Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons™

Open Access. Powered by Scholars. Published by Universities.®

2010

Discipline
Institution
Keyword
Publication
Publication Type
File Type

Articles 5551 - 5580 of 8625

Full-Text Articles in Physical Sciences and Mathematics

Re-Interpreting Great Lakes Shorelines As Components Of Wave-Influenced Deltas: An Example From The Portage River, Lake Erie, Ohio, James E. Evans Jan 2010

Re-Interpreting Great Lakes Shorelines As Components Of Wave-Influenced Deltas: An Example From The Portage River, Lake Erie, Ohio, James E. Evans

James E. Evans

No abstract provided.

Go to article

Optimal Dynamic Policies For Influenza Management, Michael Ludkovski, Jarad Niemi Jan 2010

Optimal Dynamic Policies For Influenza Management, Michael Ludkovski, Jarad Niemi

Jarad Niemi

Management policies for influenza outbreaks balance the expected morbidity and mortality costs versus the cost of intervention policies. We present a methodology for dynamic determination of optimal policies in a completely observed stochastic compartmental model with parameter uncertainty. Our approach is simulation-based and searches the full set of sequential control strategies. For each time point, it generates a policy map describing the optimal intervention to implement as a function of outbreak state and Bayesian parameter posteriors. As a running example, we study a stochastic SIR model with isolation and vaccination as two possible interventions. Numerical simulations based on a classic …

Go to article

Application Of The Tissue Residue Approach In Ecological Risk Assessment, Steven P. Bradbury, Keith G. Sappington, Todd S. Bridges, Russell J. Erickson, A. Jan Hendriks, Roman P. Lanno, James P. Meador, David R. Mount, Mike H. Salazar, Doug J. Spry Jan 2010

Application Of The Tissue Residue Approach In Ecological Risk Assessment, Steven P. Bradbury, Keith G. Sappington, Todd S. Bridges, Russell J. Erickson, A. Jan Hendriks, Roman P. Lanno, James P. Meador, David R. Mount, Mike H. Salazar, Doug J. Spry

Steven P. Bradbury

The objective of this work is to present a critical review of the application of the tissue residue approach (TRA) in ecological risk and/or impact assessment (ERA) of chemical stressors and environmental criteria development. A secondary goal is to develop a framework for integrating the TRA into ecological assessments along with traditional, exposure concentration-based assessment approaches. Although widely recognized for its toxicological appeal, the utility of the TRA in specific applications will depend on numerous factors, such as chemical properties, exposure characteristics, assessment type, availability of tissue residue-response data, and ability to quantify chemical exposure. Therefore, the decision to use …

Go to article

Meeting The Common Needs Of A More Effective And Efficient Testing And Assessment Paradigm For Chemical Risk Management, Steven P. Bradbury, Vicki Dellarco, Tala Henry, Phil Sayre, Jennifer Seed Jan 2010

Meeting The Common Needs Of A More Effective And Efficient Testing And Assessment Paradigm For Chemical Risk Management, Steven P. Bradbury, Vicki Dellarco, Tala Henry, Phil Sayre, Jennifer Seed

Steven P. Bradbury

Significant advances have been made in human health and ecological risk assessment over the last decade. Substantial challenges, however, remain in providing credible scientific information in a timely and efficient manner to support chemical risk assessment and management decisions. A major challenge confronting risk managers is the need for critical information to address risk uncertainties in large chemical inventories such as high- and medium-production-volume industrial chemicals or pesticide inert ingredients. From a strategic and tactical viewpoint, an integrated approach that relies on all existing knowledge and uses a range of methods, including those from emerging and novel technologies, is needed …

Go to article

Quaternary Geology And Geochronology Of The Uppermost Arkansas Valley, Colorado- Glaciers, Ice Dams, Landslides, And Floods, James P. Mccalpin Jan 2010

Quaternary Geology And Geochronology Of The Uppermost Arkansas Valley, Colorado- Glaciers, Ice Dams, Landslides, And Floods, James P. Mccalpin

James P. McCalpin

This field trip to the uppermost Arkansas Valley of central Colorado is based mainly on work performed since 2008, in an area with a long history of bedrock mapping by renowned geologists of the U.S. Geological Survey beginning in the 1880s (e.g. Emmons, 1886). The Quaternary features of the region were first described by Capps in 1909. Despite over 100 years of intermittent geologic studies here, there were still new discoveries to be made in the past few years. Day 1 of the trip emphasizes landslides (in the morning) and glacial deposits (in the afternoon). The “take-home messages” of the …

Go to article

Vinyl Cations Substituted With Β Π-Donors Have Triplet Ground States, Arthur Winter, Daniel E. Falvey Jan 2010

Vinyl Cations Substituted With Β Π-Donors Have Triplet Ground States, Arthur Winter, Daniel E. Falvey

Arthur Winter

Computations at the CASPT2, CBS-QB3, and B3LYP levels of theory demonstrate that β-substitution of vinyl cations with π-donors switches the ground state of these ions from the familiar closed-shell singlet state to a carbene-like triplet state similar to the electronic state of triplet phenyl cations. Although the parent vinyl cation is a ground-state singlet species with a very large energy gap to the lowest energy triplet state, substituting the β hydrogens with just one strong π-donor (e.g., NH2, NMe2, OMe) or two moderate π-donors (e.g., F, OH, Ar, vinyl) makes the triplet state the computed ground electronic state. In many …

Go to article

Size Effect Of Ruthenium Nanoparticles In Catalytic Carbon Monoxide Oxidation, Sang Hoon Joo, Jeong Y. Park, J. Russell Renzas, Derek R. Butcher, Wenyu Huang, Gabor A. Somorjai Jan 2010

Size Effect Of Ruthenium Nanoparticles In Catalytic Carbon Monoxide Oxidation, Sang Hoon Joo, Jeong Y. Park, J. Russell Renzas, Derek R. Butcher, Wenyu Huang, Gabor A. Somorjai

Wenyu Huang

Carbon monoxide oxidation over ruthenium catalysts has shown an unusual catalytic behavior. Here we report a particle size effect on CO oxidation over Ru nanoparticle (NP) catalysts. Uniform Ru NPs with a tunable particle size from 2 to 6 nm were synthesized by a polyol reduction of Ru(acac)3 precursor in the presence of poly(vinylpyrrolidone) stabilizer. The measurement of catalytic activity of CO oxidation over two-dimensional Ru NPs arrays under oxidizing reaction conditions (40 Torr CO and 100 Torr O2) showed an activity dependence on the Ru NP size. The CO oxidation activity increases with NP size, and the 6 nm …

Go to article

Highly Active Heterogeneous Palladium Nanoparticle Catalysts For Homogeneous Electrophilic Reactions In Solution And The Utilization Of A Continuous Flow Reactor, Wenyu Huang, Jack Hung Chang Liu, Pinar Alayoglu, Yimin Li, Cole A. Whitman, Chia-Kuang Tsung, F. Dean Toste, Gabor A/ Somorjai Jan 2010

Highly Active Heterogeneous Palladium Nanoparticle Catalysts For Homogeneous Electrophilic Reactions In Solution And The Utilization Of A Continuous Flow Reactor, Wenyu Huang, Jack Hung Chang Liu, Pinar Alayoglu, Yimin Li, Cole A. Whitman, Chia-Kuang Tsung, F. Dean Toste, Gabor A/ Somorjai

Wenyu Huang

highly active heterogeneous Pd-nanoparticle catalyst for the intramolecular addition of phenols to alkynes was developed and employed in a continuous flow reaction system. Running the reaction in flow mode revealed reaction kinetics, such as the activation energy and catalyst deactivation, and provides many potential practical advantages.

Go to article

Seedless Polyol Synthesis And Co Oxidation Activity Of Monodisperse (111)- And (100)-Oriented Rhodium Nanocrystals In Sub-10 Nm Sizes, Yawen Zhang, Michael E. Grass, Wenyu Huang, Gabor A. Somoraji Jan 2010

Seedless Polyol Synthesis And Co Oxidation Activity Of Monodisperse (111)- And (100)-Oriented Rhodium Nanocrystals In Sub-10 Nm Sizes, Yawen Zhang, Michael E. Grass, Wenyu Huang, Gabor A. Somoraji

Wenyu Huang

Monodisperse sub-10 nm (6.5 nm) sized Rh nanocrystals with (111) and (100) surface structures were synthesized by a seedless polyol reduction in ethylene glycol, with poly(vinylpyrrolidone) as a capping ligand. When using [Rh(Ac)2]2 as the metal precursor, (111)-oriented Rh nanopolyhedra containing 76% (111)-twinned hexagons (in 2D projection) were obtained; whereas, when employing RhCl3 as the metal precursor in the presence of alkylammonium bromide, such as tetramethylammonium bromide and trimethyl(tetradecyl)ammonium bromide, (100)-oriented Rh nanocubes were obtained with 85% selectivity. The {100} faces of the Rh nanocrystals are stabilized by chemically adsorbed Br− ions from alkylammonium bromides, which led to (100)-oriented nanocubes. …

Go to article

Furan Hydrogenation Over Pt(111) And Pt(100) Single-Crystal Surfaces And Pt Nanoparticles From 1 To 7 Nm: A Kinetic And Sum Frequency Generation Vibrational Spectroscopy Study, Christopher J. Kliewer, Cesar Aliaga, Marco Bieri, Wenyu Huang, Chia-Kuang Tsung, Jennifer B. Wood, Kyriankos Komvopoulos, Gabor A. Somorjai Jan 2010

Furan Hydrogenation Over Pt(111) And Pt(100) Single-Crystal Surfaces And Pt Nanoparticles From 1 To 7 Nm: A Kinetic And Sum Frequency Generation Vibrational Spectroscopy Study, Christopher J. Kliewer, Cesar Aliaga, Marco Bieri, Wenyu Huang, Chia-Kuang Tsung, Jennifer B. Wood, Kyriankos Komvopoulos, Gabor A. Somorjai

Wenyu Huang

Sum frequency generation surface vibrational spectroscopy and kinetic measurements using gas chromatography have been used to systematically study the adsorption and hydrogenation of furan over Pt(111) and Pt(100) single-crystal surfaces and size-controlled 1.0-nm, 3.5-nm and 7.0-nm Pt nanoparticles at Torr pressures (10 Torr of furan, 100 Torr of H2) to form dihydrofuran, tetrahydrofuran, and the ring-cracking products butanol and propylene. As determined by SFG, the furan ring lies parallel to all Pt surfaces studied under hydrogenation conditions. Upright THF and the oxametallacycle intermediate are observed over the nanoparticle catalysts under reaction conditions. Butoxy increases in surface concentration over Pt(111) with …

Go to article

Oscillatory And Monotonic Modes Of Long-Wave Marangoni Convection In A Thin Film, Sergey Shklyaev, Mikhail Khenner, Alexei Alabuzhev Jan 2010

Oscillatory And Monotonic Modes Of Long-Wave Marangoni Convection In A Thin Film, Sergey Shklyaev, Mikhail Khenner, Alexei Alabuzhev

Mikhail Khenner

We study long-wave Marangoni convection in a layer heated from below. Using the scaling k=OBi, where k is the wave number and Bi is the Biot number, we derive a set of amplitude equations. Analysis of this set shows presence of monotonic and oscillatory modes of instability. Oscillatory mode has not been previously found for such direction of heating. Studies of weakly nonlinear dynamics demonstrate that stable steady and oscillatory patterns can be found near the stability threshold.

Go to article

Mid-Gap Electronic States In Zn1-Xmnxo., C. A. Johnson, Kevin R. Kittilstved, T. C. Kaspar, T. C. Droubay, S. A. Chambers, G. M. Salley, D. R. Gamelin Jan 2010

Mid-Gap Electronic States In Zn1-Xmnxo., C. A. Johnson, Kevin R. Kittilstved, T. C. Kaspar, T. C. Droubay, S. A. Chambers, G. M. Salley, D. R. Gamelin

Kevin R. Kittilstved

Electronic absorption, magnetic circular dichroism (MCD), photoconductivity, and valence-band x-ray photoelectron (XPS) spectroscopic measurements were performed on epitaxial Zn1−xMnxO films to investigate the origin of the mid-gap band that appears upon introduction of Mn2+ into the ZnO lattice. Absorption and MCD spectroscopies reveal Mn2+-related intensity at energies below the first excitonic transition of ZnO, tailing well into the visible energy region, with an onset at ∼2.2 eV. Photoconductivity measurements show that excitation into this visible band generates mobile charge carriers, consistent with assignment as a Mn2+/3+ photoionization transition. XPS measurements reveal the presence of occupied Mn2+ levels just above the …

Go to article

Array-Based Sensing Of Normal, Cancerous, And Metastatic Cells Using Conjugated Fluorescent Polymers, A Bajaj, Or Miranda, R Phillips, Ib Kim, Dj Jerry, Uhf Bunz, Vm Rotello Jan 2010

Array-Based Sensing Of Normal, Cancerous, And Metastatic Cells Using Conjugated Fluorescent Polymers, A Bajaj, Or Miranda, R Phillips, Ib Kim, Dj Jerry, Uhf Bunz, Vm Rotello

Vincent Rotello

A family of conjugated fluorescent polymers was used to create an array for cell sensing. Fluorescent conjugated polymers with pendant charged residues provided multivalent interactions with cell membranes, allowing the detection of subtle differences between different cell types on the basis of cell surface features. Highly reproducible characteristic patterns were obtained from different cell types as well as from isogenic cell lines, enabling the identification of the cell type as well differentiating between normal, cancerous, and metastatic isogenic cell types with high accuracy.

Go to article

Management Strategies To Improve Yield And Nitrogen Use Of Spring Wheat And Field Pea In The Semi-Arid Northern Great Plains Usa, Andrew W. Lenssen, Brett Allen, Upendra Sainju, Thecan Caesar, Robert Lartey, Robert Evans Jan 2010

Management Strategies To Improve Yield And Nitrogen Use Of Spring Wheat And Field Pea In The Semi-Arid Northern Great Plains Usa, Andrew W. Lenssen, Brett Allen, Upendra Sainju, Thecan Caesar, Robert Lartey, Robert Evans

Andrew W. Lenssen

Available water and N fertility are primary constraints to crop production in the northern Great Plains of the USA. A field trial was initiated in 2004 to compare four crop rotations in a complete factorial of two tillage and two management systems. Rotations were continuous spring wheat (SW), pea-SW, barley hay-pea-SW, and barley hay-corn-pea-SW. Tillage systems were no till and field cultivator tillage, while management systems were conventional and ecological. Conventional management included broadcast nitrogen fertilizer, standard seeding rates, and short stubble height. Ecological management practices varied by crop, and included banded nitrogen fertilizer for cereals, increased seeding rate, delayed …

Go to article

Preparation And Characterization Of Pt/Γ-Al2o3 Model Catalyst On Nial Alloy, Zhongfan Zhang, Long Li, Lin-Lin Wang, Sergio I. Sanchez, Ross V. Grieshaber, Qi Wang, Duane D. Johnson, Anatoly I. Frenkel, Ralph G. Nuzzo, Judith C. Yang Jan 2010

Preparation And Characterization Of Pt/Γ-Al2o3 Model Catalyst On Nial Alloy, Zhongfan Zhang, Long Li, Lin-Lin Wang, Sergio I. Sanchez, Ross V. Grieshaber, Qi Wang, Duane D. Johnson, Anatoly I. Frenkel, Ralph G. Nuzzo, Judith C. Yang

Duane D. Johnson

Numerous studies of heterogeneous catalysis systems clearly demonstrate that the metal nanoparticle (NPs)/support interaction is significant in determining the catalytic chemistry. Theoretical simulations have been performed to understand the metal/support interactions [1,2]. For example, theorists discovered that electronic and oxygen defects of γ-Al2O3 anchor the active particles [1]. Platinum NPs dispersed on γ-alumina is one of the most widely used heterogeneous catalysts and Pt performs extremely well as a catalyst for the oxygen-reduction reaction used in fuel cell industries. Hence, we chose Pt/γ-Al2O3 as a model heterogeneous catalyst system to investigate the metal NPs/support interface by electron microscopy methods with …

Go to article

Interphase Energies Of Hcp Precipitates In Fcc Metals: A Density-Functional Theory Study In Al-Ag, Daniel Finkenstadt, Duane D. Johnson Jan 2010

Interphase Energies Of Hcp Precipitates In Fcc Metals: A Density-Functional Theory Study In Al-Ag, Daniel Finkenstadt, Duane D. Johnson

Duane D. Johnson

Density-functional theory (DFT) calculations of interphase boundary energies relevant to hexagonal-close-packed (hcp) γ-precipitate formation were performed within approximate unit cells that mirror the experimental conditions in face-centered-cubic (fcc) Al-Ag solid solutions. In Al-rich, fcc Al-Ag, γ precipitates are observed to form rapidly with large (300+) aspect ratios even though the Al stacking-fault energy is high (approximately 130 mJ/m2), which should suppress hcp ribbon formation according to standard arguments. Our DFT results show why high-aspect ratio plates occur and why previous estimates based on Wulff construction were orders of magnitude less than observed values. Using DFT, we obtain a Gibbs free-energy …

Go to article

10,12-Dimethylpteridino[6,7-F][1,10]- Phenanthroline-11,13(10h,12h)-Dione– Chloroform (1/1), Waynie Olaprath, Jennifer Rodin, Kraig A. Wheeler, Mark E. Mcguire Jan 2010

10,12-Dimethylpteridino[6,7-F][1,10]- Phenanthroline-11,13(10h,12h)-Dione– Chloroform (1/1), Waynie Olaprath, Jennifer Rodin, Kraig A. Wheeler, Mark E. Mcguire

Kraig A. Wheeler

In the title co-crystal, C18H12N6O2_CHCl3, intramolecular Cl3C—H_ _ _N hydrogen-bonding interactions occur between a single CHCl3 and both N atoms at the 1,10-positions on the phenanthroline portion of the molecule. The interplanar distance between inversion-related molecules is 3.241 (2) A ° .

Go to article

Lunar Dependent Equatorial Ionospheric Effects During Sudden Stratosphericwarmings, Bela G. Fejer, M. E. Olson, J. L. Chau, C. Stolle, H. Luhr, L. P. Goncharenko, K. Yumoto, T. Nagatsuma Jan 2010

Lunar Dependent Equatorial Ionospheric Effects During Sudden Stratosphericwarmings, Bela G. Fejer, M. E. Olson, J. L. Chau, C. Stolle, H. Luhr, L. P. Goncharenko, K. Yumoto, T. Nagatsuma

Bela G. Fejer

[1] We have used plasma drift and magnetic field measurements during the 2001–2009 December solstices to study, for the first time, the longitudinal dependence of equatorial ionospheric electrodynamic perturbations during sudden stratospheric warmings. Jicamarca radar measurements during these events show large dayside downward drift (westward electric field) perturbations followed by large morning upward and afternoon downward drifts that systematically shift to later local times. Ground-based magnetometer measurements in the American, Indian, and Pacific equatorial regions show strongly enhanced electrojet currents in the morning sector and large reversed currents (i.e., counterelectrojets) in the afternoon sector with onsets near new and full …

Go to article

Chvátal-Erdös Type Theorems, Ralph J. Faudree, Jill R. Faudree, Ronald J. Gould, Michael S. Jacobson, Colton Magnant Jan 2010

Chvátal-Erdös Type Theorems, Ralph J. Faudree, Jill R. Faudree, Ronald J. Gould, Michael S. Jacobson, Colton Magnant

Colton Magnant

The Chvátal-Erdös theorems imply that if G is a graph of order n ≥ 3 with κ(G) ≥ α(G), then G is hamiltonian, and if κ(G) > α(G), then G is hamiltonian-connected. We generalize these results by replacing the connectivity and independence number conditions with a weaker minimum degree and independence number condition in the presence of sufficient connectivity. More specifically, it is noted that if G is a graph of order n and k ≥ 2 is a positive integer such that κ(G) ≥ k, δ(G) > (n+k2-k)/(k+1), and δ(G) ≥ α(G)+k-2, then G is hamiltonian. It is shown that if …

Go to article

Origins Of The Extragalactic Background At 1mm From A Combined Analysis Of The Aztec And Mambo Data In Goods-N, Kyle Penner, Alexandra Pope, Edward L. Chapin, Thomas R. Greve, Frank Bertoldi, Mark Brodwin, Ranga-Ram Chary, Christopher J, Conselice, Kristen Coppin, Mauro Giavalisco, David H. Hughes, Rob J. Ivison, Thushara Perera, Douglas Scott, Kimberly Scott, Grant Wilson Jan 2010

Origins Of The Extragalactic Background At 1mm From A Combined Analysis Of The Aztec And Mambo Data In Goods-N, Kyle Penner, Alexandra Pope, Edward L. Chapin, Thomas R. Greve, Frank Bertoldi, Mark Brodwin, Ranga-Ram Chary, Christopher J, Conselice, Kristen Coppin, Mauro Giavalisco, David H. Hughes, Rob J. Ivison, Thushara Perera, Douglas Scott, Kimberly Scott, Grant Wilson

Mauro Giavalisco

We present a study of the cosmic infrared background, which is a measure of the dust obscured activity in all galaxies in the Universe. We venture to isolate the galaxies responsible for the background at 1mm; with spectroscopic and photometric redshifts we constrain the redshift distribution of these galaxies. We create a deep 1.16mm map (sigma ~ 0.5mJy) by combining the AzTEC 1.1mm and MAMBO 1.2mm datasets in GOODS-N. This combined map contains 41 secure detections, 13 of which are new. By averaging the 1.16mm flux densities of individually undetected galaxies with 24um flux densities > 25uJy, we resolve 31--45 per …

Go to article

A Spectroscopic Search For Leaking Lyman Continuum At Z~0.7, Carrie R. Bridge, Harry I. Teplitz, Brian Siana, Claudia Scarlata, Christopher J. Conselice, Henry C. Ferguson, Thomas M. Brown, Mara Salvato, Gwen C. Rudie, Duilia F. De Mello, James Colbert, Jonathan P. Gardner, Mauro Giavalisco, Lee Armus Jan 2010

A Spectroscopic Search For Leaking Lyman Continuum At Z~0.7, Carrie R. Bridge, Harry I. Teplitz, Brian Siana, Claudia Scarlata, Christopher J. Conselice, Henry C. Ferguson, Thomas M. Brown, Mara Salvato, Gwen C. Rudie, Duilia F. De Mello, James Colbert, Jonathan P. Gardner, Mauro Giavalisco, Lee Armus

Mauro Giavalisco

We present the results of rest-frame, UV slitless spectroscopic observations of a sample of 32 z~0.7 Lyman break galaxy (LBG) analogs in the COSMOS field. The spectroscopic search was performed with the Solar Blind Channel (SBC) on Hubble Space Telescope. We report the detection of leaking Lyman continuum (LyC) radiation from an AGN-starburst composite. While we find no direct detections of LyC emission in the remainder of our sample, we achieve individual lower limits (3 sigma) of the observed non-ionizing UV to LyC flux density ratios, f_{nu}(1500A)/f_{nu}(830A) of 20 to 204 (median of 73.5) and 378.7 for the stack. Assuming …

Go to article

Improving The Estimation Of Star Formation Rates And Stellar Population Ages Of High-Redshift Galaxies From Broadband Photometry, Seong-Kook Lee, Henry C. Ferguson, Rachel S. Somerville, Tommy Wiklind, Mauro Giavalisco Jan 2010

Improving The Estimation Of Star Formation Rates And Stellar Population Ages Of High-Redshift Galaxies From Broadband Photometry, Seong-Kook Lee, Henry C. Ferguson, Rachel S. Somerville, Tommy Wiklind, Mauro Giavalisco

Mauro Giavalisco

We explore methods to improve the estimates of star formation rates and mean stellar population ages from broadband photometry of high redshift star-forming galaxies. We use synthetic spectral templates with a variety of simple parametric star formation histories to fit broadband spectral energy distributions. These parametric models are used to infer ages, star formation rates and stellar masses for a mock data set drawn from a hierarchical semi-analytic model of galaxy evolution. Traditional parametric models generally assume an exponentially declining rate of star-formation after an initial instantaneous rise. Our results show that star formation histories with a much more gradual …

Go to article

The Bright End Of The Z ~ 7 Uv Luminosity Function From A Wide And Deep Hawk-I Survey, M. Castellano, A. Fontana, D. Paris, A. Grazian, L. Pentericci, K. Boutsia, P. Santini, V. Testa, M. Dickinson, Mauro Giavalisco, R. Bouwens, J.-G. Cuby, F. Mannucci, B. Clément, S. Cristiani, F. Fiore, S. Gallozzi, E. Giallongo, R. Maiolino, N. Menci, A. Moorwood, N. Nonino, A. Renzini, P. Rosati, S. Salimbeni, E. Vanzella Jan 2010

The Bright End Of The Z ~ 7 Uv Luminosity Function From A Wide And Deep Hawk-I Survey, M. Castellano, A. Fontana, D. Paris, A. Grazian, L. Pentericci, K. Boutsia, P. Santini, V. Testa, M. Dickinson, Mauro Giavalisco, R. Bouwens, J.-G. Cuby, F. Mannucci, B. Clément, S. Cristiani, F. Fiore, S. Gallozzi, E. Giallongo, R. Maiolino, N. Menci, A. Moorwood, N. Nonino, A. Renzini, P. Rosati, S. Salimbeni, E. Vanzella

Mauro Giavalisco

(Abridged) We present here the second half of an ESO Large Programme, which exploits the unique combination of area and sensitivity provided in the near-IR by the camera Hawk-I at the VLT. We have obtained - 30 observing hours with Hawk-I in the Y-band of two high galactic latitude fields. We combined the Y-band data with deep J and K Hawk-I observations, and with FORS1/FORS2 U, B, V, R, I, and Z observations to select z-drop galaxies having Z - Y > 1, no optical detection and flat Y - J and Y - K colour terms. We detect 8 high-quality …

Go to article

The Hubble Space Telescope Goods Nicmos Survey: Overview And The Evolution Of Massive Galaxies At 1.5 < Z < 3, C. J. Conselice, A. F. L. Bluck, F. Buitrago, A. E. Bauer, R. Grützbauch, R. J. Bouwens, S. Bevan, A. Mortlock, M. Dickinson, E. Daddi, H. Yan, Douglas Scott, S. C. Chapman, R.-R. Chary, H. C. Ferguson, Mauro Giavalisco, N. Grogin, G. Illingworth, S. Jogee, A. M. Koekemoer, Ray A. Lucas, B. Mobasher, L. Moustakas, C. Papovich, S. Ravindranath, B. Siana, H. Teplitz, I. Trujillo, M. Urry, T. Weinzirl Jan 2010

The Hubble Space Telescope Goods Nicmos Survey: Overview And The Evolution Of Massive Galaxies At 1.5 < Z < 3, C. J. Conselice, A. F. L. Bluck, F. Buitrago, A. E. Bauer, R. Grützbauch, R. J. Bouwens, S. Bevan, A. Mortlock, M. Dickinson, E. Daddi, H. Yan, Douglas Scott, S. C. Chapman, R.-R. Chary, H. C. Ferguson, Mauro Giavalisco, N. Grogin, G. Illingworth, S. Jogee, A. M. Koekemoer, Ray A. Lucas, B. Mobasher, L. Moustakas, C. Papovich, S. Ravindranath, B. Siana, H. Teplitz, I. Trujillo, M. Urry, T. Weinzirl

Mauro Giavalisco

We present the details and early results from a deep near-infrared survey utilising the NICMOS instrument on the Hubble Space Telescope centred around massive M_* > 10^11 M_0 galaxies at 1.7 < z < 2.9 found within the Great Observatories Origins Deep Survey (GOODS) fields. The GOODS NICMOS Survey (GNS) was designed to obtain deep F160W (H-band) imaging of 80 of these massive galaxies, as well as other colour selected objects such as Lyman-break drop-outs, BzK objects, Distant Red Galaxies, EROs, Spitzer Selected EROs, BX/BM galaxies, as well as sub-mm galaxies. We present in this paper details of the observations, our sample selection, as well as a description of features of the massive galaxies found within our survey fields. This includes: photometric redshifts, rest-frame colours, and stellar masses. We furthermore provide an analysis of the selection methods for finding massive galaxies at high redshifts, including colour selection, and how galaxy populations selected through different methods overlap. We find that a single colour selection method cannot locate all of the massive galaxies, with no one method finding more than 70 percent. We however find that the combination of these colour methods finds nearly all the massive galaxies, as selected by photometric redshifts with the exception of apparently rare blue massive galaxies. By investigating the rest-frame (U-B) vs. M_B diagram for these galaxies we furthermore show that there exists a bimodality in colour-magnitude space at z < 2, driven by stellar mass, such that the most massive galaxies are systematically red up to z~2.5, while lower mass galaxies tend to be blue. We also discuss the number densities for galaxies with stellar masses M_* > 10^11 M_0, whereby we find an increase of a factor of eight between z = 3 and z = 1.5, demonstrating that this is an epoch when massive galaxies establish most of their mass.

Go to article

A Critical Analysis Of The Uv Luminosity Function At Redshift~7 From Deep Wfc3 Data, A. Grazian, M. Castellano, A. M. Koekemoer, A. Fontana, L. Pentericci, V. Testa, K. Boutsia, E. Giallongo, Mauro Giavalisco, P. Santini Jan 2010

A Critical Analysis Of The Uv Luminosity Function At Redshift~7 From Deep Wfc3 Data, A. Grazian, M. Castellano, A. M. Koekemoer, A. Fontana, L. Pentericci, V. Testa, K. Boutsia, E. Giallongo, Mauro Giavalisco, P. Santini

Mauro Giavalisco

The study of the Luminosity Function (LF) of Lyman Break Galaxies (LBGs) at z=7 is important for ascertaining their role in the reionization of the Universe. We perform a detailed and critical analysis of the statistical and systematic errors in the z~7 LF determination: we have assembled a large sample of candidate LBGs at z~7 from different surveys, spanning a large variety of areas and depths. In particular, we have combined data from the deep (J<27.4) and ultradeep (J<29.2) surveys recently acquired with the new WFC3 NIR camera on HST, over the GOODS-ERS and the HUDF fields, with ground based surveys in wide and shallow areas from VLT and Subaru. We have used public ACS images in the z-band to select z-dropout galaxies, and other public data both in the blue (BVI) and in the red bands to reject possible low-redshift interlopers. We have compared our results with extensive simulations to quantify the observational effects of our selection criteria as well as the effects of photometric scatter, color selections or the morphology of the candidates. We have found that the number density of faint LBGs at z~7 is only marginally sensitive to the color selection adopted, but it is strongly dependent from the assumption made on the half light distributions of the simulated galaxies, used to correct the observed sample for incompleteness. The slope of the faint end of the LBGs LF has thus a rather large uncertainty, due to the unknown distribution of physical sizes of the z~7 LBGs. We conclude that galaxies at z~7 are unable to reionize the Universe unless there is a significant evolution in the clumpiness of the IGM or in the escape fraction of ionising photons or, alternatively, there is a large population of z~7 LBGs with large physical dimensions but still not detected by the present observations.

Go to article

Candels: The Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey - The Hubble Space Telescope Observations, Imaging Data Products And Mosaics, Anton M. Koekemoer, S. M. Faber, Henry C. Ferguson, Norman A. Grogin, Dale D. Kocevski, David C. Koo, Kamson Lai, Jennifer M. Lotz, Ray. A. Lucas, Elizabeth J. Mcgrath, Sara Ogaz, Abhijith Rajan, Adam G. Riess, Steve A. Rodney, Louis Strolger, Stefano Casertano, Marco Castellano, Tomas Dahlen, Mark Dickinson, Timothy Dolch, Adriano Fontana, Mauro Giavalisco, Andrea Grazian, Yicheng Guo, Nimish P. Hathi, Kuang-Han Huang, Arjen Van Der Wel, Hao-Jing Yan, Viviana Acquaviva, David M. Alexander, Omar Almaini, Matthew L. N. Ashby, Marco Barden, Eric F. Bell, Frédéric Bournaud, Thomas M. Brown, Karina I. Caputi, Paolo Cassata, Peter Challis, Ranga-Ram Chary, Edmond Cheung, Michele Cirasuolo, Christopher J. Conselice, Asantha Roshan, Darren J. Croton, Emanuele Daddi, Romeel Davé, Dulia F. De Mello, Loic De Ravel, Avishai Dekel, Jennifer L. Donley, James S. Dunlop, Aaron A. Dutton, David Elbaz, Giovanni G. Fazio, Alex F. Filippenko, Steven L. Finkelstein, Chris Frazer, Jonathan P. Gardner, Peter M. Garnavich, Eric Gawiser, Ruth Gruetzbauch, Will G. Hartley, Boris Häussler, Jessica Herrington, Philip F. Hopkins, Jia-Sheng Huang, Saurabh Jha, Andrew Johnson, Jeyhan S. Kartaltepe, Ali Ahmad Khostovan, Robert P. Kirshner, Caterina Lani, Kyoung-Soo Lee, Weidong Li, Piero Madau, Patrick J. Mccarthy, Daniel H. Mcintosh, Ross J. Mclure, Conor Mcpartland, Bahram Mobasher, Heidi Moreira, Alice Mortlock, Leonidas A. Moustakas, Mark Mozena, Kirpal Nandra, Jeffrey A. Newman, Jennifer L. Nielsen, Sami Niemi, Kai G. Noeske, Casey J. Papovich, Laura Pentericci, Alexandra Pope, Joel R. Primack, Swara Ravindranath, Naveen A. Reddy, Alvio Renzini, Hans-Walter Rix, Aday R. Robaina, David J. Rosario, Piero Rosati, Sara Salimbeni, Claudia Scarlata, Brian Siana, Luc Simard, Joseph Smidt, Diana Snyder, Rachel S. Somerville, Hyron Spinrad, Amber N. Straughn, Olivia Telford, Harry I. Teplitz, Jonathan R. Trump, Carlos Vargas, Carolin Villforth, Cory R. Wagner, Pat Wandro, Risa H. Wechsler, Benjamin J. Weiner, Tommy Wiklind, Vivienne Wild, Grant Wilson, Stijn Wuyts, Min S. Yun Jan 2010

Candels: The Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey - The Hubble Space Telescope Observations, Imaging Data Products And Mosaics, Anton M. Koekemoer, S. M. Faber, Henry C. Ferguson, Norman A. Grogin, Dale D. Kocevski, David C. Koo, Kamson Lai, Jennifer M. Lotz, Ray. A. Lucas, Elizabeth J. Mcgrath, Sara Ogaz, Abhijith Rajan, Adam G. Riess, Steve A. Rodney, Louis Strolger, Stefano Casertano, Marco Castellano, Tomas Dahlen, Mark Dickinson, Timothy Dolch, Adriano Fontana, Mauro Giavalisco, Andrea Grazian, Yicheng Guo, Nimish P. Hathi, Kuang-Han Huang, Arjen Van Der Wel, Hao-Jing Yan, Viviana Acquaviva, David M. Alexander, Omar Almaini, Matthew L. N. Ashby, Marco Barden, Eric F. Bell, Frédéric Bournaud, Thomas M. Brown, Karina I. Caputi, Paolo Cassata, Peter Challis, Ranga-Ram Chary, Edmond Cheung, Michele Cirasuolo, Christopher J. Conselice, Asantha Roshan, Darren J. Croton, Emanuele Daddi, Romeel Davé, Dulia F. De Mello, Loic De Ravel, Avishai Dekel, Jennifer L. Donley, James S. Dunlop, Aaron A. Dutton, David Elbaz, Giovanni G. Fazio, Alex F. Filippenko, Steven L. Finkelstein, Chris Frazer, Jonathan P. Gardner, Peter M. Garnavich, Eric Gawiser, Ruth Gruetzbauch, Will G. Hartley, Boris Häussler, Jessica Herrington, Philip F. Hopkins, Jia-Sheng Huang, Saurabh Jha, Andrew Johnson, Jeyhan S. Kartaltepe, Ali Ahmad Khostovan, Robert P. Kirshner, Caterina Lani, Kyoung-Soo Lee, Weidong Li, Piero Madau, Patrick J. Mccarthy, Daniel H. Mcintosh, Ross J. Mclure, Conor Mcpartland, Bahram Mobasher, Heidi Moreira, Alice Mortlock, Leonidas A. Moustakas, Mark Mozena, Kirpal Nandra, Jeffrey A. Newman, Jennifer L. Nielsen, Sami Niemi, Kai G. Noeske, Casey J. Papovich, Laura Pentericci, Alexandra Pope, Joel R. Primack, Swara Ravindranath, Naveen A. Reddy, Alvio Renzini, Hans-Walter Rix, Aday R. Robaina, David J. Rosario, Piero Rosati, Sara Salimbeni, Claudia Scarlata, Brian Siana, Luc Simard, Joseph Smidt, Diana Snyder, Rachel S. Somerville, Hyron Spinrad, Amber N. Straughn, Olivia Telford, Harry I. Teplitz, Jonathan R. Trump, Carlos Vargas, Carolin Villforth, Cory R. Wagner, Pat Wandro, Risa H. Wechsler, Benjamin J. Weiner, Tommy Wiklind, Vivienne Wild, Grant Wilson, Stijn Wuyts, Min S. Yun

Mauro Giavalisco

This paper describes the Hubble Space Telescope imaging data products and data reduction procedures for the Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey (CANDELS). This survey is designed to document the evolution of galaxies and black holes at $z\sim1.5-8$, and to study Type Ia SNe beyond $z>1.5$. Five premier multi-wavelength sky regions are selected, each with extensive multiwavelength observations. The primary CANDELS data consist of imaging obtained in the Wide Field Camera 3 / infrared channel (WFC3/IR) and UVIS channel, along with the Advanced Camera for Surveys (ACS). The CANDELS/Deep survey covers \sim125 square arcminutes within GOODS-N and GOODS-S, …

Go to article

A High Resolution Line Survey Of Irc +10216 With Herschel/Hifi, Robin Lombaert, Jose Cenicharo, L.B.F.M. Waters, Leen Decin, Pierre Encrenaz, A.G.G.M. Tielens, Marcelino Agundez, Elvire De Beck, Holger S.P. Muller, Javier R. Goicoechea, Michael J. Barlow, Arnold Benz, Nicolas Crimier, Fabien Daniel, Anna Maria Di Giorgio, Michael Fich, Todd Gaier, Pedro Garcia-Lario, Alex De Koter, Theo Khouri, Rene Liseau, Neal A. Erickson, Juan R. Pardo, John C. Pearson, Russell Shipman, Carmen Sanchez Contreras, David Teyssier Jan 2010

A High Resolution Line Survey Of Irc +10216 With Herschel/Hifi, Robin Lombaert, Jose Cenicharo, L.B.F.M. Waters, Leen Decin, Pierre Encrenaz, A.G.G.M. Tielens, Marcelino Agundez, Elvire De Beck, Holger S.P. Muller, Javier R. Goicoechea, Michael J. Barlow, Arnold Benz, Nicolas Crimier, Fabien Daniel, Anna Maria Di Giorgio, Michael Fich, Todd Gaier, Pedro Garcia-Lario, Alex De Koter, Theo Khouri, Rene Liseau, Neal A. Erickson, Juan R. Pardo, John C. Pearson, Russell Shipman, Carmen Sanchez Contreras, David Teyssier

Neal Erickson

We present the first results of a high-spectral-resolution survey of the carbon-rich evolved star IRC+10216 that was carried out with the HIFI spectrometer onboard Herschel. This survey covers all HIFI bands, with a spectral range from 488 to 1901 GHz. In this letter we focus on the band-1b spectrum, in a spectral range 554.5 − 636.5 GHz, where we identified 130 spectral features with intensities above 0.03K and a signal–to– noise ratio >5. Detected lines arise from HCN, SiO, SiS, CS, CO, metal-bearing species and, surprisingly, silicon dicarbide (SiC2). We identified 55 SiC2 transitions involving energy levels between 300 and …

Go to article

A Z=1.82 Analog Of Local Ultra-Massive Elliptical Galaxies, M. Onodera, E. Daddi, R. Gobat, M. Cappellari, N. Arimoto, A. Renzini, Y. Yamada, H. J. Mccracken, C. Mancini, P. Capak, M. Carollo, A. Cimatti, Mauro Giavalisco, O. Ilbert, X. Kong, S. Lilly, K. Motohara, K. Ohta, D. B. Sanders, N. Scoville, N. Tamura, Y. Taniguchi Jan 2010

A Z=1.82 Analog Of Local Ultra-Massive Elliptical Galaxies, M. Onodera, E. Daddi, R. Gobat, M. Cappellari, N. Arimoto, A. Renzini, Y. Yamada, H. J. Mccracken, C. Mancini, P. Capak, M. Carollo, A. Cimatti, Mauro Giavalisco, O. Ilbert, X. Kong, S. Lilly, K. Motohara, K. Ohta, D. B. Sanders, N. Scoville, N. Tamura, Y. Taniguchi

Mauro Giavalisco

We present observations of a very massive galaxy at z=1.82 which show that its morphology, size, velocity dispersion and stellar population properties that are fully consistent with those expected for passively evolving progenitors of today's giant ellipticals. These findings are based on a deep optical rest-frame spectrum obtained with the Multi-Object InfraRed Camera and Spectrograph (MOIRCS) on the Subaru telescope of a high-z passive galaxy candidate (pBzK) from the COSMOS field, for which we accurately measure its redshift of z=1.8230 and obtain an upper limit on its velocity dispersion sigma_star<326 km/s. By detailed stellar population modeling of both the galaxy broad-band SED and the rest-frame optical spectrum we derive a star-formation-weighted age and formation redshift of t_sf~1-2 Gyr and z_form~2.5-4, and a stellar mass of M_star~(3-4)x10^{11} M_sun. This is in agreement with a virial mass limit of M_vir<7x10^{11}M_sun, derived from the measured sigma_star value and stellar half-light radius, as well as with the dynamical mass limit based on the Jeans equations. In contrast with previously reported super-dense passive galaxies at z~2, the present galaxy at z=1.82 appears to have both size and velocity dispersion similar to early-type galaxies in the local Universe with similar stellar mass. This suggests that z~2 massive and passive galaxies may exhibit a wide range of properties, then possibly following quite different evolutionary histories from z~2 to z=0.

Go to article

A Detailed Study Of Photometric Redshifts For Goods-South Galaxies, Tomas Dahlen, Bahram Mobasher, Mark Dickinson, Henry C. Ferguson, Mauro Giavalisco, Norman A. Grogin, Yicheng Guo, Anton Koekemoer, Kyoung-Soo Lee, Seong-Kook Lee, Mario Nonino, Adam G. Reiss, Sara Salimbeni Jan 2010

A Detailed Study Of Photometric Redshifts For Goods-South Galaxies, Tomas Dahlen, Bahram Mobasher, Mark Dickinson, Henry C. Ferguson, Mauro Giavalisco, Norman A. Grogin, Yicheng Guo, Anton Koekemoer, Kyoung-Soo Lee, Seong-Kook Lee, Mario Nonino, Adam G. Reiss, Sara Salimbeni

Mauro Giavalisco

We use the deepest and the most comprehensive photometric data currently available for GOODS-South galaxies to measure their photometric redshifts. The photometry includes VLT/VIMOS (U-band), HST/ACS (F435W, F606W, F775W, and F850LP bands), VLT/ISAAC (J-, H-, and Ks-bands), and four Spitzer/IRAC channels (3.6, 4.5, 5.8, and 8.0 micron). The catalog is selected in the z-band (F850LP) and photometry in each band is carried out using the recently completed TFIT algorithm, which performs PSF matched photometry uniformly across different instruments and filters, despite large variations in PSFs and pixel scales. Photometric redshifts are derived using the GOODZ code, which is based on …

Go to article

A Deep Hst Search For Escaping Lyman Continuum Flux At Z~1.3: Evidence For An Evolving Ionizing Emissivity, Brian Siana, Harry I. Teplitz, Henry C. Ferguson, Thomas M. Brown, Mauro Giavalisco, Mark Dickinson, Carrie R. Bridge, Ranga-Ram Chary, Duilia F. De Mello, Christopher J. Conselice, Jonathan P. Gardner, James W. Colbert, Claudia Scarlata Jan 2010

A Deep Hst Search For Escaping Lyman Continuum Flux At Z~1.3: Evidence For An Evolving Ionizing Emissivity, Brian Siana, Harry I. Teplitz, Henry C. Ferguson, Thomas M. Brown, Mauro Giavalisco, Mark Dickinson, Carrie R. Bridge, Ranga-Ram Chary, Duilia F. De Mello, Christopher J. Conselice, Jonathan P. Gardner, James W. Colbert, Claudia Scarlata

Mauro Giavalisco

We have obtained deep Hubble Space Telescope far-UV images of 15 starburst galaxies at z~1.3 in the GOODS fields to search for escaping Lyman continuum photons. These are the deepest far-UV images m_{AB}=28.7, 3\sigma, 1" diameter) over this large an area (4.83 arcmin^2) and provide the best escape fraction constraints for any galaxy at any redshift. We do not detect any individual galaxies, with 3\sigma limits to the Lyman Continuum (~700 \AA) flux 50--149 times fainter (in f_nu) than the rest-frame UV (1500 \AA) continuum fluxes. Correcting for the mean IGM attenuation (factor ~2), as well as an intrinsic stellar …

Go to article

First Prev Next Last