On the Estimation of Euler Equations in the Presence of a Potential Regime Shift

The concept of a peso problem is formalized in terms of a linear Euler equation and a nonlinear marginal model describing the dynamics of the exogenous driving process. It is shown that, using a threshold autoregressive model as a marginal model, it is possible to produce time-varying peso premia. A Monte Carlo method and a method based on the numerical solution of integral equations are considered as tools for computing conditional future expectations in the marginal model. A Monte Carlo study illustrates the poor performance of the generalized method of moment (GMM) estimator in small and even relatively large samples. The poor performance is particularly acute in the presence of a peso problem but is also serious in the simple linear case.peso problem; Euler equations; GMM; threshold autoregressive models

Guest editorial

The 21st International EurOMA (EurOMA, 2014) Conference was hosted by Università degli Studi di Palermo. The conference theme was Operations Management in an Innovation Economy. According to innovation economists what primarily drives economic growth in today’s knowledge-based economy is not capital accumulation but innovative capacity spurred by appropriable knowledge and technological externalities. Economics growth in innovation economics is the end- product of knowledge, R&D expenditures, licenses, technological spillovers, and externalities between collaborative firms, i.e. supply chains and networks of innovation. When firms do not explicitly acknowledge and manage their operations as a concurrent activity to the management of innovation, they often encounter problems late in product development, or with manufacturing launch, logistical support, quality control, and production costs. As such, innovation process and operations management should be coordinated, rather than being viewed as separate sets of decisions and activities. We received 592 abstracts and used a doubled-blind review process, involving 127 members of the Scientific Committee, to review 586 abstracts (six abstracts were desk rejected) and provide feedback to the authors. Of these, 513 were accepted and 73 rejected. The accepted abstracts resulted in 405 full papers in the Scientific Programme. With three papers subsequently withdrawn, there were 402 paper presentations in prospect. The most recurrent OM themes were: sustainability in operations and logistics (42 papers); supply chain management (35 papers); innovation, product and service development (32 papers); managing inter-firm relationships in supply chains (30 papers); healthcare OM (21 papers); lean and agile operations (21 papers). The Scientific Programme incorporated 134 parallel sessions and was enriched by two keynote speakers: Professor Robert Handfield (Bank of America University Distinguished Professor of Supply Chain Management, North Carolina State University) and the Chief Operations Officer of Luxottica, Massimo Vian, who provided insightful reflections on the conference theme from their academic and industry perspectives, respectively. In addition there were six special sessions providing unique opportunities for engagement and insights on teaching in OM, crowdsourcing and open innovation in OM, OM as practice, OM research in the fashion industry, new supply chains, and the role of social media in OM and EurOMA. Also, besides this interesting topic-specific special sessions, the conference hosted a “Meet the Editors” session with editors and co-editors from eight OM journals

Introducing \u201chealthcare resilience\u201d in clinical risk management

This paper reports the results of an explorative case study in an Italian hospital and presents a conceptual framework for healthcare resilience, which clarifies why and how healthcare structures need to be resilient in order to fully deal with clinical risk. In other words, it is not sufficient to take the \u201cpath to zero harm\u201d. Healthcare companies have also to pursue strategies for maximizing the organizational resilience, in terms of resistance, reliability, redundancy and flexibility. This is quite important because, no matter which CRM technique and/or best practice is adopted, sometime adverse events occur. And, in this case, being resilient can help in dampening their negative consequences. By extending the focus of traditional clinical risk management to different kinds of risk sources (not just patient safety threats) and to different kinds of risk minimization strategies (not just minimize the likelihood of occurrence but also the risk magnitude) this paper contributes to the literatures on operations management in healthcare. The conceptualization of \u201chealthcare resilience\u201d and the in-depth case results allow us to offer a number of suggestions and ideas for developing further research in the field of healthcare operations management

Performance analysis of peak tracking techniques for fiber Bragg grating interrogation systems

In this paper, we propose a spectral correlation-based technique for tracking the wavelength shift of a fiber Bragg grating. We compared this approach, by means of a Monte Carlo numerical simulation, to the typical peak tracking techniques applied in classic interrogation systems. As result, we obtained a considerable gain in terms of noise tolerance (about 20 dB), which can be further incremented by selecting large-bandwidth gratings. This permits to increase the power budget of a fiber Bragg grating interrogator without changing the optical layout, overcoming classical limitations of commercial and custom systems. Penalties due to the non-idealities have been evaluated through the same Monte Carlo approach. Finally, we discuss a practical application of the peak tracking techniques to a fiber Bragg grating-based weight sensor, in which we applied the spectral correlation to track both the Bragg wavelength position, spectral deformations due to high strain, and spectral non-linearity

High brightness 100 W-50 μm delivery blue laser diode module

Blue laser diodes are emerging as the next revolution in laser material processing, especially for high reflective materials, such as copper and gold. The paper presents the most recent evolution of a family of medium-high power and high brightness devices specifically conceived for micro-machining applications. The modules make use of a proprietary architecture based on the combination of commercial laser diodes in TO9 package. The diodes are first organized in rows staggered along the fast axis, then the rows are multiplexed along the fast axis; finally, wavelength and polarization multiplexing are exploited to achieve up to 100W of power into a 50 μm/0.22NA fiber

A Comparison of Different Topic Modeling Methods through a Real Case Study of Italian Customer Care

The paper deals with the analysis of conversation transcriptions between customers and agents in a call center of a customer care service. The objective is to support the analysis of text transcription of human-to-human conversations, to obtain reports on customer problems and complaints, and on the way an agent has solved them. The aim is to provide customer care service with a high level of efficiency and user satisfaction. To this aim, topic modeling is considered since it facilitates insightful analysis from large documents and datasets, such as a summarization of the main topics and topic characteristics. This paper presents a performance comparison of four topic modeling algorithms: (i) Latent Dirichlet Allocation (LDA); (ii) Non-negative Matrix Factorization (NMF); (iii) Neural-ProdLDA (Neural LDA) and Contextualized Topic Models (CTM). The comparison study is based on a database containing real conversation transcriptions in Italian Natural Language. Experimental results and different topic evaluation metrics are analyzed in this paper to determine the most suitable model for the case study. The gained knowledge can be exploited by practitioners to identify the optimal strategy and to perform and evaluate topic modeling on Italian natural language transcriptions of human-to-human conversations. This work can be an asset for grounding applications of topic modeling and can be inspiring for similar case studies in the domain of customer care quality

The Short- and Long-Term Impacts of COVID-19 Pandemic on the Sharing Economy: Distinguishing Between “Symptomatic” and “Asymptomatic” Platforms

Our study presents a systematic literature review on the repercussions of the COVID-19 pandemic on the different types of sharing economy platforms and the sharing economy phenomenon in its entirety. Our literature review helps understand how the characteristics of different services of the sharing economy combine with contingent factors, such as government-mandated lockdowns, changed consumer behaviors, and people's fear of contagion, to determine the magnitude of the impact of COVID-19 on the sharing economy both in the short run and in the long run. By examining these factors, we distinguish between sharing economy services/platforms that were (and possibly will be) negatively impacted by the COVID-19 pandemic (referred to as "symptomatic" platforms) and those that were not (and possibly will not be) impacted at all or even benefit (referred to as "asymptomatic" platforms). We then propose a new framework that combines traditional dimensions of sharing economy with a dimension resulting from the COVID-19 pandemic, i.e., the level of physical interaction required to deliver the sharing economy service. Building upon the extant literature, the framework helps better understand how the sharing economy will evolve after the pandemic. It also helps identify important research gaps that both academics and practitioners working on the field of sharing economy should address in the near future

A simplified approach for the seismic loss assessment of rc buildings at urban scale: The case study of Potenza (Italy)

Comprehensive methodologies based on a fully probabilistic approach (i.e., the performance- based earthquake engineering approach, PBEE), represent a refined and accurate tool for the seismic performance assessment of structures. However, those procedures are suitable for building-specific evaluations, appearing extremely time-consuming if applied at the urban scale. In the proposed contribution, simplified loss assessment procedure will be applied at the urban scale with reference to the residential building stock of the center of Potenza. After the identification of the main reinforced concrete (RC) structural typologies and the definition of specific archetype building numerical models, the direct estimation of expected annual loss (DEAL) methodology will be applied to derive the EAL (i.e., expected annual loss) of RC buildings, deriving information on the effectively seismic quality (or seismic resilience) of the aforementioned built heritage at urban scale. Similarly, the monetary losses associated with downtime are evaluated. Preliminary considerations on the socio-economic effects of seismic scenarios on the territorial scale are also proposed

Vertically resolved aerosol properties by multi-wavelength lidar measurements

An approach based on the graphical method of Gobbi and co-authors (2007) is introduced to estimate the dependence on altitude of the aerosol fine mode radius (<i>R</i>_f) and of the fine mode contribution (η) to the aerosol optical thickness (AOT) from three-wavelength lidar measurements. The graphical method of Gobbi and co-authors (2007) was applied to AERONET (AErosol RObotic NETwork) spectral extinction observations and relies on the combined analysis of the Ångstrom exponent (<i>å</i>) and its spectral curvature Δ<i>å</i>. Lidar measurements at 355, 532 and 1064 nm were used in this study to retrieve the vertical profiles of <i>å</i> and Δ<i>å</i> and to estimate the dependence on altitude of <i>R</i>_f and η(532 nm) from the <i>å</i>–Δ<i>å</i> combined analysis. Lidar measurements were performed at the Department of Mathematics and Physics of the Universita' del Salento, in south-eastern Italy. Aerosol from continental Europe, the Atlantic, northern Africa, and the Mediterranean Sea are often advected over south-eastern Italy and as a consequence, mixed advection patterns leading to aerosol properties varying with altitude are dominant. The proposed approach was applied to ten measurement days to demonstrate its feasibility in different aerosol load conditions. The selected days were characterized by AOTs spanning the 0.26–0.67, 0.15–0.39, and 0.04–0.27 range at 355, 532, and 1064 nm, respectively. Mean lidar ratios varied within the 31–83, 32–84, and 11–47 sr range at 355, 532, and 1064 nm, respectively, for the high variability of the aerosol optical and microphysical properties. <i>å</i> values calculated from lidar extinction profiles at 355 and 1064 nm ranged between 0.1 and 2.5 with a mean value &pm; 1 standard deviation equal to 1.3 ± 0.7. Δ<i>å</i> varied within the −0.1–1 range with mean value equal to 0.25 ± 0.43. <i>R</i>_f and η(532 nm) values spanning the 0.05–0.3 μm and the 0.3–0.99 range, respectively, were associated with the <i>å</i>–&Delta;<i>å</i> data points. <i>R</i>_f and η values showed no dependence on the altitude. 60% of the data points were in the &Delta;<i>å</i>–<i>å</i> space delimited by the &eta; and <i>R</i>_f curves varying within 0.80–0.99 and 0.05–0.15 μm, respectively, for the dominance of fine-mode particles in driving the AOT over south-eastern Italy. Vertical profiles of the linear particle depolarization ratio retrieved from lidar measurements, aerosol products from AERONET sun photometer measurements collocated in space and time, analytical back trajectories, satellite true colour images, and dust concentrations from the BSC–DREAM (Barcelona Super Computing Center-Dust REgional Atmospheric Model) model were used to demonstrate the robustness of the proposed method