Phase diagram of the mean field model of simplicial gravity

We discuss the phase diagram of the balls in boxes model, with a varying number of boxes. The model can be regarded as a mean-field model of simplicial gravity. We analyse in detail the case of weights of the form $p(q) = q^{-\beta}$, which correspond to the measure term introduced in the simplicial quantum gravity simulations. The system has two phases~: {\em elongated} ({\em fluid}) and {\em crumpled}. For $\beta\in (2,\infty)$ the transition between these two phases is first order, while for $\beta \in (1,2]$ it is continuous. The transition becomes softer when $\beta$ approaches unity and eventually disappears at $\beta=1$. We then generalise the discussion to an arbitrary set of weights. Finally, we show that if one introduces an additional kinematic bound on the average density of balls per box then a new {\em condensed} phase appears in the phase diagram. It bears some similarity to the {\em crinkled} phase of simplicial gravity discussed recently in models of gravity interacting with matter fields.Comment: 15 pages, 5 figure

ARPES studies of cuprate Fermiology: superconductivity, pseudogap, and quasiparticle dynamics

We present angle-resolved photoemission spectroscopy (ARPES) studies of the cuprate high-temperature superconductors which elucidate the relation between superconductivity and the pseudogap and highlight low-energy quasiparticle dynamics in the superconducting state. Our experiments suggest that the pseudogap and superconducting gap represent distinct states, which coexist below T$_c$. Studies on Bi-2212 demonstrate that the near-nodal and near-antinodal regions behave differently as a function of temperature and doping, implying that different orders dominate in different momentum-space regions. However, the ubiquity of sharp quasiparticles all around the Fermi surface in Bi-2212 indicates that superconductivity extends into the momentum-space region dominated by the pseudogap, revealing subtlety in this dichotomy. In Bi-2201, the temperature dependence of antinodal spectra reveals particle-hole asymmetry and anomalous spectral broadening, which may constrain the explanation for the pseudogap. Recognizing that electron-boson coupling is an important aspect of cuprate physics, we close with a discussion of the multiple 'kinks' in the nodal dispersion. Understanding these may be important to establishing which excitations are important to superconductivity.Comment: To appear in a focus issue on 'Fermiology of Cuprates' in New Journal of Physic

Multiwavelength Studies of PSR J1420-6048, a Young Pulsar in the Kookaburra

We present X-ray, radio, and infrared observations of the 68 ms pulsar PSR J1420-6048 and its surrounding nebula, a possible counterpart of the gamma-ray source GeV J1417-6100/3EG J1420-6038. Pulsed X-ray emission at the radio period is marginally detected by ASCA from a source embedded in the hard spectrum X-ray nebula AX J1420.1-6049. At radio wavelengths, the pulsar is found to be strongly linearly and circularly polarized, and the polarization sweep is measured. A comparison of high resolution ATCA radio imaging of the Kookaburra's upper wing (G313.6+0.3), which contains the pulsar and the X-ray nebula, with infrared images suggests the radio emission is partly non-thermal.Comment: 8 pages, 4 figures, to appear in Astrophysical Journal Letter

Still waters run deep: latent cytokine activity in nonlesional psoriasis skin

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/116968/1/bjd14248_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/116968/2/bjd14248.pd

Signaling Virtue or Vulnerability? The Changing Impact of Exchange Rate Regimes on Government Bond Yields

Do exchange rate regimes affect the conditions under which developed countries borrow? This paper argues that they do, but their impact on yields depends on the prevailing macroeconomic context. When investors regard inflation as the most relevant risk to bond holdings, monetary union has a distinct advantage over floating and fixed exchange rates because of its credible in-built mechanism to control inflation. However, once default is seen as the most relevant risk, exchange rate rigidity becomes a liability due to its constraining effect on governments’ ability to respond to adverse shocks. We test our argument with a moving window panel analysis for twenty-three OECD countries from 1980 to 2017. We find that before the late 2000s, inflation was penalized under floating and (to a lesser extent) fixed exchange rate regimes, but not in countries in monetary union. Since the 2010s, inflation carries no penalty under any exchange rate regime. Variables linked to default risk (debt and entitlement spending) did not affect yields under any exchange rate arrangements until the mid-2000s. Afterwards, countries in monetary union (and to a lesser extent in fixed exchange rate regimes) were significantly penalized for public debt and entitlement spending, whereas countries with floating regimes were not. Our results speak to the literatures on governments’ institutional commitments and “room to move.”Haben Wechselkursregime einen Einfluss auf die Konditionen, zu denen entwickelte Länder Staatsanleihen ausgeben können? Wir argumentieren in diesem Beitrag, dass dies der Fall ist, wobei ihre Wirkung auf die Anleiherenditen vom vorherrschenden makroökonomischen Kontext abhängt. Erachten Investoren Inflation als das entscheidende Risiko für Investitionen in Anleihen, so hat eine Währungsunion durch ihren glaubwürdigen inte­grierten Mechanismus zur Inflationskontrolle klare Vorteile gegenüber flexiblen und festen Wechselkursen. Wird jedoch ein Ausfall der Rückzahlungen als das entscheidende Risiko angesehen, werden starre Wechselkurse zum Nachteil, da sie die Fähigkeit von Regierungen, auf negative Schocks zu reagieren, verringern. Wir testen unser Argument mithilfe einer für den Zeitraum von 1980 bis 2017 mit gleitenden Zeitfenstern durchgeführten Panelana­lyse von 23 OECD-Ländern. Die Ergebnisse zeigen, dass Inflation vor den späten 2000er-Jahren in flexiblen und (weniger stark) in festen Wechselkursregimen finanziell abgestraft wurde, jedoch nicht in den Ländern einer Währungsunion. Seit den 2010er-Jahren wirkt sich Inflation in keinem der Wechselkursregime auf die Renditen aus. Mit dem Ausfallri­siko verknüpfte Variablen (Staatsverschuldung und Sozialausgaben) hatten bis zur Mitte der 2000er-Jahre in keinem der Wechselkursregime einen Einfluss auf die Renditen. Danach wurden Länder in einer Währungsunion erheblich (und Länder in festen Wechselkursregimen weniger stark) für Staatsverschuldung und Sozialausgaben abgestraft, während dies bei Ländern in flexiblen Regimen nicht der Fall war. Unsere Ergebnisse tragen zur Literatur über institutionelle Selbstverpflichtungen und Handlungsspielräume von Regierungen bei.Contents 1 Introduction 2 Commitment devices and policy autonomy from a theoretical perspective 3 Inflation risk, default risk, and exchange rate regimes: An analysis of twenty-three OECD countries 4 Results section Results Robustness checks 5 Discussion and conclusion Appendix A Sources used for identifying sample countries’ exchange rate regimes over time Appendix B Results controlling for capital mobility (measured via the Chinn-Ito capital account openness index) Appendix C Results excluding countries with a greater share of foreign currency-denominated debt than 2 percent (Canada and Sweden) Appendix D Results for crawling peg exchange rate regime Appendix E Results excluding heavily indebted EMU countries (Belgium, Greece, and Italy) Appendix F Results excluding EMU countries with the lowest sovereign credit ratings prior to the crisis (Greece, Italy, and Portugal) Reference

Material and doping dependence of the nodal and anti-nodal dispersion renormalizations in single- and multi-layer cuprates

In this paper we present a review of bosonic renormalization effects on electronic carriers observed from angle-resolved photoemission spectra in the cuprates. We specifically discuss the viewpoint that these renormalizations represent coupling of the electrons to the lattice, and review how the wide range of materials dependence, such as the number of CuO$_2$ layers, and the doping dependence can be straightforwardly understood as arising due to novel electron-phonon coupling.Comment: 9 pages and 6 figures. Submitted as a review article for Advances in Condensed Matter Physic

Designing for Ballet Classes: Identifying and Mitigating Communication Challenges Between Dancers and Teachers

Dancer-teacher communication in a ballet class can be challenging: ballet is one of the most complex forms of movements, and learning happens through multi-faceted interactions with studio tools (mirror, barre, and floor) and the teacher. We conducted an interview-based qualitative study with seven ballet teachers and six dancers followed by an open-coded analysis to explore the communication challenges that arise while teaching and learning in the ballet studio. We identified key communication issues, including adapting to multi-level dancer expertise, transmitting and realigning development goals, providing personalized corrections and feedback, maintaining the state of flow, and communicating how to properly use tools in the environment. We discuss design implications for crafting technological interventions aimed at mitigating these communication challenges

Reprogramming of lysosomal gene expression by interleukin-4 and Stat6.

BACKGROUND: Lysosomes play important roles in multiple aspects of physiology, but the problem of how the transcription of lysosomal genes is coordinated remains incompletely understood. The goal of this study was to illuminate the physiological contexts in which lysosomal genes are coordinately regulated and to identify transcription factors involved in this control. RESULTS: As transcription factors and their target genes are often co-regulated, we performed meta-analyses of array-based expression data to identify regulators whose mRNA profiles are highly correlated with those of a core set of lysosomal genes. Among the ~50 transcription factors that rank highest by this measure, 65% are involved in differentiation or development, and 22% have been implicated in interferon signaling. The most strongly correlated candidate was Stat6, a factor commonly activated by interleukin-4 (IL-4) or IL-13. Publicly available chromatin immunoprecipitation (ChIP) data from alternatively activated mouse macrophages show that lysosomal genes are overrepresented among Stat6-bound targets. Quantification of RNA from wild-type and Stat6-deficient cells indicates that Stat6 promotes the expression of over 100 lysosomal genes, including hydrolases, subunits of the vacuolar H⁺ ATPase and trafficking factors. While IL-4 inhibits and activates different sets of lysosomal genes, Stat6 mediates only the activating effects of IL-4, by promoting increased expression and by neutralizing undefined inhibitory signals induced by IL-4. CONCLUSIONS: The current data establish Stat6 as a broadly acting regulator of lysosomal gene expression in mouse macrophages. Other regulators whose expression correlates with lysosomal genes suggest that lysosome function is frequently re-programmed during differentiation, development and interferon signaling

High stress monitoring of prestressing tendons in nuclear concrete vessels using fibre-optic sensors

Maintaining the structural health of prestressed concrete nuclear containments is a key element in ensuring nuclear reactors are capable of meeting their safety requirements. This paper discusses the attachment, fabrication and characterisation of optical fibre strain sensors suitable for the prestress monitoring of irradiated steel prestressing tendons. The all-metal fabrication and welding process allowed the instrumented strand to simultaneously monitor and apply stresses up to 1300 MPa (80% of steel's ultimate tensile strength). There were no adverse effects to the strand's mechanical properties or integrity. After sensor relaxation through cyclic stress treatment, strain transfer between the optical fibre sensors and the strand remained at 69%. The fibre strain sensors could also withstand the non-axial forces induced as the strand was deflected around a 4.5 m bend radius. Further development of this technology has the potential to augment current prestress monitoring practices, allowing distributed measurements of short- and long-term prestress losses in nuclear prestressed-concrete vessels

Integrable models and quantum spin ladders: comparison between theory and experiment for the strong coupling ladder compounds

(abbreviated) This article considers recent advances in the investigation of the thermal and magnetic properties of integrable spin ladder models and their applicability to the physics of real compounds. The ground state properties of the integrable two-leg spin-1/2 and the mixed spin-(1/2,1) ladder models at zero temperature are analyzed by means of the Thermodynamic Bethe Ansatz. Solving the TBA equations yields exact results for the critical fields and critical behaviour. The thermal and magnetic properties of the models are investigated in terms of the recently introduced High Temperature Expansion method, which is discussed in detail. It is shown that in the strong coupling limit the integrable spin-1/2 ladder model exhibits three quantum phases: (i) a gapped phase in the regime $H<H_{c1}$, (ii) a fully polarised phase for $H>H_{c2}$, and (iii) a Luttinger liquid magnetic phase in the regime $H_{c1}<H<H_{c2}$. The critical behaviour in the vicinity of the critical points is of the Pokrovsky-Talapov type. The temperature-dependent thermal and magnetic properties are directly evaluated from the exact free energy expression and compared to known experimental results for a range of strong coupling ladder compounds. Similar analysis of the mixed spin-(1/2,1) ladder model reveals a rich phase diagram, with a 1/3 and a full saturation magnetisation plateau within the strong antiferromagnetic rung coupling regime. For weak rung coupling, the fractional magnetisation plateau is diminished and a new quantum phase transition occurs. The phase diagram can be directly deduced from the magnetisation curve obtained from the exact result derived from the HTE. The thermodynamics of the spin-orbital model with different single-ion anisotropies is also investigated.Comment: 90 pages, 33 figures, extensive revisio