1,854 research outputs found
Astrometric Effects of Gravitational Wave Backgrounds with non-Luminal Propagation Speeds
A passing gravitational wave causes a deflection in the apparent astrometric positions of distant stars. The effect of the speed of the gravitational wave on this astrometric shift is discussed. A stochastic background of gravitational waves would result in a pattern of astrometric deflections which are correlated on large angular scales. These correlations are quantified and investigated for backgrounds of gravitational waves with sub- and super-luminal group velocities. The statistical properties of the correlations are depicted in two equivalent and related ways: as correlation curves and as angular power spectra. Sub-(super-)luminal gravitational wave backgrounds have the effect of enhancing (suppressing) the power in low-order angular modes. Analytical representations of the redshift-redshift and redshift-astrometry correlations are also derived. The potential for using this effect for constraining the speed of gravity is discussed
Fast post-adiabatic waveforms in the time domain: Applications to compact binary coalescences in LIGO and Virgo
We present a computationally efficient (time-domain) multipolar waveform model for quasi-circular spin-aligned compact binary coalescences. The model combines the advantages of the numerical-relativity informed, effective-one-body (EOB) family of models with a post-adiabatic solution of the equations of motion for the inspiral part of the two-body dynamics. We benchmark this model against other state-of-the-art waveforms in terms of efficiency and accuracy. We find a speed-up of one to two orders of magnitude compared to the underlying time-domain EOB model for the total mass range . More specifically, for a low total-mass system, such as a binary neutron star with equal masses of , like GW170817, the computational speedup is around 100 times; for an event with total mass and mass ratio , like GW190412, the speedup is by a factor of , while for a binary system of comparable masses and total mass of , like GW150914, it is by a factor of . We demonstrate that the new model is extremely faithful to the underlying EOB model with unfaithfulness less than across the entire applicable region of parameter space. Finally, we present successful applications of this new waveform model to parameter estimation studies and tests of general relativity
A femtoscopic Correlation Analysis Tool using the Schr\"odinger equation (CATS)
We present a new analysis framework called "Correlation Analysis Tool using
the Schr\"odinger equation" (CATS) which computes the two-particle femtoscopy
correlation function , with being the relative momentum for the
particle pair. Any local interaction potential and emission source function can
be used as an input and the wave function is evaluated exactly. In this paper
we present a study on the sensitivity of to the interaction potential
for different particle pairs: p-p, p-, -p,
-p, p- and -.
For the p-p Argonne and Reid Soft-Core potentials have been tested.
For the other pair systems we present results based on strong potentials
obtained from effective Lagrangians such as EFT for p-,
J\"ulich models for -N and Nijmegen models for
-. For the p- pairs we
employ the latest lattice results from the HAL QCD collaboration. Our detailed
study of different interacting particle pairs as a function of the source size
and different potentials shows that femtoscopic measurements can be exploited
in order to constrain the final state interactions among hadrons. In
particular, small collision systems of the order of 1~fm, as produced in pp
collisions at the LHC, seem to provide a suitable environment for quantitative
studies of this kind.Comment: 16 pages, 13 figures, submitted to EPJ
Extremal Kerr Black Hole Dark Matter from Hawking Evaporation
The Hawking process results in a monotonic decrease of the black hole mass,
but a biased random walk of the black hole angular momentum. We demonstrate
that this stochastic process leads to a significant fraction of primordial
black holes becoming extremal Kerr black holes (EKBHs) of one to a few Planck
masses regardless of their initial mass. For these EKBHs, the probability of
ever absorbing a photon or other particle from the cosmic environment is small,
even in the cores of galaxies. Assuming that EKBHs are stable, they behave as
cold dark matter, and can comprise all of the dark matter if they are formed
with the correct initial abundance.Comment: 11 Pages, 7 figure
Laparoscopic vs. open surgical access radical cystectomy with subsequent orthotopic reconstruction in the treatment of invasive urothelial carcinoma of the bladder
Introduction: Radical cystectomy combined with extended lymph node dissection is the treatment of choice for muscle-invasive bladder cancer and can be performed using open, laparoscopic, or robot-assisted surgical access. Aim: To compare the outcomes of laparoscopic (LRC) and open-access (ORC) radical cystectomy in terms of surgery, oncology, functional outcomes, and complications. Materials and methods: We conducted a retrospective study of 200 patients who had all undergone cystectomy for muscle-invasive bladder cancer within the last 4 years. All patients were divided into groups according to the surgical access: LRC in 30 patients and ORC in 170 patients. Oncologic outcomes, expressed as perioperative complications and postoperative results, were analyzed. Results: Overall survival rates were most significantly associated with the histological type, as well as the ‘positive’ lymph nodes and positive resection margin. The average duration of the procedure was shorter in ORC than in LRC (245.5 min and 345.3 min, respectively). Hospital stay was on average 9.18 days in LRC and 12.63 days in ORC, and this duration could vary depending on the type of diversion. The average blood loss in LRC (250-320 ml) was lower than that in ORC (200-720 ml). The complications rate was lower with LRC than with ORC; however, with subsequent orthotopic reconstruction, the functional results were better in ORC. Conclusions: LRC is an alternative option to ORC, considering the fewer complications, less amount of blood loss, and greater surgical precision, as well as shorter hospital stay. Orthotopic diversion has better functional outcomes in ORC
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