Frequency domain model of ff-mode dynamic tides in gravitational waveforms from compact binary inspirals

The recent detection of gravitational waves (GWs) from the neutron star binary inspiral GW170817 has opened a unique avenue to probe matter and fundamental interactions in previously unexplored regimes. Extracting information on neutron star matter from the observed GWs requires robust and computationally efficient theoretical waveform models. We develop an approximate frequency-domain GW phase model of a main GW signature of matter: dynamic tides associated with the neutron stars' fundamental oscillation modes ($f$-modes). We focus on nonspinning objects on circular orbits and demonstrate that, despite its mathematical simplicity, the new "$f$-mode tidal" (fmtidal) model is in good agreement with the effective-one-body dynamical tides model up to GW frequencies of $\gtrsim 1$ kHz and gives physical meaning to part of the phenomenology captured in tidal models tuned to numerical-relativity. The advantages of the fmtidal model are that it makes explicit the dependence of the GW phasing on the characteristic equation-of-state parameters, i.e., tidal deformabilities and $f$-mode frequencies; it is computationally efficient; and it can readily be added to any frequency-domain baseline waveform. The fmtidal model is easily amenable to future improvements and provides the means for a first step towards independently measuring additional fundamental properties of neutron star matter beyond the tidal deformability as well as performing novel tests of general relativity from GW observations.Comment: 7 pages, 3 figures; matches published versio

Gravitational-Wave Asteroseismology with Fundamental Modes from Compact Binary Inspirals

The first detection of gravitational waves (GWs) from the binary neutron star (NS) inspiral GW170817 has opened a unique channel for probing the fundamental properties of matter at supra-nuclear densities inaccessible elsewhere in the Universe. This observation yielded the first constraints on the equation of state (EoS) of NS matter from the GW imprint of tidal interactions. Tidal signatures in the GW arise from the response of a matter object to the spacetime curvature sourced by its binary companion. They crucially depend on the EoS and are predominantly characterised by the tidal deformability parameters $\Lambda_{\ell}$, where $\ell=2,3$ denotes the quadrupole and octupole respectively. As the binary evolves towards merger, additional dynamical tidal effects become important when the orbital frequency approaches a resonance with the stars' internal oscillation modes. Among these modes, the fundamental ($f_\ell$-)modes have the strongest tidal coupling and can give rise to a cumulative imprint in the GW signal even if the resonance is not fully excited. Here we present the first direct constraints on fundamental oscillation mode frequencies for GW170817 using an inspiral GW phase model with an explicit dependence on the $f$-mode frequency and without assuming any relation between $f_\ell$ and $\Lambda_\ell$. We rule out anomalously small values of $f_\ell$ and, for the larger companion, determine a lower bound on the $f_2$-mode ($f_3$-mode) frequency of $\geq 1.39$ kHz ($\geq 1.86$ kHz) at the 90\% credible interval (CI). We then show that networks of future GW detectors will be able to measure $f$-mode frequencies to within tens of Hz from the inspiral alone. Such precision astroseismology will enable novel tests of fundamental physics and the nature of compact binaries.Comment: 8 pages, 5 figure

A long term histological study using a sheep model

Deckblatt-Impressum Inhaltsverzeichnis Einleitung Literaturteil Eigene Untersuchungen Ergebnisse Diskussion Zusammenfassung Summary Literaturverzeichnis AnhangAllogene freie Sehnentransplantate zum Ersatz des vorderen Kreuzbandes (VKB) gewinnen aufgrund der im Vergleich zu autologen Transplantaten geringeren Entnahmemorbidität, ihrer besseren Verfügbarkeit und Dimensionierbarkeit, und Reduktion bisher vorhandener Nachteile durch Entwicklung neuer Fixationstechniken zunehmend an Bedeutung. Um das Langzeitüberleben eines Kreuzbandtransplantates nach Ersatz des VKB zu gewährleisten und Umbauprozesse im Rahmen des Remodellings zu ermöglichen, muß das Transplantat revaskularisiert werden. Die Revaskularisierung des primär avaskulär transplantierten Gewebes geht dabei initial von den umgebenden Geweben wie dem Hoffaschen Fettkörper und der synovialen Umhüllung aus, wobei zuerst eine Versorgung durch Diffusion stattfindet, dann kommt es zur Einsprossung von Gefäßen aus der Peripherie, die nach zentral fortschreitend in das komplette Transplantat einwachsen. In dieser Phase kommt es zu einer gegenüber dem nativen VKB bestehenden Hypervaskularität, einhergehend mit verminderten mechanischen Eigenschaften des Transplantats. Abschließend kommt es zu einer Normalisierung des Gefäßgehaltes, und die Transplantate erreichen ein Gefäßniveau dem nativen vorderen Kreuzband gleichend. Dabei konnten in bisherigen Studien keine einheitlichen Beobachtungen bezüglich Dauer und Fortschreiten der Revaskularisierung freier allogener Sehnentransplantate gemacht werden, es wurde aber immer wieder eine verzögerte Revaskularisierung der allogenen Kreuzbandtransplantate diskutiert. Gleichzeitig wird in der Klinik aufgrund der gesenkten Entnahmemorbidität ein aggressiveres post operatives Rehabilitationsmanagement proklamiert, wobei es beim allogenen Kreuzbandersatz häufiger zum Transplantatversagen kommt, als nach autologem VKB- Ersatz, wobei die Ursache ein eventuell verzögert ablaufender Remodelling- und Revaskularisierungsprozeß sein könnte. Ziel der vorliegenden Studie war es daher, die Revaskularisierung und die zellulären Veränderungen im Rahmen des Remodellings autologer und allogener freier Sehnentransplantate vergleichend zu untersuchen. 59 ausgewachsene weibliche Merinomixschafe erhielten einen Ersatz des vorderen Kreuzbandes, von denen jedoch nur 54 Tiere in den Versuch aufgenommen wurden. Jeweils die Hälfte der aufgenommenen Tiere erhielt ein autologes, die andere Hälfte ein allogenes Flexorsehnentransplantat. Nach 6, 12, und 52 Wochen erfolgte die Tötung der Tiere und die Gewinnung eines intraartikulär gelegenen Teils des Transplantats. Nach histologischer Aufarbeitung erfolgte die Färbung der gewonnenen Quer- und Längsschnitte mit konventionellen Methoden zur deskriptiven Auswertung der zellulären und strukturellen Umbauvorgänge. Zur Darstellung der Revaskularisierung wurden die Querschnitte immunhistochemisch mit anti-von-Willebrandt-Faktor (FVIII) zur Detektion von Endothelzellen der Gefäßwand gefärbt. Die Auswertung erfolgte mittels Lichtmikroskopie bzw im Fall der immunhistochemisch gefärbten Präparate mittels eines digitalen Bildanalysesystems. Die Untersuchungen ergaben zum einen eine Verzögerung der zellulären Umbauprozesse der allogenen Transplantate mit länger bestehender A- und Hypozellularität. Zum anderen zeigte die Auswertung der Gefäßdichte eine verzögert beginnende Revaskularisierung der allogenen Transplantate und eine Tendenz des weiteren Ansteigens der Vaskularität von 12 nach 52 Wochen, wohingegen die autologen Transplantate einen Rückgang der Gefäße tendentiell zu Werten des nativen vorderen Kreuzbandes hin zeigten. Grundsätzlich konnte aber auch gezeigt werden, dass auch bei allogenen Transplantaten eine Revaskularisierung stattfindet. Damit konnte in dieser Studie erstmals mittels höchst sensitivem Nachweisverfahren eine verzögert ablaufende Revaskularisierung freier allogener Sehnentransplantate nachgewiesen werden. In Verbindung der in dieser Studie erarbeiteten Ergebnisse mit den von einer zweiten Doktorandin ermittelten biomechanischen Daten, die zum 52 Wochenzeitpunkt signifikant schlechtere Werte der allogenen gegenüber den autologen Transplantaten zeigten, muss also von einem zu aggressiven postoperativen Rehabilitationsprogramm abgeraten werden. Eine schnellere Rückkehr zur Belastung unter Vermeidung von Spitzenbelastungen könnte einen Kompromiss darstellen. Grundsätzlich aber stellen allogene freie Sehnentransplantate eine gute Möglichkeit zum Ersatz des vorderen Kreuzbandes dar.Allograft use for ACL reconstruction has become more and more popular due to the avoidance of graft harvest morbidity, the unlimited supply of grafts for ligament reconstruction and their ease to adapt to any possible anatomic requirement. New improved fixation techniques have envolved that eliminate the previous disadvantages in fixation strength of soft tissue grafts. The requirement for healing, remodelling and survival of the graft is the revascularisation during the course of healing after ACL reconstruction. We showed that revascularisation starts from the periphery of the grafts, mainly at its synovial sheet. Later vessels start to grow into the graft from the periphery to its central portions. During the first phase of revascularisation the graft shows a hypervascularity and the mechanical properties of the graft decrease. With progressive remodelling the vascularity of the graft nearly returns to the level of the native ACL. In he literature, no general information can be found about the duration of the remodelling and revascularisation process of a free soft tissue allograft after ACL reconstruction. However, it is often hypothesized that revascularisation of free tendon allografts lags behind autologous ACL Reconstruction. At the same time many people proclaim a more aggressive rehabilitation program and an earlier return to full load bearing because of the lower donor- site morbidity of allografts. Some clinical studies report higher failure rates with allograft compared with autograft use. The reason could be a delayed revascularisation of the allografts. The objective of this study was the comparison of the remodelling and the revascularisation of free soft tissue autologous and fresh frozen allogenic ACL reconstruction. 54 mature sheep underwent open ACL reconstruction using either a free tendon auto- or allograft. Animals were sacrified at 6, 12 and 52 weeks. Midsubstance tissue samples were obtained and cells were visualized with standard histological techniques, endothelial cells were immunostained with anti-v. Willebrandt factor. Tissue sections were analysed using microscopy and the immunostained tissue sections were analysed using a digital image analysis system. In this study it was shown that the revascularisation and remodelling of free tendon allografts lag behind autologous graft tissue. The revascularisation of the allogarfts started delayed and was not completed at 52 weeks. The autografts showed a return nearly to the level of the native ACL up to 52 weeks without achieving this level exactly. This was the first study that could show with a new, more sensitive method, that allografts undergo a delayed process of revascularisation but we also could show that there is some revascularisation as we can find in autografts. In combination with the results of the mechanical tests, which showed significantly reduced mechanical properties of the allografts at one year, we recommend avoiding too early aggressive rehabilitation after ACL reconstruction with allogenic tissue. A steady controlled return from partial to full weight bearing might be a compromise that will ensure adequate graft healing and maturation into a fully functional ACL replacement that provides the biological and mechanical properties to allow unrestricted use of such reconstructed knee joint

Foreword

Proteins that contain long disordered regions are prevalent in the proteome and frequently associated with diseases. However, the mechanisms by which such intrinsically disordered proteins (IDPs) recognize their targets are not well understood. Here, we report the first experimental investigation of the interaction kinetics of the nuclear co-activator binding domain of CREB-binding protein and the activation domain from the p160 transcriptional co-activator for thyroid hormone and retinoid receptors. Both protein domains are intrinsically disordered in the free state and synergistically fold upon binding each other. Using the stopped-flow technique, we found that the binding reaction is fast, with an association rate constant of 3 x 10(7) M-1 s(-1) at 277 K. Mutation of a conserved buried intermolecular salt bridge showed that electrostatics govern the rapid association. Furthermore, upon mutation of the salt bridge or at high salt concentration, an additional kinetic phase was detected (similar to 20 and similar to 40 s(-1), respectively, at 277 K), suggesting that the salt bridge may steer formation of the productive bimolecular complex in an intramolecular step. Finally, we directly measured slow kinetics for the IDP domains (similar to 1 s(-1) at 277 K) related to conformational transitions upon binding. Together, the experiments demonstrate that the interaction involves several steps and accumulation of intermediate states. Our data are consistent with an induced fit mechanism, in agreement with previous simulations. We propose that the slow transitions may be a consequence of the multipartner interactions of IDPs

Meson wave function from holographic approaches

We discuss the light-front wave function for the valence quark state of mesons using the AdS/CFT correspondence. We consider two kinds of wave functions obtained in different holographic Soft-Wall approachesComment: 4 pages, 3 figures, to appear in the Proceedings of the VIII Latin American Symposium on Nuclear Physics and Applications, Santiago, Chile, 15-19 December 2009. Talk presented by A.

Beruf und Familie vereinbar? Auf familienfreundliche Arbeitszeiten und ein gutes Betriebsklima kommt es an

Wir haben mithilfe einer logistischen Regression die Einflussfaktoren auf die Einschätzung der Vereinbarkeit der Arbeitszeiten mit der Familie sowie die Bewertung der Familienfreundlichkeit des Betriebes untersucht. Im Abschnitt 2 werden der Forschungsstand und die zu prüfenden Hypothesen dargestellt. Anschließend werden die Methode und die Variablen der Befragung erläutert. Abschnitt 4 präsentiert zuerst die bivariaten und anschließend die multivariaten empirischen Ergebnisse. Zum Schluss werden die Ergebnisse zusammengefasst und ein Fazit gezogen. --

Reflective equilibrium is enough: against the need for preselecting considered judgements

Neste artigo focamo-nos num elemento controverso do método do equilíbrio reflexivo, nomeadamente a ideia de Rawls de que os compromissos que entram no processo justificatório deveriam ser pré-seleccionados ou filtrados: de acordo com Rawls, apenas os juízos bem ponderados deveriam ser levados em conta na filosofia moral. Os críticos deste processo de filtragem distribuem-se por dois campos: 1) Os críticos do equilíbrio reflexivo rejeitam o processo de filtragem rawlsiano por ser excessivamente fraco e procuram um que seja mais fiável e que constituiria um diferente método epistémico; 2) Os proponentes do equilíbrio reflexivo rejeitam o processo de filtragem Rawlsiano por ser excessivamente excludente. Nós defendemos o ER, em oposição aos seus críticos, argumentando que este método pode assegurar compromissos razoáveis sem estar dependente de um processo externo forte de filtragem. No entanto, alinhamo-nos com os proponentes críticos do equilíbrio reflexivo, defendendo que, sem este processo de filtragem fraco, o ER rawlsiano revela-se como mais plausível tanto como um método geral, como no contexto da filosofia moral.In this paper, we focus on one controversial element of the method of reflective equilibrium, namely Rawls’ idea that the commitments that enter the justificatory procedure should be pre-selected or filtered: According to him, only considered judgements should be taken into account in moral philosophy. There are two camps of critics of this filtering process: 1) Critics of reflective equilibrium: They reject the Rawlsian filtering process as too weak and seek a more reliable one, which would actually constitute a distinct epistemic method. 2) Proponents of reflective equilibrium: They reject the Rawlsian filtering process as too exclusionary. We defend RE against its critics, arguing that the method can secure reasonable commitments without depending on a strong external filtering process. However, we side with the critical proponents of reflective equilibrium and argue that without the Rawlsian weak filtering process, RE is more plausible both as a general method as well as in the context of moral philosophy