162,069 research outputs found
Primordial black hole formation during first-order phase transitions
No full textPrimordial black holes (PBHs) may form in the early universe when pre-existing adiabatic density fluctuations enter into the cosmological horizon and recollapse. It has been suggested that PBH formation may be facilitated when fluctuations enter into the horizon during a strongly first-order phase transition which proceeds in approximate equilibrium. We employ general-relativistic hydrodynamics numerical simulations in order to follow the collapse of density fluctuations during first-order phase transitions. We find that during late stages of the collapse fluctuations separate into two regimes, an inner part existing exclusively in the high-energy density phase with energy density εh, surrounded by an outer part which exists exclusively in the low-energy density phase with energy density εh-L, where L is the latent heat of the transition. We confirm that the fluctuation density threshold δε/ε required for the formation of PBHs during first-order transitions decreases with increasing L and falls below that for PBH formation during ordinary radiation dominated epochs. Our results imply that, in case PBHs form at all in the early universe, their mass spectrum is most likely dominated by the approximate horizon masses during epochs when the universe undergoes phase transitions. ©1999 The American Physical Society
[Report to Chief J. E. Curry, by an unknown author #1]
No full textReport to Chief J. E. Curry, by an unknown author. The report contains a list of officers who gave depositions to the United States Attorney
[Report to Chief J. E. Curry, by an unknown author #2]
No full textReport to Chief J. E. Curry, by an unknown author. The report contains a list of officers who gave depositions to the United States Attorney
Near-critical gravitational collapse and the initial mass function of primordial black holes
No full textThe recent discovery of critical phenomena arising in gravitational collapse near the threshold of black hole formation is used to estimate the initial mass function of primordial black holes (PBHs). It is argued that the scaling relation between black hole mass and initial perturbation found for a collapsing radiation fluid in an asymptotically flat space-time also applies to PBH formation in a Friedmann Universe, indicating the possible formation of PBHs with masses much smaller than one horizon mass. Owing to the natural fine-tuning of initial conditions by the exponential decline of the probability distribution for primordial density fluctuations, sub-horizon mass PBHs are expected to form at all epochs. This result suggests that the constraints on the primordial fluctuation spectrum based on the abundance of PBHs at different mass scales may have to be revisited. (orig.)19 refs.Available from TIB Hannover: RR 4697(1081) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman
Murder on the mountain: author talk with Peter J. Wosh
No full textAuthor talk by Peter J. Wosh on May 5th, 2022, on his book, "Murder on the Mountain: crime, passion, and punishment in gilded age New Jersey.
Machine learning applied to fiber-fed focal plane wavefront sensing: a study of aberrated wave transmission through multimode optical fibers
No full textThis research explores the potential of machine learning and neural networks in recognizing the input features of aberrated wavefronts transmitted through multimode optical fibers, in view of applications for wavefront sensing in ground-based telescopes. Recent studies highlight the efficacy of multimode fibers for imaging and sensing, suggesting neural networks' effectiveness in mapping relationships between output distortions and input wavefront aberrations. The initial step of our study concerned multimode fiber propagation simulations. An input Gaussian beam was distorted with known aberrations and then sent through the fiber to analyze the effects on the output. This groundwork was used to train and validate a Convolutional Neural Network architecture. Its main role was to understand, from output images, which type of aberration was superimposed in input. We obtained promising results with test accuracy of 85% and 87%, while achieving good performance in network training and generalization
Mr. Melvin J. Collier, RWWL AUC, June 2011
No full textThis video is a conversation with Mr. Melvin J. Collier. Mr. Collier talks about his book, "From Mississippi to Africa: A Journey of Discovery". Daniel Le, AUC Woodruff Library, is the interviewer
A Tripartite Post-Recession Rebalancing
No full textIn this latest Advance & Rutgers Report, entitled “A Tripartite Post-Recession Rebalancing,” Dean James W. Hughes and Professor Joseph J. Seneca deliver an incisive assessment of the current market conditions and obstacles in the path of our economic recovery. They offer a statistical cautionary tale that the private and public sector need to hear and acknowledge in order for the economy to make continued progress.This report was published as Issue Paper Number 7, November 2011, in Advance & Rutgers Report
Evidence for the decay B0→J/ψω and measurement of the relative branching fractions of meson decays to J/ψη and J/ψη′
No full textFirst evidence of the B 0 → J / ψ ω decay is found and the B s 0 → J / ψ η and B s 0 → J / ψ η ′ decays are studied using a dataset corresponding to an integrated luminosity of 1.0 fb -1 collected by the LHCb experiment in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV. The branching fractions of these decays are measured relative to that of the B 0 → J / ψ ρ 0 decay:frac(B (B 0 → J / ψ ω), B (B 0 → J / ψ ρ 0)) = 0.89 ± 0.19 (stat) - 0.13 + 0.07 (syst),frac(B (B s 0 → J / ψ η), B (B 0 → J / ψ ρ 0)) = 14.0 ± 1.2 (stat) - 1.5 + 1.1 (syst) - 1.0 + 1.1 (frac(f d, f s)),frac(B (B s 0 → J / ψ η ′), B (B 0 → J / ψ ρ 0)) = 12.7 ± 1.1 (stat) - 1.3 + 0.5 (syst) - 0.9 + 1.0 (frac(f d, f s)), where the last uncertainty is due to the knowledge of f d / f s, the ratio of b-quark hadronization factors that accounts for the different production rate of B 0 and B s 0 mesons. The ratio of the branching fractions of B s 0 → J / ψ η ′ and B s 0 → J / ψ η decays is measured to befrac(B (B s 0 → J / ψ η ′), B (B s 0 → J / ψ η)) = 0.90 ± 0.09 (stat) - 0.02 + 0.06 (syst)
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