Linear gas stoppers are widely used to convert high-energy, rare-isotope beams and reaction products into low-energy beams with small transverse emittance and energy spread. Stopping of the high-energy ions is achieved through interaction with a buffer gas, typically helium, generating large quantities of He+/e− pairs. The Advanced Cryogenic Gas Stopper (ACGS) was designed for fast, efficient stopping and extraction of high-intensity, rare-isotope beams. As part of the design process, a comprehensive particle-in-cell code was developed to optimize the transport and extraction of rare isotopes from the ACGS in the presence of space charge, including He+/e− dynamics, buffer gas interactions including gas flow, radio-frequency carpets, and ion extraction through a nozzle or orifice. Details of the simulations are presented together with comparison to experiment when available.

VL - 496 UR - https://www.sciencedirect.com/science/article/pii/S0168583X21001117 ER - TY - JOUR T1 - Ice cover, winter circulation, and exchange in Saginaw Bay and Lake Huron JF - Limnology and Oceanography Y1 - 2017 A1 - Tuan D. Nguyen A1 - Nathan Hawley A1 - Mantha S. Phanikumar AB -Winter circulation exerts a strong control on the release and timing of nutrients and contaminants from bays into the adjoining lakes. To estimate winter residence times of solutes in the presence of ice cover, we used an ice model coupled to hydrodynamic, thermal and solute transport models of Saginaw Bay and Lake Huron for two low (2010 and 2013) and two high (2009 and 2014) ice years. The models were tested using temperature data from thermistor chains and current data from ADCP moorings deployed during the winter- time. Simulated water temperatures compared favorably to lake-wide average surface temperatures derived from NOAA’s AVHRR satellite imagery. Simulated results of ice cover are in agreement with observed data from the Great Lakes Ice Atlas. Our results indicate that ice cover significantly dampens water movement producing almost stagnant conditions around February. Estimates of residence times for Saginaw Bay (defined as the e-folding flushing time based on vertically integrated dye concentrations) show that the mean resi- dence times in a low ice year (2013) are 2.2 months for the inner bay, and 3.5 months for the entire bay. The corresponding numbers for a high ice year (2014) are 4.9 and 5.3 months, respectively. Considering the entire bay, solutes stored in the bay can be expected to be released into the lake between March (low ice year) and April (high ice year). These results are expected to aid in understanding the behavior of contami- nants in the Great Lakes during the winter months and in early spring.

VL - 62 UR - http://www.egr.msu.edu/~phani/lno10431.pdf IS - 1 ER - TY - JOUR T1 - Twist-averaged boundary conditions for nuclear pasta Hartree-Fock calculations Y1 - 2015 A1 - B. Schuetrumpf A1 - W. Nazarewicz VL - 92 JO - Physical Review C ER - TY - JOUR T1 - Determining the rp-Process Flow through 56Ni: Resonances in 57Cu(p,g)58Zn Indentified with GRETINA JF - PHYSICAL REVIEW LETTERS Y1 - 2014 A1 - C. Langer A1 - F. Montes A1 - A. Aprahamian A1 - D.W. Bardayan A1 - D. Bazin A1 - B. A. Brown A1 - J. Browne A1 - H. Crawford A1 - R. Cyburt A1 - C. Domingo-Pardo A1 - A. Gade A1 - S. George A1 - P. Hosmer A1 - L. Keek A1 - A. Kontos A1 - I.Y. Lee A1 - A. Lemasson A1 - E. Lunderberg A1 - Y. Maeda A1 - M. Matos A1 - Z. Meisel A1 - S. Noji A1 - F.M. Nunes A1 - A. Nystrom A1 - G. Perdikakis A1 - J. Pereira A1 - S.J. Quinn A1 - F. Recchia A1 - H. Schatz A1 - M. Scott A1 - K. Siegl A1 - A. Simon A1 - M. Smith A1 - A. Spyrou A1 - J. Stevens A1 - S.R. Stroberg A1 - D. Weisshaar A1 - J. Wheeler A1 - K. Wimmer A1 - R.G.T. Zegers VL - 113 UR - http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.113.032502 ER - TY - JOUR T1 - Shell and Shape Evolution at N=28: The 40Mg Ground State JF - PHYSICAL REVIEW C Y1 - 2014 A1 - H.L. Crawford A1 - P. Fallon A1 - A.O. Macchiavelli A1 - R.M. Clark A1 - B. A. Brown A1 - J.A. Tostevin A1 - D. Bazin A1 - N. Aoi A1 - P. Doornenbal A1 - M. Matsushita A1 - H. Scheit A1 - D. Steppenbeck A1 - S. Takeuchi A1 - H. Baba A1 - C.M. Campbell A1 - M. Cromaz A1 - E. Ideguchi A1 - N. Kobayashi A1 - Y. Kondo A1 - G. Lee A1 - I.Y. Lee A1 - J. Lee A1 - K. Li A1 - S. Michimasa A1 - T. Motobayashi A1 - T. Nakamura A1 - S. Ota A1 - S. Paschalis A1 - M. Petri A1 - T. Sako A1 - H. Sakurai A1 - S. Shimoura A1 - M. Takechi A1 - Y. Togano A1 - H. Wang A1 - K. Yoneda VL - 80 UR - http://journals.aps.org/prc/abstract/10.1103/PhysRevC.89.041303 ER - TY - JOUR T1 - CLASH: The Enhanced Lensing Efficiency of the Highly Elongated Merging Cluster MACS J0416.1-2403 JF - The Astrophysical Journal Letters Y1 - 2013 A1 - Zitrin, A. A1 - Meneghetti, M A1 - Umetsu, K A1 - Broadhurst, T. A1 - Bartelmann, M A1 - Bouwens, R. A1 - Bradley, L A1 - Carrasco, M. A1 - Coe, D. A1 - Ford, H A1 - Kelson, D. A1 - Koekemoer, A. M A1 - Medezinski, E A1 - Moustakas, J. A1 - Moustakas, L. A. A1 - Nonino, M. A1 - Postman, M. A1 - Rosati, P. A1 - Seidel, G A1 - Seitz, S. A1 - Sendra, I A1 - Shu, X A1 - Vega, J A1 - Zheng, W KW - dark matter KW - galaxies: clusters: general KW - galaxies: clusters: individual: MACS J0416.1–2403 KW - Galaxies: High-Redshift KW - gravitational lensing: strong VL - 762 IS - 2 ER - TY - JOUR T1 - CLASH: The Enhanced Lensing Efficiency of the Highly Elongated Merging Cluster MACS J0416.1-2403 JF - The Astrophysical Journal Letters Y1 - 2013 A1 - Zitrin, A. A1 - Meneghetti, M A1 - Umetsu, K A1 - Broadhurst, T. A1 - Bartelmann, M A1 - Bouwens, R. A1 - Bradley, L A1 - Carrasco, M. A1 - Coe, D. A1 - Ford, H A1 - Kelson, D. A1 - Koekemoer, A. M A1 - Medezinski, E A1 - Moustakas, J. A1 - Moustakas, L. A. A1 - Nonino, M. A1 - Postman, M. A1 - Rosati, P. A1 - Seidel, G A1 - Seitz, S. A1 - Sendra, I A1 - Shu, X A1 - Vega, J A1 - Zheng, W KW - dark matter KW - galaxies: clusters: general KW - galaxies: clusters: individual: MACS J0416.1–2403 KW - Galaxies: High-Redshift KW - gravitational lensing: strong VL - 762 ER - TY - JOUR T1 - The joint effects of efficacy and compliance: a study of household water treatment effectiveness against childhood diarrhea JF - Water research Y1 - 2013 A1 - Enger, Kyle S A1 - Nelson, Kara L A1 - Rose, Joan B A1 - Eisenberg, Joseph N S AB -The effectiveness of household water treatment ({HWT)} at reducing diarrheal disease is related to the efficacy of the {HWT} method at removing pathogens, how people comply with {HWT}, and the relative contributions of other pathogen exposure routes. We define compliance with {HWT} as the proportion of drinking water treated by a community. Although many {HWT} methods are efficacious at removing or inactivating pathogens, their effectiveness within actual communities is decreased by imperfect compliance. However, the quantitative relationship between compliance and effectiveness is poorly understood. To assess the effectiveness of {HWT} on childhood diarrhea incidence via drinking water for three pathogen types (bacterial, viral, and protozoan), we developed a quantitative microbial risk assessment ({QMRA)} model. We examined the relationship between log(10) removal values ({LRVs)} and compliance with {HWT} for scenarios varying by: baseline incidence of diarrhea; etiologic fraction of diarrhea by pathogen type; pattern of compliance within a community; and size of contamination spikes in source water. Benefits from increasing {LRVs} strongly depend on compliance. For perfect compliance, diarrheal incidence decreases as {LRVs} increase. However, if compliance is incomplete, there are diminishing returns from increasing {LRVs} in most of the scenarios we considered. Higher {LRVs} are more beneficial if: contamination spikes are large; contamination levels are generally high; or some people comply perfectly. The effectiveness of {HWT} interventions at the community level may be limited by imperfect compliance, such that the benefits of high {LRVs} are not realized. Compliance with {HWT} should be carefully measured during {HWT} field studies and {HWT} dissemination programs. Studies of pathogen concentrations in a variety of developing-country source waters are also needed. Guidelines are needed for measuring and promoting compliance with {HWT.}

VL - 47 N1 - {PMID:} 23290123 ER - TY - JOUR T1 - A Census of Star-Forming Galaxies in the z~9-10 Universe based on HST+Spitzer Observations Over 19 CLASH clusters: Three Candidate z~9-10 Galaxies and Improved Constraints on the Star Formation Rate Density at z~9.2 JF - Astrophysical Journal Y1 - 2012 A1 - Bouwens, R, A1 - Bradley, L A1 - Zitrin, A. A1 - Coe, D. A1 - Franx, M. A1 - Zheng, W A1 - Smit, R A1 - Host, O. A1 - Postman, M. A1 - Moustakas, L A1 - Labbe, I A1 - Carrasco, M. A1 - Molino, A. A1 - Donahue, M A1 - Kelson, D. D A1 - Meneghetti, M A1 - Jha, S. A1 - Benitez, N A1 - Lemze, D A1 - Umetsu, K A1 - Broadhurst, T. A1 - Moustakas, J. A1 - Rosati, P. A1 - Bartelmann, M A1 - Ford, H A1 - Graves, G. A1 - Grillo, C. A1 - Infante, L A1 - Jiminez-Teja, Y A1 - Jouvel, S A1 - Lahav, O. A1 - Maoz, D A1 - Medezinski, E A1 - Melchior, P A1 - Merten, J A1 - Nonino, M. A1 - Ogaz, S. A1 - Seitz, S. KW - Astrophysics - Cosmology and Extragalactic Astrophysics ER - TY - JOUR T1 - CLASH: Discovery of a Bright z ~= 6.2 Dwarf Galaxy Quadruply Lensed by MACS J0329.6-0211 JF - The Astrophysical Journal Letters Y1 - 2012 A1 - Zitrin, A. A1 - Moustakas, J. A1 - Bradley, L A1 - Coe, D. A1 - Moustakas, L. A. A1 - Postman, M. A1 - Shu, X A1 - Zheng, W A1 - Benítez, N. A1 - Bouwens, R. A1 - Broadhurst, T. A1 - Ford, H A1 - Host, O. A1 - Jouvel, S A1 - Koekemoer, A. A1 - Meneghetti, M A1 - Rosati, P. A1 - Donahue, M A1 - Grillo, C. A1 - Kelson, D. A1 - Lemze, D A1 - Medezinski, E A1 - Molino, A. A1 - Nonino, M. A1 - Ogaz, S. KW - dark matter KW - galaxies: clusters: general KW - galaxies: clusters: individual: MACS J0329.6-0211 KW - Galaxies: High-Redshift KW - gravitational lensing: strong VL - 747 IS - 1 ER - TY - JOUR T1 - CLASH: Mass Distribution in and around MACS J1206.2-0847 from a Full Cluster Lensing Analysis JF - The Astrophysical Journal Y1 - 2012 A1 - Umetsu, Keiichi A1 - Medezinski, Elinor A1 - Nonino, Mario A1 - Merten, Julian A1 - Zitrin, Adi A1 - Molino, Alberto A1 - Grillo, Claudio A1 - Carrasco, Mauricio A1 - Donahue, Megan A1 - Mahdavi, Andisheh A1 - Coe, Dan A1 - Postman, Marc A1 - Koekemoer, Anton A1 - Czakon, Nicole A1 - Sayers, Jack A1 - Mroczkowski, Tony A1 - Golwala, Sunil A1 - Koch, Patrick M A1 - Lin, Kai-Yang A1 - Molnar, Sandor M A1 - Rosati, Piero A1 - Balestra, Italo A1 - Mercurio, Amata A1 - Scodeggio, Marco A1 - Biviano, Andrea A1 - Anguita, Timo A1 - Infante, Leopoldo A1 - Seidel, Gregor A1 - Sendra, Irene A1 - Jouvel, Stephanie A1 - Host, Ole A1 - Lemze, Doron A1 - Broadhurst, Tom A1 - Meneghetti, Massimo A1 - Moustakas, Leonidas A1 - Bartelmann, Matthias A1 - Benítez, Narciso A1 - Bouwens, Rychard A1 - Bradley, Larry A1 - Ford, Holland A1 - Jiménez-Teja, Yolanda A1 - Kelson, Daniel A1 - Lahav, Ofer A1 - Melchior, Peter A1 - Moustakas, John A1 - Ogaz, Sara A1 - Seitz, Stella A1 - Zheng, Wei KW - cosmology: observations KW - dark matter KW - galaxies: clusters: individual: MACS J1206.2-0847 KW - gravitational lensing: strong KW - gravitational lensing: weak VL - 755 IS - 1 ER - TY - JOUR T1 - CLASH: New Multiple Images Constraining the Inner Mass Profile of MACS J1206.2-0847 JF - The Astrophysical Journal Y1 - 2012 A1 - Zitrin, A. A1 - Rosati, P. A1 - Nonino, M. A1 - Grillo, C. A1 - Postman, M. A1 - Coe, D. A1 - Seitz, S. A1 - Eichner, T A1 - Broadhurst, T. A1 - Jouvel, S A1 - Balestra, I. A1 - Mercurio, A A1 - Scodeggio, M A1 - Benítez, N. A1 - Bradley, L A1 - Ford, H A1 - Host, O. A1 - Jimenez-Teja, Y A1 - Koekemoer, A. A1 - Zheng, W A1 - Bartelmann, M A1 - Bouwens, R. A1 - Czoske, O A1 - Donahue, M A1 - Graur, O A1 - Graves, G. A1 - Infante, L A1 - Jha, S. A1 - Kelson, D. A1 - Lahav, O. A1 - Lazkoz, R A1 - Lemze, D A1 - Lombardi, M. A1 - Maoz, D A1 - McCully, C. A1 - Medezinski, E A1 - Melchior, P A1 - Meneghetti, M A1 - Merten, J A1 - Molino, A. A1 - Moustakas, L. A. A1 - Ogaz, S. A1 - Patel, B. A1 - Regoes, E. A1 - Riess, A. A1 - Rodney, S A1 - Umetsu, K A1 - Van der Wel, A. KW - dark matter KW - galaxies: clusters: general KW - galaxies: clusters: individual: MACS J1206.2–0847 KW - Galaxies: High-Redshift KW - gravitational lensing: strong VL - 749 IS - 2 ER - TY - JOUR T1 - CLASH: Precise New Constraints on the Mass Profile Galaxy Cluster A2261 JF - The Astrophysical Journal Y1 - 2012 A1 - Coe, Dan A1 - Umetsu, Keiichi A1 - Zitrin, Adi A1 - Donahue, Megan A1 - Medezinski, Elinor A1 - Postman, Marc A1 - Carrasco, Mauricio A1 - Anguita, Timo A1 - Geller, Margaret J A1 - Rines, Kenneth J. A1 - Diaferio, Antonaldo A1 - Kurtz, Michael J A1 - Bradley, Larry A1 - Koekemoer, Anton A1 - Zheng, Wei A1 - Nonino, Mario A1 - Molino, Alberto A1 - Mahdavi, Andisheh A1 - Lemze, Doron A1 - Infante, Leopoldo A1 - Ogaz, Sara A1 - Melchior, Peter A1 - Host, Ole A1 - Ford, Holland A1 - Grillo, Claudio A1 - Rosati, Piero A1 - Jiménez-Teja, Yolanda A1 - Moustakas, John A1 - Ascaso, Begoña A1 - Lahav, Ofer; A1 - Bartelmann, Matthias A1 - Benítez, Narciso A1 - Bouwens, Rychard A1 - Graur, Or A1 - Graves, Genevieve A1 - Jha, Saurab A1 - Jouvel, Stephanie A1 - Kelson, Daniel A1 - Moustakas, Leonidas A1 - Maoz, Dan A1 - Meneghetti, Massimo A1 - Merten, Julian A1 - Riess, Adam A1 - Rodney, Steve A1 - Seitz, Stella VL - 757 IS - 1 ER - TY - JOUR T1 - A magnified young galaxy from about 500 million years after the Big Bang JF - Nature Y1 - 2012 A1 - Zheng, Wei A1 - Postman, Marc A1 - Zitrin, Adi A1 - Moustakas, John A1 - Shu, Xinwen A1 - Jouvel, Stephanie A1 - Høst, Ole A1 - Molino, Alberto A1 - Bradley, Larry A1 - Coe, Dan A1 - Moustakas, Leonidas A A1 - Carrasco, Mauricio A1 - Ford, Holland A1 - Benítez, Narciso A1 - Lauer, Tod R A1 - Seitz, Stella; B A1 - Bouwens, Rychard A1 - Koekemoer, Anton A1 - Medezinski, Elinor A1 - Bartelmann, Matthias A1 - Broadhurst, Tom A1 - Donahue, Megan A1 - Grillo, Claudio A1 - Infante, Leopoldo A1 - Jha, Saurabh W A1 - Kelson, Daniel D. A1 - Lahav, Ofer A1 - Lemze, Doron A1 - Melchior, Peter A1 - Meneghetti, Massimo A1 - Merten, Julian A1 - Nonino, Mario A1 - Ogaz, Sara A1 - Rosati, Piero A1 - Umetsu, Keiichi A1 - van der Wel, Arjen VL - 489 IS - 7416 ER - TY - JOUR T1 - The Comprehensive Phytopathogen Genomics Resource: An electronic resource for data-mining plant pathogen genomes JF - Database, doi: 10.1093/database/bar053. Y1 - 2011 A1 - Hamilton, J. P. A1 - Neeno-Eckwall, E. A1 - Adhikari, B. A1 - Perna, N. A1 - Tisserat, N. A1 - Leach, J.E. A1 - Lévesque, C. A. A1 - C. R. Buell ER - TY - JOUR T1 - Evaluating error propagation in coupled land-atmosphere models JF - Earth Interactions Y1 - 2011 A1 - Pijanowski, Bryan A1 - Moore, Nathan A1 - Mauree, Desaraden A1 - Niyogi, Dev VL - 15 ER - TY - JOUR T1 - Modeling the combined effect of surface roughness and shear rate on slip flow of simple fluids JF - Physical Review E Y1 - 2010 A1 - A. Niavarani A1 - N. V Priezjev AB -Molecular dynamics (MD) and continuum simulations are carried out to investigate the influence of shear rate and surface roughness on slip flow of a Newtonian fluid. For weak wall-fluid interaction energy, the nonlinear shear-rate dependence of the intrinsic slip length in the flow over an atomically flat surface is computed by MD simulations. We describe laminar flow away from a curved boundary by means of the effective slip length defined with respect to the mean height of the surface roughness. Both the magnitude of the effective slip length and the slope of its rate dependence are significantly reduced in the presence of periodic surface roughness. We then numerically solve the Navier-Stokes equation for the flow over the rough surface using the rate-dependent intrinsic slip length as a local boundary condition. Continuum simulations reproduce the behavior of the effective slip length obtained from MD simulations at low shear rates. The slight discrepancy between MD and continuum results at high shear rates is explained by examination of the local velocity profiles and the pressure distribution along the wavy surface. We found that in the region where the curved boundary faces the mainstream flow, the local slip is suppressed due to the increase in pressure. The results of the comparative analysis can potentially lead to the development of an efficient algorithm for modeling rate-dependent slip flows over rough surfaces.

VL - 81 IS - 1 ER - TY - JOUR T1 - The Properties of X-ray Cold Fronts in a Statistical Sample of Simulated Galaxy Clusters JF - \apj Y1 - 2010 A1 - Hallman, E. J. A1 - Skillman, S. W. A1 - undefined A1 - Smith, B. D. A1 - O'Shea, B. W. A1 - Burns, J. O. A1 - Norman, M. L. KW - galaxies: clusters: intracluster medium KW - large-scale structure of universe KW - methods: numerical KW - X-rays: galaxies: clusters VL - 725 ER - TY - JOUR T1 - Dark Matter Annihilation and Primordial Star Formation JF - \apj Y1 - 2009 A1 - Natarajan, A. A1 - Tan, J. C. A1 - O'Shea, B. W. KW - cosmology: theory KW - dark matter KW - early universe KW - galaxies: formation KW - stars: formation VL - 692 ER - TY - JOUR T1 - The effective slip length and vortex formation in laminar flow over a rough surface JF - Physics of Fluids Y1 - 2009 A1 - A. Niavarani A1 - N. V Priezjev KW - external flows KW - laminar flow KW - Navier-Stokes equations KW - rough surfaces KW - shear flow KW - slip flow KW - vortices AB -The flow of viscous incompressible fluid over a periodically corrugated surface is investigated numerically by solving the Navier–Stokes equation with the local slip and no-slip boundary conditions. We consider the effective slip length which is defined with respect to the level of the mean height of the surface roughness. With increasing corrugation amplitude the effective no-slip boundary plane is shifted toward the bulk of the fluid, which implies a negative effective slip length. The analysis of the wall shear stress indicates that a flow circulation is developed in the grooves of the rough surface provided that the local boundary condition is no-slip. By applying a local slip boundary condition, the center of the vortex is displaced toward the bottom of the grooves and the effective slip length increases. When the intrinsic slip length is larger than the corrugation amplitude, the flow streamlines near the surface are deformed to follow the boundary curvature, the vortex vanishes, and the effective slip length saturates to a constant value. Inertial effects promote vortex flow formation in the grooves and reduce the effective slip length.

VL - 21 IS - 5 ER - TY - JOUR T1 - The Santa Fe Light Cone Simulation Project. II. The Prospects for Direct Detection of the Whim with SZE Surveys JF - \apj Y1 - 2009 A1 - Hallman, E. J. A1 - O'Shea, B. W. A1 - Smith, B. D. A1 - Burns, J. O. A1 - Norman, M. L. KW - cosmic microwave background KW - cosmology: observations KW - cosmology: theory KW - galaxies: clusters: general KW - hydrodynamics KW - methods: numerical VL - 698 ER - TY - JOUR T1 - Three Modes of Metal-Enriched Star Formation in the Early Universe JF - \apj Y1 - 2009 A1 - Smith, B. D. A1 - Turk, M. J. A1 - Sigurdsson, S. A1 - O'Shea, B. W. A1 - Norman, M. L. KW - early universe KW - stars: formation VL - 691 ER - TY - JOUR T1 - The Biermann Battery in Cosmological MHD Simulations of Population III Star Formation JF - \apjl Y1 - 2008 A1 - Xu, H. A1 - O'Shea, B. W. A1 - Collins, D. C. A1 - Norman, M. L. A1 - Li, H. A1 - Shuhua Li KW - cosmology: theory KW - Galaxies: High-Redshift KW - Magnetohydrodynamics: MHD KW - stars: formation VL - 688 ER - TY - JOUR T1 - Cosmological Shocks in Adaptive Mesh Refinement Simulations and the Acceleration of Cosmic Rays JF - \apj Y1 - 2008 A1 - Skillman, S. W. A1 - O'Shea, B. W. A1 - Hallman, E. J. A1 - Burns, J. O. A1 - Norman, M. L. KW - cosmology: theory KW - hydrodynamics KW - ISM: Cosmic Rays KW - methods: numerical VL - 689 ER - TY - JOUR T1 - The Destruction of Cosmological Minihalos by Primordial Supernovae JF - \apj Y1 - 2008 A1 - Whalen, D. J. A1 - van Veelen, B. A1 - O'Shea, B. W. A1 - Norman, M. L. KW - Cosmology: Early Universe KW - cosmology: theory KW - hydrodynamics KW - Stars: Early-Type KW - Stars: Supernovae: Individual VL - 682 ER - TY - JOUR T1 - How the First Stars Regulated Local Star Formation. I. Radiative Feedback JF - \apj Y1 - 2008 A1 - Whalen, D. J. A1 - O'Shea, B. W. A1 - Smidt, J. A1 - Norman, M. L. KW - Cosmology: Early Universe KW - cosmology: theory KW - ISM: H II Regions VL - 679 ER - TY - JOUR T1 - Rheological study of polymer flow past rough surfaces with slip boundary conditions JF - Journal of Chemical Physics Y1 - 2008 A1 - A. Niavarani A1 - N. V Priezjev KW - liquid films KW - molecular dynamics method KW - polymer melts KW - rheology KW - shear flow KW - slip flow KW - surface roughness AB -The slip phenomena in thin polymer films confined by either flat or periodically corrugated surfaces are investigated by molecular dynamics and continuum simulations. For atomically flat surfaces and weak wall-fluid interactions, the shear rate dependence of the slip length has a distinct local minimum which is followed by a rapid increase at higher shear rates. For corrugated surfaces with wavelength larger than the radius of gyration of polymer chains, the effective slip length decays monotonically with increasing corrugation amplitude. At small amplitudes, this decay is reproduced accurately by the numerical solution of the Stokes equation with constant and rate-dependent local slip length. When the corrugation wavelength is comparable to the radius of gyration, the continuum predictions overestimate the effective slip length obtained from molecular dynamics simulations. The analysis of the conformational properties indicates that polymer chains tend to stretch in the direction of shear flow above the crests of the wavy surface.

VL - 129 IS - 14 ER - TY - JOUR T1 - Slip boundary conditions for shear flow of polymer melts past atomically flat surfaces JF - Physical Review E Y1 - 2008 A1 - A. Niavarani A1 - N. V Priezjev KW - molecular dynamics KW - shear rate KW - slip length KW - slip velocity KW - smooth thermal surfaces AB -Molecular dynamics simulations are carried out to investigate the dynamic behavior of the slip length in thin polymer films confined between atomically smooth thermal surfaces. For weak wall-fluid interactions, the shear rate dependence of the slip length acquires a distinct local minimum followed by a rapid growth at higher shear rates. With increasing fluid density, the position of the local minimum is shifted to lower shear rates. We found that the ratio of the shear viscosity to the slip length, which defines the friction coefficient at the liquid/solid interface, undergoes a transition from a nearly constant value to power law decay as a function of the slip velocity. In a wide range of shear rates and fluid densities, the friction coefficient is determined by the product of the value of the surface-induced peak in the structure factor and the contact density of the first fluid layer near the solid wall.

VL - 77 IS - 4 ER - TY - JOUR T1 - Active-Space Symmetry-Adapted-Cluster Configuration-Interaction and Equation-of-Motion Cluster Methods for High Accuracy Calculations of Potential Energy Surfaces of Radicals JF - The Journal of Chemical Physics Y1 - 2007 A1 - Y. Ohtsuka A1 - Piotr Piecuch A1 - J. R Gour A1 - M. Ehara A1 - H. Nakatsuji KW - configuration interactions KW - coupled cluster calculations KW - electron attachment KW - excited states KW - free radicals KW - ground states KW - ionisation KW - organic compounds KW - oxygen compounds KW - potential energy surfaces AB -The electron-attached (EA) and ionized (IP) symmetry-adapted-cluster configuration-interaction (SAC-CI) methods and their equation-of-motion coupled-cluster (EOMCC) analogs provide an elegant framework for studying open-shell systems. As shown in this study, these schemes require the presence of higher-order excitations, such as the four-particle-three-hole (4p-3h) or four-hole–three-particle (4h-3p) terms, in the electron attaching or ionizing operator R in order to produce accurate ground- and excited-state potential energy surfaces of radicals along bond breaking coordinates. The full inclusion of the 4p-3h/4h-3p excitations in the EA/IP SAC-CI and EOMCC methods leads to schemes which are far too expensive for calculations involving larger radicals and realistic basis sets. In order to reduce the large costs of such schemes without sacrificing accuracy, the active-space EA/IP EOMCC methodology [ J. R. Gour et al., J. Chem. Phys. 123, 134113 (2005) ] is extended to the EA/IP SAC-CI approaches with 4p-3h/4h-3p excitations. The resulting methods, which use a physically motivated set of active orbitals to pick out the most important 3p-2h/3h-2p and 4p-3h/4h-3p excitations, represent practical computational approaches for high-accuracy calculations of potential energy surfaces of radicals. To illustrate the potential offered by the active-space EA/IP SAC-CI approaches with up to 4p-3h/4h-3p excitations, the results of benchmark calculations for the potential energy surfaces of the low-lying doublet states of CH and OH are presented and compared with other SAC-CI and EOMCC methods, and full CI results.

VL - 126 IS - 16 ER - TY - JOUR T1 - Coupled-Cluster Theory for Three-Body Hamiltonians JF - Physical Review C Y1 - 2007 A1 - G. Hagen A1 - T. Papenbrock A1 - D. J. Dean A1 - A. Schwenk A1 - A. NHogga A1 - M. Wloch A1 - Piotr Piecuch AB -We derive coupled-cluster equations for three-body Hamiltonians. The equations for the one- and two-body cluster amplitudes are presented in a factorized form that leads to an efficient numerical implementation. We employ low-momentum two- and three-nucleon interactions and calculate the binding energy of 4He. The results show that the main contribution of the three-nucleon interaction stems from its density-dependent zero-, one-, and two-body terms that result from the normal ordering of the Hamiltonian in coupled-cluster theory. The residual three-body terms that remain after normal ordering can be neglected.

VL - 76 IS - 3 ER - TY - JOUR T1 - Shape and Structure of N = Z 64Ge: Electromagnetic Transition Rates from the Application ￼of the Recoil Distance Method to a Knockout Reaction JF - PHYSICAL REVIEW LETTERS Y1 - 2007 A1 - K. Starosta A1 - A. Dewald A1 - A. Dunomes A1 - P. Adrich A1 - A.M. Amthor A1 - T. Baumann A1 - D. Bazin A1 - M. Bowen A1 - B. A. Brown A1 - A. Chester A1 - A. Gade A1 - D. Galaviz A1 - T. Glasmacher A1 - T. Ginter A1 - M. Hausmann A1 - M. Horoi A1 - J. Jolie A1 - B. Melon A1 - D. Miller A1 - V. Moeller A1 - R.P. Norris A1 - T. Pissulla A1 - M. Portillo A1 - W. Rother A1 - Y. Shimbara A1 - A. Stolz A1 - C. Vaman A1 - P. Voss A1 - D. Weisshaar A1 - V. Zelevinsky VL - 99 UR - http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.99.042503 ER - TY - JOUR T1 - Can a Single-Reference Approach Provide a Balanced Description of Ground and Excited States? A Comparison of the Completely Renormalized Equation-of-the-Motion Coupled-Cluster Method with Multi-Reference Quasi-Degenerate Perturbation Theory Near a Conical JF - Journal of Chemical Physics A Y1 - 2005 A1 - Piotr Piecuch A1 - S. Nangia A1 - Truhlar, D.G. A1 - M. J. {McGuire} AB -We calculated the two lowest electronically adiabatic potential energy surfaces of ammonia in the region of the conical intersection and at a sequence of geometries along which one of the N-H bonds is broken. We employed both a multireference (MR) method and a single-reference (SR) method. The MR calculations are based on multiconfiguration quasidegenerate perturbation theory (MC-QDPT) with a 6-311+G(3df,3pd) basis set. The SR calculations, carried out with the same basis, employ the completely renormalized equation-ofmotion coupled-cluster method with singles and doubles, and a noniterative treatment of triples, denoted CR-EOMCCSD(T). At 91 geometries used for comparison, including geometries near a conical intersection, the surfaces agree to 7% on average.

VL - 109 IS - 51 ER -