Hierarchical Cosmic Shear Power Spectrum Inference

We develop a Bayesian hierarchical modelling approach for cosmic shear power spectrum inference, jointly sampling from the posterior distribution of the cosmic shear field and its (tomographic) power spectra. Inference of the shear power spectrum is a powerful intermediate product for a cosmic shear analysis, since it requires very few model assumptions and can be used to perform inference on a wide range of cosmological models \emph{a posteriori} without loss of information. We show that joint posterior for the shear map and power spectrum can be sampled effectively by Gibbs sampling, iteratively drawing samples from the map and power spectrum, each conditional on the other. This approach neatly circumvents difficulties associated with complicated survey geometry and masks that plague frequentist power spectrum estimators, since the power spectrum inference provides prior information about the field in masked regions at every sampling step. We demonstrate this approach for inference of tomographic shear $E$-mode, $B$-mode and $EB$-cross power spectra from a simulated galaxy shear catalogue with a number of important features; galaxies distributed on the sky and in redshift with photometric redshift uncertainties, realistic random ellipticity noise for every galaxy and a complicated survey mask. The obtained posterior distributions for the tomographic power spectrum coefficients recover the underlying simulated power spectra for both $E$- and $B$-modes.Comment: 16 pages, 8 figures, accepted by MNRA

Intrauterine repair of gastroschisis in fetal rabbits

Objective: Infants with gastroschisis (GS) still face severe morbidity. Prenatal closure may prevent gastrointestinal organ damage, but intrauterine GS repair (GSR) has not been established yet. Methods: In New Zealand White rabbits we developed and compared GS versus GSR: creation of GS was achieved by hysterotomy, right-sided laparotomy of the fetus and pressure on the abdominal wall to provoke evisceration. GSR was accomplished by careful reposition of eviscerated organs and a running suture of the fetal abdominal wall. For study purposes, 18 animals were divided equally into 3 groups: GS, GS with GSR after 2 h, and unmanipulated controls (C). Vitality was assessed by echocardiography. After 5 h all animals were sacrificed. Results: GSR inflicted no increased mortality, because all fetuses survived GS or GS with GSR. All fetuses with GS demonstrated significant evisceration of abdominal organs. In contrast, the abdominal wall of the fetuses from GSR was intact. Conclusion:The present animal model demonstrated the technical feasibility and success of an intrauterine repair of GS for the first time. However, further long-term studies (leaving GS and GSR in utero for several days) will be necessary to compare survival rates and intestinal injury, motility or absorption. The clinical application of GSR in utero remains a vision so far. Copyright (C) 2003 S. Karger AG, Basel

Streaking temporal double slit interference by an orthogonal two-color laser field

We investigate electron momentum distributions from single ionization of Ar by two orthogonally polarized laser pulses of different color. The two-color scheme is used to experimentally control the interference between electron wave packets released at different times within one laser cycle. This intracycle interference pattern is typically hard to resolve in an experiment. With the two-color control scheme these features become the dominant contribution to the electron momentum distribution. Furthermore the second color can be used for streaking of the otherwise interfering wave packets establishing a which-way marker. Our investigation shows that the visibility of the interference fringes depends on the degree of the which-way information determined by the controllable phase between the two pulses.Comment: submitted to PR

The Local Group's mass: probably no more than the sum of its parts

The total mass of the Local Group (LG) and the masses of its primary constituents, the Milky Way and M31, are important anchors for several cosmological questions. In recent years, independent measurements have consistently yielded halo masses close to $10^{12} \mathrm{M_\odot}$ for the MW, and $1-2 \times 10^{12} \mathrm{M_\odot}$ for M31, while estimates derived from the pair's kinematics via the `timing argument' have yielded a combined mass of around $5 \times 10^{12} \mathrm{M_\odot}$. Here, we analyse the extremely large Uchuu simulation to constrain the mass of the Local Group and its two most massive members. First, we demonstrate the importance of selecting LG analogues whose kinematics are dominated by mutual interactions to a similar extent as the LG. Adopting the observed separation and radial velocity, we obtain a weighted posterior of $75_{-40}^{+65}$ kms$^{-1}$ for the uncertain transverse velocity. Via Gaussian process regression, we infer a total mass of $3.2^{+1.2}_{-0.9} \times 10^{12} \mathrm{M_\odot}$, significantly below the timing argument prediction. Importantly, we show that the remaining uncertainty is not rooted in the analysis or observational errors, but in the irreducible scatter in the kinematics-mass relation. We further find a mass for the less massive halo of $0.9_{-0.3}^{+0.6} \times 10^{12} \mathrm{M_\odot}$ and for the more massive halo of $2.3_{-0.9}^{+1.0} \times 10^{12} \mathrm{M_\odot}$, consistent with independent measurements of the masses of MW and M31, respectively. Incorporating the mass of the MW as an additional prior allows us to further constrain all measurements and determine that the MW is very likely to be the lower mass object of the two.Comment: 15 pages, submitted to MNRAS. Full source code provided, comments are welcom

A study for active control research and validation using the Total In-Flight Simulator (TIFS) aircraft

The results of a feasibility study and preliminary design for active control research and validation using the Total In-Flight Simulator (TIFS) aircraft are documented. Active control functions which can be demonstrated on the TIFS aircraft and the cost of preparing, equipping, and operating the TIFS aircraft for active control technology development are determined. It is shown that the TIFS aircraft is as a suitable test bed for inflight research and validation of many ACT concepts

Nuklearna reakcija 164Dy(d, p) 165Dy

The 164Dy(d, p) 165Dy reaction was investigated with very high resolution. The spectra were recorded with two sets of measurements, with Ed = 14 MeV at the angle of 45◦ and Ed = 22 MeV at 35◦ . The intensity ratio of these measurements is a measure for the transfered angular momentum ∆l.Istraživana je nuklearna reakcija 164Dy(d, p) 165Dy s visokom rezolucijom. Preliminarni spektri dobiveni su za dva niza mjerenja, s Ed = 14 MeV pod kutom od 45◦ i s Ed = 22 MeV pod kutom od 35

Nuklearna reakcija 164Dy(d, p) 165Dy

The 164Dy(d, p) 165Dy reaction was investigated with very high resolution. The spectra were recorded with two sets of measurements, with Ed = 14 MeV at the angle of 45◦ and Ed = 22 MeV at 35◦ . The intensity ratio of these measurements is a measure for the transfered angular momentum ∆l.Istraživana je nuklearna reakcija 164Dy(d, p) 165Dy s visokom rezolucijom. Preliminarni spektri dobiveni su za dva niza mjerenja, s Ed = 14 MeV pod kutom od 45◦ i s Ed = 22 MeV pod kutom od 35

The Timeless Timing Argument and the Mass of the Local Group

The Timing Argument connects the motion of a two-body system to its mass in an expanding Universe with a finite age, under the assumption that it has evolved on a self-gravitating orbit. It is commonly applied to the present-day Milky Way-M31 system in order to infer its unknown mass from the measured kinematics. We use a set of Local Group analogues from the Uchuu simulation to investigate the Timing Argument over cosmic time. We find that the median inferred mass remains almost constant over the past 12 Gyr, even while the haloes themselves grew in mass by more than an order of magnitude. By contrast, we find a closer, and nearly time-invariant agreement between the Timing Argument value and the mass within a sphere of radius equal to the MW-M31 separation, and we identify this as the total mass of the system. We conclude that the comparatively close present-day agreement between the Timing Argument and the sum of the halo masses reflects no underlying relation, but merely echoes the fact that the MW and M31 now contain most (but not all) of the mass of the Local Group system.Comment: 6 pages, 4 figures, this version accepted to MNRAS Letter

The timeless timing argument and the total mass of the Local Group

The timing argument connects the motion of a two-body system to its mass in an expanding Universe with a finite age, under the assumption that it has evolved on a self-gravitating orbit. It is commonly applied to the present-day Milky Way (MW)–M31 system in order to infer its unknown mass from the measured kinematics. We use a set of Local Group analogues from the UCHUU simulation to investigate the timing argument over cosmic time. We find that the median inferred mass remains almost constant over the past 12 Gyr, even while the haloes themselves grew in mass by more than an order of magnitude. By contrast, we find a closer, and nearly time-invariant agreement between the timing argument value and the mass within a sphere of radius equal to the MW–M31 separation, and we identify this as the total mass of the system. We conclude that the comparatively close present-day agreement between the timing argument and the sum of the halo masses reflects no underlying relation, but merely echoes the fact that the MW and M31 now contain most (but not all) of the mass of the Local Group system