On the definition of temperature in FPU systems

It is usually assumed, in classical statistical mechanics, that the temperature should coincide, apart from a suitable constant factor, with the mean kinetic energy of the particles. We show that this is not the case for \FPU systems, in conditions in which energy equipartition between the modes is not attained. We find that the temperature should be rather identified with the mean value of the energy of the low frequency modes.Comment: 12 pages, 4 Figure

Volatility in International Financial Market Issuance: The Role of the Financial Center

We study the pattern of volatility of gross issuance in international capital markets since 1980. We find several short-lived episodes of high volatility. Over the long run, however, volatility has declined, suggesting that international financial integration has not made financial markets more erratic. We use VAR analysis to examine the determinants of the time-varying pattern of volatility, focusing in particular on the role of financial centers. Our results suggest that a significant portion of the decline in volatility of issuance in international capital markets can be explained by the reduction in the volatility of U.S. interest rates.

Digital technology: coming of age?

Editoria

GUIDELINES FOR A DIGITAL REINTERPRETATION OF ARCHITECTURAL RESTORATION WORK: REALITY-BASED MODELS AND REVERSE MODELLING TECHNIQUES APPLIED TO THE ARCHITECTURAL DECORATION OF THE TEATRO MARITTIMO, VILLA ADRIANA

The Maritime Theatre is one of the iconic buildings of Hadrian's Villa, Tivoli. The state of conservation of the theatre is not only the result of weathering over time, but also due to restoration work carried out during the Fifties of the past century. Although this anastylosis process had the virtue of partially restoring a few of the fragments of the compound's original image, it now reveals diverse inconsistencies and genuine errors in the reassembling of the fragments. This study aims at carrying out a digital reinterpretation of the restoration of the architectural fragments in relation to the architectural order, with particular reference to the miscellaneous decoration of the frieze of the Teatro Marittimo (vestibule and atrium). Over the course of the last few years the Teatro Marittimo has been the target of numerous surveying campaigns using digital methodology (laser scanner and photogrammetry SfM/MVS). Starting with the study of the remains of the opus caementicium on the ground, it is possible to identify surfaces which are then used in the model for subsequent cross sections, so as to achieve the best fitting circumferences to use as reference points to put the fragments back into place

Testing silicone digit extensions as a way to suppress natural sensation to evaluate supplementary tactile feedback

Dexterous use of the hands depends critically on sensory feedback, so it is generally agreed that functional supplementary feedback would greatly improve the use of hand prostheses. Much research still focuses on improving non-invasive feedback that could potentially become available to all prosthesis users. However, few studies on supplementary tactile feedback for hand prostheses demonstrated a functional benefit. We suggest that confounding factors impede accurate assessment of feedback, e.g., testing non-amputee participants that inevitably focus intently on learning EMG control, the EMG’s susceptibility to noise and delays, and the limited dexterity of hand prostheses. In an attempt to assess the effect of feedback free from these constraints, we used silicone digit extensions to suppress natural tactile feedback from the fingertips and thus used the tactile feedback-deprived human hand as an approximation of an ideal feed-forward tool. Our non-amputee participants wore the extensions and performed a simple pick-and-lift task with known weight, followed by a more difficult pick-and-lift task with changing weight. They then repeated these tasks with one of three kinds of audio feedback. The tests were repeated over three days. We also conducted a similar experiment on a person with severe sensory neuropathy to test the feedback without the extensions. Furthermore, we used a questionnaire based on the NASA Task Load Index to gauge the subjective experience. Unexpectedly, we did not find any meaningful differences between the feedback groups, neither in the objective nor the subjective measurements. It is possible that the digit extensions did not fully suppress sensation, but since the participant with impaired sensation also did not improve with the supplementary feedback, we conclude that the feedback failed to provide relevant grasping information in our experiments. The study highlights the complex interaction between task, feedback variable, feedback delivery, and control, which seemingly rendered even rich, high-bandwidth acoustic feedback redundant, despite substantial sensory impairment

FROM THE GENERAL DOCUMENTATION OF HADRIAN'S VILLA TO DESIGN ANALYSIS OF COMPLEX CUPOLAS: A PROCEDURAL APPROACH

Abstract. The paper illustrates the progress of Hadrian's Villa digital documentation with special emphasis on a series of modelling issues emerged while studying vaults and cupolas of the site. Together with the more general problem of giving scientific coherence to both active and passive sensor outputs – systematically gathered from 2013 – a methodological problem concerning data interpretation of complex opus caementicium vaults have become dramatically important for the interdisciplinary research team. A methodology for improving the understanding the original shapes of Hadrianic cupolas was designed to provide scholars and professionals operating at the Villa with reliable and easy to use outputs, for interpretation, restoration, maintenance practice. Sensors integration played a fundamental role since allowed researchers a global understanding of intrados and extrados surfaces using reverse modelling applications. Features and 2D primitives extracted from high-resolution models were analysed in order to create flexible procedural models of reconstruction hypothesis/completion of cupolas. Due to the very nature of these shapes (apparently irregular), but with a solid geometric conception, we applied the last achievements of Catmull-Clark bicubic surfaces in combination with Visual Programming Language (VPL).</p

Learning algebraic structures with the help of Borel equivalence relations

We study algorithmic learning of algebraic structures. In our framework, a learner receives larger and larger pieces of an arbitrary copy of a computable structure and, at each stage, is required to output a conjecture about the isomorphism type of such a structure. The learning is successful if the conjectures eventually stabilize to a correct guess. We prove that a family of structures is learnable if and only if its learning domain is continuously reducible to the relation E0 of eventual agreement on reals. This motivates a novel research program, that is, using descriptive set theoretic tools to calibrate the (learning) complexity of nonlearnable families. Here, we focus on the learning power of well-known benchmark Borel equivalence relations (i.e., E1, E2, E3, Z0, and Eset)

Testing silicone digit extensions as a way to suppress natural sensation to evaluate supplementary tactile feedback

Dexterous use of the hands depends critically on sensory feedback, so it is generally agreed that functional supplementary feedback would greatly improve the use of hand prostheses. Much research still focuses on improving non-invasive feedback that could potentially become available to all prosthesis users. However, few studies on supplementary tactile feedback for hand prostheses demonstrated a functional benefit. We suggest that confounding factors impede accurate assessment of feedback, e.g., testing non-amputee participants that inevitably focus intently on learning EMG control, the EMG's susceptibility to noise and delays, and the limited dexterity of hand prostheses. In an attempt to assess the effect of feedback free from these constraints, we used silicone digit extensions to suppress natural tactile feedback from the fingertips and thus used the tactile feedback-deprived human hand as an approximation of an ideal feed-forward tool. Our non-amputee participants wore the extensions and performed a simple pick-and-lift task with known weight, followed by a more difficult pick-and-lift task with changing weight. They then repeated these tasks with one of three kinds of audio feedback. The tests were repeated over three days. We also conducted a similar experiment on a person with severe sensory neuropathy to test the feedback without the extensions. Furthermore, we used a questionnaire based on the NASA Task Load Index to gauge the subjective experience. Unexpectedly, we did not find any meaningful differences between the feedback groups, neither in the objective nor the subjective measurements. It is possible that the digit extensions did not fully suppress sensation, but since the participant with impaired sensation also did not improve with the supplementary feedback, we conclude that the feedback failed to provide relevant grasping information in our experiments. The study highlights the complex interaction between task, feedback variable, feedback delivery, and control, which seemingly rendered even rich, high-bandwidth acoustic feedback redundant, despite substantial sensory impairment