On tidal capture of primordial black holes by neutron stars

The fraction of primordial black holes (PBHs) of masses $10^{17} - 10^{26}$ g in the total amount of dark matter may be constrained by considering their capture by neutron stars (NSs), which leads to the rapid destruction of the latter. The constraints depend crucially on the capture rate which, in turn, is determined by the energy loss by a PBH passing through a NS. Two alternative approaches to estimate the energy loss have been used in the literature: the one based on the dynamical friction mechanism, and another on tidal deformations of the NS by the PBH. The second mechanism was claimed to be more efficient by several orders of magnitude due to the excitation of particular oscillation modes reminiscent of the surface waves. We address this disagreement by considering a simple analytically solvable model that consists of a flat incompressible fluid in an external gravitational field. In this model, we calculate the energy loss by a PBH traversing the fluid surface. We find that the excitation of modes with the propagation velocity smaller than that of PBH is suppressed, which implies that in a realistic situation of a supersonic PBH the large contributions from the surface waves are absent and the above two approaches lead to consistent expressions for the energy loss.Comment: 7 page

Proteomic Investigations of Complex I Composition: How to Define a Subunit?

Complex I is present in almost all aerobic species. Being the largest complex of the respiratory chain, it has a central role in energizing biological membranes and is essential for many organisms. Bacterial complex I is composed of 14 subunits that are sufficient to achieve the respiratory functions. Eukaryotic enzymes contain orthologs of the 14 bacterial subunits and around 30 additional subunits. This complexity suggests either that complex I requires more stabilizing subunits in mitochondria or that it fulfills additional functions. In many organisms recent work on complex I concentrated on the determination of its exact composition. This review summarizes the work done to elucidate complex I composition in the model plant Arabidopsis and proposes a model for the organization of its 44 confirmed subunits. The comparison of the different studies investigating the composition of complex I across species identifies sample preparation for the proteomic analysis as critical to differentiate between true subunits, assembly factors, or proteins associated with complex I. Coupling comparative proteomics with biochemical or genetic studies is thus required to define a subunit and its function within the complex

A New Chronostratigraphy of the Late Weichselian Loess Units in Middle Europe based on Thermoluminescence Dating

Diese Untersuchung wurde innerhalb des Verbreitungsgebietes des Eltviller Tuffs (Abb. 1) durchgeführt, wobei die Tephralage sowie ein fossiler Boden (E4-Naßboden + Innerwürmboden II + Nagelbeek-Kryoturbationszungenhorizont + J 3 d-Boden) als Leithorizonte benutzt werden. In der Abbildung 3 sind die bisherige Chronostratigraphie (untere Skala) sowie die neue Chronostratigraphie (obere Skala) oberer Weichsel-Lösse angegeben. Die durch Thermoluminescenz neu datierten Proben (Rocourt und Lixhe/Belgien, Ringen/B. R. D.) sind in der Abbildung lokalisiert. Die neuen Ergebnisse sowie frühere Thermoluminescenz- und 14 C-Altersbestimmungen wurden in der Abbildung 3 dargestellt. So können Tephralagen, fossile Böden sowie Lößkörper aufgrund einer hangenden Folge von 23 Thermoluminescenz- sowie zwei 14C-Altersbestimmungen festgestellt werden. Die lithostratigraphischen Angaben der hochglazialen Lösse weisen darauf hin, daß keine deutliche Erwärmung zwischen dem Ende des mittel-weichselzeitlichen Interstadials (28.000 J. B. P.) und 15.000 J. B. P. stattgefunden hat und daher müssen Laugerie- sowie Lascaux-Interstadiale höchstens als Oszillation betrachtet werden. Die erste deutliche Erwärmung nach dem mittel-weichselzeitlichen Interstadial hat zwischen ca. 15.000 und 14.000 J.B.P. stattgefunden. Diese wird als „Nagelbeek Oszillation" bezeichnet. Nach der bisherigen Chronostratigraphie muß diese warme Oszillation in die Mitte der ältesten Tundrenzeit eingestuft werden. Dabei wird die kalte Oszillation verkürzt, da ihr unterster Teil an das ausklingende Weichsel-Hochglazial angeschlossen werden kann. Die obigen Ergebnisse stimmen mit der Interpretation der äquivalenten Zeitabschnitte des Pollendiagrammes von Les Echets/Frankreich überein. Zwischen 14.000 J.B.P. und dem Beginn der Bölling-Oszillation (ca. 12.400 J.B.P.) wurde eine relativ dicke Lößdecke mit einer Rate von ca. 2 mm/Jahr abgelagert. Aufgrund der neuen Altersbestimmungen können auch der Eltviller Tuff auf ca. 16.200 J.B.P. und der Rambacher/Wallertheimer Tuff auf ca. 19.400 J.B.P. datiert werden.researc

A systematic 1/c1/c-expansion of form factor sums for dynamical correlations in the Lieb-Liniger model

We introduce a framework for calculating dynamical correlations in the Lieb-Liniger model in arbitrary energy eigenstates and for all space and time, that combines a Lehmann representation with a $1/c$ expansion. The $n^{\rm th}$ term of the expansion is of order $1/c^n$ and takes into account all $\lfloor \tfrac{n}{2}\rfloor+1$ particle-hole excitations over the averaging eigenstate. Importantly, in contrast to a 'bare' $1/c$ expansion it is uniform in space and time. The framework is based on a method for taking the thermodynamic limit of sums of form factors that exhibit non integrable singularities. We expect our framework to be applicable to any local operator. We determine the first three terms of this expansion and obtain an explicit expression for the density-density dynamical correlations and the dynamical structure factor at order $1/c^2$. We apply these to finite-temperature equilibrium states and non-equilibrium steady states after quantum quenches. We recover predictions of (nonlinear) Luttinger liquid theory and generalized hydrodynamics in the appropriate limits, and are able to compute sub-leading corrections to these.Comment: 78 pages; corresponds to published versio

Unified description of the optical phonon modes in NN-layer MoTe2_2

$N$-layer transition metal dichalcogenides provide a unique platform to investigate the evolution of the physical properties between the bulk (three dimensional) and monolayer (quasi two-dimensional) limits. Here, using high-resolution micro-Raman spectroscopy, we report a unified experimental description of the $\Gamma$-point optical phonons in $N$-layer $2H$-molybdenum ditelluride (MoTe$_2$). We observe a series of $N$-dependent low-frequency interlayer shear and breathing modes (below $40~\rm cm^{-1}$, denoted LSM and LBM) and well-defined Davydov splittings of the mid-frequency modes (in the range $100-200~\rm cm^{-1}$, denoted iX and oX), which solely involve displacements of the chalcogen atoms. In contrast, the high-frequency modes (in the range $200-300~\rm cm^{-1}$, denoted iMX and oMX), arising from displacements of both the metal and chalcogen atoms, exhibit considerably reduced splittings. The manifold of phonon modes associated with the in-plane and out-of-plane displacements are quantitatively described by a force constant model, including interactions up to the second nearest neighbor and surface effects as fitting parameters. The splittings for the iX and oX modes observed in $N$-layer crystals are directly correlated to the corresponding bulk Davydov splittings between the $E_{2u}/E_{1g}$ and $B_{1u}/A_{1g}$ modes, respectively, and provide a measurement of the frequencies of the bulk silent $E_{2u}$ and $B_{1u}$ optical phonon modes. Our analysis could readily be generalized to other layered crystals.Comment: Main Text (5 Figures, 2 Tables) + Supporting Information (12 Figures