Metastability in Bubbling AdS Space

We study the dynamics of probe M5 branes with dissolved M2 charge in bubbling geometries with SO(4) x SO(4) symmetry. These solutions were constructed by Bena-Warner and Lin-Lunin-Maldacena and correspond to the vacua of the maximally supersymmetric mass-deformed M2 brane theory. We find that supersymmetric probe M2 branes polarize into M5 brane shells whose backreaction creates an additional bubble in the geometry. We explicitly check that the supersymmetric polarization potential agrees with the one found within the Polchinski-Strassler approximation. The main result of this paper is that probe M2 branes whose orientation is opposite to the background flux can polarize into metastable M5 brane shells. These decay to a supersymmetric configuration via brane-flux annihilation. Our findings suggest the existence of metastable states in the mass-deformed M2 brane theory.Comment: 38 pages, 8 figure

Frequency modulated pulses for quantum bits coupled to time-dependent baths

We consider the coherent control of a quantum bit by the use of short pulses with finite duration \tau_p. By shaping the pulse, we perturbatively decouple the dynamics of the bath from the dynamics of the quantum bit during the pulse. Such shaped pulses provide single quantum bit gates robust against decoherence which are useful for quantum information processing. We extend previous results in two ways: (i) we treat frequency modulated pulses and (ii) we pass from time-independent baths to analytically time-dependent baths. First and second order solutions for \pi- and \pi/2-pulses are presented. They are useful in experiments where amplitude modulation is difficult to realize.Comment: 10 pages, 6 figure

Anomalous behavior of control pulses in presence of noise with singular autocorrelation

We report on the anomalous behavior of control pulses for spins under spin-spin relaxation and subject to classical noise with a singular autocorrelation function. This behavior is not detected for noise with analytic autocorrelation functions. The effect is manifest in the different scaling behavior of the deviation of a real pulse to the ideal, instantaneous one. While a standard pulse displays scaling $\propto \tau_\mathrm{p}^1$, a first-order refocusing pulse normally shows scaling $\propto \tau_\mathrm{p}^2$. But in presence of cusps in the noise autocorrelation the scaling $\propto \tau_\mathrm{p}^{3/2}$ occurs. Cusps in the autocorrelation are characteristic for fast fluctuations in the noise with a spectral density of Lorentzian shape. We prove that the anomalous exponent cannot be avoided; it represents a fundamental limit. On the one hand, this redefines the strategies one has to adopt to design refocusing pulses. On the other hand, the anomalous exponent, if found in experiment, provides important information on the noise properties.Comment: 11 pages, 8 figure

Evaluation of the state of the art of psychological variables among exercisers at different levels

There is growing interest in the field of sport psychology to measure psychological variables among exercisers at different levels and between exercisers and non-exercisers, in order to identify beneficial activities in non-clinical and clinical groups (such as patients with metabolic diseases or osteoarticular disorders) and to implement psychological drivers for the promotion of greater athletic achievement and healthier lifestyles. [Clemente et al. 2019; Bernstein et al 2019; Zur et al. 2019]. The populations involved in these studies are highly heterogeneous and vary from professional athletes to laypeople, including fragile populations, such as the elderly, and people with chronic diseases, such as diabetes or obesity, who can benefit from physical activity [Kosteli et al. 2018; Ku et al. 2017; Matson et al. 2019]. Variables such as self-efficacy and self-regulation, depression, emotion, stress, and affect have been analysed and compared among athletes of various levels. Furthermore, a correlation of these variables with physical activity has been demonstrated [Zur et al. 2019; Myers et al 2017; Looyestyn et al. 2018]. Among different sport populations (e.g. athletes, semi-professional sport performers, and amateurs), psychological variables are assessed through validated scales and questionnaires and can be correlated with sport performance using objectively measured physical parameters (e.g. resting muscle tension, skin conductance, and respiration rate) through biofeedback technology [Myers et al 2017]. Novel technologies, including the use of computerised tests or online surveys, the involvement of participants using social media, the use of micro-electromechanical systems (MEMS) including wearables devices and sensor systems (such as global positioning systems - GPS, accelerometers, and heart rate monitoring sensors) appear promising for collection of relevant physical parameters [Lutz et al. 2019] and can be used both in regular exercise performers and laypeople [Looyestyn et al. 2018; Lin et al. 2018; Myers et al 2017]

The History of Photovoltaics with Emphasis on CdTe Solar Cells and Modules

Among thin-film photovoltaic technology, cadmium telluride (CdTe) has achieved a truly impressive development that can commercially compete with silicon, which is still the king of the market. Solar cells made on a laboratory scale have reached efficiencies close to 22%, while modules made with fully automated in-line machines show efficiencies above 18%. This success represents the result of over 40 years of research, which led to effective and consolidated production processes. Based on a large literature survey on photovoltaics and on the results of research developed in our laboratories, we present the fabrication processes of both CdTe polycrystalline thin-film solar cells and photovoltaic modules. The most common substrates, the constituent layers, their interaction, the interfaces and the different “tricks” necessary to obtain highly efficient devices will be analyzed. A realistic industrial production process will be analytically described. Moreover, environmental aspects, end-of-life recycling and the life cycle assessment of CdTe-based modules will be deepened and discussed

Exploring Perceived and Objective Measures of the Neighborhood Environment and Associations with Physical Activity among Adults: A Review and a Meta-Analytic Structural Equation Model

There is an urgent need to understand factors that promote physical activities (PA) because it is one of the modifiable risk factors for global mortality. None of the previous reviews considered both perceived and objective characteristics of the same environment. The first aim was to review the literature on studies investigating the relationship between PA behavior of adults and perceived and objective physical environment measures. The second aim was to verify the potential mediational role of the perceived measure in the relationship between the objective measure of the environment and PA using meta-analytic SEM. Only 15 studies reported a relationship between PA and both environmental measures. One of the most studied characteristics of the physical environment is the accessibility to recreational/PA facilities. Both objective and subjective measures of accessibility to PA facilities are associated with PA. Meta-SEM results suggest a significant effect of the objective accessibility to facilities on PA behavior ( = 0.15) and on the perceived measure ( = 0.10), but the indirect effect was not significant. No significant effect was found for the perceived measure on PA, suggesting that individuals’ level of awareness about their environments may have played a role. This prompts a need to create awareness campaigns

Efficient Coherent Control by Optimized Sequences of Pulses of Finite Duration

Reliable long-time storage of arbitrary quantum states is a key element for quantum information processing. In order to dynamically decouple a spin or quantum bit from a dephasing environment, we introduce an optimized sequence of $N$ control pulses of finite durations \tau\pp and finite amplitudes. The properties of this sequence of length $T$ stem from a mathematically rigorous derivation. Corrections occur only in order $T^{N+1}$ and \tau\pp^3 without mixed terms such as T^N\tau\pp or T^N\tau\pp^2. Based on existing experiments, a concrete setup for the verification of the properties of the advocated realistic sequence is proposed.Comment: 8 pages, 1 figur

Linear and nonlinear influences of climatic changes on migration flows: a case study for the 'Mediterranean bridge'

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An Automatic Framework for the Non-rigid Alignment of Electroanatomical Maps and Preoperative Anatomical Scans in Atrial Fibrillation

In atrial fibrillation, electro-anatomical maps (EAM) are used for ablation guidance. Yet, the anatomy reconstructed by the navigation system is known to be poorly accurate. This makes catheter navigation challenging and, as such, might affects ablation’s outcome. To ease navigation, existing systems allow co-registering EAMs with pre-operative MR scans by rigidly matching a set of manual landmarks. Nevertheless, the deformation between the two datasets is highly non-rigid. The aim of this work was therefore to develop a framework for the non-rigid alignment of EAMs and anatomical scans to improve ablation guidance