lefèvre, Nicholas Menguy, Fernanda Abreu, Ulysses Lins, Mihály Pósfai, Tanya Prozorov, David Pignol, Richard B. Frankel, Dennis A. Bazylinski Dec 2011

A Cultured Greigite-Producing Magnetotactic Bacterium In A Novel Group Of Sulfate-Reducing Bacteria, Christopher T. Lefèvre, Nicholas Menguy, Fernanda Abreu, Ulysses Lins, Mihály Pósfai, Tanya Prozorov, David Pignol, Richard B. Frankel, Dennis A. Bazylinski

Physics

Magnetotactic bacteria contain magnetosomes—intracellular, membrane-bounded, magnetic nanocrystals of magnetite (Fe3O4) or greigite (Fe3S4)—that cause the bacteria to swim along geomagnetic field lines. We isolated a greigite-producing magnetotactic bacterium from a brackish spring in Death Valley National Park, California, USA, strain BW-1, that is able to biomineralize greigite and magnetite depending on culture conditions. A phylogenetic comparison of BW-1 and similar uncultured greigite- and/or magnetite-producing magnetotactic bacteria from freshwater to hypersaline habitats shows that these organisms represent a previously unknown group of sulfate-reducing bacteria in the Deltaproteobacteria. Genomic analysis of BW-1 reveals …

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Veritas Observations Of Gamma-Ray Bursts Detected By Swift, V. A. Acciari, E. Aliu, T. Arlen, T. Aune, M. Beilicke, W. Benbow, S. M. Bradbury, J. H. Buckley, V. Bugaev, K. Byrum, A. Cannon, A. Cesarini, J. L. Christiansen, L. Ciupik, E. Collins-Hughes, M. P. Connolly, W. Cui, C. Duke, M. Errando, A. Falcone, J. P. Finley, G. Finnegan, L. Fortson, A. Furniss, N. Galante, D. Gall, S. Godambe, S. Griffin, J. Grube, R. Guenette, G. Gyuk, D. Hanna, J. Holder, G. Hughes, C. M. Hui, T. B. Humensky, D. J. Jackson, P. Kaaret, N. Karlsson, M. Kertzman, D. Kieda, H. Krawczynski, F. Krennrich, M. J. Lang, A. S. Madhavan, G. Maier, S. Mcarthur, A. Mccann, P. Moriarty, M. D. Newbold, R. A. Ong, M. Orr, A. N. Otte, N. Park, J. S. Perkins, M. Pohl, H. Prokoph, J. Quinn, K. Ragan, L. C. Reyes, P. T. Reynolds, E. Roache, H. J. Rose, J. Ruppel, D. B. Saxon, M. Schroedter, G. H. Sembroski, G. D. Şentürk, A. W. Smith, D. Staszak, S. P. Swordy, G. Tešić, M. Theiling, S. Thibadeau, K. Tsurusaki, A. Varlotta, V. V. Vassiliev, S. Vincent, M. Vivier, S. P. Wakely, J. E. Ward, T. C. Weekes, A. Weinstein, T. Weisgarber, D. A. Williams, M. Wood Dec 2011

Veritas Observations Of Gamma-Ray Bursts Detected By Swift, V. A. Acciari, E. Aliu, T. Arlen, T. Aune, M. Beilicke, W. Benbow, S. M. Bradbury, J. H. Buckley, V. Bugaev, K. Byrum, A. Cannon, A. Cesarini, J. L. Christiansen, L. Ciupik, E. Collins-Hughes, M. P. Connolly, W. Cui, C. Duke, M. Errando, A. Falcone, J. P. Finley, G. Finnegan, L. Fortson, A. Furniss, N. Galante, D. Gall, S. Godambe, S. Griffin, J. Grube, R. Guenette, G. Gyuk, D. Hanna, J. Holder, G. Hughes, C. M. Hui, T. B. Humensky, D. J. Jackson, P. Kaaret, N. Karlsson, M. Kertzman, D. Kieda, H. Krawczynski, F. Krennrich, M. J. Lang, A. S. Madhavan, G. Maier, S. Mcarthur, A. Mccann, P. Moriarty, M. D. Newbold, R. A. Ong, M. Orr, A. N. Otte, N. Park, J. S. Perkins, M. Pohl, H. Prokoph, J. Quinn, K. Ragan, L. C. Reyes, P. T. Reynolds, E. Roache, H. J. Rose, J. Ruppel, D. B. Saxon, M. Schroedter, G. H. Sembroski, G. D. Şentürk, A. W. Smith, D. Staszak, S. P. Swordy, G. Tešić, M. Theiling, S. Thibadeau, K. Tsurusaki, A. Varlotta, V. V. Vassiliev, S. Vincent, M. Vivier, S. P. Wakely, J. E. Ward, T. C. Weekes, A. Weinstein, T. Weisgarber, D. A. Williams, M. Wood

Physics

We present the results of 16 Swift-triggered Gamma-ray burst (GRB) follow-up observations taken with the Very Energetic Radiation Imaging Telescope Array System (VERITAS) telescope array from 2007 January to 2009 June. The median energy threshold and response time of these observations were 260 GeV and 320 s, respectively. Observations had an average duration of 90 minutes. Each burst is analyzed independently in two modes: over the whole duration of the observations and again over a shorter timescale determined by the maximum VERITAS sensitivity to a burst with a t−1.5 time profile. This temporal model is characteristic of GRB …

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The Lick Agn Monitoring Project 2011: Reverberation Mapping Of Markarian 50, Aaron J. Barth, Anna Pancoast, Shawn J. Thorman, Vardha N. Bennert, David J. Sand, Weidong Li, Gabriela Canalizo, Alexei V. Filippenko, Elinor L. Gates, Jenny E. Greene, Matthew A. Malkan, Daniel Stern, Tommaso Treu, Jong-Hak Woo, Roberto J. Assef, Hyun-Jin Bae, Brendon J. Brewer, Tabitha Buehler, S. Bradley Cenko, Kelsey I. Clubb, Michael C. Cooper, Aleksandar M. Diamond-Stanic, Kyle D. Hiner, Sebastian F. Hönig, Michael D. Joner, Michael T. Kandrashoff, C. David Laney, Mariana S. Lazarova, A. M. Nierenberg, Dawoo Park, Jeffrey M. Silverman, Donghoon Son, Alessandro Sonnenfeld, Erik J. Tollerud, Jonelle L. Walsh, Richard Walters, Robert L. Da Silva, Michele Fumagalli, Michael D. Gregg, Chelsea E. Harris, Eric Y. Hsiao, Jeffrey Lee, Liliana Lopez, Jacob Rex, Nao Suzuki, Jonathan R. Trump, David Tytler, Gábor Worseck, Hassan M. Yesuf Dec 2011

The Lick Agn Monitoring Project 2011: Reverberation Mapping Of Markarian 50, Aaron J. Barth, Anna Pancoast, Shawn J. Thorman, Vardha N. Bennert, David J. Sand, Weidong Li, Gabriela Canalizo, Alexei V. Filippenko, Elinor L. Gates, Jenny E. Greene, Matthew A. Malkan, Daniel Stern, Tommaso Treu, Jong-Hak Woo, Roberto J. Assef, Hyun-Jin Bae, Brendon J. Brewer, Tabitha Buehler, S. Bradley Cenko, Kelsey I. Clubb, Michael C. Cooper, Aleksandar M. Diamond-Stanic, Kyle D. Hiner, Sebastian F. Hönig, Michael D. Joner, Michael T. Kandrashoff, C. David Laney, Mariana S. Lazarova, A. M. Nierenberg, Dawoo Park, Jeffrey M. Silverman, Donghoon Son, Alessandro Sonnenfeld, Erik J. Tollerud, Jonelle L. Walsh, Richard Walters, Robert L. Da Silva, Michele Fumagalli, Michael D. Gregg, Chelsea E. Harris, Eric Y. Hsiao, Jeffrey Lee, Liliana Lopez, Jacob Rex, Nao Suzuki, Jonathan R. Trump, David Tytler, Gábor Worseck, Hassan M. Yesuf

Physics

The Lick AGN Monitoring Project 2011 observing campaign was carried out over the course of 11 weeks in spring 2011. Here we present the first results from this program, a measurement of the broad-line reverberation lag in the Seyfert 1 galaxy Mrk 50. Combining our data with supplemental observations obtained prior to the start of the main observing campaign, our data set covers a total duration of 4.5 months. During this time, Mrk 50 was highly variable, exhibiting a maximum variability amplitude of a factor of ~4 in the U-band continuum and a factor of ~2 in the Hβ …

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The Relation Between Black Hole Mass And Host Spheroid Stellar Mass Out To Z~2, Vardha N. Bennert, Matthew A. Auger, Tommaso Treu, Jong-Hak Woo, Matthew A. Malkan Dec 2011

The Relation Between Black Hole Mass And Host Spheroid Stellar Mass Out To Z~2, Vardha N. Bennert, Matthew A. Auger, Tommaso Treu, Jong-Hak Woo, Matthew A. Malkan

Physics

We combine Hubble Space Telescope images from the Great Observatories Origins Deep Survey with archival Very Large Telescope and Keck spectra of a sample of 11 X-ray-selected broad-line active galactic nuclei in the redshift range 1 < z < 2 to study the black-hole-mass-stellar-mass relation out to a look-back time of 10 Gyr. Stellar masses of the spheroidal component (M sph, ) are derived from multi-filter surface photometry. Black hole masses (M BH) are estimated from the width of the broad Mg II emission line and the 3000 Å nuclear luminosity. Comparing with a uniformly measured local sample and taking into account selection effects, we find evolution in the form M BH/M sph, (1 + z)1.96 …

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Morphological Features Of Elongated-Anisotropic Magnetosome Crystals In Magnetotactic Bacteria Of The Nitrospirae Phylum And The Deltaproteobacteria Class, Christopher T. Lefèvre, Mihály Pósfai, Fernanda Abreu, Ulysses Lins, Richard B. Frankel, Dennis A. Bazlinski Dec 2011

Morphological Features Of Elongated-Anisotropic Magnetosome Crystals In Magnetotactic Bacteria Of The Nitrospirae Phylum And The Deltaproteobacteria Class, Christopher T. Lefèvre, Mihály Pósfai, Fernanda Abreu, Ulysses Lins, Richard B. Frankel, Dennis A. Bazlinski

Physics

High resolution transmission electron microscopy was used to study the crystallographic habits of the elongated magnetite crystals, variously described as bullet-, tooth- or arrowhead-shaped, in two recently described, uncultured, magnetotactic bacteria belonging to the Nitrospirae phylum designated Candidatus Magnetoovum mohavensis strain LO-1, and Candidatus Thermomagnetovibrio paiutensis strain HSMV-1; and a cultured sulfate-reducing magnetotactic bacterium of the Deltaproteobacteria class of the Proteobacteria phylum designated strain AV-1. The elongation axes of the magnetosomes do not coincide with the easy magnetization axis (which is [111]) but they are parallel to [100] in LO-1 and AV-1 and parallel to [110] in HSMV-1. In all …

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Achieving Laser Wavelength Stability For Use In Neutral Atom Quantum Computing, Jennifer H. Rushing Dec 2011

Achieving Laser Wavelength Stability For Use In Neutral Atom Quantum Computing, Jennifer H. Rushing

Physics

Quantum computing may still be decades away from realization but the pieces necessary for the construction of the first quantum chip are beginning to come together. One piece still eluding researchers is the ability to address individual atoms within a scalable quantum chip structure. The resolution to this issue may be found in any one of several promising implementations, including the use of neutral atoms trapped in 2D optical lattices. One method of constructing such lattices, which has been shown to be computationally viable, employs the diffraction pattern just behind a circular aperture. Laser wavelength stability plays a crucial role …

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Hubble Space Telescope Imaging Of Post-Starburst Quasars, S. L. Cales, M. S. Brotherton, Zhaohui Shang, Vardha N. Bennert, G. Canalizo, R. Stoll, R. Ganguly, D. Vanden Berk, C. Paul, A. Diamond-Stanic Nov 2011

Hubble Space Telescope Imaging Of Post-Starburst Quasars, S. L. Cales, M. S. Brotherton, Zhaohui Shang, Vardha N. Bennert, G. Canalizo, R. Stoll, R. Ganguly, D. Vanden Berk, C. Paul, A. Diamond-Stanic

Physics

We present images of 29 post-starburst quasars (PSQs) from a Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) Wide Field Channel Snapshot program. These broadlined active galactic nuclei (AGNs) possess the spectral signatures of massive (M burst ~ 1010 M ☉), moderate-aged stellar populations (hundreds of Myr). Thus, their composite nature provides insight into the AGN-starburst connection. We measure quasar-to-host galaxy light contributions via semi-automated two-dimensional light profile fits of point-spread-function-subtracted images. We examine the host morphologies and model the separate bulge and disk components. The HST/ACS-F606W images reveal an equal number …

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Toward High-Performance Nanostructured Thermoelectric Materials: The Progress Of Bottom-Up Solution Chemistry Approaches, Yixin Zhao, Jeffrey S. Dyck, Clemens Burda Oct 2011

Toward High-Performance Nanostructured Thermoelectric Materials: The Progress Of Bottom-Up Solution Chemistry Approaches, Yixin Zhao, Jeffrey S. Dyck, Clemens Burda

Physics

Significant research effort has recently gone into the synthesis of thermoelectric nanomaterials through different chemical approaches since nanomaterials chemistry became a promising strategy for improving thermoelectric performance. Different thermoelectric nanocrystals, especially PbTe, Bi2Te3 and CoSb3, with various compositions and morphologies have been successfully prepared by solvo/hydrothermal, electrochemical, and ligand-based synthesis methods. Such nanoscale materials show not only substantial reduction in thermal conductivity due to increased phonon scattering at nanoscale grain boundaries and lower densities of phonon states but possibly also an enhancement in thermopower due to electronic quantum size effects. More recently, the notoriously low …

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Similarity Scaling Of Turbulence Spectra And Cospectra In A Shallow Tidal Flow, Ryan K. Walter, Nicholas J. Nidzieko, Stephen G. Monismith Oct 2011

Similarity Scaling Of Turbulence Spectra And Cospectra In A Shallow Tidal Flow, Ryan K. Walter, Nicholas J. Nidzieko, Stephen G. Monismith

Physics

Measured turbulence power spectra, cospectra, and ogive curves from a shallow tidal flow were scaled using Monin‐Obukhov similarity theory to test the applicability to a generic tidal flow of universal curves found from a uniform, neutrally stable atmospheric boundary layer (ABL). While curves from individual 10 min data bursts deviate significantly from similarity theory, averages over large numbers of sufficiently energetic bursts follow the general shape. However, there are several differences: (1) Variance in the measured curves was shifted toward higher frequencies, (2) at low frequencies, velocity spectra were significantly more energetic than theory while cospectra were weaker, and (3) …

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Detection Of Pulsed Gamma Rays Above 100 Gev From The Crab Pulsar, E. Aliu, T. Arlen, T. Aune, M. Beilicke, W. Benbow, A. Bouvier, S. M. Bradbury, J. H. Buckley, V. Bugaev, K. Byrum, A. Cannon, A. Cesarini, J. L. Christiansen, L. Ciupik, E. Collins-Hughes, M. P. Connolly, W. Cui, R. Dickherber, C. Duke, M. Errando, A. Falcone, J. P. Finley, G. Finnegan, L. Fortson, A. Furniss, N. Galante, D. Gall, K. Gibbs, G. H. Gillanders, S. Godambe, S. Griffin, J. Grube, R. Guenette, G. Gyuk, D. Hanna, J. Holder, H. Huan, G. Hughes, C. M. Hui, T. B. Humensky, A. Imran, P. Kaaret, N. Karlsson, M. Kertzman, D. Kieda, H. Krawczynski, F. Krennrich, M. J. Lang, M. Lyutikov, A. S. Madhavan, G. Maier, P. Majumdar, S. Mcarthur, A. Mccann, M. Mccutcheon, P. Moriarty, R. Mukherjee, P. Nuñez, R. A. Ong, M. Orr, A. N. Otte, N. Park, J. S. Perkins, P. T. Reynolds, E. Roache, J. Rose, J. Ruppel, D. B. Saxon, M. Schroedter, G. H. Sembroski, G. D. Şentürk, A. W. Smith, D. Staszak, G. Tešić, M. Theiling, S. Thibadeau, K. Tsurusaki, J. Tyler, A. Varlotta, V. V. Vassiliev, S. Vincent, M. Vivier, S. P. Wakely, J. E. Ward, T. C. Weekes, A. Weinstein, T. Weisgarber, D. A. Williams, B. Zitzer Oct 2011

Detection Of Pulsed Gamma Rays Above 100 Gev From The Crab Pulsar, E. Aliu, T. Arlen, T. Aune, M. Beilicke, W. Benbow, A. Bouvier, S. M. Bradbury, J. H. Buckley, V. Bugaev, K. Byrum, A. Cannon, A. Cesarini, J. L. Christiansen, L. Ciupik, E. Collins-Hughes, M. P. Connolly, W. Cui, R. Dickherber, C. Duke, M. Errando, A. Falcone, J. P. Finley, G. Finnegan, L. Fortson, A. Furniss, N. Galante, D. Gall, K. Gibbs, G. H. Gillanders, S. Godambe, S. Griffin, J. Grube, R. Guenette, G. Gyuk, D. Hanna, J. Holder, H. Huan, G. Hughes, C. M. Hui, T. B. Humensky, A. Imran, P. Kaaret, N. Karlsson, M. Kertzman, D. Kieda, H. Krawczynski, F. Krennrich, M. J. Lang, M. Lyutikov, A. S. Madhavan, G. Maier, P. Majumdar, S. Mcarthur, A. Mccann, M. Mccutcheon, P. Moriarty, R. Mukherjee, P. Nuñez, R. A. Ong, M. Orr, A. N. Otte, N. Park, J. S. Perkins, P. T. Reynolds, E. Roache, J. Rose, J. Ruppel, D. B. Saxon, M. Schroedter, G. H. Sembroski, G. D. Şentürk, A. W. Smith, D. Staszak, G. Tešić, M. Theiling, S. Thibadeau, K. Tsurusaki, J. Tyler, A. Varlotta, V. V. Vassiliev, S. Vincent, M. Vivier, S. P. Wakely, J. E. Ward, T. C. Weekes, A. Weinstein, T. Weisgarber, D. A. Williams, B. Zitzer

Physics

We report the detection of pulsed gamma rays from the Crab pulsar at energies above 100 giga–electron volts (GeV) with the Very Energetic Radiation Imaging Telescope Array System (VERITAS) array of atmospheric Cherenkov telescopes. The detection cannot be explained on the basis of current pulsar models. The photon spectrum of pulsed emission between 100 mega–electron volts and 400 GeV is described by a broken power law that is statistically preferred over a power law with an exponential cutoff. It is unlikely that the observation can be explained by invoking curvature radiation as the origin of the observed gamma rays above …

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Paleomagnetism And Investigation Of 40 Ma Lavas, Liverpool Range, New South Whales, Australia, Nathan M. Padilla Oct 2011

Paleomagnetism And Investigation Of 40 Ma Lavas, Liverpool Range, New South Whales, Australia, Nathan M. Padilla

Physics

The main focus of this project is the continued study of a reversal of the earth’s magnetic field recorded from lavas in the Liverpool Range of New South Whales, Australia. This reverse-to-normal transition, recently dated at ~40 Ma, was first reported in Nature in 1986. [2] In March 2011 some 200+ cores were drilled from several sections about the volcanic range—Jemmy’s Creek, Bald Hill, Rock Creek, Yarraman, and Coolah Tops Road. Here we focus on paleomagnetic findings from samples drilled from the most extensive section, that being along the trail near Jemmy’s Creek. Results from alternating field demagnetization show the …

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Radio Frequency Noise Effects On The Cern Large Hadron Collider Beam Diffusion, Themis Mastoridis, P. Baudrenghien, A. Butterworth, J. Molendijk, C. Rivetta, J.D. Fox Sep 2011

Radio Frequency Noise Effects On The Cern Large Hadron Collider Beam Diffusion, Themis Mastoridis, P. Baudrenghien, A. Butterworth, J. Molendijk, C. Rivetta, J.D. Fox

Physics

No abstract provided.

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Loss Of Landau Damping In The Lhc, E. Shaposhnikova, T. Argyropoulos, T. Bohl, C. Bhat, P. Baudrenghien, A. Butterworth, T. Mastoridis, J. Esteban Muller, G. Papotti, J. Tuckmantel, W. Venturini Delsolaro, U. Wehrle Sep 2011

Loss Of Landau Damping In The Lhc, E. Shaposhnikova, T. Argyropoulos, T. Bohl, C. Bhat, P. Baudrenghien, A. Butterworth, T. Mastoridis, J. Esteban Muller, G. Papotti, J. Tuckmantel, W. Venturini Delsolaro, U. Wehrle

Physics

Loss of Landau damping leading to a single bunch longitudinal instability has been observed in the LHC during the ramp and on the 3.5 TeV flat top for small injected longitudinal emittances. The first measurements are in reasonable agreement with the threshold calculated for the expected longitudinal reactive impedance budget of the LHC as well as with the threshold dependence on beam energy. The cure is a controlled longitudinal emittance blow-up during the ramp which for a constant threshold through the cycle should provide an emittance proportional to the square root of energy.

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Longitudinal Emittance Blow-Up In The Lhc, P. Baudrenghien, A. Butterworth, M. Jaussi, T. Mastoridis, G. Papotti, E. Shaposhnikova, J. Tuckmantel Sep 2011

Longitudinal Emittance Blow-Up In The Lhc, P. Baudrenghien, A. Butterworth, M. Jaussi, T. Mastoridis, G. Papotti, E. Shaposhnikova, J. Tuckmantel

Physics

The LHC relies on Landau damping for longitudinal stability. To avoid decreasing the stability margin at high energy, the longitudinal emittance must be continuously increased during the acceleration ramp. Longitudinal blow-up provides the required emittance growth. The method was implemented through the summer of 2010. We inject band-limited RF phase-noise in the main accelerating cavities during the whole ramp of about 11 minutes. Synchrotron frequencies change along the energy ramp, but the digitally created noise tracks the frequency change. The position of the noise-band, relative to the nominal synchrotron frequency, and the bandwidth of the spectrum are set by pre-defined …

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Projection Of Diffracted Optical Atom Traps, Jeremy Kruger Sep 2011

Projection Of Diffracted Optical Atom Traps, Jeremy Kruger

Physics

Theoretical calculations were performed for the projection of a diffraction pattern created by a pinhole through a single-lens system using vector diffraction theory and a combination of programs (MathCAD, Igor, etc.). The projected diffraction patterns were then experimentally created, recorded, and analyzed. This work is part of a larger collaboration with Dr. Kat Gillen, to trap and manipulate atoms in a Magneto Optical Trap (MOT) and to make further steps in the direction of Quantum Computing using trapped neutral atoms.

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A Sporadic Low‐Velocity Layer Atop The Western U.S. Mantle Transition Zone And Short‐Wavelength Variations In Transition Zone Discontinuities, B. Schmandt, K.G. Dueker, S.M. Hansen, John J. Jasbinsek, Z. Zhang Aug 2011

A Sporadic Low‐Velocity Layer Atop The Western U.S. Mantle Transition Zone And Short‐Wavelength Variations In Transition Zone Discontinuities, B. Schmandt, K.G. Dueker, S.M. Hansen, John J. Jasbinsek, Z. Zhang

Physics

Teleseismic receiver function analysis of data from six dense arrays in the western U.S. is used to investigate mantle transition zone (MTZ) discontinuities and the prevalence of a low‐velocity layer atop the 410 km discontinuity (410‐LVL). Negative polarity Ps arrivals indicative of a low‐velocity layer with a top 25–60 km above the 410 are identified in 8–11 out of 18 stacks of receiver functions from highly sampled back azimuth corridors. The 410‐LVL is interpreted as partial melt resulting from upwelling of hydrated mantle across a water solubility contrast at the 410. The 669 km mean depth of the 660 km …

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Isolation Of Obligately Alkaliphilic Magnetotactic Bacteria From Extremely Alkaline Environments, Christopher T. Lefevre, Richard B. Frankel, Mihály Pósfai, Tanya Prozorov, Dennis A. Bazylinski Aug 2011

Isolation Of Obligately Alkaliphilic Magnetotactic Bacteria From Extremely Alkaline Environments, Christopher T. Lefevre, Richard B. Frankel, Mihály Pósfai, Tanya Prozorov, Dennis A. Bazylinski

Physics

Large numbers of magnetotactic bacteria were discovered in mud and water samples collected from a number of highly alkaline aquatic environments with pH values of ~ 9.5. These bacteria were helical in morphology and biomineralized chains of bullet-shaped crystals of magnetite and were present in all the highly alkaline sites sampled. Three strains from different sites were isolated and cultured and grew optimally at pH 9.0–9.5 but not at 8.0 and below, demonstrating that these organisms truly require highly alkaline conditions and are not simply surviving/growing in neutral pH micro-niches in their natural habitats. All strains grew anaerobically through the …

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Biaxial Smectic-A∗ Phase And Its Possible Misidentification As A Smectic-CΑ* Phase, Karl Saunders Jul 2011

Biaxial Smectic-A∗ Phase And Its Possible Misidentification As A Smectic-CΑ* Phase, Karl Saunders

Physics

The biaxial smectic-A* (Sm-AB*) phase, appearing in the phase sequence Sm-A*–Sm-AB*–Sm-C*, is analyzed using Landau theory. It is found to possess a helical superstructure with a pitch that is significantly shorter than the pitch of the Sm-C* helical superstructure. The Sm-AB*–Sm-C* transition can be either first or second order, and correspondingly there will be either a jump or continuous variation in the pitch. The behaviors of the birefringence and electroclinic effect are analyzed and found to be similar to those of a Sm-Cα …

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Generic Transient Memory Formation In Disordered Systems With Noise, Nathan C. Keim, Sidney R. Nagel Jul 2011

Generic Transient Memory Formation In Disordered Systems With Noise, Nathan C. Keim, Sidney R. Nagel

Physics

Out-of-equilibrium disordered systems may form memories of external driving in a remarkable fashion. The system ‘‘remembers’’ multiple values from a series of training inputs yet ‘‘forgets’’ nearly all of them at long times despite the inputs being continually repeated. Here, learning and forgetting are inseparable aspects of a single process. The memory loss may be prevented by the addition of noise. We identify a class of systems with this behavior, giving as an example a model of non-Brownian suspensions under cyclic shear.

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Reducing Zero-Point Systematics In Dark Energy Supernova Experiments, L. Faccioli, A. G. Kim, R. Miquel, G. Bernstein, A. Bonissent, M. Brown, W. Carithers, Jodi L. Christiansen, N. Connolly, S. Deustua, D. Gerdes, L. Gladney, G. Kushner, E. V. Linder, S. Mckee, A. Mostek, H. Shukla, A. Stebbins, C. Stoughton, D. Tucker Jul 2011

Reducing Zero-Point Systematics In Dark Energy Supernova Experiments, L. Faccioli, A. G. Kim, R. Miquel, G. Bernstein, A. Bonissent, M. Brown, W. Carithers, Jodi L. Christiansen, N. Connolly, S. Deustua, D. Gerdes, L. Gladney, G. Kushner, E. V. Linder, S. Mckee, A. Mostek, H. Shukla, A. Stebbins, C. Stoughton, D. Tucker

Physics

We study the effect of filter zero-point uncertainties on future supernova dark energy missions. Fitting for calibration parameters using simultaneous analysis of all Type Ia supernova standard candles achieves a significant improvement over more traditional fit methods. This conclusion is robust under diverse experimental configurations (number of observed supernovae, maximum survey redshift, inclusion of additional systematics). This approach to supernova fitting considerably eases otherwise stringent mission calibration requirements. As an example we simulate a space-based mission based on the proposed JDEM satellite; however the method and conclusions are general and valid for any future supernova dark energy mission, ground or …

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Photoexcitation And Photoionization From The 2p53p[5/2]2,3 Levels In Neon, M. A. Baig, I. A. Bokhari, M. Rafiq, M. A. Kalyar, T. Hussian, Raheel Ali, Naveed K. Piracha Jul 2011

Photoexcitation And Photoionization From The 2p53p[5/2]2,3 Levels In Neon, M. A. Baig, I. A. Bokhari, M. Rafiq, M. A. Kalyar, T. Hussian, Raheel Ali, Naveed K. Piracha

Physics

We present measurements of the excitation spectra from the 2p53p [5/2]3,2 levels in neon using two-step laser excitation and ionization in conjunction with an optogalvanic detection in dc and rf discharge cells. The 2p53p [5/2]3,2 intermediate levels have been approached via the collisionally populated 2p53s [3/2]2 metastable level. The Rydberg series 2p5(2P3/2)nd [7/2]4 (12 ⩽ n ⩽ 44), 2p5(2P3/2)ns [3/2]2 (13 ⩽ n ⩽ 35) and the parity forbidden transitions 2p5(2P3/2)np …

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The Mass Of The Black Hole In Arp 151 From Bayesian Modeling Of Reverberation Mapping Data, Brendon J. Brewer, Tommaso Treu, Anna Pancoast, Aaron J. Barth, Vardha N. Bennert, Misty C. Bentz, Alexei V. Filippenko, Jenney E. Greene, Matthew A. Malkan, Jong-Hak Woo Jun 2011

The Mass Of The Black Hole In Arp 151 From Bayesian Modeling Of Reverberation Mapping Data, Brendon J. Brewer, Tommaso Treu, Anna Pancoast, Aaron J. Barth, Vardha N. Bennert, Misty C. Bentz, Alexei V. Filippenko, Jenney E. Greene, Matthew A. Malkan, Jong-Hak Woo

Physics

Supermassive black holes are believed to be ubiquitous at the centers of galaxies. Measuring their masses is extremely challenging yet essential for understanding their role in the formation and evolution of cosmic structure. We present a direct measurement of the mass of a black hole in an active galactic nucleus (Arp 151) based on the motion of the gas responsible for the broad emission lines. By analyzing and modeling spectroscopic and photometric time series, we find that the gas is well described by a disk or torus with an average radius of 3.99 ± 1.25 light days and an opening …

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Megamaser Detection And Nuclear Obscuration In Seyfert Galaxies, M. Ramolla, M. Hass, V. N. Bennert, R. Chini Jun 2011

Megamaser Detection And Nuclear Obscuration In Seyfert Galaxies, M. Ramolla, M. Hass, V. N. Bennert, R. Chini

Physics

We revisit the relation between H2O maser detection rate and nuclear obscuration for a sample of 114 Seyfert galaxies drawn from the CfA, 12 μm, and IRAS F25/F60 catalogs. These sources have mid-infrared spectra from the Spitzer Space Telescope and we search for accompanying X-ray and [O III] 5007 Å fluxes from the literature. We use the strength of the [O IV] 25.9 μm emission line as a tracer of the intrinsic AGN strength. After the normalization by [O IV], the observed X-ray flux provides information about X-ray absorption. The distribution of X-ray/[O IV] flux ratios …

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130Te Neutrinoless Double-Beta Decay With Cuoricino, E. Andreotti, C. Arnaboldi, F.T. Avignone Iii, M. Balata, I. Bandac, M. Barucci, J.W. Beeman, F. Bellini, C. Brofferio, A. Bryant, C. Bucci, L. Canonica, S. Capelli, L. Carbone, M. Carrettoni, M. Clemenza, O. Cremonesi, R.J. Creswick, D. Di Domizio, M.J. Dolinski, L. Ejzak, R. Faccini, H. A. Farach, E. Ferri, E. Fiorini, L. Foggetta, A. Giachero, L. Gironi, A. Giuliani, P. Gorla, E. Guardincerri, Thomas D. Gutierrez, E. E. Haller, K. Kazkaz, S. Kraft, L. Kogler, C. Maiano, R. H. Maruyama, C. Martinez, M. Martinez, S. Newman, S. Nisi, C. Nones, E. B. Norman, A. Nucciotti, F. Orio, M. Pallavicini, V. Palmieri, L. Pattavina, M. Pavan, M. Pedretti, G. Pessina, S. Pirro, E. Previtali, L. Risegari, C. Rosenfeld, C. Rusconi, C. Salvioni, S. Sangiorgio, D. Schaeffer, N. D. Scielzo, M. Sisti, A. R. Smith, C. Tomei, G. Ventura, M. Vignati Jun 2011

130Te Neutrinoless Double-Beta Decay With Cuoricino, E. Andreotti, C. Arnaboldi, F.T. Avignone Iii, M. Balata, I. Bandac, M. Barucci, J.W. Beeman, F. Bellini, C. Brofferio, A. Bryant, C. Bucci, L. Canonica, S. Capelli, L. Carbone, M. Carrettoni, M. Clemenza, O. Cremonesi, R.J. Creswick, D. Di Domizio, M.J. Dolinski, L. Ejzak, R. Faccini, H. A. Farach, E. Ferri, E. Fiorini, L. Foggetta, A. Giachero, L. Gironi, A. Giuliani, P. Gorla, E. Guardincerri, Thomas D. Gutierrez, E. E. Haller, K. Kazkaz, S. Kraft, L. Kogler, C. Maiano, R. H. Maruyama, C. Martinez, M. Martinez, S. Newman, S. Nisi, C. Nones, E. B. Norman, A. Nucciotti, F. Orio, M. Pallavicini, V. Palmieri, L. Pattavina, M. Pavan, M. Pedretti, G. Pessina, S. Pirro, E. Previtali, L. Risegari, C. Rosenfeld, C. Rusconi, C. Salvioni, S. Sangiorgio, D. Schaeffer, N. D. Scielzo, M. Sisti, A. R. Smith, C. Tomei, G. Ventura, M. Vignati

Physics

We report the final result of the CUORICINO experiment. Operated between 2003 and 2008, with a total exposure of 19.75 kg · y of 130Te, CUORICINO was able to set a lower bound on the 130Te 0vββ half-life of 2.8 x 1024 years at 90% C.L. The limit here reported includes the effects of systematic uncertainties that are examined in detail in the paper. The corresponding upper bound on the neutrino Majorana mass is in the range 300–710 meV, depending on the adopted nuclear matrix element evaluation.

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Quantum Mechanics, Quantum Computation, And The Density Operator In Sympy, Addison Cugini Jun 2011

Quantum Mechanics, Quantum Computation, And The Density Operator In Sympy, Addison Cugini

Physics

Because aspects of quantum mechanics are both difficult to understand and difficult algebraically, there is a need for software which symbolically simulates quantum mechanical phenomena. To accomplish this goal, code has been added to an open-source computer algebra system, called SymPy, which models the abstraction of Dirac notation and the density operator. Additionally, a quantum computer simulation has been built using this abstraction. This paper shall discuss the code that has been added as well as any relevant physics important to understanding the code. In particular, we shall focus on the density operator of statistical quantum mechanics using SymPy's density …

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Laser-Induced Breakdown Spectroscopy, Connor Drake Jun 2011

Laser-Induced Breakdown Spectroscopy, Connor Drake

Physics

The goal of this work is to use a Neodymium-Doped Yttrium Aluminum Garnet (Nd:YAG) Laser, spectrometer, and computer to create a Laser Induced Breakdown Spectroscopy (LIBS) system. LIBS utilizes a focused, high-powered, pulsed laser whose peak electric field ionizes materials at the beam focal point, creating localized plasma. The plasma state includes broken molecular bonds, atom/electron-ionization, and excited electrons, which on the macroscopic level is a loud “snap” and a bright spark. In this project, a fiber optic cable is used to capture light emitted from the spark, and direct it into a spectrometer which tallies the number of photons …

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Symbolic Quantum Circuit Simplification In Sympy, Matthew Curry Jun 2011

Symbolic Quantum Circuit Simplification In Sympy, Matthew Curry

Physics

In the field of quantum information science, one can design a series of quantum logic operations known as a circuit. Circuits are the basis for quantum computations in quantum computing. As circuits will most likely be designed from a logical standpoint, there could exist mathematical redundancies which will lead to a larger circuit than necessary. These redundancies are computationally expensive, and there is a need for them to be found and eliminated to simplify the circuit. We present our research on finding the rules for simplifying circuits and its implementation in SymPy.

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Ferrofluids, James Patt Jun 2011

Ferrofluids, James Patt

Physics

Ferrofluids are truly fascinating. Technologically savvy artists have been able to capture the human imagination with little but a judicious application of a magnetic field. The substance seems to defy gravity, flowing and shaping itself seemingly like magic (see Figure 1). The true magic, however, is the vast range of properties that this intrinsically simple substance can exhibit. It can vary its viscosity given the strength of the magnetic field. It can draw heat away from an over worked mechanical component. It can even split a beam of light in two. It’s hard to imagine what kind of strange and …

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Projected Pinhole Diffraction, David Moore Jun 2011

Projected Pinhole Diffraction, David Moore

Physics

The goal of this experiment was to observe the effects of passing light through a pinhole, more specifically, to observe the interference and diffraction that occurs due to the pinhole and to successfully achieve CCD camera recording of a projected diffraction pattern from a pinhole. This experiment involved the diffraction of a laser incident upon a 100-mm diameter circular aperture. The diffraction pattern is then projected using a 100-mm focal length plano-convex lens. The lens allows for the pattern to be magnified and stretched a few focal lengths past the lens where it can be then viewed using a CCD …

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Analysis Of The 2008 Flare Of Markarian 421 Flare With Veritas, Casey Allard Jun 2011

Analysis Of The 2008 Flare Of Markarian 421 Flare With Veritas, Casey Allard

Physics

A theoretical light curve model is fit to an observed short term flare of Markarian (Mrk) 421 in the very high energy spectrum. The flare is characterized by its measured light curve from the Very Energetic Radiation Imaging telescope Array System (VERITAS). The flare we analyzed occurred in May 2008. We successfully fit a theoretical model to the Mrk 421 data light curve. The data appears to agree with the Wagner [1] and Salvati [2] models. These models appear to fit both broad and sharp flaring regions found in the measured light curve. Furthermore the Wagner model is used to …

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