1,640 research outputs found
Toward stable 3D numerical evolutions of black-hole spacetimes
Three dimensional (3D) numerical evolutions of static black holes with
excision are presented. These evolutions extend to about 8000M, where M is the
mass of the black hole. This degree of stability is achieved by using
growth-rate estimates to guide the fine tuning of the parameters in a
multi-parameter family of symmetric hyperbolic representations of the Einstein
evolution equations. These evolutions were performed using a fixed gauge in
order to separate the intrinsic stability of the evolution equations from the
effects of stability-enhancing gauge choices.Comment: 4 pages, 5 figures. To appear in Phys. Rev. D. Minor additions to
text for clarification. Added short paragraph about inner boundary dependenc
Improved compression molding technology for continuous fiber reinforced composite laminates. Part 2: AS-4/Polyimidesulfone prepreg system
AS-4/polyimidesulfone (PISO2) composite prepreg was utilized for the improved compression molding technology investigation. This improved technique employed molding stops which advantageously facilitate the escape of volatile by-products during the B-stage curing step, and effectively minimize the neutralization of the consolidating pressure by intimate interply fiber-fiber contact within the laminate in the subsequent molding cycle. Without the modifying the resin matrix properties, composite panels with both unidirectional and angled plies with outstanding C-scans and mechanical properties were successfully molded using moderate molding conditions, i.e., 660 F and 500 psi, using this technique. The size of the panels molded were up to 6.00 x 6.00 x 0.07 in. A consolidation theory was proposed for the understanding and advancement of the processing science. Processing parameters such as vacuum, pressure cycle design, prepreg quality, etc. were explored
Numerical simulations of neutron star-black hole binaries in the near-equal-mass regime
Simulations of neutron star-black hole (NSBH) binaries generally consider
black holes with masses in the range , where we expect to find
most stellar mass black holes. The existence of lower mass black holes,
however, cannot be theoretically ruled out. Low-mass black holes in binary
systems with a neutron star companion could mimic neutron star-neutron (NSNS)
binaries, as they power similar gravitational wave (GW) and electromagnetic
(EM) signals. To understand the differences and similarities between NSNS
mergers and low-mass NSBH mergers, numerical simulations are required. Here, we
perform a set of simulations of low-mass NSBH mergers, including systems
compatible with GW170817. Our simulations use a composition and temperature
dependent equation of state (DD2) and approximate neutrino transport, but no
magnetic fields. We find that low-mass NSBH mergers produce remnant disks
significantly less massive than previously expected, and consistent with the
post-merger outflow mass inferred from GW170817 for moderately asymmetric mass
ratio. The dynamical ejecta produced by systems compatible with GW170817 is
negligible except if the mass ratio and black hole spin are at the edge of the
allowed parameter space. That dynamical ejecta is cold, neutron-rich, and
surprisingly slow for ejecta produced during the tidal disruption of a neutron
star : . We also find that the final mass of the remnant
black hole is consistent with existing analytical predictions, while the final
spin of that black hole is noticeably larger than expected -- up to for our equal mass case
Actions speak louder than words: outsiders' perceptions of diversity mixed messages
To attract a gender diverse workforce, many employers use diversity statements to publicly signal that they value gender diversity. However, this often represents a misalignment between words and actions (i.e., a diversity mixed message) because most organizations are male dominated, especially in board positions. We conducted 3 studies to investigate the potentially indirect effect of such diversity mixed messages through perceived behavioral integrity on employer attractiveness. In Study 1, following a 2 x 2 design, participants (N = 225) were either shown a pro gender diversity statement or a neutral statement, in combination with a gender diverse board (4 men and 4 women) or a uniform all-male board (8 men). Participants' perceived behavioral integrity of the organization was assessed. In Study 2, participants (N = 251) either read positive or negative reviews of the organization's behavioral integrity. Employer attractiveness was then assessed. Study 3 (N = 427) investigated the impact of board gender composition on perceived behavioral integrity and employer attractiveness using a bootstrapping procedure. Both the causal-chain design of Study 1 and 2, as well as the significance test of the proposed indirect relationship in Study 3, revealed that a diversity mixed message negatively affected an organization's perceived behavioral integrity, and low behavioral integrity in turn negatively impacted employer attractiveness. In Study 3, there was also evidence for a tipping point (more than 1 woman on the board was needed) with regard to participants' perceptions of the organization's behavioral integrity
Roles of Na,K-ATPase in early development and trophectoderm differentiation.
Before implantation into the uterine wall, the mammalian embryo undergoes a period of cell division, cell shape change, and cell differentiation leading to the formation of an outer epithelium, the trophectoderm. The trophectoderm is the part of the embryo that initiates uterine contact and, after transformation to become the trophoblast, uterine invasion. Similar to the kidney nephron, the trophectoderm is a transporting epithelium with distinct apical and basolateral membrane domains; its function is to facilitate transepithelial Na+ and fluid transport for blastocoel formation. That transport is driven by Na,K-adenosine triphosphatase (ATPase) localized in basolateral membranes of the trophectoderm. Preimplantation embryos express multiple alpha and beta subunit isoforms of Na,K-ATPase, potentially constituting multiple isozymes, but the basolaterally located alpha1beta1 isozyme appears to function uniquely to drive fluid transport. Embryos unable to express alpha1 subunits because of targeted deletion of the gene are able to form a blastocoel, but they fail to maintain their integrity and expire during the peri-implantation period. Preimplantation embryos also express the gamma subunit, a modulator of Na,K-ATPase activity, but targeted deletion of that gene did not reveal an essential developmental role. The preimplantation embryo offers a unique model for understanding the roles of Na,K-ATPase subunit isoforms in epithelial development and transepithelial transport
Rushworth M. Kidder: 10-13-1978
In an interview recorded October 13, 1978, Rushworth M. Kidder discusses the poetry and painting of E. E. Cummings. The video includes paintings donated to the College at Brockport by James Sibley Watson, Jr.
Images Discussed:
Sound #5
Masked Female Nudes
Seated Red-Headed Nude
Dance Hall
Scofield Thayer
The Paris Rooftops
Mount Chocorua Sunset
Flowers and Hat: Patchin Placehttps://digitalcommons.brockport.edu/writers_videos/1029/thumbnail.jp
Using Full Information When Computing Modes of Post-Newtonian Waveforms From Inspiralling Compact Binaries in Circular Orbit
The increasing sophistication and accuracy of numerical simulations of
compact binaries (especially binary black holes) presents the opportunity to
test the regime in which post-Newtonian (PN) predictions for the emitted
gravitational waves are accurate. In order to confront numerical results with
those of post-Newtonian theory, it is convenient to compare multipolar
decompositions of the two waveforms. It is pointed out here that the individual
modes can be computed to higher post-Newtonian order by examining the radiative
multipole moments of the system, rather than by decomposing the 2.5PN
polarization waveforms. In particular, the dominant (l = 2, m = 2) mode can be
computed to 3PN order. Individual modes are computed to as high a
post-Newtonian order as possible given previous post-Newtonian results.Comment: 15 page
Analytic Gradients for Complete Active Space Pair-Density Functional Theory
Analytic gradient routines are a desirable feature for quantum mechanical
methods, allowing for efficient determination of equilibrium and transition
state structures and several other molecular properties. In this work, we
present analytical gradients for multiconfiguration pair-density functional
theory (MC-PDFT) when used with a state-specific complete active space
self-consistent field reference wave function. Our approach constructs a
Lagrangian that is variational in all wave function parameters. We find that
MC-PDFT locates equilibrium geometries for several small- to medium-sized
organic molecules that are similar to those located by complete active space
second-order perturbation theory but that are obtained with decreased
computational cost
We Never Can Forget It, or The Memories of Andersonville Prison Pens
1. Oh, we never can forget it.Thro\u27 the many years to come,How we lingered, starved, and waitedIn the prison far from home!How at night we longed for morning,And the morning brought despair,As we breathed the pois\u27nous vaporsOf the vile and stagnant air.
REFRAINFreezing! starving! living death!Father can they know at home?Oh! we never can forget itIn all the years to come.
2. How we suffered in our weaknessFreezing, starving none can tell;Stagg\u27ring near the fatal deadline, Where so many gladly fell;Gazing into ghastly faces,When all joy and hope had fled;Longing, dying for the firelight,With no shelter, clothes, or bed.
3. Oh, we never can forget itNo, that prison-pen so bare,Where we watched in weary silenceFor our scanty, wretched fare:For the loathsome, rancid bacon,And the bitter, mouldy bread,That we clutched with bloodless fingers,Like the fingers of the dead.Refrain. Freezing, starving, &c.
4. How we wondered, in our anguish,If our kindred were no moreIf the starry banner floatedNow as proudly as beforeIf our mothers, sisters, brothers,Prayed for us when they did kneel?Thus when thinking of our home-scenesHow the giddy brain would reel!Refrain. Freezing, starving, &c.
5. Oh, we never can forget it,When the gates were opened wide,When we saw the Union Banner,And our friends were at our side;How we laughed and cried like children,Though we tried to feel like men,As we shouted in our gladness, Home, yes, home; sweet home again. Refrain. Freezing, starving, &c
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