Contact Terms and Duality Symmetry in The Critical Dissipative Hofstadter Model

The dissipative Hofstadter model describes the quantum mechanics of a charged particle in two dimensions subject to a periodic potential, uniform magnetic field, and dissipative force. Its phase diagram exhibits an SL(2,Z) duality symmetry and has an infinite number of critical circles in the dissipation/magnetic field plane. In addition, multi-critical points on a particular critical circle correspond to non-trivial solutions of open string theory. The duality symmetry is expected to provide relations between correlation functions at different multi-critical points. Many of these correlators are contact terms. However we expect them to have physical significance because under duality they transform into functions that are non-zero for large separations of the operators. Motivated by the search for exact, regulator independent solutions for these contact terms, in this paper we derive many properties and symmetries of the coordinate correlation functions at the special multi-critical points. In particular, we prove that the correlation functions are homogeneous, piecewise-linear functions of the momenta, and we prove a weaker version of the anticipated duality transformation. Consequently, the possible forms of the correlation functions are limited to lie in a finite dimensional linear space. We treat the potential perturbatively and these results are valid to all orders in perturbation theory.Comment: 65 pages, six figures, CTP#217

Influence of model parameters on synthesized high-frequency strong-motion waveforms

Waveform modeling is an important and helpful instrument of modern seismology that may provide valuable information. However, synthesizing seismograms requires to define many parameters, which differently affect the final result. Such parameters may be: the design of the grid, the structure model, the source time functions, the source mechanism, the rupture velocity. Variations in parameters may produce significantly different seismograms. We synthesize seismograms from a hypothetical earthquake and numerically estimate the influence of some of the used parameters. Firstly, we present the results for high-frequency near-fault waveforms obtained from defined model by changing tested parameters. Secondly, we present the results of a quantitative comparison of contributions from certain parameters on synthetic waveforms by using misfit criteria. For the synthesis of waveforms we used 2D/3D elastic finite-difference wave propagation code E3D [1] based on the elastodynamic formulation of the wave equation on a staggered grid. This code gave us the opportunity to perform all needed manipulations using a computer cluster. To assess the obtained results, we use misfit criteria [2] where seismograms are compared in time-frequency and phase by applying a continuous wavelet transform to the seismic signal. [1] - Larsen, S. and C.A. Schultz (1995). ELAS3D: 2D/3D elastic finite-difference wave propagation code, Technical Report No. UCRL-MA-121792, 19 pp. [2] - Kristekova, M., Kristek, J., Moczo, P., Day, S.M., 2006. Misfit criteria for quantitative comparison of seismograms. Bul. of Seis. Soc. of Am. 96(5), 1836–1850

Slip distribution, coseismic deformation and Coulomb stress change for the 12 May 2008Wenchuan (China, Mw7.9) earthquake

The May 12, 2008 Wenchuan earthquake (Mw7.9) took place at the transition between the mountainous chain of Shan and the basin of Sichuan along the Longmen Shan Fault zone (31.1oN, 103.3oE; USGS). With a magnitude of 7.9 and a depth of ∼19 km the earthquake produced a 300-km-long fault rupture. It was the largest earthquake recorded in the region during the last centuries. It claimed more than 69,000 lives, induced widespread destruction over the region and raised concern about seismic hazard and source characterization for the Sichuan province. In the frame of our study, we selected 40 broadband waveforms (IRIS Consortium, USA) with good quality and satisfactory azimuthal coverage. Body waveforms were prepared for inversion using Kikuchi and Kanamori’s method [1] to obtain the spatiotem- poral slip distribution of a finite rupture model (length=300 km, strike=229o, dip=33o, width=60 km). The slip distribution model obtained was used to determine the coseismic deformation and the stress change distribution using the Coulomb 3.0 software [2]. Our coseismic deformation results was compared with data from GPS stations located near the fault rupture. Results show that directions of coseismic deformations are consistent with GPS observations close to the fault. Finally, we compare aftershock hypocenters that occurred during one month after the main shock with the Coulomb stress changes caused by this shock in the region. We observed that most aftershocks are located along the main fault plane without any noticeable clustering in the areas of increased stress. Our results suggest the rupture of the 2008 Wenchuan earthquake was essentially unilateral, from SW to NE (N49E), covering a 260km length and with duration about 105 sec. The strongest moment release occurred about 85km from the hypocenter, ∼30sec after the start of the rupture. Motions are dominated by thrust mechanism, but the superficial section of the second half of the rupture also shows a significant strike-slip component. [1]- Kikuchi, M., and Kanamori, H., 1982, Inversion of complex body waves: Bull. Seismol. Soc. Am., v. 72, p. 491-506. [2] -King, G. C. P., Stein, R. S. y Lin, J, 1994, Static stress changes and the triggering of earthquakes. Bull. Seismol. Soc. Am. 84,935-953

Recent Seismic Activity in the Azores Region

This seismic activity in the Azores Region is characterized by sequences of low-magnitude events, usually with epicenter off-shore. These seismic sequences are sometimes triggered by larger events, felt by the population, that could produce significant material and human losses. This characteristic is confirmed by the historical and instrumental seismicity, in particular by the recent earthquakes occurred on 1980 (Mw=6.8), 1997 (Mw=6.2), 1998 (Mw=6.2) and 2007 (Mw=6.3, Mw=6.1). The mechanism responsible for this spatial and temporal seismic pattern still yet not very well known. In this work we discuss the recent (2007) seismic activity of the Azores region by analyzing the spatial and temporal distribution of seismic events associated with two sequences with different characteristics. The fisrt one is a seismic swarm started on April 21st 2007, centered at about 40 kilometers west of the Faial Island (maximum magnitude mb=4.0). The second one corresponds to an aftershock sequence associated to the events of 2007/04/05 (Mw=6.3) and 2007/04/07 (Mw=6.1), both with epicenter in the Formigas Islets and felt (I=V/VI in Mercali scale) in S. Miguel. We calculate the static Coulomb stress change for both events using focal mechanisms derived from the inversion of body waves. We find that the static stress change caused by the April 5 event is higher, about 2 bar at the location of the second event (April 7), triggering the second rupture. Locations of aftershocks do not agree well with areas of increased Coulomb failure stress

The 2007 Azores earthquakes: A case of triggering?

On 5 April (Mw=6.3) and 7 April 2007 (Mw=6.1 ) two earthquakes occur at the Formigas Islets (Azores Islands), both with same epicenter and felt (I=V/VI MSK) in S. Miguel Island. The rupture process of these earthquakes has been studied from body wave inversion of broad band data at telesesimic distances. Results obtained shown normal faulting for both shocks, with planes oriented in NW–SE direction, with focus at shallow depth (10 km and 6 km respectively). The slip distribution over the fault plane (152/44/-88) shows for the 05-04-07 event, the rupture propagating downward and a duration of 12s for the source time function. For the 07-04-07 event, the slip distribution over the fault plane (125/52/-81) shows de rupture propagating downward and duration of 10s for the STF. From these results we have estimated the static Coulomb stress change. We find that the static stress change caused by the 5 April event is higher, about 2 bar at epicenter the location of the second event (April 7), triggering the second rupture. Locations of aftershocks do not agree well with areas of increased Coulomb failure stress, which can be explained by the complexities of the rupture process oy by uncertainties at the hypocerter locatio

Seismicity along the western part of the Eurasia-Nubian plate boundary

The seismicity along the western part of the Eurasia-Nubian plate boundary is characterized by a very complex pattern. In average, the motion is transtensional in the Azores, dextral along the Gloria transform zone and convergent between the SW Portuguese Atlantic margin and the Ibero-Maghrebian zone. To constraint the factors controlling the seismicity, we provide a new seismotectonic synthesis using several significant seismic events. We show that the studied area can be divided into six different regions, each one characterized by a coherent seismicity pattern. The total seismic moment tensor and the average slip velocities are provided for each one of them. To understand the spatial distribution of the seismicity, we compute for each event from the focal mechanism the slip vector and compare it to the relative velocity between the Eurasia and Nubia plates, deduced from global kinematics models. Despite local departures in the Alboran Sea and in the proximity of the Mid Atlantic Ridge, we find a good correlation between these two independent vectors sets. Quantitatively, the slip velocities display a linear, non-affine correlation with the norms of the relative kinematics velocities. The norm of the slip velocities seems to also depend on the tectonic regime and on the morphology of the plates’ boundary

Critical Theories of the Dissipative Hofstadter Model

It has recently been shown that the dissipative Hofstadter model (dissipative quantum mechanics of an electron subject to uniform magnetic field and periodic potential in two dimensions) exhibits critical behavior on a network of lines in the dissipation/magnetic field plane. Apart from their obvious condensed matter interest, the corresponding critical theories represent non-trivial solutions of open string field theory, and a detailed account of their properties would be interesting from several points of view. A subject of particular interest is the dependence of physical quantities on the magnetic field since it, much like $\theta_{\rm QCD}$, serves only to give relative phases to different sectors of the partition sum. In this paper we report the results of an initial investigation of the free energy, $N$-point functions and boundary state of this type of critical theory. Although our primary goal is the study of the magnetic field dependence of these quantities, we will present some new results which bear on the zero magnetic field case as well.Comment: 42 pages (25 reduced

The Gulf of Cádiz: thrusting or strike-slip motion?

In the Gulf of Cádiz (SW Iberian Peninsula) the boundary between Eurasia and Nubia plates corresponds to a narrow band well defined by the seismicity, where large earthquakes (M>7.0) may be associated to N-S to NNW-SSE horizontal compression due to the convergence between the two plates. Most of these earthquakes are at shallow depth (less than 40 km), with some foci at intermediate-depth, showing E-W distribution and limited by a narrow band less than 20 km wide that broadens as we move to the Strait of Gibraltar. In this area the lithospheric material is relatively rigid and the stresses are released by larger earthquakes. General tectonic models proposed for the Azores-Tunisia plate boundary explain fairly well the nature of its seismicity and tectonic motions; however, details of some of its aspects are still poorly understood and controversial. Zittelini et al. (2009) has recently proposed for the Gulf of Cádiz, transcurrent-transpressional motion along a long strike slip fault based on multichannel seismic reflection surveys. However, this contradicts the compressional motion and reverse faulting of large 1755 Lisbon earthquake (~Mw9), which generate a large tsunami and the recent moderate (Mw>6.0) in 1964, 2007 and 2009 and large (Mw= 8.0) in 1969 earthquakes occurred in the region. These earthquakes show thrusting motion along E-W faults with the southern block going under, corresponding to horizontal NW-SE compression, and they can be related directly to the plate convergence between Nubia and Iberia. References Zitellini et al., 2009. The quest for the Africa–Eurasia plate boundary west of the Strait of Gibraltar. Earth and Planetary Science Letters 280 (2009) 13–50

Impact of public-private partnership on the healh budget program in Portugal (2010-2020)

Mestrado Bolonha em Economia Internacional e Estudos EuropeusPublic-Private Partnerships (PPP) have emerged as a model that allows the State to increase efficiency in its resource´s application. The option for a PPP is based on the principle that the private sector is more efficient in the management of its resources, compared to the public sector. Based on the defined object of study for this research, focused on the impact of Public-Private Partnerships on the health budget program in Portugal (2010-2020), we start off with a literature review on the new concept of governance, known as New Public Management, a paradigm that has redefined the tasks and functions of the State, paving the way for the emergence of PPPs. Resorting to the historical element, we will pinpoint the 90s of the 20th century as the beginning of PPPs, a privileged financing model for road infrastructure at first, expanding later to collective equipment, with particular emphasis on hospitals, replacing public intervention in the health sector. However, the reinforcement of the private initiative contribution would be contradicted by the Basic Health Law (2019) and by Decree-Law no. 23/2020, of May 27, which departs from the regime that was in force since 2002, limiting private intervention to a "supplementary and temporary nature" and only when there is a "justified need". The economic and financial research will show that the PPP experience in the Portuguese health sector has generated savings for the State and guaranteed the desired quality at the lowest possible cost, i.e., with a higher VfM. Specifically, we will see how the hospital units which have operated under PPPs contracts have asserted themselves as potentially beneficial investment tools for the State.As Parcerias Público-Privadas (PPP) surgiram como um modelo que permite ao Estado aumentar a eficiência na aplicação dos recursos públicos. A opção por uma PPP assenta na premissa de que o setor privado é mais eficiente na gestão dos seus recursos, em comparação com o setor público. A partir do objeto de estudo definido para esta investigação, centrado no impacto das Parcerias Público-Privadas no programa orçamental de saúde em Portugal (2010-2020), inicia-se uma revisão de literatura sobre a nova conceção de governação, designada por New Public Management, paradigma que veio redefinir as tarefas e funções do Estado, abrindo caminho para o aparecimento das PPP. Recorrendo ao elemento histórico, situaremos a década de 90 do século XX, como o início das PPP, um modelo de financiamento privilegiado de estruturas rodoviárias num primeiro momento, expandindo-se mais tarde, aos equipamentos coletivos com particular destaque para os hospitais e substituindo a intervenção pública na área da saúde. Porém, o reforço da contribuição da iniciativa privada, será contrariada pelo Lei de Bases da Saúde (2019) e pelo Decreto-Lei n.º 23/2020, de 27 de maio, que se afasta do regime que vigorava desde 2002, limitando a intervenção dos privados a um “caráter supletivo e temporário” e apenas quando haja uma “necessidade fundamentada”. Os dados económicos e financeiros, irão permitir demonstrar que a experiência das PPP no sector da Saúde em Portugal, geraram poupanças para o Estado, e garantiram a qualidade desejada ao menor custo possível, isto é, com maior VfM. Em concreto, veremos como as unidades hospitalares que operaram através de PPP, se afirmaram como ferramentas de investimento potencialmente benéficas para o Estado.info:eu-repo/semantics/publishedVersio