A taxonomy of interactions in socio-technical systems: A functional perspective

Although the modelling of interactions has long been at the core of socio-technical systems theory, and is a key for understanding resilience, there is a lack of a holistic taxonomy of interactions. This study introduces a taxonomy of interactions to be used in association with the Functional Resonance Analysis Method (FRAM). The taxonomy has nine criteria: nature of agents, output nature, levelling, waiting time, distance, degree of coupling, visibility, safety and/or security hazards, and parallel replications. For each criterion, two descriptors are proposed: what the interaction looks like; and - when applicable - the variability level of the interaction. The use of the taxonomy is presented for three systems with clearly distinct complexity characteristics: cash withdrawal from an ATM, teaching a university course, and manufacturing operations. These case studies indicate the usefulness of the taxonomy for the identification of leverage points in work system design. They also show the value of modelling the variability of the interactions in FRAM models, in addition to the traditional modelling of the variability of the outputs of functions. Implications of the taxonomy for resilience engineering are discussed

A Competitive Approach for Designing Multi-Antenna Cognitive Access Networks

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A system-approach for recoverable spare parts management using the discreteweibull distribution

Optimal spare parts management strategies allow sustaining a system's availability, while ensuring timely and effective maintenance. Following a systemic perspective, this paper starts from the Multi-Echelon Technique for Recoverable Item Control (METRIC) to investigate the potential use of a Weibull distribution for modelling items' demand in case of failure. Adapting the analytic formulation of METRIC through a Discrete Weibull distribution, this study originally proposes a METRIC-based model (DW-METRIC) to be used for modelling the stochastic demand in multi-item systems, in order to ensure process sustainability. The DW-METRIC has been tested in a case study related to an industrial plant constituted by 98 items in a passive redundancy configuration. Comparing the results via a simulation model, the outcomes of the study allow defining applicability criteria for the DW-METRIC, in those settings where the DW-METRIC offers more accurate estimations than the traditional METRIC

Monitor, anticipate, respond, and learn: developing and interpreting a multilayer social network of resilience abilities

Resilient performance is influenced by social interactions of several types, which may be analysed as layers of interwoven networks. The combination of these layers gives rise to a “network of networks”, also known as a multilayer network. This study presents an approach to develop and interpret multilayer networks in light of resilience engineering. Layers correspond to the four abilities of resilient systems: monitor, anticipate, respond, and learn. The proposal is applied in a 34-bed intensive care unit. To map relationships between actors in each layer, a questionnaire was devised and answered by 133 staff members, including doctors, nurses, nurse technicians, and allied health professionals. Two multilayer networks were developed: one considering that actors are 100% available and reliable (work-as-imagined) and another considering suboptimal availability and reliability (work-as-done). The multilayer networks were analysed through actor-centred (Katz centrality, degree deviation, and neighbourhood centrality) and layer-centred metrics (inter-layer correlation, and assortativity correlation). Strengths and weaknesses of social interactions at the ICU are discussed based on the adopted metrics

A benchmark activity on the fatigue life assessment of AlSi10Mg components manufactured by L-PBF

One of the challenges associated with additive manufacturing (AM) is the definition of an assessment route which considers the main process signatures of the AM process. To this end, this work presents a complete benchmark activity for the assessment of an AlSi10Mg component produced by a laser pow- der bed fusion process, aimed at advancing the understanding of the fatigue resistance of AM materials with particular focus on the comparison between the fatigue performances of small coupons and demon- strators. Four builds of AlSi10Mg specimen geometries were manufactured to: (i) determine the fatigue curves for both as-built and machined conditions; (ii) measure the fatigue crack growth rate; (iii) produce and test under fatigue a benchmark component used as a reference for the validation of the fatigue assessment procedure. Tools and concepts of flaw tolerance were then used to perform the fatigue assess- ment of the benchmark component and were shown to be successful in the life prediction. Results obtained from this wide database (related to internal defects and surface features) show that only a fracture-based fatigue assessment is able to provide precise life estimates consistent with material crack growth properties. Eventually, all the experimental results including specimens design, analysis of frac- ture surfaces and raw tests’ data will be made available in a database which can be accessed and used by the industrial and scientific communities to calibrate and validate alternative fatigue assessment proce- dures of AM parts

Breakdown of the mean-field approximation in a wealth distribution model

One of the key socioeconomic phenomena to explain is the distribution of wealth. Bouchaud and M\'ezard have proposed an interesting model of economy [Bouchaud and M\'ezard (2000)] based on trade and investments of agents. In the mean-field approximation, the model produces a stationary wealth distribution with a power-law tail. In this paper we examine characteristic time scales of the model and show that for any finite number of agents, the validity of the mean-field result is time-limited and the model in fact has no stationary wealth distribution. Further analysis suggests that for heterogeneous agents, the limitations are even stronger. We conclude with general implications of the presented results.Comment: 11 pages, 3 figure

Resonance-like phenomena of the mobility of a chain of nonlinear coupled oscillators in a two-dimensional periodic potential

We study the Langevin dynamics of a two-dimensional discrete oscillator chain absorbed on a periodic substrate and subjected to an external localized point force. Going beyond the commonly used harmonic bead-spring model, we consider a nonlinear Morse interaction between the next-nearest-neighbors. We focus interest on the activation of directed motion instigated by thermal fluctuations and the localized point force. In this context the local transition states are identified and the corresponding activation energies are calculated. As a novel feature it is found that the transport of the chain in point force direction is determined by stepwise escapes of a single unit or segments of the chain due to the existence of multiple locally stable attractors. The non-vanishing net current of the chain is quantitatively assessed by the value of the mobility of the center of mass. It turns out that the latter as a function of the ratio of the competing length scales of the system, that is the period of the substrate potential and the equilibrium distance between two chain units, shows a resonance behavior. More precisely there exist a set of optimal parameter values maximizing the mobility. Interestingly, the phenomenon of negative resistance is found, i.e. the mobility possesses a minimum at a finite value of the strength of the thermal fluctuations for a given overcritical external driving force.Comment: 25 pages, 12 figure

Phenolic Compounds in Extracts from Eucalyptus globulus Leaves and Calendula officinalis Flowers

Selection of the optimal solvent system for extraction of the phenolics from Eucalyptus globules leaves and Calendula officinalis flowers, determination of the reducing potential and identification of the phenolics in these extracts was performed. The highest content of phenolics was obtained for methanol: water extracts from both sources. All of the Eucalyptus leaf extracts had higher reducing potential than those from the Calendula flowers. Solid-phase purification of the crude extracts removed 57% to 78% of the compounds in the crude extracts. The reducing potential of the purified extracts varied from 0.17 to 2.92 mg caffeic acid/g dry weight. The extracts from Eucalyptus leaves and Calendula flowers both contained chlorogenic acid, rutin and quercetin 3-glucuronide. Ellagic acid derivatives were identified only in the leaves of Eucalyptus, while beside caffeic acid and salicylic acid, quercetin 3-glucuronide, and pinobanksin 3-acetate was found in the Calendula flower extract for the first time.Fil: Dos Santos Ferreira, Cristina Isabel. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias; ArgentinaFil: Pereyra, A.. University of Ljubljana. Biotechnical Faculty; EsloveniaFil: Patriarca, Andrea Rosana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Micología y Botánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Micología y Botánica; ArgentinaFil: Mazzobre, Maria Florencia. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Polak, T.. University of Ljubljana. Biotechnical Faculty; EsloveniaFil: Abram, V.. University of Ljubljana. Biotechnical Faculty; EsloveniaFil: Buera, Maria del Pilar. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Poklar Ulrih, N.. University of Ljubljana. Biotechnical Faculty; Esloveni

A clinical trial of oral hyposensitization in systemic allergy to nickel.

Nickel allergy is the most common contact allergy. Some nickel-sensitive patients present systemic (cutaneous and/or digestive) symptoms related to the ingestion of high nickel-content foods, which significantly improve after a specific low nickel-content diet. The etiopathogenetic role of nickel in the genesis of systemic disorders is, furthermore, demonstrated by the relapse of previous contact lesions, appearance of widespread eczema and generalized urticaria-like lesions after oral nickel challenge test. The aim of this study is to investigate the safety and efficacy of a specific oral hyposensitization to nickel in patients with both local contact disorders and systemic symptoms after the ingestion of nickel-containing foods. Inclusion criteria for the recruitment of these patients were (other than a positive patch test) a benefit higher than 80% from a low nickel-content diet and a positive oral challenge with nickel. Based on the previous experiences, our group adopted a therapeutic protocol by using increasing oral doses of nickel sulfate associated to an elimination diet. Results have been excellent: this treatment has been effective in inducing clinical tolerance to nickel-containing foods, with a low incidence of side effects (gastric pyrosis, itching erythema)

Experts’ consensus on the definition and management of high risk multiple myeloma

High risk multiple myeloma (HRMM) at diagnosis is currently recognized according to the Revised International Staging System (R-ISS) which was set up in 2015. Since then, new clinical and biological prognostic factors have been developed, which could implement the definition of High Risk (HR) category. We conducted a survey in order to identify which additional parameters, both clinical and biological, are considered more useful for the clinical practice and to evaluate if the management of Multiple Myeloma (MM) should change on the basis of the risk category. A questionnaire, consisting of 8 statements, was submitted to 6 Italian experts, from the European Myeloma Network (EMN) Research Italy, using the Delphi method. The colleagues were asked to answer each question using a scale between 0 and 100. If a statement did not reach at least 75 out of 100 points from all the participants, it was rephrased on the basis of the proposal of the experts and resubmitted in a second or further round, until a consensus was reached among all. From the first round of the survey a strong consensus was reached regarding the opportunity to revise the R-ISS including chromosome 1 abnormality, TP53 mutation or deletion, circulating plasma cells by next generation flow and extramedullary plasmacytomas. No consensus was reached for the definition of “double hit” MM and for the application in clinical practice of treatment strategies based on the risk category. In the second round of the Delphi questionnaire, “double-hit” MM was recognized by the association of at least two high-risk cytogenetic or molecular abnormalities. Moreover, the experts agreed to reserve an intensified treatment only to specific conditions, such as plasma cell leukaemia or patients with multiple extramedullary plasmacytomas, while they admitted that there are not sufficient real word data in order to modify treatment on the basis of MRD assessment in clinical practice. This survey suggests that the definition of HRMM should be implemented by additional clinical and biological risk factors, that will be useful to guide treatment in the future