Nuclearity and Thermal States in Conformal Field Theory

We introduce a new type of spectral density condition, that we call L^2-nuclearity. One formulation concerns lowest weight unitary representations of SL(2,R) and turns out to be equivalent to the existence of characters. A second formulation concerns inclusions of local observable von Neumann algebras in Quantum Field Theory. We show the two formulations to agree in chiral Conformal QFT and, starting from the trace class condition for the semigroup generated by the conformal Hamiltonian L_0, we infer and naturally estimate the Buchholz-Wichmann nuclearity condition and the (distal) split property. As a corollary, if L_0 is log-elliptic, the Buchholz-Junglas set up is realized and so there exists a beta-KMS state for the translation dynamics on the net of C*-algebras for every inverse temperature beta>0. We include further discussions on higher dimensional spacetimes. In particular, we verify that L^2-nuclearity is satisfied for the scalar, massless Klein-Gordon field.Comment: 37 pages, minor correction

Ubic: Bridging the gap between digital cryptography and the physical world

Advances in computing technology increasingly blur the boundary between the digital domain and the physical world. Although the research community has developed a large number of cryptographic primitives and has demonstrated their usability in all-digital communication, many of them have not yet made their way into the real world due to usability aspects. We aim to make another step towards a tighter integration of digital cryptography into real world interactions. We describe Ubic, a framework that allows users to bridge the gap between digital cryptography and the physical world. Ubic relies on head-mounted displays, like Google Glass, resource-friendly computer vision techniques as well as mathematically sound cryptographic primitives to provide users with better security and privacy guarantees. The framework covers key cryptographic primitives, such as secure identification, document verification using a novel secure physical document format, as well as content hiding. To make a contribution of practical value, we focused on making Ubic as simple, easily deployable, and user friendly as possible.Comment: In ESORICS 2014, volume 8712 of Lecture Notes in Computer Science, pp. 56-75, Wroclaw, Poland, September 7-11, 2014. Springer, Berlin, German

Energy Reduction in Public Building Stock: Assessing the Impact of Control Strategy over Expected Energy Savings and Indoor Comfort Level

peer reviewedIn the framework of EU FP7 BRICKER project, the renovation of public owned nonresidential buildings is addressed through the installation of innovative passive and active technologies. The expected impact is a primary energy reduction of about 50% with respect to the existing scenario with a large replication potential under different European countries. In order to achieve such ambitious goal one issue that cannot be ignored is the effect of control strategy, not only over the resulting energy performance but also over the resulting indoor comfort conditions. In this paper, the actual control strategy implemented in the Belgian demo of Bricker project is introduced, compared against an ideal approach and accordingly optimized. The resulting proposed approach is then tested by means of numerical simulations over a base case scenario before renovation. The main conclusion of this work is the demonstration that control strategy of energy generation and distribution systems has to be revised whenever deep renovation of passive or active building technologies is undertaken. Contrarily to which, project renovation goals cannot be met.BRICKER - Total Renovation Strategies for Energy Reduction in Public Building Stock (BRICKER

Scaling algebras and pointlike fields: A nonperturbative approach to renormalization

We present a method of short-distance analysis in quantum field theory that does not require choosing a renormalization prescription a priori. We set out from a local net of algebras with associated pointlike quantum fields. The net has a naturally defined scaling limit in the sense of Buchholz and Verch; we investigate the effect of this limit on the pointlike fields. Both for the fields and their operator product expansions, a well-defined limit procedure can be established. This can always be interpreted in the usual sense of multiplicative renormalization, where the renormalization factors are determined by our analysis. We also consider the limits of symmetry actions. In particular, for suitable limit states, the group of scaling transformations induces a dilation symmetry in the limit theory.Comment: minor changes and clarifications; as to appear in Commun. Math. Phys.; 37 page

El cambio global

En este artículo se analiza un subconjunto de los fenómenos conocidos como Cambio Global y en los que el autor ha realizado algunas investigaciones. Desde que se originó, hace unos cuatro mil seiscientos millones de años (4,6 Ga) hasta el presente, la Tierra ha sido un planeta cambiante. El cambio es producido por enormes fuerzas naturales que elevan montañas, quiebran la corteza terrestre, hacen emerger volcanes que cambian el paisaje geológico, crean islas y archipiélagos y otros fenómenos de similar magnitud que, a veces, cambian el clima. La acción humana es irrelevante ante los cambios producidos por estas fuerzas naturales. Sin embargo, en pequeña escala, acumulativa, la humanidad produce otros cambios que pueden controlarse, evitarse o modificarse. Estos cambios se operan principalmente en la atmósfera y tienen efectos sobre uno o más subsistemas de la Tierra.Universidad Nacional de La Plat

El cambio global

En este artículo se analiza un subconjunto de los fenómenos conocidos como Cambio Global y en los que el autor ha realizado algunas investigaciones. Desde que se originó, hace unos cuatro mil seiscientos millones de años (4,6 Ga) hasta el presente, la Tierra ha sido un planeta cambiante. El cambio es producido por enormes fuerzas naturales que elevan montañas, quiebran la corteza terrestre, hacen emerger volcanes que cambian el paisaje geológico, crean islas y archipiélagos y otros fenómenos de similar magnitud que, a veces, cambian el clima. La acción humana es irrelevante ante los cambios producidos por estas fuerzas naturales. Sin embargo, en pequeña escala, acumulativa, la humanidad produce otros cambios que pueden controlarse, evitarse o modificarse. Estos cambios se operan principalmente en la atmósfera y tienen efectos sobre uno o más subsistemas de la Tierra.Universidad Nacional de La Plat

From Operator Algebras to Superconformal Field Theory

We make a review on the recent progress in the operator algebraic approach to (super)conformal field theory. We discuss representation theory, classification results, full and boundary conformal field theories, relations to supervertex operator algebras and Moonshine, connections to subfactor theory and noncommutative geometry

El cambio global

En este artículo se analiza un subconjunto de los fenómenos conocidos como Cambio Global y en los que el autor ha realizado algunas investigaciones. Desde que se originó, hace unos cuatro mil seiscientos millones de años (4,6 Ga) hasta el presente, la Tierra ha sido un planeta cambiante. El cambio es producido por enormes fuerzas naturales que elevan montañas, quiebran la corteza terrestre, hacen emerger volcanes que cambian el paisaje geológico, crean islas y archipiélagos y otros fenómenos de similar magnitud que, a veces, cambian el clima. La acción humana es irrelevante ante los cambios producidos por estas fuerzas naturales. Sin embargo, en pequeña escala, acumulativa, la humanidad produce otros cambios que pueden controlarse, evitarse o modificarse. Estos cambios se operan principalmente en la atmósfera y tienen efectos sobre uno o más subsistemas de la Tierra.Universidad Nacional de La Plat

GRANVILLE SHARP PATTISON (1791.–1851.): ŠKOTSKI ANATOM I KIRURG SKLON SUKOBIMA

Granville Sharp Pattison was a Scottish anatomist and surgeon who also taught in the United States. This character from the history of anatomy lived a very colourful life. As many are unaware of Pattison, the present review of his life, contributions, and controversies seemed appropriate. Although Pattison was known to be a good anatomist, he will be remembered for his association with a propensity for conflict both in Europe and the United States.Granville Sharp Pattison je škotski anatom i kirurg koji je također podučavao u Sjedinjenim Američkim Državama. Ovaj lik iz povijesti anatomije živio je vrlo šaroliki život. Budući da mnogi nisu upoznati s Pattisonom, ovaj pregled njegova života, doprinosa i kontroverzi čini se prikladnim. Iako je Pattison bio poznat kao dobar anatom, on će biti zapamćen po svojoj povezanosti sa sklonošću sukobima i u Europi i u SAD-u

On the uniqueness of diffeomorphism symmetry in Conformal Field Theory

A Moebius covariant net of von Neumann algebras on S^1 is diffeomorphism covariant if its Moebius symmetry extends to diffeomorphism symmetry. We prove that in case the net is either a Virasoro net or any at least 4-regular net such an extension is unique: the local algebras together with the Moebius symmetry (equivalently: the local algebras together with the vacuum vector) completely determine it. We draw the two following conclusions for such theories. (1) The value of the central charge c is an invariant and hence the Virasoro nets for different values of c are not isomorphic as Moebius covariant nets. (2) A vacuum preserving internal symmetry always commutes with the diffeomorphism symmetries. We further use our result to give a large class of new examples of nets (even strongly additive ones), which are not diffeomorphism covariant; i.e. which do not admit an extension of the symmetry to Diff^+(S^1).Comment: 25 pages, LaTe