3,622 research outputs found

    Home Front to War Front: The Navy Nurse Corps During World War II

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    The Navy Nurse Corps was created in 1908, when President Theodore Roosevelt signed the Naval Appropriations Bill. Twenty women were selected to become the corps’ first members. These women were referred to as the “The Sacred Twenty.” On December 7, 1941, when the Japanese bombed Pearl Harbor, the Navy Nurse Corps, was one of the first groups to respond. These women were important in preventing further deaths following the attack. However the experiences of Navy nurses during World II are often left untold because their story is overshadowed by the Army Nurse Corps, which doubled in size during the war. However, not one person’s experience is typical. This paper tells the stories of the women in the Navy Nurse Corps during World War II, through the experiences of Dora Cline Fechtmann, Dorothy Still Danner, Mary Rose “Red” Harrington and other Navy nurses

    Optimal control of circular cylinder wakes using long control horizons

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    The classical problem of suppressing vortex shedding in the wake of a circular cylinder by using body rotation is revisited in an adjoint-based optimal control framework. The cylinder's unsteady and fully unconstrained rotation rate is optimized at Reynolds numbers between 75 and 200 and over horizons that are longer than in previous studies, where they are typically of the order of a vortex shedding period or shorter. In the best configuration, the drag is reduced by 19%, the vortex shedding is effectively suppressed, and this low drag state is maintained with minimal cylinder rotation after transients. Unlike open-loop control, the optimal control is shown to maintain a specific phase relationship between the actuation and the shedding in order to stabilize the wake. A comparison is also given between the performance of optimizations for different Reynolds numbers, cost functions, and horizon lengths. It is shown that the long horizons used are necessary in order to stabilize the vortex shedding efficiently

    Final spin of a coalescing black-hole binary: an Effective-One-Body approach

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    We update the analytical estimate of the final spin of a coalescing black-hole binary derived within the Effective-One-Body (EOB) approach. We consider unequal-mass non-spinning black-hole binaries. It is found that a more complete account of relevant physical effects (higher post-Newtonian accuracy, ringdown losses) allows the {\it analytical} EOB estimate to `converge towards' the recently obtained {\it numerical} results within 2%. This agreement illustrates the ability of the EOB approach to capture the essential physics of coalescing black-hole binaries. Our analytical approach allows one to estimate the final spin of the black hole formed by coalescing binaries in a mass range (Μ=m1m2/(m1+m2)2<0.16\nu=m_1m_2/(m_1+m_2)^2 < 0.16 ) which is not presently covered by numerical simulations.Comment: 8 pages, two figures. To appear in Phys. Rev.

    Comparing Effective-One-Body gravitational waveforms to accurate numerical data

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    We continue the program of constructing, within the Effective-One-Body (EOB) approach, high accuracy, faithful analytic waveforms describing the gravitational wave signal emitted by inspiralling and coalescing binary black holes (BHs). We present the comparable-mass version of a new, resummed 3PN-accurate EOB quadrupolar waveform recently introduced in the small-mass-ratio limit. We compare the phase and the amplitude of this waveform to the recently published results of a high-accuracy numerical relativity (NR) simulation of 15 orbits of an inspiralling equal-mass binary BHs system performed by the Caltech-Cornell group. We find a remarkable agreement, both in phase and in amplitude, between the new EOB waveform and the published numerical data. More precisely: (i) in the gravitational wave (GW) frequency domain Mω<0.08M\omega <0.08 where the phase of one of the non-resummed ``Taylor approximant'' (T4) waveform matches well with the numerical relativity one, we find that the EOB phase fares as well, while (ii) for higher GW frequencies, 0.08<Mωâ‰Č0.140.08<M\omega\lesssim 0.14, where the TaylorT4 approximant starts to significantly diverge from the NR phase, we show that the EOB phase continues to match well the NR one. We further propose various methods of tuning the two inspiral flexibility parameters, a5a_5 and vpolev_{\rm pole}, of the EOB waveform so as to ``best fit'' EOB predictions to numerical data. We find that the maximal dephasing between EOB and NR can then be reduced below 10−310^{-3} GW cycles over the entire span (30 GW cycles) of the simulation. Our resummed EOB amplitude agrees much better with the NR one than any of the previously considered non-resummed, post-Newtonian one.Comment: 15 pages, 7 figures, submitted to Phys. Rev. D. Revised version. Figs. 2-7 improved. Slight changes in a few numbers. One reference adde

    Getting that Sinking Feeling: Analysis and Impacts of Sea Level Rise on Three National Parks along the East Coast, USA

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    Due to global climate change, sea level rise (SLR) has become a threat for future generations, but the extent of this danger is unknown. To help understand the possible effects of SLR on the east coast of the United States, we studied three national parks: Acadia National Park (ACAD), Assateague Island National Seashore (ASIS) and Everglades National Park (EVER). We predicted that ACAD would be less affected by SLR than ASIS and EVER due to the construction of its beach profile. By measuring the beach profile, we found that Sand Beach in ACAD was reflective with an average slope of 3.2 cm/m while South Ocean Beach in ASIS had an intermediate morphology with an average slope of 1.57 cm/m. The Snake Bight Channel beach in EVER was dissipative and had no slope. Using historical Landsat imagery from 1984 to 2016, we estimated that ACAD’s water area increased by 1.61%, that ASIS’s water area increased by 2.47%, and that the EVER’s water area decreased by 0.22% between 1992 and 2011. Using RCP scenarios from the latest IPCC report, we estimated future inundation levels in each park along with the percent change between the best and worst-case scenarios. Under the RCP8.5 scenario, ACAD had 1.36 km2 of inundation, ASIS had 37.11 km2, and EVER had 366.47 km2. ACAD had the highest percent change between the worst and best RCP scenario at 15.70%. ASIS had a slightly smaller percent change at 14.25% and EVER had even less at 10.42%. This study suggests that continued SLR will cause national parks billions of dollars in property damage and the loss of their inherent ecological value

    Gravitational Self Force in a Schwarzschild Background and the Effective One Body Formalism

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    We discuss various ways in which the computation of conservative Gravitational Self Force (GSF) effects on a point mass moving in a Schwarzschild background can inform us about the basic building blocks of the Effective One-Body (EOB) Hamiltonian. We display the information which can be extracted from the recently published GSF calculation of the first-GSF-order shift of the orbital frequency of the last stable circular orbit, and we combine this information with the one recently obtained by comparing the EOB formalism to high-accuracy numerical relativity (NR) data on coalescing binary black holes. The information coming from GSF data helps to break the degeneracy (among some EOB parameters) which was left after using comparable-mass NR data to constrain the EOB formalism. We suggest various ways of obtaining more information from GSF computations: either by studying eccentric orbits, or by focussing on a special zero-binding zoom-whirl orbit. We show that logarithmic terms start entering the post-Newtonian expansions of various (EOB and GSF) functions at the fourth post-Newtonian (4PN) level, and we analytically compute the first logarithm entering a certain, gauge-invariant "redshift" GSF function (defined along the sequence of circular orbits).Comment: 44 page

    Water immersion increases the concentration of the immunoreactive N-terminal fragment of pro-atrial natriuretic factor in human plasma

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    Atrial natriuretic factor (ANF) N-terminal (ANF 1–98) and C-terminal (ANF 99–126) fragments were determined by radioimmunoassay in human plasma. Mean basal plasma ANF N-terminal concentrations in 9 healthy subjects were 461 ± 58 fmol/ml,significantly (p<0.0001) higher than ANF C-terminal concentrations ( 4.8 ± 0.5 fmol/ml). Central volume stimulation by one hour head-out water immersion (WI) induced a significant (p<0.01) increase of the C-terminal peptide levels to 11.6 ± 2.3 fmol/ml,paralleled by a significant (p<0.001) increase of the N-terminal fragment levels to 749 ± 96 fmol/ml. Increases of plasma concentrations of both fragments upon WI correlated significantly (r=0.71;p<0.05). These data suggest cosecretion of the N-terminal fragment with the C-terminal fragment of pro ANF 1–126 following a physiological stimulus of ANF release in man
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