Topological calculation of the phase of the determinant of a non self-adjoint elliptic operator

We study the zeta-regularized determinant of a non self-adjoint elliptic operator on a closed odd-dimensional manifold. We show that, if the spectrum of the operator is symmetric with respect to the imaginary axis, then the determinant is real and its sign is determined by the parity of the number of the eigenvalues of the operator, which lie on the positive part of the imaginary axis. It follows that, for many geometrically defined operators, the phase of the determinant is a topological invariant. In numerous examples, coming from geometry and physics, we calculate the phase of the determinants in purely topological terms. Some of those examples were known in physical literature, but no mathematically rigorous proofs and no general theory were available until now.Comment: To appear in Communications of Mathematical Physic

Confronting fluctuations of conserved charges in central nuclear collisions at the LHC with predictions from Lattice QCD

We construct net baryon number and strangeness susceptibilities as well as correlations between electric charge and strangeness from experimental data of the ALICE Collaboration at the CERN LHC. The data were taken in Pb-Pb collisions at $\sqrt{s_{NN}}$=2.76 TeV. The resulting fluctuations and correlations are consistent with Lattice QCD results at the chiral crossover pseudocritical temperature $T_c\simeq 155$ MeV. This agreement lends strong support to the assumption that the fireball created in these collisions is of thermal origin and exhibits characteristic properties expected in QCD at the transition from the quark gluon plasma to the hadronic phase. The volume of the fireball for one unit of rapidity at $T_c$ is found to exceed 4000 fm$^3$. A detailed discussion on uncertainties in the temperature and volume of the fireball is presented. The results are linked to pion interferometry measurements and predictions from percolation theory.Comment: 7 pages, 4 figures Accepted for publication in PL

Management und Investitionen - Infrastrukturprojekte neu denken

Seit einigen Jahren besteht in der Bundesrepublik Deutschland ein massiver Nachholbedarf im Hinblick auf Investitionen in öffentliche Infrastruktur. Ein erheblicher Teil dieses Rück-stands ist dabei auf der kommunalen Ebene zu verorten. Neben der allgemein angespann-ten Finanzlage der Kommunen konnten vor allem Steuerungs- und Managementprobleme im Investitionsprozess als entscheidende Treiber dieser Entwicklung ausgemacht werden. Vor diesem Hintergrund wurde im Jahr 2014 die unabhängige Expertenkommission „Stär-kung von Investitionen in Deutschland“ vom damaligen Bundeswirtschaftsminister Sigmar Gabriel beauftragt, Lösungsansätze für die bestehenden Probleme zu erarbeiten. Heraus-gekommen sind Vorschläge, die die Ursachen des Investitionsrückstands berücksichtigen, allerdings hinsichtlich der konkreten Ausgestaltung der sog. Infrastrukturgesellschaften in weiten Teilen vage bleiben. Insbesondere wird nicht geklärt, ob und inwieweit bzw. unter welchen organisatorischen Rahmenbedingungen sich die Vorschläge auf die kommunale Ebene übertragen lassen. Im Rahmen dieser Analyse werden die Vorschläge der Expertenkommission einer kritischen Betrachtung unterzogen. Dazu werden im ersten Schritt aus den Vorschlägen der Exper-tenkommission Grundkonzeptionen abgeleitet. Die Aufgabenbereiche der Infrastrukturge-sellschaften umfassen so die Bereitstellung von Beratungsleistungen, die Projektrealisierung sowie die Projektfinanzierung. Im zweiten Schritt werden dafür vorhandene Anwendungs-beispiele identifiziert und analysiert. Zusammenfassend ist dabei festzustellen: Überregionale Beratungseinrichtungen bieten eine Möglichkeit, den Investitionsprozess für Kommunen transparenter zu gestalten und ihnen spezifisches Know-how zur Verfügung zu stellen. Eine über die Beratung hinausge-hende Gesellschaft, die zusätzlich eigenständig Aufgaben des Projektmanagement und der -steuerung oder den gesamten Realisierungsprozess sowie ggf. auch die Bewirtschaf-tung der Infrastruktureinrichtung übernehmen kann, erscheint ebenfalls sinnvoll. In der Praxis ist dies für die kommunale Ebene allerdings schwer umsetzbar. Zweckverbände, die den Infrastrukturbetrieb für Kommunen gebündelt wahrnehmen, können als erster Zwi-schenschritt gesehen werden, der schon heute in einigen Bereichen vorzufinden ist. Angesichts der Herausforderungen des demographischen Wandels sowie der allgemein angespannten Finanzsituation vieler Kommunen muss in der Zukunft aber verstärkt über den Ausbau solcher Arrangements und praktikable Alternativen nachgedacht werden. Die Implementierung von Infrastrukturfonds, die finanzschwachen Kommunen zusätzliches Kapital für Investitionen zur Verfügung stellen sollen, lohnt sich für die Kommunen nur dann, wenn tatsächlich eine finanzielle Entlastung stattfindet. Hierzu könnte die Bündelung einer Vielzahl ähnlicher kommunaler Projekte innerhalb eines Fonds beitragen, allerdings existiert ein derartiges Modell derzeit noch nicht

Eine schmale Brücke in die Zukunft?: Stellungnahme zum Förderprogramm des Freistaates Sachsen

„800 Millionen Euro für Schulen, Straßen, Sportstätten und ÖPNV“ konnte man im Februar 2016 einer Pressemitteilung der sächsischen Staatsregierung entnehmen. Von Investitionen, welche „direkt vor Ort in Sachsens Städten und Gemeinden spürbar sein [sollen]“, war auf der Homepage der CDU-Fraktion Sachsen die Rede. Sachsens Ministerpräsident Tillich sprach von einem Konjunkturpaket mit „Einmaligkeitscharakter“, CDU-Fraktionschef Frank Kupfer vom größten Sonderprogramm in der Geschichte des Landes Sachsen. Bei diesem Paket handelt es sich um das Investitionsprogramm „Brücken in die Zukunft“, welches der Freistaat Sachsen auf Grundlage des Gesetzes zur Stärkung der kommunalen Investitionskraft aufgesetzt hat. Die finanziellen Mittel sollen demnach den sächsischen Kommunen zur Finanzierung von Infrastrukturprojekten zur Verfügung gestellt werden

Confronting fluctuations of conserved charges in central nuclear collisions at the LHC with predictions from Lattice QCD

We construct net baryon number and strangeness susceptibilities as well as correlations between electric charge, strangeness and baryon number from experimental data at midrapidity of the ALICE Collaborationat CERN. The data were taken in central Pb–Pb collisions at √sNN = 2.76 TeV and cover one unit of rapidity. The resulting fluctuations and correlations are consistent with Lattice QCD results at the chiral crossover pseudocritical temperature Tc ≃ 155 MeV. This agreement lends strong support to the assumption that the fireball created in these collisions is of thermal origin and exhibits characteristic properties expected in QCD at the transition from the quark gluon plasma to the hadronic phase. The volume of the fireball for one unit of rapidity at Tc is found to exceed 3000 fm³. A detailed discussion on uncertainties in the temperature and volume of the fireball is presented. The results are linked to pion interferometry measurements and predictions from percolation theory

Measurement of charm production at central rapidity in proton-proton collisions at s=2.76\sqrt{s} = 2.76 TeV

The $p_{\rm T}$-differential production cross sections of the prompt (B feed-down subtracted) charmed mesons D$^0$, D$^+$, and D$^{*+}$ in the rapidity range $|y|<0.5$, and for transverse momentum $1< p_{\rm T} <12$ GeV/$c$, were measured in proton-proton collisions at $\sqrt{s} = 2.76$ TeV with the ALICE detector at the Large Hadron Collider. The analysis exploited the hadronic decays D$^0 \rightarrow$K$\pi$, D$^+ \rightarrow$K$\pi\pi$, D$^{*+} \rightarrow$D$^0\pi$, and their charge conjugates, and was performed on a $L_{\rm int} = 1.1$ nb$^{-1}$ event sample collected in 2011 with a minimum-bias trigger. The total charm production cross section at $\sqrt{s} = 2.76$ TeV and at 7 TeV was evaluated by extrapolating to the full phase space the $p_{\rm T}$-differential production cross sections at $\sqrt{s} = 2.76$ TeV and our previous measurements at $\sqrt{s} = 7$ TeV. The results were compared to existing measurements and to perturbative-QCD calculations. The fraction of cdbar D mesons produced in a vector state was also determined.Comment: 20 pages, 5 captioned figures, 4 tables, authors from page 15, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/307

K-Decompositions and 3d Gauge Theories

This paper combines several new constructions in mathematics and physics. Mathematically, we study framed flat PGL(K,C)-connections on a large class of 3-manifolds M with boundary. We define a space L_K(M) of framed flat connections on the boundary of M that extend to M. Our goal is to understand an open part of L_K(M) as a Lagrangian in the symplectic space of framed flat connections on the boundary, and as a K_2-Lagrangian, meaning that the K_2-avatar of the symplectic form restricts to zero. We construct an open part of L_K(M) from data assigned to a hypersimplicial K-decomposition of an ideal triangulation of M, generalizing Thurston's gluing equations in 3d hyperbolic geometry, and combining them with the cluster coordinates for framed flat PGL(K)-connections on surfaces. Using a canonical map from the complex of configurations of decorated flags to the Bloch complex, we prove that any generic component of L_K(M) is K_2-isotropic if the boundary satisfies some topological constraints (Theorem 4.2). In some cases this implies that L_K(M) is K_2-Lagrangian. For general M, we extend a classic result of Neumann-Zagier on symplectic properties of PGL(2) gluing equations to reduce the K_2-Lagrangian property to a combinatorial claim. Physically, we use the symplectic properties of K-decompositions to construct 3d N=2 superconformal field theories T_K[M] corresponding (conjecturally) to the compactification of K M5-branes on M. This extends known constructions for K=2. Just as for K=2, the theories T_K[M] are described as IR fixed points of abelian Chern-Simons-matter theories. Changes of triangulation (2-3 moves) lead to abelian mirror symmetries that are all generated by the elementary duality between N_f=1 SQED and the XYZ model. In the large K limit, we find evidence that the degrees of freedom of T_K[M] grow cubically in K.Comment: 121 pages + 2 appendices, 80 figures; Version 2: reorganized mathematical perspective, swapped Sections 3 and

Pathogenic Mechanisms and Host Interactions in Staphylococcus epidermidis Device-Related Infection

Staphylococcus epidermidis is a permanent member of the normal human microbiota, commonly found on skin and mucous membranes. By adhering to tissue surface moieties of the host via specific adhesins, S. epidermidis is capable of establishing a lifelong commensal relationship with humans that begins early in life. In its role as a commensal organism, S. epidermidis is thought to provide benefits to human host, including out-competing more virulent pathogens. However, largely due to its capacity to form biofilm on implanted foreign bodies, S. epidermidis has emerged as an important opportunistic pathogen in patients receiving medical devices. S. epidermidis causes approximately 20% of all orthopedic device-related infections (ODRIs), increasing up to 50%in late-developing infections. Despite this prevalence, it remains underrepresented in the scientific literature, in particular lagging behind the study of the S. aureus. This review aims to provide an overview of the interactions of S. epidermidis with the human host, both as a commensal and as a pathogen. The mechanisms retained by S. epidermidis that enable colonization of human skin as well as invasive infection, will be described, with a particular focus upon biofilm formation. The host immune responses to these infections are also described, including how S. epidermidis seems to trigger low levels of pro-inflammatory cytokines and high levels of interleukin-10, which may contribute to the sub-acute and persistent nature often associated with these infections. The adaptive immune response to S. epidermidis remains poorly described, and represents an area which may provide significant new discoveries in the coming years

Forward-central two-particle correlations in p-Pb collisions at root s(NN)=5.02 TeV

Two-particle angular correlations between trigger particles in the forward pseudorapidity range (2.5 2GeV/c. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B. V.Peer reviewe

Event-shape engineering for inclusive spectra and elliptic flow in Pb-Pb collisions at root(NN)-N-S=2.76 TeV

Peer reviewe