Physical Sciences and Mathematics Commons^™

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 …

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 …

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 …

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 …}

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 …

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 …

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) …

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 …

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.

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.

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 …

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 …

The Role Of Llnl's Fast Calibration Facility In Diagnosing Nif Fusion Plasmas, Joshua G. Thompson, Carey Scott, Greg V. Brown

STAR Program Research Presentations

The Fusion and Astrophysics (FAST) Calibration and Diagnostic Facility uses the original Electron Beam Ion Trap (EBIT-I) to profile x-ray filters that are used in the Dante Soft X-Ray Diagnostic at the National Ignition Facility (NIF). FAST has an advantage over any other facility not only for its high accuracy, but also for its proximity to NIF in the Lawrence Livermore National Laboratory (LLNL). This makes for highly accurate and near-instantaneous filter calibration turnover.

EBIT-I was first constructed to create, trap, and observe static highly charged ions (HCIs) and conduct experimental astrophysics (creating an x-ray spectroscopy catalogue of ions). To …

Laboratory Astrophysics: Using Ebit Measurements To Interpret High Resolution Spectra From Celestial Sources, Carey Scott, Joshua Thompson, N. Hell, Greg V. Brown

STAR Program Research Presentations

Astrophysicists use radiation to investigate the physics controlling a variety of celestial sources, including stellar atmospheres, black holes, and binary systems. By measuring the spectrum of the emitted radiation, astrophysicists can determine a source’s temperature and composition. Accurate atomic data are needed for reliably interpreting these spectra. Here we present an overview of how LLNL’s EBIT facility is used to put the atomic data on sound footing for use by the high energy astrophysics community.

Assessing Laser Lifetime Test Performance, Joe Weichman, Hamid Hemmati, Malcolm Wright

STAR Program Research Presentations

Assessing expected component lifetime is necessary in developing instruments for future space-flight projects to ensure long term operation in the challenging environment. Although semiconductor diode lasers have widespread use in terrestrial applications, their use in space is still an emerging technology that requires on-going testing to demonstrate their capability. The project called for re-establishing the test setup for assessing lifetime performance of 20 continuously running 200mW 830 nm diode lasers. These lasers underwent previous testing based on parameters for NuSTAR’s laser metrology system, and met the six month lifetime project requirements under nominal operating conditions. Laser testing is currently underway …

Beam Halo Measurements At The Spear3 Synchrotron, Jonathan B. Kamp, Jeff Corbett

STAR Program Research Presentations

It is known that in an intense beam, particles will start to spread from the core of the beam. This spreading of particles outside the core beam is known as a halo. The affects of unwanted particles spreading from a core beam can have detrimental effects to nearby machinery and personal. The issue with understanding beam halo lies with its low intensity compared to the core beam. In order to analyze the halo, we will use a digital micro mirror array device (DMA) to block out the core of a visible beam coming from the SPEAR3 synchrotron and image the …

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 …

Exploring Methods For Earthquake Prediction: The Effects Of Water On The Flow Of Stress-Activated Electric Currents In Igneous Rocks, Aaron M. Jahoda, Friedemann T. Freund

STAR Program Research Presentations

Much of the devastation and damage of earthquakes can be attributed to the fact that they occur suddenly and without much warning, which limits the ability of people to evacuate and/or properly prepare. One method, however, that might be used to predict seismic events is the generation of electric currents in rocks when stresses are applied. It is observed in this research that the application of direct force onto samples of igneous rock causes the rocks to generate a measurable current, which is attributed to positive-hole charges moving within the oxygen sub-lattice. Because large and changing forces are acted upon …

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

Physics

The biaxial smectic-A^* (Sm-A_B^*) phase, appearing in the phase sequence Sm-A^*–Sm-A_B^*–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-A_B^*–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-C_{α …}

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.

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 …

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 …

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 …

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.

Broad-Line Reverberation In The Kepler-Field Seyfert Galaxy Zw 220-015, Aaron J. Barth, My L. Nguyen, Matthew A. Malkan, Alexei V. Filippenko, Weidong Li, Varoujan Gorjian, Michael D. Joner, Vardha N. Bennert, Janos Botyanski, S. Bradley Cenko, Michael Childress, Jieun Choi, Julia M. Comerford, Antonino Cucciara, Robert Da Silva, Gaspard Duchêne, Michele Fumagalli, Mohan Ganeshalingam, Elinor L. Gates, Brian F. Gerke, Christopher V. Griffith, Chelsea Harris, Eric G. Hintz, Eric Hsiao, Michael T. Kandrashoff, William C. Keel, David Kirkman, Io K.W. Kleiser, C. David Laney, Jeffrey Lee, Liliana Lopez, Thomas B. Lowe, J. Ward Moody, Alexzandir Morton, A. M. Nierenberg, Peter Nugent, Anna Pancoast, Jacob Rex, R. Michael Rich, Jeffrey M. Silverman, Graeme H. Smith, Alessandro Sonnenfeld, Nao Suzuki, David Tytler, Jonelle L. Walsh, Jong-Hak Woo, Yizhe Yang, Carl Zeisse

Physics

The Seyfert 1 galaxy Zw 229-015 is among the brightest active galaxies being monitored by the Kepler mission. In order to determine the black hole mass in Zw 229-015 from Hβ reverberation mapping, we have carried out nightly observations with the Kast Spectrograph at the Lick 3 m telescope during the dark runs from 2010 June through December, obtaining 54 spectroscopic observations in total. We have also obtained nightly V-band imaging with the Katzman Automatic Imaging Telescope at Lick Observatory and with the 0.9 m telescope at the Brigham Young University West Mountain Observatory over the same period. We …

The Implications Of A Robust Curriculum In Introductory Mechanics, Chance Hoellwarth, Matthew J. Moelter

Physics

We have developed a curriculum for introductory mechanics that emphasizes interactive engagement and conceptual understanding using the studio format. As previously reported, we have shown in three different quarters that the curriculum much improved the students’ conceptual understanding compared to the traditional course without significantly affecting the scores on a traditional final exam. Here we report the results for the entire three-year period during which the course was taught, 34 sections of the course were taught with 11 different instructors to over 1200 students. In each term, these sections had common exams, syllabus, and schedule. Student experiences were very similar …

Perturbed Breakup Of Gas Bubbles In Water: Memory, Gas Flow, And Coalescence, Nathan C. Keim

Physics

The pinch-off of an air bubble from an underwater nozzle ends in a singularity with a remarkable sensitivity to a variety of perturbations. I report on experiments that break both the axial (i.e., vertical) and azimuthal symmetry of the singularity formation. The density of the inner gas influences the axial asymmetry of the neck near pinch-off. For denser gases, flow through the neck late in collapse changes the pinch-off dynamics. Gas density is also implicated in the formation of satellite bubbles. The azimuthal shape oscillations described by Schmidt et al. can be initiated by anisotropic boundary conditions in the liquid …

Search For Cosmic Strings In The Cosmos Survey, Jodi L. Christiansen, E. Albin, T. Fletcher, J. Goldman, I. P.W. Teng, M. Foley, G. F. Smoot

Physics

We search the COSMOS survey for pairs of galaxies consistent with the gravitational lensing signature of a cosmic string. The COSMOS survey imaged 1.64 square degrees using the Advanced Camera for Surveys (ACS) aboard the Hubble Space Telescope (HST). Our technique includes estimates of the efficiency for finding the lensed galaxy pair. We find no evidence for cosmic strings with a mass per unit length of Gμ/c² < 3.0 × 10⁻⁷ out to redshifts greater than 0.6 and set 95% upper limits. This corresponds to a global 95% upper limit of Ω_strings < 0.0028.

Thermal Rise Time In Nuclear Reactors After Loss Of Coolant Or Loss Of Power Accidents, David Hafemeister

Physics

No abstract provided.

Investigation Of Factors Affecting The Accumulation Of Vinyl Chloride In Polyvinyl Chloride Piping Used In Drinking Water Distribution Systems, Ryan Walter, Po-Hsun Lin, Marc Edwards, Ruth E. Richardson

Physics

Plastic piping made of polyvinyl chloride (PVC), and chlorinated PVC (CPVC), is being increasingly used for drinking water distribution lines. Given the formulation of the material from vinyl chloride (VC), there has been concern that the VC (a confirmed human carcinogen) can leach from the plastic piping into drinking water. PVC/CPVC pipe reactors in the laboratory and tap samples collected from consumers homes (n = 15) revealed vinyl chloride accumulation in the tens of ng/L range after a few days and hundreds of ng/L after two years. While these levels did not exceed the EPA’s maximum contaminant level (MCL) …