How dark is dark matter? Robust limits on dark matter - radiation interactions from cosmological observations

Extensions to the canonical LCDM model which incorporate elastic scattering between dark matter and Standard Model radiation predict the suppression of matter perturbations on small scales and modifications to the cosmic microwave background anisotropies. Studying these scenarios not only allows us to constrain the particle physics properties of dark matter, it also reveals if they can alleviate remaining tensions in cosmological data sets. In this context, the present thesis considers several aspects of dark matter-photon and dark matter-neutrino interactions. One central aspect of our work is the accurate description of additional scattering terms in the numerical solutions. In the context of dark matter-photon interactions, we demonstrate the robustness of earlier studies with respect to inconsistencies in the tight coupling approximation and to the negligence of the dark matter sound speed. Accounting for the latter, however, potentially tightens limits from large-scale structure observations for light dark matter candidates. Our updated constraints, derived from the Planck 2015 data release, are about 20% tighter than previous CMB limits in the most conservative case. We further extend dark matter-photon interactions to a mixed dark matter scenario in which two components, one collisional and one collisionless, contribute to the relic abundance. In particular a small fraction of interacting dark matter impacts the matter power spectrum in a fashion very similar to massive neutrinos. In this case, CMB data only imposes weak constraints on the interaction strength, and our Fisher forecast for the DESI survey predicts notably larger error margins on the neutrino mass. Dark matter-neutrino interactions alter the initial conditions and cause inconsistencies in the ultra-relativistic fluid approximation, which impact the matter power spectrum on small scales. Still, we can reinforce the validity of previous studies that neglected those effects. In addition to the canonical collisional damping, dark matter-neutrino interactions imply the suppression of structure by mixed damping. Indeed, our exploration of the parameter space reveals the relevance of mixed damping for observational constraints. To provide insight into the underlying physical processes, we derive an analytical approximation to the evolution of dark matter perturbations in the mixed damping regime, which accomplishes to capture all qualitative features of our full numerical results

Cosmology inference at the field level from biased tracers in redshift-space

Cosmology inference of galaxy clustering at the field level with the EFT likelihood in principle allows for extracting all non-Gaussian information from quasi-linear scales, while robustly marginalizing over any astrophysical uncertainties. A pipeline in this spirit is implemented in the \texttt{LEFTfield} code, which we extend in this work to describe the clustering of galaxies in redshift space. Our main additions are: the computation of the velocity field in the LPT gravity model, the fully nonlinear displacement of the evolved, biased density field to redshift space, and a systematic expansion of velocity bias. We test the resulting analysis pipeline by applying it to synthetic data sets with a known ground truth at increasing complexity: mock data generated from the perturbative forward model itself, sub-sampled matter particles, and dark matter halos in N-body simulations. By fixing the initial-time density contrast to the ground truth, while varying the growth rate $f$, bias coefficients and noise amplitudes, we perform a stringent set of checks. These show that indeed a systematic higher-order expansion of the velocity bias is required to infer a growth rate consistent with the ground truth within errors. Applied to dark matter halos, our analysis yields unbiased constraints on $f$ at the level of a few percent for a variety of halo masses at redshifts $z=0,\,0.5,\,1$ and for a broad range of cutoff scales $0.08\,h/\mathrm{Mpc} \leq \Lambda \leq 0.20\,h/\mathrm{Mpc}$. Importantly, deviations between true and inferred growth rate exhibit the scaling with halo mass, redshift and cutoff that one expects based on the EFT of Large Scale Structure. Further, we obtain a robust detection of velocity bias through its effect on the redshift-space density field and are able to disentangle it from higher-derivative bias contributions

Analyse des Transferverhaltens von Americium und Europium in Pflanzen mittels Spektroskopie und Massenspektrometrie

Die ökologischen Folgen der Freisetzung von Radionukliden durch den Reaktorunfall in Tschernobyl 1986 sind noch bis heute spürbar. Unter den vielen emittierten Radionukliden stellt das Americiumisotop Am-241 zum jetzigen Zeitpunkt den dominierenden α-Emitter in der Sperrzone dar und kann von Pflanzen aus kontaminiertem Boden aufgenommen werden. Damit öffnet sich ein Pfad in die menschliche Nahrungskette. Um die Aufnahme auf makroskopischer Ebene zu verstehen, wird Winterroggen (Secale cereale L.) mit Americium und dem chemischen Homolog Europium kontaminiert und Speziesanalysen durchgeführt. Mit einer Kombination aus Lumineszenz-Spektroskopie, Mikroskopie und hochauflösender Massenspektrometrie konnten erste chemische Verbindungen identifiziert werden. Dazu fand die Aufzucht der Pflanzen im flüssigen Nährmedium, der Hoagland-Lösung, statt. Im Hoagland-Medium wurden Veränderungen der Europiumspezies nach Pflanzenkontakt untersucht und die Aufnahme des Eu3+-Ions und von [Eu(H2EDTA)]+ festgestellt. Außerdem zeigten die Ergebnisse die Anwesenheit des Pflanzenexsudats Malat komplexiert mit Europium. Anhand der Lumineszenz-Mikroskopie wurde erstmals die Speziesverteilung von drei Eu-Verbindungen mit organischem und anorganischem Phosphat sowie eine Protein-Spezies bildgebend dargestellt und Akkumulationen in bestimmten Pflanzenregionen sichtbar gemacht. Dazu ergaben Extraktionsexperimente mögliche Eu-Malat, Eu-Citrat und Eu-Aspartat- Verbindungen in der Pflanzenwurzel, welche auf einen Einfluss in den Pflanzenmetabolismus der Mitochondrien hindeuten. Weitere Informationen über die Aufnahme von Europium und Americium in Pflanzen wurde durch Untersuchungen der Auswirkung der Komplexbildner EDTA, Citrat, Malonat und Oxalat nach Zugabe zum Nährmedium erhalten und Spezies in Lösung identifiziert. Die erhaltenen Ergebnisse geben erstmalig Hinweise auf das Verhalten von Europium- und Americiumspezies in Secale cereale L. und weisen auf verschiedene Transportmechanismen in Anwesenheit von organischen Komplexbildnern hin. Einhergehend mit den unterschiedlichen Eigenschaften der identifizierten Komplexe in Bezug auf die Resorption im menschlichen Körper, kann die Toxizität variieren. Dies unterstreicht die wichtige Rolle der Speziesanalyse bei der Gefährdungsbeurteilung von Radionukliden.Ecological consequences of the radionuclide release during the Chernobyl nuclear accident 1986 are still being observed today. Among various released nuclides, the long-lived americium isotope 241Am represents the dominating α-emitter in the Chernobyl exclusion zone. Americium can enter the human food chain via uptake from contaminated soil by plants. In this work, the plant uptake of americium, its homologue europium, and their chemical species in plants were investigated on microscopic scale. For this purpose, Secale cereale L. (winter rye) was grown as hydroponics in the Hoagland-solution. By using a combination of luminescence spectroscopy, microscopy, and high-resolution mass spectrometry, chemical compounds were identified in plant and solution. In the nutrition medium, changes in the europium species after plant contact and the possible uptake of Eu3+ ions and [Eu(H2EDTA)]+ was determined. Afterwards, europium malate species were identified in the Hoagland-medium, whereby the organic ligand acts as plant exudate. In winter rye, at least three europium species were determined with the possible binding to organic and inorganic phosphate groups as well as a protein-bound species. In combination with luminescence microscopy, the species distribution was shown to be different for each species inside the plant parts. Extraction experiments resulted in possible europium malate, citrate, and aspartate compounds inside the plant root, indicating an impact on the plant metabolism in the mitochondria. Furthermore, the influence of the complexing agents EDTA, citrate, malonate, and oxalate on the europium and americium uptake was investigated. After the addition to the nutrition medium chemical species were identified. For the first time, evidences on the behaviour of europium and americium species in Secale cereale L. have been obtained and point to different transport mechanisms in the presence of organic complexing agents. Along with the different properties of the identified complexes with respect to the resorption into the human body, the toxicity varies. This highlights the important role of species analysis for the risk assessment of radionuclides

On Your Mark, Get Set, Self-Control, Go: A Differentiated View on the Cortical Hemodynamics of Self-Control during Sprint Start

Most sports are self-control demanding. For example, during a sprint start, athletes have to respond as fast as possible to the start signal (action initiation) while suppressing the urge to start too early (action inhibition). Here, we examined the cortical hemodynamic response to these demands by measuring activity in the two lateral prefrontal cortices (lPFC), a central area for self-control processes. We analyzed activity within subregions of the lPFC, while subjects performed a sprint start, and we assessed if activation varied as a function of hemisphere and gender. In a counterbalanced within-subject design, 39 participants (age: mean (M) = 22.44, standard deviation (SD) = 5.28, 22 women) completed four sprint start conditions (blocks). In each block, participants focused on inhibition (avoid false start), initiation (start fast), no start (do not start) and a combined condition (start fast; avoid false start). We show that oxyhemoglobin in the lPFC increased after the set signal and this increase did not differ between experimental conditions. Increased activation was primarily observed in ventral areas of the lPFC, but only in males, and this increase did not vary between hemispheres. This study provides further support for the involvement of the ventral lPFC during a sprint start, while highlighting gender differences in the processing of sprint start-induced self-control demands

While corporate UK was for Remain, their business strategies tell a different story

While corporate UK was strongly opposed to Brexit, their strategies tell a slightly different story, write Michael Mayer, Julia Hautz, Christian Stadler and Richard Whittington. In contrast to their European counterparts, British businesses have long looked for markets primarily outside of Europe

A close look at British business: Was it destined to leave the EU?

While corporate UK was strongly opposed to Brexit, their strategies tell a slightly different story, write Michael Mayer, Julia Hautz, Christian Stadler and Richard Whittingto

Was British business destined to leave the EU?

Was British business destined to leave the EU? While corporate UK was strongly opposed to Brexit, their strategies tell a slightly different story, write Michael Mayer, Julia Hautz, Christian Stadler and Richard Whittington. Always good to start with a confession: we are what Brexiteers call Remoaners. As Michael Bloomberg says, "it is really hard to understand why a country that was doing ..

Structural and Physical Properties of CaFe4As3 Single Crystals

We report the synthesis, and structural and physical properties of CaFe4As3 single crystals. Needle-like single crystals of CaFe4As3 were grown out of Sn flux and the compound adopts an orthorhombic structure as determined by X-ray diffraction measurements. Electrical, magnetic, and thermal properties indicate that the system undergoes two successive phase transitions occurring at TN1 ~ 90 K and TN2 ~ 26 K. At TN1, electrical resistivities (\rho(b) and \rho(ac)) are enhanced while magnetic susceptibilities (\chi(b) and \chi(ac)) are reduced in both directions parallel and perpendicular to the b-axis, consistent with the scenario of antiferromagnetic spin-density-wave formation. At TN2, specific heat reveals a slope change, and \chi(ac) decreases sharply but \chi(b) has a clear jump before it decreases again with decreasing temperature. Remarkably, both \rho(b) and \rho(ac) decrease sharply with thermal hysteresis, indicating the first-order nature of the phase transition at TN2. At low temperatures, \rho(b) and \rho(ac) can be described by {\rho} = {\rho}0 + AT^\alpha ({\rho}0, A, and {\alpha} are constants). Interestingly, these constants vary with applied magnetic field. The ground state of CaFe4As3 is discussed.Comment: 15 pages, 8 figures, Submitted to Physical Review

Update on shedding and transmission routes of porcine haemotrophic mycoplasmas in naturally and experimentally infected pigs

Horizontal transmission of Mycoplasma suis via parenteral exposure during standard practices or through bites during fightings have been identified as key epidemiological routes. However, as knowledge gaps on other potential shedding and transmission routes exist, the present study combines both laboratory experiments and field surveys to gain new insights into the epidemiology of porcine haemotrophic mycoplasmas. Splenectomised pigs were orally inoculated with a M. suis field strain and investigated for clinical signs related to infectious anaemia of pigs (IAP) and the presence of M. suis in blood, urine and saliva samples by qPCR. All blood samples were negative for M. suis and animals did not show obvious clinical signs of IAP throughout the entire study period. Additionally, urine, nasal and saliva samples from sows of conventional piglet producing farms and semen samples from a boar stud revealed no detection of M. suis and ‘Candidatus Mycoplasma haemosuis’ by qPCR. Thus, the results indicate that blood-independent transmission routes might be of minor relevance under field conditions

Reproductive performance of pandemic influenza A virus infected sow herds before and after implementation of a vaccine against the influenza A (H1N1)pdm09 virus

Background: Reproductive failure in sow herds due to infection with influenza A viruses has been described in the literature, but only a few studies have focused on the pathogenesis and the clinical signs of the infection. Case reports indicate an association between infections with influenza A viruses and reduced reproductive performance, although it has been difficult to experimentally reproduce the clinical outcome of poor reproductive performance. The aim of the present longitudinal field study was to compare the reproductive performance parameters before and after the implementation of vaccination against the influenza A (H1N1)pdm09 virus in sow herds infected with pandemic influenza A virus. Therefore, farm-specific data of 137 sow herds in Germany, including 60,153 sows, as well as the clinical presentation of the infection were surveyed via questionnaire. Furthermore, average performance parameters (return to oestrus rate, abortion rate, stillbirth rate, number of piglets born alive per litter, preweaning mortality rate and number of piglets weaned per sow per year) were recorded for 6 months before vaccination and 6 months after completion of primary vaccination. Results: In 79.8% of the farms, the clinical presentation of the infection was characterised by a reduced reproductive performance. These findings were confirmed by analysis of the performance parameters, which revealed a significant decline in the return to oestrus rate (p < 0.001), abortion rate (p < 0.001) and preweaning mortality rate (p = 0.023) and a significant increase of the number in piglets born alive (p = 0.001) and piglets weaned per sow per year (p < 0.001) after immunisation. The stillbirth rate did not change significantly. Conclusion: The present study represents the first attempt to demonstrate the association of influenza A virus infection, vaccination and the alteration in reproductive performance parameters, investigating a large number of cases. The results show that by vaccinating against the influenza A (H1N1)pdm09 virus, an improvement in reproductive performance can be achieved in sow herds infected with pandemic influenza A virus. Additionally, the large number of herds that were affected by poor reproductive performance after infection with the aforementioned virus confirms the assumption of an association between pandemic influenza A virus and reproductive losses