Physical Sciences and Mathematics Commons^™

The Arctic Research Of The Composition Of The Troposphere From Aircraft And Satellites (Arctas) Mission: Design, Execution, And First Results, D J. Jacob, J H. Crawford, H Maring, A D. Clarke, J E. Dibb, L K. Emmons, R A. Ferrare, C A. Hostetler, P B. Russell, H B. Singh, A M. Thompson, G E. Shaw, E Mccauley, J R. Pederson, J A. Fisher

Jenny A Fisher

The NASA Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) mission was conducted in two 3-week deployments based in Alaska (April 2008) and western Canada (June–July 2008). Its goal was to better understand the factors driving current changes in Arctic atmospheric composition and climate, including (1) influx of mid-latitude pollution, (2) boreal forest fires, (3) aerosol radiative forcing, and (4) chemical processes. The June–July deployment was preceded by one week of flights over California (ARCTAS-CARB) focused on (1) improving state emission inventories for greenhouse gases and aerosols, (2) providing observations to test and improve models …

Sources, Distribution, And Acidity Of Sulfate-Ammonium Aerosol In The Arctic In Winter-Spring, Jenny A. Fisher, Daniel J. Jacob, Q Wang, Roya Bahreini, C C. Carouge, M J. Cubison, Jack E. Dibb, Thomas Diehl, J L. Jimenez, E M. Leibensperger, Zifeng Lu, Marcel B.J Meinders, H. O T. Pye, Patricia K. Quinn, Sangeeta Sharma, David G. Streets, Aaron Van Donkelaar, R M. Yantosca

Jenny A Fisher

We use GEOS-Chem chemical transport model simulations of sulfate–ammonium aerosol data from the NASA ARCTAS and NOAA ARCPAC aircraft campaigns in the North American Arctic in April 2008, together with longer-term data from surface sites, to better understand aerosol sources in the Arctic in winter–spring and the implications for aerosol acidity. Arctic pollution is dominated by transport from mid-latitudes, and we test the relevant ammonia and sulfur dioxide emission inventories in the model by comparison with wet deposition flux data over the source continents. We find that a complicated mix of natural and anthropogenic sources with different vertical signatures is …

Effects Of Aging On Organic Aerosol From Open Biomass Burning Smoke In Aircraft And Laboratory Studies, M J. Cubison, A M. Ortega, P L. Hayes, D K. Farmer, D Day, M J. Lechner, W H. Brune, E Apel, G S. Diskin, J A. Fisher, H E. Fuelberg, A Hecobian, D J. Knapp, T Mikoviny, D Riemer, G W. Sachse, W Sessions, R Weber, A J. Weinheimer, A Wisthaler, J L. Jimenez

Jenny A Fisher

Biomass burning (BB) is a large source of primary and secondary organic aerosols (POA and SOA). This study addresses the physical and chemical evolution of BB organic aerosols. Firstly, the evolution and lifetime of BB POA and SOA signatures observed with the Aerodyne Aerosol Mass Spectrometer are investigated, focusing on measurements at high-latitudes acquired during the 2008 NASA ARCTAS mission, in comparison to data from other field studies and from laboratory aging experiments. The parameter f60 , the ratio of the integrated signal at m/z 60 to the total signal in the organic component mass spectrum, is used as a …

Riverine Source Of Arctic Ocean Mercury Inferred From Atmospheric Observations, Jenny A. Fisher, Daniel J. Jacob, Anne L. Soerensen, Helen M. Amos, Alexandra Steffen, Elsie M. Sunderland

Jenny A Fisher

Methylmercury is a potent neurotoxin that accumulates in aquatic food webs. Human activities, including industry and mining, have increased inorganic mercury inputs to terrestrial and aquatic ecosystems. Methylation of this mercury generates methylmercury, and is thus a public health concern. Marine methylmercury is a particular concern in the Arctic, where indigenous peoples rely heavily on marine-based diets. In the summer, atmospheric inorganic mercury concentrations peak in the Arctic, whereas they reach a minimum in the northern mid-latitudes. Here, we use a global three-dimensional ocean–atmosphere model to examine the cause of this Arctic summertime maximum. According to our simulations, circumpolar rivers …

Global Estimates Of Co Sources With High Resolution By Adjoint Inversion Of Multiple Satellite Datasets (Mopitt, Airs, Sciamachy, Tes), M Kopacz, D J. Jacob, J A. Fisher, J A. Logan, L Zhang, I A. Megretskaia, R M. Yantosca, K Singh, D K. Henze, J P. Burrows, M Buchwitz, I Khlystova, W. W Mcmillan, J C. Gille, D P. Edwards, A Eldering, V Thouret, P Nedelec

Jenny A Fisher

We combine CO column measurements from the MOPITT, AIRS, SCIAMACHY, and TES satellite instruments in a full-year (May 2004–April 2005) global inversion of CO sources at 4◦ ×5◦ spatial resolution and monthly temporal resolution. The inversion uses the GEOS-Chem chemical transport model (CTM) and its adjoint applied to MOPITT, AIRS, and SCIAMACHY. Observations from TES, surface sites (NOAA/GMD), and aircraft (MOZAIC) are used for evaluation of the a posteriori solution. Using GEOSChem as a common intercomparison platform shows global consistency between the different satellite datasets and with the in situ data. Differences can be largely explained by different averaging kernels …

Sources Of Carbonaceous Aerosols And Deposited Black Carbon In The Arctic In Winter-Spring: Implications For Radiative Forcing, Q Wang, D J. Jacob, J A. Fisher, J Mao, E M. Leibensperger, C C. Carouge, P Le Sager, Y Kondo, J L. Jimenez, M J. Cubison, S J. Doherty

Jenny A Fisher

We use a global chemical transport model (GEOS-Chem CTM) to interpret observations of black carbon (BC) and organic aerosol (OA) from the NASA ARCTAS aircraft campaign over the North American Arctic in April 2008, as well as longer-term records in surface air and in snow (2007-2009). BC emission inventories for North America, Europe, and Asia in the model are tested by comparison with surface air observations over these source regions. Russian open fires were the dominant source of OA in the Arctic troposphere during ARCTAS but we find that BC was of prevailingly anthropogenic (fossil fuel and biofuel) origin, particularly …

Chemistry Of Hydrogen Oxide Radicals (Hox) In The Arctic Troposphere In Spring, J Mao, D J. Jacob, M J. Evans, J R. Olson, X Ren, W H. Brune, T M. St. Clair, J D. Crounse, K M. Spencer, M R. Beaver, P O. Wennberg, M J. Cubison, J L. Jimenez, A Fried, P Weibring, J G. Walega, S R. Hall, A J. Weinheimer, R C. Cohen, G Chen, J H. Crawford, C Mcnaughton, A D. Clarke, L Jaegle, Jenny A. Fisher, R M. Yantosca, P Le Sager, C C. Carouge

Jenny A Fisher

We use observations from the April 2008 NASA ARCTAS aircraft campaign to the North American Arctic, interpreted with a global 3-D chemical transport model (GEOS-Chem), to better understand the sources and cycling of hydrogen oxide radicals (HOx≡H+OH+peroxy radicals) and their reservoirs (HOy≡HOx+peroxides) in the springtime Arctic atmosphere. We find that a standard gas-phase chemical mechanism overestimates the observed HO2 and H2O2 concentrations. Computation of HOx and HOy gas-phase chemical budgets on the basis of the aircraft observations also indicates a large missing sink for both. We hypothesize that this could reflect HO2 uptake by aerosols, favored by low temperatures and …

Meteorological Modes Of Variability For Fine Particulate Matter (Pm2.5) Air Quality In The United States: Implications For Pm2.5 Sensitivity To Climate Change, A. P K. Tai, L J. Mickley, D J. Jacob, E M. Leibensperger, L Zhang, J A. Fisher, H. O T. Pye

Jenny A Fisher

We applied a multiple linear regression model to understand the relationships of PM2.5 with meteorological variables in the contiguous US and from there to infer the sensitivity of PM2.5 to climate change. We used 2004–2008 PM2.5 observations from ~1000 sites (~200 sites for PM2.5 components) and compared to results from the GEOS-Chem chemical transport model (CTM). All data were deseasonalized to focus on synoptic-scale correlations. We find strong positive correlations of PM2.5 components with temperature in most of the US, except for nitrate in the Southeast where the correlation is negative. Relative humidity (RH) is generally positively correlated with sulfate …

Source Attribution And Interannual Variability Of Arctic Pollution In Spring Constrained By Aircraft (Arctas, Arcpac) And Satellite (Airs) Observations Of Carbon Monoxide, J A. Fisher, D J. Jacob, M T. Purdy, M Kopacz, P Le Sager, C C. Carouge, C D. Holmes, R M. Yantosca, R L. Batchelor, K Strong, G S. Diskin, H E. Fuelberg, J S. Holloway, E J. Hyer, W. W Mcmillan, J Warner, D G. Streets, Q Zhang, Y Yang, S Wu

Jenny A Fisher

We use aircraft observations of carbon monoxide (CO) from the NASA ARCTAS and NOAA ARCPAC campaigns in April 2008 together with multiyear (2003– 2008) CO satellite data from the AIRS instrument and a global chemical transport model (GEOS-Chem) to better understand the sources, transport, and interannual variability of pollution in the Arctic in spring. Model simulation of the aircraft data gives best estimates of CO emissions in April 2008 of 26 Tg month−1 for Asian anthropogenic, 9.4 for European anthropogenic, 4.1 for North American anthropogenic, 15 for Russian biomass burning (anomalously large that year), and 23 for Southeast Asian biomass …

North Polar Frontal Clouds And Dust Storms On Mars During Spring And Summer, Huiqun Wang, Jenny A. Fisher

Jenny A Fisher

The complete archive of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) Mars Daily Global Maps (MDGM) are used to study north polar clouds and dust storms that exhibit frontal structures during the spring and summer (Ls 0–180°). Results show that frontal events generally follow the edge of the polar cap during spring and mid/late summer with a gap in the distribution in early summer. The exact duration and timing of the gap vary from year to year. Twww.lw20.comen to twenty percent of spring and summer time frontal events exhibit complex morphologies. Distinct temperature signatures are associated with features observed …

A Survey Of Martian Dust Devil Activity Using Mars Global Surveyor Mars Orbiter Camera Images, Jenny A. Fisher, Mark I. Richardson, Claire E. Newman, Mark A. Szwast, Chelsea Graf, Shabari Basu, Shawn P. Ewald, Anthony D. Toigo, R. John Wilson

Jenny A Fisher

A survey of dust devils using the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide- and narrow-angle (WA and NA) images has been undertaken. The survey comprises two parts: (1) sampling of nine broad regions from September 1997 to July 2001 and (2) a focused seasonal monitoring of variability in the Amazonis region, an active dust devil site, from March 2001 to April 2004. For part 1, dust devils were identified in NA and WA images, and dust devil tracks were identified in NA images. Great spatial variability in dust devil occurrence is highlighted, with Amazonis Planitia being the …

Gas-Particle Partitioning Of Atmospheric Hg(Ii) And Its Effect On Global Mercury Deposition, H M. Amos, D J. Jacob, C D. Holmes, Jenny A. Fisher, Q Wang, R M. Yantosca, E S. Corbitt, E Galarneau, A P. Rutter, M S. Gustin, A Steffen, J J. Schauer, J A. Graydon, V L. St Louis, R W. Talbot, E S. Edgerton, Y Zhang, E N. Sunderland

Jenny A Fisher

Atmospheric deposition represents a major input of mercury to surface environments. The phase of mercury (gas or particle) has important implications for its removal from the atmosphere. We use long-term observations of reactive gaseous mercury (RGM), particle-bound mercury (PBM), fine particulate matter (PM2.5), and temperature at five sites in North America to derive an empirical gas-particle partitioning relationship log10(K-1) = (10 ± 1) − (2500 ± 300)/T where K = (PBM/PM2.5)/RGM with PBM and RGM in common mixing ratio units, PM2.5 in μg m−3, and T in Kelvin. This relationship is in the range of previous work but is based …

Exploring Co Pollution Episodes Observed At Rishiri Island By Chemical Weather Simulations And Airs Satellite Measurements: Long-Range Transport Of Burning Plumes And Implications For Emissions Inventories, Hiroshi Tanimoto, Keiichi Sato, Tim Butler, Mark G. Lawrence, Jenny A. Fisher, M Kopacz, Robert M. Yantosca, Yugo Kanaya, Shungo Kato, Tomoaki Okuda, Shigeru Tanaka, Jiye Zeng

Jenny A Fisher

The summer of 2003 was an active forest fire season in Siberia. Several events of elevated carbon monoxide (CO) were observed at Rishiri Island in northern Japan during an intensive field campaign in September 2003. A simulation with a global chemistry-transport model is able to reproduce the general features of the baseline levels and variability in the observed CO, and a source attribution for CO in the model suggests that the contribution from North Asia dominated, accounting for approximately 50% on average, with contributions of 7% from North America and 8% from Europe and 30% from oxidation of hydrocarbons. With …

Error Correlation Between Co2 And Co As Constraint For Co2 Flux Inversions Using Satellite Data, H Wang, D J. Jacob, M Kopacz, D B. A Jones, P Suntharalingam, J A. Fisher, R Nassar, S Pawson, J E. Nielsen

Jenny A Fisher

Inverse modeling of CO2 satellite observations to better quantify carbon surface fluxes requires a chemical transport model (CTM) to relate the fluxes to the observed column concentrations. CTM transport error is a major source of uncertainty. We show that its effect can be reduced by using CO satellite observations as additional constraint in a joint CO2-CO inversion. CO is measured from space with high precision, is strongly correlated with CO2, and is more sensitive than CO2 to CTM transport errors on synoptic and smaller scales. Exploiting this constraint requires statistics for the CTM transport error correlation between CO2 and CO, …

The Extended Tracking Network And Indications Of Baseline Precision And Accuracy In The North Andes, Jeffrey Freymueller, James Kellogg

James N Kellogg

The CASA UNO Global Positioning System (GPS) experiment (January-February 1988) included an extended tracking network which covered three continents in addition to the network of scientific interest in Central and South America. The repeatability of long baselines (400-1000 km) in South America is improved by up to a factor of two in the horizontal vector baseline components by using tracking stations in the Pacific and Europe to supplement stations in North America. In every case but one, the differences between the mean solutions obtained using different tracking networks was equal to or smaller than day-to-day rms repeatabilities for the same …

Reply To Comment On "Subduction Of The Caribbean Plate And Basement Uplifts In The Overriding South American Plate", James Kellogg, William Bonini

James N Kellogg

No abstract provided.

Central And South America Gps Geodesy- Casa Uno, James Kellogg, Timothy Dixon

James N Kellogg

In January 1988, scientists from over 25 organizations in 13 countries and territories cooperated in the largest Global Positioning System (GPS) campaign in the world to date (Table 1). 43 GPS receivers collected approximately 590 station-days of data in America, Samoa, Australia, Canada, Colombia, Costa Rica, Ecuador, New Zealand, Norway, Panama, Sweden, United States, West Germany, and Venezuela. The experiment was entitled CASA UNO, an acronym for Central and South America -- and uno is the Spanish word for one, designating first epoch measurements. The CASA UNO experiment was the first civilian effort implementing a global GPS satellite tracking network. …

Plate Motions In The North Andean Region, Jeffrey T. Freymueller, James N. Kellogg, Victor Vega

James N Kellogg

Repeated geodetic measurements with the Global Positioning System (GPS) provide direct measurements of displacements due to plate motions and active crustal deformation in Central America and northern South America, an area of complex interaction of the Nazca, Cocos, Caribbean and South American plates. The displacement rates for the period 1988-1991, obtained from the results of the first three Central And South America (CASA) GPS campaigns, are in general agreement with the predictions of the NUVEL-1 plate motion model, but there are differences in detail between the observations and the model. The Nazca-North Andes convergence rate vector measured by GPS is …

A 3-D Gravity Tectonic Study Of Ita Mai Tai Guyot: An Uncompensated Seamount In The East Mariana Basin, Bruce Wedgeworth, James Kellogg

James N Kellogg

Ita Mai Tai is a large, locally uncompensated seamount on the eastern edge of the East Mariana Basin. A large positive gravity anomaly of 254 mgal characterizes the summit and a low of -69 mgal, the surrounding moat. Using polygonal prisms to approximate the bathymetry, the observed gravity was inverted to calculate an average density of 2.59 g/ems for the seamount. Observed-calculated gravity residuals are reduced by including the flanking sedimentary basins and a dense volcanic conduit. The drill sites from DSDP Legs 20 and 89 describe a volcanic edifice formed in the Aptian!Albian on Jmassic/Cretaceous crust. The volcanism is …

Cenozoic Tectonic History Of The Sierra De Perija, Venezuela- Colombia, And Adjacent Basins, James N. Kellogg

James N Kellogg

The four major Cenozoic tectonic phases in the Sierra de Perija and adjacent basins are the early Eocene tectonic phase, the middle Eocene Caribbean orogeny, the late Oligocene phase, and the late Miocene to present Andean orogeny. Ages of unconformities associated with particularly rapid regional uplift during these phases are early Eocene (53 m.y.), middle Eocene (45 m.y.), late Oligocene (25 m.y.), and Pliocene (3 m.y.). Northwest-southeast compression may have commenced in the Perija and the Maracaibo Basin as early as the early Eocene. By the early Eocene the Macoa-Totumo arch had begun to to form during intense alpine-type folding …

Seismic Evidence For Blind Thrusting Of The Northwestern Flank Of The Venezuelan Andes, Bruno De Toni, James Kellogg

James N Kellogg

Surface geology and seismic and well data from the northwestern flank of the Venezuelan Andes indicate overthrusting of Andean basement rocks toward the adjacent Maracaibo Basin along a blind thrust fault. The frontal monocline is interpreted as the forelimb of a northwestward verging fault-related fold deformed over a crustal-scarle map. The Andean block has been thrust 20 km to the northwest and uplifted 10 km on a ramp that dips about 20o-30o southeastward. The thrust fault ramps up through crystalline basement rocks to a decollement horizon within the shaly units of the Cretaceous Colon-Mito Juan formations. Backthrusts in the monocline …

First Gps Baseline Results From The North Andes, James Kellogg, Jeffrey Freymueller, Timothy Dixon, Ruth Neilan, Clemente Ropain U., Sergio Camargo M., Benjamin Fernandez Ch., James Stowell, Anibal Salazar, Jaime Mora V., Luis Espin, Vernon Perdue, Leonard Leos

James N Kellogg

The CASA UNO GPS (Global Positioning System) experiment (January-February 1988) has provided the first epoch baseline measurements for the study of plate motions and crustal deformation in and around the North Andes. Two dimensional horizontal baseline repeatabilities are as good as 5 parts in 10⁸ for short baselines (100-1000km), and better than3 parts in 10⁸ for long baselines (>1000km). Vertical repeatabilities are typically 4 -6 cm, with a weak dependence on baseline length. The expected rate of plate convergence across the Colombia Trench is 6-8 cm/yr, which should be detectable by the repeat experiment planned for 1991. …

Isostatic Compensation And Conduit Structures Of Western Pacific Seamounts: Results Of Three-Dimensional Gravity Modeling, James Kellogg, Bruce Wedgeworth, Jeffrey Freymueller

James N Kellogg

Detailed three-dimensional polygonal prism models of two large western Pacific seamounts show that the 135 mgal difference in the observed sea surface gravity over the two can be best explained by similar mean densities (2.6 gjcm3) and crustal thickening under one seamount (Airy isostatic compensation). Observed calculated residuals are further reduced by including dense (2.9 gjcm3) vertical feeder pipes or volcanic conduits in the models. Dense conduits or fracture zones 5 to 17 km in diameter are located under many, if not all, craters on volcanic islands and seamounts. Results from the detailed seamount studies can be generalized using exact …

New Standards For Reducing Gravity Data: The North American Gravity Database, William Hinze, Carlos Aiken, John Brozena, Bernard Coakley, David Dater, Guy Flanagan, Rene Forsberg, Thomas Hildenbrand, G. Keller, James Kellogg, Robert Kucks, Xiong Li, Andre Mainville, Robert Morin, Mark Pilkington, Donald Plouff, Dhananjay Ravat, Daniel Roman, Jamie Urrutia-Fucugauchi, Marc Veronneau, Michael Webring, Daniel Winester

James N Kellogg

The North American gravity database as well as databases from Canada, Mexico, and the United States are being revised to improve their coverage, versatility, and accuracy. An important part of this effort is revising procedures for calculating gravity anomalies, taking into account our enhanced computational power, improved terrain databases and datums, and increased interest in more accurately defining long-wavelength anomaly components. Users of the databases may note minor differences between previous and revised database values as a result of these procedures. Generally, the differences do not impact the interpretation of local anomalies but do improve regional anomaly studies. The most …

Fdou Project 26a Part 5 Task 1 - Our Florida Reefs (Ofr) Survey Outreach Efforts, Brian K. Walker, Amanda Rose Costaregni

Marine & Environmental Sciences Faculty Reports

This report contains summaries of the OFR survey outreach activities completed in Miami-

Dade, Broward, Palm Beach, and Martin counties between October 1st, 2014 and February

2nd, 2015.

A total of seven presentations were given in Broward, Palm Beach, and Martin Counties.

These presentations were for groups such as dive clubs, underwater photography clubs, fishing clubs, and environmental professionals clubs. Unfortunately, due to scheduling conflicts no survey presentations have been given in Miami-Dade County to-date. Summaries of these outreach presentations include the name of the club, location of the presentation, number of people reached, demographics, questions and responses during the …

A Contribution To The Vascular Flora Of The Sequatchie Valley Within Sequatchie County, Tennessee, John Richard Evans

John Evans

The vascular flora of the Sequatchie Valley within Sequatchie County, Tennessee was studied for three growing seasons from 2008 through 2010. The Sequatchie Valley is located within the southeastern portion of the Cumberland Plateau and is generally considered to be part of the Cumberland Plateau Physiographic Province. Nevertheless, a number of geological and ecological factors distinguish the Sequatchie Valley from the elevated Cumberland Plateau, suggesting that the floristic composition of the valley may be different from the surrounding region. Although several previous floristic studies have been conducted on the plateau surface, very little attention has been given to the Sequatchie …

Real-Time Monitoring Of Tectonic Displacements In The Pacific Northwest Through An Array Of Gps Receivers, Răzvan Popovici, Răzvan Andonie, Walter M. Szeliga, Timothy I. Melbourne, Craig W. Scrivner

All Faculty Scholarship for the College of the Sciences

The Pacific Northwest Geodesic Array at Central Washington University collects telemetered streaming data from 450 GPS stations. These real-time data are used to monitor and mitigate natural hazards arising from earthquakes, volcanic eruptions, landslides, and coastal sea-level hazards in the Pacific Northwest. The displacement measurements are performed at millimeter-scale, and require stringent analysis and parameter estimation techniques. Recent improvements in both accuracy of positioning measurements and latency of terrestrial data communication have led to the ability to collect data with higher sampling rates, of up to 1 Hz. For seismic monitoring applications, this means 1350 separate position streams from stations …

Van Allen Probes Observations Linking Radiation Belt Electrons To Chorus Waves During 2014 Multiple Storms, Si Liu, Fuliang Xiao, Chang Yang, Yihua He, Qinghua Zhou, C A. Kletzing, W. S. Kurth, G. B. Hospodarsky, Harlan E. Spence, Geoffrey Reeves, H. O. Funsten, J. B. Blake, D. N. Baker, J. R. Wygant

Physics & Astronomy

Abstract

During 18 February to 2 March 2014, the Van Allen Probes encountered multiple geomagnetic storms and simultaneously observed intensified chorus and hiss waves. During this period, there were substantial enhancements in fluxes of energetic (53.8–108.3 keV) and relativistic (2–3.6 MeV) electrons. Chorus waves were excited at locations L = 4–6.2 after the fluxes of energetic were greatly enhanced, with a lower frequency band and wave amplitudes ∼20–100 pT. Strong hiss waves occurred primarily in the main phases or below the location L = 4 in the recovery phases. Relativistic electron fluxes decreased in the main phases due to the …

Cosmic Evolution Of Black Holes And Spheroids. V. The Relation Between Black Hole Mass And Host Galaxy Luminosity For A Sample Of 79 Active Galaxies, Daeseong Park, Jong-Hak Woo, Vardha N. Bennert, Tommaso Treu, Matthew W. Auger, Matthew A. Malkan

Physics

We investigate the cosmic evolution of the black hole (BH) mass–bulge luminosity relation using a sample of 52 active galaxies at z ∼ 0.36 and z ∼ 0.57 in the BH mass range of 107.4–109.1 M0. By consistently applying multicomponent spectral and structural decomposition to high-quality Keck spectra and high-resolution Hubble Space Telescope images, BH masses (MBH) are estimated using the Hβ broad emission line combined with the 5100 Å nuclear luminosity, and bulge luminosities (Lbul ) are derived from surface photometry. Comparing the resulting MBH − Lbul relation to local active galaxies and taking into account selection effects, we …

Role Of Disorder In Finite-Amplitude Shear Of A 2d Jammed Material, Nathan C. Keim, Paulo E. Arratia

Physics

A material’s response to small but finite deformations can reveal the roots of its response to much larger deformations. Here, we identify commonalities in the responses of 2D soft jammed solids with different amounts of disorder. We cyclically shear the materials while tracking their constituent particles, in experiments that feature a stable population of repeated structural relaxations. Using bidisperse particle sizes creates a more amorphous material, while monodisperse sizes yield a more polycrystalline one. We find that the materials’ responses are very similar, both at the macroscopic, mechanical level and in the microscopic motions of individual particles. However, both locally …