53 research outputs found
Properties of scalar wave emission in a scalar-tensor theory with kinetic screening
We study numerically the scalar wave emission by a non-spherical oscillationof neutron stars in a scalar-tensor theory of gravity with kinetic screening,considering both the monopole and quadrupole mode emission. In agreement withprevious results in the literature, we find that the monopole is alwayssuppressed by the screening effect, regardless of the size of the screeningradius, . For the quadrupole mode, however, our analysis shows thatthe suppression only occurs for screening radius larger than the wavelength ofscalar waves, , but not for r_{\rm sc} wave}. This demonstrates that to fully understand the nature of this theory,it is necessary to study other more complex systems, such as neutron starbinaries, considering a wide range of values.<br
Accretion of a symmetry-breaking scalar field by a Schwarzschild black hole
We simulate the behaviour of a Higgs-like field in the vicinity of a Schwarzschild black hole using a highly accurate numerical framework. We consider both the limit of the zero-temperature Higgs potential and a toy model for the time-dependent evolution of the potential when immersed in a slowly cooling radiation bath. Through these numerical investigations, we aim to improve our understanding of the non-equilibrium dynamics of a symmetry-breaking field (such as the Higgs) in the vicinity of a compact object such as a black hole. Understanding this dynamics may suggest new approaches for studying properties of scalar fields using black holes as a laboratory
Relativistic drag forces on black holes from scalar dark matter clouds of all sizes
We use numerical simulations of scalar field dark matter evolving on a moving black hole background to confirm the regime of validity of (semi)analytic expressions derived from first principles for both dynamical friction and momentum accretion in the relativistic regime. We cover both small and large clouds (relative to the de Broglie wavelength of the scalars), and light and heavy particle masses (relative to the black hole size). In the case of a small dark matter cloud, the effect of accretion is a non-negligible contribution to the total force on the black hole, even for small scalar masses. We confirm that this momentum accretion transitions between two regimes (wave and particlelike) and we identify the mass of the scalar at which the transition between regimes occurs
KiDS+VIKING-450 and DES-Y1 combined:Cosmology with cosmic shear
We present a combined tomographic weak gravitational lensing analysis of the
Kilo Degree Survey (KV450) and the Dark Energy Survey (DES-Y1). We homogenize
the analysis of these two public cosmic shear datasets by adopting consistent
priors and modeling of nonlinear scales, and determine new redshift
distributions for DES-Y1 based on deep public spectroscopic surveys. Adopting
these revised redshifts results in a reduction in the DES-inferred
value for , which decreases to a reduction when including a
systematic redshift calibration error model from mock DES data based on the
MICE2 simulation. The combined KV450 + DES-Y1 constraint on is in tension with the Planck 2018 constraint from the
cosmic microwave background at the level of . This result highlights
the importance of developing methods to provide accurate redshift calibration
for current and future weak lensing surveys.Comment: 8 pages, 4 figures, new appendix added including a simulated
analysis, version accepted for publication by A&A Letters, chains can be
found at https://github.com/sjoudaki/kidsde
An Efficient and Versatile System for Visualization and Genetic Modification of Dopaminergic Neurons in Transgenic Mice.
BACKGROUND & AIMS: The brain dopaminergic (DA) system is involved in fine tuning many behaviors and several human diseases are associated with pathological alterations of the DA system such as Parkinson's disease (PD) and drug addiction. Because of its complex network integration, detailed analyses of physiological and pathophysiological conditions are only possible in a whole organism with a sophisticated tool box for visualization and functional modification. METHODS & RESULTS: Here, we have generated transgenic mice expressing the tetracycline-regulated transactivator (tTA) or the reverse tetracycline-regulated transactivator (rtTA) under control of the tyrosine hydroxylase (TH) promoter, TH-tTA (tet-OFF) and TH-rtTA (tet-ON) mice, to visualize and genetically modify DA neurons. We show their tight regulation and efficient use to overexpress proteins under the control of tet-responsive elements or to delete genes of interest with tet-responsive Cre. In combination with mice encoding tet-responsive luciferase, we visualized the DA system in living mice progressively over time. CONCLUSION: These experiments establish TH-tTA and TH-rtTA mice as a powerful tool to generate and monitor mouse models for DA system diseases
Early diagnostic and repair of choanal atresia in childhood with low-dose CT and transnasal endoscopic approach - ten cases
The phenomenology of beyond Horndeski gravity
We study the phenomenology of the beyond Horndeski class of scalar-tensor theories of gravity, which on cosmological scales can be characterised in terms of one extra function of time, βH, as well as the usual four Horndeski set of free functions. We show that βH can be directly related to the damping of the matter power spectrum on both large and small scales. We also find that the temperature power spectrum of the cosmic microwave background (CMB) is enhanced at low multipoles and the lensing potential is decreased, as a function of βH. For a particular choice of time dependence we find constraints on βH of order (1) using measurements of the temperature and polarisation of the CMB, as well as the lensing potential derived from it, combined with large scale structure data. We find that redshift space distortion measurements can play a significant role in constraining these theories. Finally, we comment on the recent constraints from the observation of an electromagnetic counterpart to a gravitational wave signal; we find that these constraints reduce the number of free parameters of the model but do not significantly change the constraints on the remaining parameters
Chirurgische Strategie bei Fällen mit Schädigung des Nervus Opticus von Nasennebenhöhlenpathologie: Unsere Erfahrung
Einleitung: Die Schaedigung des N. opticus bei entzuendlichen Erkrankungen der Orbita von Nasennebenhoehlenpathologie sind ziemlich seltenes, aber sehr ernstes Problem.Material und Methode: Seit 1997 bis 2005 haben wir insgesamt 22 Patienten mit orbitalen Komplikationen beobachtet. Davon 7 Kinder, 8 Frauen, 7 Maenner. 6 von den Patienten/37%/ haben eine Schaedigung des N.opticus mit Visusminderung gezeigt. 12/55%/ von allen 22 Patienten wurden mikroendoskopisch operiert - Ethmoidektomie oder Pansinusotomie , in 2 Faellen mit phlegmonoese Entzuendung der Orbita wurde die endonasale Operation mit einer lateralen Kanthotomie und transantrale Dekompression kombiniert.Ergebnisse: Bei 4 Patienten/67%/ hat sich der Visus normalisiert, bei 2 war die Schaedigung definitiv.Schlussfolgerungen: Bei schwerwiegenden Komplikationen der Nasennebenhoehlenentzuendungen und speziell Schaedigung des N.opticus, muss die operative Therapie, im Sinne einer endonasalen Ethmoidektomie oder Pansinusotomie mit Dekompression der Orbita sofort eingesetzt werden. In Faellen mit einem Orbitaphlegmon reicht die endonasale Operation nicht. Trotz einer transantralen Dekompression oder einer lateralen Kanthotomie ist die Gefahr von einer Erblindung sehr gross
Dynamical friction from scalar dark matter in the relativistic regime
Light bosonic scalars (e.g. axions) may form clouds around black holes via
superradiant instabilities, or via accretion if they form some component of the
dark matter. It has been suggested that their presence may lead to a
distinctive dephasing of the gravitational wave signal when a small compact
object spirals into a larger black hole. Motivated by this, we study
numerically the dynamical friction force on a black hole moving at relativistic
velocities in a background scalar field with an asymptotically homogeneous
energy density. We show that the relativistic scaling is analogous to that
found for supersonic collisional fluids, assuming an approximate expression for
the pressure correction which depends on the velocity and scalar mass. While we
focus on a complex scalar field, our results confirm the expectation that real
scalars would exert a force which oscillates between positive and negative
values in time with a frequency set by the scalar mass. The complex field
describes the time averaged value of this force, but in a real scalar the rapid
force oscillations could in principle leave an imprint on the trajectory. The
approximation we obtain can be used to inform estimates of dephasing in the
final stages of an extreme mass ratio inspiral.Comment: 17 pages, 13 figures, 1 table; Version as accepted in PRD - minor
change
Mucocele of the Paranasal Sinuses – Retrospective Analysis of a Series of Seven Cases
Aim: The present study aimed at identifying the risk factors, typical clinical symptoms and applied treatment in seven cases with mucocele of the paranasal sinuses
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