410 research outputs found
Geometric modular action for disjoint intervals and boundary conformal field theory
In suitable states, the modular group of local algebras associated with
unions of disjoint intervals in chiral conformal quantum field theory acts
geometrically. We translate this result into the setting of boundary conformal
QFT and interpret it as a relation between temperature and acceleration. We
also discuss aspects ("mixing" and "charge splitting") of geometric modular
action for unions of disjoint intervals in the vacuum state.Comment: Dedicated to John E. Roberts on the occasion of his 70th birthday; 24
pages, 3 figure
Carnot-Caratheodory metric and gauge fluctuation in Noncommutative Geometry
Gauge fields have a natural metric interpretation in terms of horizontal
distance. The latest, also called Carnot-Caratheodory or subriemannian
distance, is by definition the length of the shortest horizontal path between
points, that is to say the shortest path whose tangent vector is everywhere
horizontal with respect to the gauge connection. In noncommutative geometry all
the metric information is encoded within the Dirac operator D. In the classical
case, i.e. commutative, Connes's distance formula allows to extract from D the
geodesic distance on a riemannian spin manifold. In the case of a gauge theory
with a gauge field A, the geometry of the associated U(n)-vector bundle is
described by the covariant Dirac operator D+A. What is the distance encoded
within this operator ? It was expected that the noncommutative geometry
distance d defined by a covariant Dirac operator was intimately linked to the
Carnot-Caratheodory distance dh defined by A. In this paper we precise this
link, showing that the equality of d and dh strongly depends on the holonomy of
the connection. Quite interestingly we exhibit an elementary example, based on
a 2 torus, in which the noncommutative distance has a very simple expression
and simultaneously avoids the main drawbacks of the riemannian metric (no
discontinuity of the derivative of the distance function at the cut-locus) and
of the subriemannian one (memory of the structure of the fiber).Comment: published version with additional figures to make the proof more
readable. Typos corrected in this ultimate versio
Conformal mapping of Unruh temperature
Thanks to a local interpetation of the KMS condition, the mapping from
(unbounded) wedge regions of Minkowski space-time to (bounded) double-cone
regions is extended to the Unruh temperature associated to relevant observers
in both regions. A previous result, the diamond's temperature, is shown to be
proportional to the inverse of the conformal factor (Weyl rescaling of the
metric) of this map. One thus explains from a mathematical point of view why an
observer with finite lifetime experiences the vacuum as a thermal state
whatever his acceleration, even vanishing.Comment: Paper shortened and reorganized. To be published in Modern Physics
Letters
A Prevention through Design Approach for the Environmental S&H Conditions and the Ventilation System at an Italian Underground Quarry
Even if the number of the Italian quarrying operations in underground is steadily growing, in many cases the safety criticalities are somehow underestimated, in spite of the regulations D.Lgs. 81/08 and D.Lgs. 624/96, Italian enforcements of the European Directives.
Ventilation system is conceived to face very simplified requirements, whilst critical pollutants or emergency situations are not taken in due considerations. Asides, the ventilation system fault and availability analysis is seldom included in the project.
The paper deals with the results of a research work started some years ago at an underground quarry exploited through drift sublevel based on drill and blast technique, to identify criteria suitable to grant effective safety and health -S&H- conditions for the workers operating in the underground in the Prevention through Design approach.
Taken into account that the phases for an effective approach to the S&H problems in underground must follow a hierarchic method in which the risk management should be faced from an effective hazard reduction to a minimum at the sources, and the ventilation should be considered only as a 4th level
solution, the possibilities of control at the main pollution sources, i.e. the emission of pollutants due to the rock winning and mucking operations, have been examined.
The residual risk was then faced with both the original underground and airways layout definition for a new exploitation development, based on technical and efficiency considerations, and on fire emergency computer simulations.
Finally, the paper summarizes the results of an availability analysis of the ventilation system for the normal operating conditions and the emergencies management, on the basis of the results of Hazard Evaluation techniques, in particular Hazard and Operability Analysis and Fault Tree Analysis
An algebraic Birkhoff decomposition for the continuous renormalization group
This paper aims at presenting the first steps towards a formulation of the
Exact Renormalization Group Equation in the Hopf algebra setting of Connes and
Kreimer. It mostly deals with some algebraic preliminaries allowing to
formulate perturbative renormalization within the theory of differential
equations. The relation between renormalization, formulated as a change of
boundary condition for a differential equation, and an algebraic Birkhoff
decomposition for rooted trees is explicited
A Prevention through Design Approach for the Environmental S&H Conditions and the Ventilation System at an Italian Underground Quarry
Even if the number of the Italian underground quarrying operations is steadily growing, in many cases the safety criticalities are somehow underestimated, in spite of the regulations D.Lgs. 81/08 and D.Lgs.
624/96, Italian enforcements of the former European Directives 89/391/EEC, 92/91/EEC and 92/104/EEC.
Ventilation system is conceived to face very simplified requirements, whilst critical pollutants or emergency
situations are not taken in due consideration. Asides, the ventilation system fault and availability analysis are seldom included in the project.
The paper deals with the results of a research work started some years ago at an underground quarry exploited through drift sublevel based on drill and blast technique, to identify criteria suitable to grant effective safety and health -S&H- conditions for the workers operating in the underground in the Prevention through Design approach.
Taken into account that the phases for an effective approach to the S&H problems in underground must follow a hierarchic method, in which the risk management should be faced from an effective hazard reduction to a minimum at the sources, and the ventilation should be considered only as a 4th level
solution, the possibilities of control at the main pollution sources, i.e. the emission of pollutants due to the rock winning and mucking operations, have been examined.
The residual risk was then faced with both the original underground and airways layout definition for a new
exploitation development, based on technical and efficiency considerations, and on fire emergency computer simulations.
Finally, the paper summarizes the results of an availability analysis of the ventilation system for normal operating conditions, and the emergencies management, on the basis of the results of Hazard Evaluation techniques, particularly Hazard and Operability Analysis and Fault Tree Analysis
Relative entropy and the Bekenstein bound
Elaborating on a previous work by Marolf et al, we relate some exact results
in quantum field theory and statistical mechanics to the Bekenstein universal
bound on entropy. Specifically, we consider the relative entropy between the
vacuum and another state, both reduced to a local region. We propose that, with
the adequate interpretation, the positivity of the relative entropy in this
case constitutes a well defined statement of the bound in flat space. We show
that this version arises naturally from the original derivation of the bound
from the generalized second law when quantum effects are taken into account. In
this formulation the bound holds automatically, and in particular it does not
suffer from the proliferation of the species problem. The results suggest that
while the bound is relevant at the classical level, it does not introduce new
physical constraints semiclassically.Comment: 12 pages, 1 figure, minor changes and references adde
Decreasing Proportion of Recent Infections among Newly Diagnosed HIV-1 Cases in Switzerland, 2008 to 2013 Based on Line-Immunoassay-Based Algorithms.
BACKGROUND: HIV surveillance requires monitoring of new HIV diagnoses and differentiation of incident and older infections. In 2008, Switzerland implemented a system for monitoring incident HIV infections based on the results of a line immunoassay (Inno-Lia) mandatorily conducted for HIV confirmation and type differentiation (HIV-1, HIV-2) of all newly diagnosed patients. Based on this system, we assessed the proportion of incident HIV infection among newly diagnosed cases in Switzerland during 2008-2013.
METHODS AND RESULTS: Inno-Lia antibody reaction patterns recorded in anonymous HIV notifications to the federal health authority were classified by 10 published algorithms into incident (up to 12 months) or older infections. Utilizing these data, annual incident infection estimates were obtained in two ways, (i) based on the diagnostic performance of the algorithms and utilizing the relationship 'incident = true incident + false incident', (ii) based on the window-periods of the algorithms and utilizing the relationship 'Prevalence = Incidence x Duration'. From 2008-2013, 3'851 HIV notifications were received. Adult HIV-1 infections amounted to 3'809 cases, and 3'636 of them (95.5%) contained Inno-Lia data. Incident infection totals calculated were similar for the performance- and window-based methods, amounting on average to 1'755 (95% confidence interval, 1588-1923) and 1'790 cases (95% CI, 1679-1900), respectively. More than half of these were among men who had sex with men. Both methods showed a continuous decline of annual incident infections 2008-2013, totaling -59.5% and -50.2%, respectively. The decline of incident infections continued even in 2012, when a 15% increase in HIV notifications had been observed. This increase was entirely due to older infections. Overall declines 2008-2013 were of similar extent among the major transmission groups.
CONCLUSIONS: Inno-Lia based incident HIV-1 infection surveillance proved useful and reliable. It represents a free, additional public health benefit of the use of this relatively costly test for HIV confirmation and type differentiation
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