Clustering stock market companies via chaotic map synchronization

A pairwise clustering approach is applied to the analysis of the Dow Jones index companies, in order to identify similar temporal behavior of the traded stock prices. To this end, the chaotic map clustering algorithm is used, where a map is associated to each company and the correlation coefficients of the financial time series are associated to the coupling strengths between maps. The simulation of a chaotic map dynamics gives rise to a natural partition of the data, as companies belonging to the same industrial branch are often grouped together. The identification of clusters of companies of a given stock market index can be exploited in the portfolio optimization strategies.Comment: 12 pages, 3 figure

Silver-palladium braze alloy recovered from masking materials

Method for recovering powdered silver-palladium braze alloy from an acrylic spray binder and rubber masking adhesive used in spray brazing is devised. The process involves agitation and dissolution of masking materials and recovery of suspended precious metal particles on a filter

Improvement of heart rate recovery after exercise training in older people.

Twenty-four subjects aged 70 and older were retrospectively selected from our archives and screened for symptoms of cardiovascular disease. Baseline exercise test was negative for myocardial ischemia in all subjects. All subjects had completed an 8-week program, performed for a variety of indications and consisting of an aerobic physical training program including 30 minutes of cycling three times per week at 65% to 75% of maximum heart rate achieved at peak exercise test performed at enrollment, an educational intervention, dietary advice, and psychological support. All subjects underwent a cardiopulmonary exercise test (CPX) before and at the end of exercise training. At the end of each CPX, peak oxygen uptake (VO2peak), the rate of increase of ventilation per unit of increase of carbon dioxide production (VE/VCO2slope), and HRR were recorded. Twenty-five healthy subjects younger than 60 with no evidence of exercise-induced myocardial ischemia and not enrolled in any exercise training program were also retrospectively selected from our archives and used as a control group for analyzing HRR. These patients performed two exercise tests several weeks apart. Several studies have shown that changes in vagal tone can be used as an outcome tool that helps identify patients or subjects with or without cardiovascular disease at risk for a cardiovascular event, although the evidence of a prognostic value of HRR in older subjects without cardiovascular disease is rather poor. In this study, exercise training resulted in HRR improvement in healthy elderly subjects, suggesting that exercise training improves vagal/sympathetic balance in older subjects without cardiovascular disease as well. Whether the observed improvement in HRR may have long-term beneficial prognostic effects was not the aim of the study, although a beneficial effect might be postulated, in light of the Framingham dat

A Bayesian Networks Approach to Operational Risk

A system for Operational Risk management based on the computational paradigm of Bayesian Networks is presented. The algorithm allows the construction of a Bayesian Network targeted for each bank using only internal loss data, and takes into account in a simple and realistic way the correlations among different processes of the bank. The internal losses are averaged over a variable time horizon, so that the correlations at different times are removed, while the correlations at the same time are kept: the averaged losses are thus suitable to perform the learning of the network topology and parameters. The algorithm has been validated on synthetic time series. It should be stressed that the practical implementation of the proposed algorithm has a small impact on the organizational structure of a bank and requires an investment in human resources limited to the computational area

Exact ground state for a class of matrix Hamiltonian models: quantum phase transition and universality in the thermodynamic limit

By using a recently proposed probabilistic approach, we determine the exact ground state of a class of matrix Hamiltonian models characterized by the fact that in the thermodynamic limit the multiplicities of the potential values assumed by the system during its evolution are distributed according to a multinomial probability density. The class includes i) the uniformly fully connected models, namely a collection of states all connected with equal hopping coefficients and in the presence of a potential operator with arbitrary levels and degeneracies, and ii) the random potential systems, in which the hopping operator is generic and arbitrary potential levels are assigned randomly to the states with arbitrary probabilities. For this class of models we find a universal thermodynamic limit characterized only by the levels of the potential, rescaled by the ground-state energy of the system for zero potential, and by the corresponding degeneracies (probabilities). If the degeneracy (probability) of the lowest potential level tends to zero, the ground state of the system undergoes a quantum phase transition between a normal phase and a frozen phase with zero hopping energy. In the frozen phase the ground state condensates into the subspace spanned by the states of the system associated with the lowest potential level.Comment: 31 pages, 13 figure

Monolithic zirconia and digital impression: case report

The aim of this study is to present a clinical case of a full arch prosthetic rehabilitation on natural teeth, combining both digital work-flow and monolithic zirconi

Sustainable choice of the location of a biomass plant: an application in Tuscany

The management of complex systems often requires taking decisions that may affect the company's future. Making decisions is not easy and requires you to take serious responsibility. The company character appointed to this task, is the “decision-makers” who, within a job or project, must make a selection among several alternatives. To carry out this task, you must perform a process called "decision analysis". It can be aided by qualitative and quantitative tools, able to rationalize a multifactorial choice and bring it to a judgment of performance parameters more easily comparable. In fact, if this problem is addressed considering only the economic aspects, other fundamental parameters will be neglected such as, for example, the environmental ones. Actually, bringing many different aspects to a simple economic performance, or anyway one-dimensional, proves to be a limiting and unsatisfactory approach. In addition, if we consider the concepts of sustainability, we should at least take into account the three dimensions that describe it, namely the economic, environmental and social issues. Then, a strategy of decision making more complete that could integrate all the three aspects, becomes much more appropriate. In this context, the multi-criteria analysis are particularly suitable for this purpose. In this study we aim at investigating how one of the most popular multi-criteria methods, the Analytic Network Process (ANP) can be used to define the location of a cogeneration plant fuelled by biomass. The novelty of this study consists of having categorized and divided into homogeneous areas an entire region. In addition, to evaluate the economic efficiency, as compared to other authoritative work on the subject, also the water content in the raw material was considered, influencing the amount of biomass consumed. The results show that the ANP allows decisions making according to an overall view, considering a wide variety of parameters and allows the decision makers to better represent the needs of the stakeholder

Hausdorff clustering of financial time series

A clustering procedure, based on the Hausdorff distance, is introduced and tested on the financial time series of the Dow Jones Industrial Average (DJIA) index.Comment: 9 pages, 3 figure

Aesthetic satisfaction in lip and palate clefts: a comparative study between secondary and tertiary bone grafting

Lip and palate cleft represent one of the most frequently occurring congenital deformity, which includes dental anomalies, such as variation in tooth number and position. In case of hypodontia implant-prosthetic rehabilitation offers significant advantages in terms of function, aesthetics and quality of life and bone graft is usually needed. Secondary bone grafting, generally performed in the mixed dentition phase (years 8-11) seems to be the most successful method to allow for rehabilitation. It's often necessary to perform a tertiary bone grafting in adult age in order to achieve better bone quantity and quality before implant placement. Aim of this retrospective study was to evaluate the aesthetic perception that patients had of themselves comparing dental implants placed in tertiary grafted alveolar cleft sites with a previous secondary grafting to only secondary grafting. Between 2009 and 2012, fourteen alveolar cleft were treated with implant rehabilitation and eleven of them received tertiary bone grafting six months prior to implant placement. All patients were questioned to give a score from 1 to 10 their aesthetic satisfaction of their smile before and after implant rehabilitation and during pre-surgery provisional rehabilitation. At the end of their prosthesis rehabilitation patients who received tertiary bone grafting resulted more satisfied than those who had secondary bone grafting only (9.5 vs 8)

Limits on the use of cobalt sulfide as anode of p-type dye-sensitized solar cells

Thin films of cobalt sulfide (CoS) of thickness l < 10m have been employed as anodes of p-type dye-sensitized solar cells (p-DSCs) when P1-sensitized nickel oxide (NiO) was the photoactive cathode and /I - constituted the redox mediator. In the role of counter electrode for p-DSCs, CoS was preferred over traditional platinized fluorine-doped indium oxide (Pt-FTO) due to the lower cost of the starting materials (Co salts) and the easier procedure of deposition onto large area substrates. The latter process was carried out via direct precipitation of CoS from aqueous solutions. The photoconversion efficiency (η) of the corresponding device was 0.07%. This value is about 35% less than the efficiency that is obtained with the analogous p-DSC employing the Pt-FTO anode (η = 0.11). Unlike p-DSCs based on Pt-FTO anodes, the photoelectrochemical cells employing CoS electrodes showed that this anodic material was not able to sustain the photocurrent densities generated by P1-sensitized NiO at a given photopotential. Illumination of the p-DSCs with CoS anodes and P1-sensitized NiO cathodes actually induced the reverse bias of the photoelectrochemical cell with CoS behaving like a p-type semiconductor with no degeneracy. © 2017 IOP Publishing Ltd