1,200 research outputs found

    Econophysics studies in Estonia

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    A short review of the econophysics research done in Estonia, devoted to the 15th anniversary of the term "econophysics".Comment: Submitted to the special issue on "Econophysics" of the journal Science & Culture (http://www.scienceandculture-isna.org/journal.htm), a publication of the Indian Science News Association, established in 193

    Dimer diffusion in a washboard potential

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    The transport of a dimer, consisting of two Brownian particles bounded by a harmonic potential, moving on a periodic substrate is investigated both numerically and analytically. The mobility and diffusion of the dimer center of mass present distinct properties when compared with those of a monomer under the same transport conditions. Both the average current and the diffusion coefficient are found to be complicated non-monotonic functions of the driving force. The influence of dimer equilibrium length, coupling strength and damping constant on the dimer transport properties are also examined in detail.Comment: Final revised version. 7 pages, 6 figure

    Phospholipid metabolism by phagocytic cells. Phospholipases A2 associated with rabbit polymorphonuclear leukocyte granules

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    Polymorphonuclear leukocytes obtained from sterile peritoneal exudates in rabbits contain two phospholipid-splitting activities (phosphatidylacylhydrolases EC 3.1.1.4), one most active at pH 5.5 and the other between pH 7.2 and 9.0. Hydrolysis of phospholipid was demonstrated using Escherichia coli labeled during growth with [1-(14)C]oleate and then autoclaved to inactivate E. coli phospholipases and to increase the accessibility of the microbial phospholipid substrates. The acid and alkaline phospholipase activities are both membrane bound, calcium dependent, and heat stable, and they appear to be specific for the 2-acyl position of phospholipids. Evidence was also obtained suggesting that the E. coli envelope phospholipids with oleate in position 2 are more readily degraded than those with palmitate. The two activities are associated with azurophilic as well as specific granules (obtained by zonal centrifugation) and with phagosomes (isolated after ingestion of paraffin particles by the granulocytes). Phospholipase A activities at pH 5.5 and pH 7.5 degrade the two major phospholipids of E. coli, phosphatidylethanolamine and phosphatidylglycerol, to the same extent, but the phospholipase activity at acid pH does not hydrolyze micellar dispersions of phosphatidylethanolamine. By contrast, phospholipase A(2) activity at pH 7.5 degrades both types of phosphatidylethanolamine substrates. Heparin and chondroitin sulfate inhibit phospholipase activity at pH 5.5 but have little effect on activity at pH 7.5. All detergents tested inhibited phospholipase activity, and both activities are inhibited by reaction products, free fatty acid and lysophosphatidylethanolamine. This product inhibition is only partially prevented by addition of albumin. Supernatant fractions of granulocyte homogenates contain a heat-labile inhibitor of granule phospholipase activity at pH 7.5. Boiling the fraction not only removes the inhibition but actually results in stimulation of hydrolysis at pH 7.5 as well as pH 5.5. These granule-associated phospholipase A activities of polymorphonuclear leukocytes differ in several of their properties from granule or lysosomal phospholipases of other phagocytic cells

    “Samhandling”: On the nuances of resilience through case study research in emergency response operations

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    Standard emergency-management procedures offer guidance on how organizations can improve their handling of all types of emergencies. However, such a generalization undermines uncertainties and oversimplifies the complexity of real work practices during an emergency response operation (ERO). The handling of the COVID-19 pandemic highlights how uncertainty and escalating consequences reinforce the need for resilience in EROs. To illustrate the key elements of our suggested approach and its practical implications, we discuss the issues in light of a case study related to a COVID-19 outbreak on a floating oil rig in the North Sea. The analysis reveals several instances of creative problem solving, and individual and collective efforts beyond the scope of the standard procedures. It also underlines how the shortcomings of resource allocation and over-planning might lead to inflexibility, thus harming EROs' efficiency. Our analysis highlights that the key to resilient EROs lies in robust coordination, the ability to improvise, transparency, and trusting communication between the actors involved. Greater focus on network building—proactively maintained through regular training and exercise activities—strengthens resilience in emergency-management systems. All these traits link to the Norwegian term “samhandling,” a notion which is here proposed to summarize and connect these resilience capacities

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

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    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

    Reviewing qualitative research approaches in the context of critical infrastructure resilience

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    Modern societies are increasingly dependent on the proper functioning of critical infrastructures (CIs). CIs produce and distribute essential goods or services, as for power transmission systems, water treatment and distribution infrastructures, transportation systems, communication networks, nuclear power plants, and information technologies. Being resilient becomes a key property for CIs, which are constantly exposed to threats that can undermine safety, security, and business continuity. Nowadays, a variety of approaches exist in the context of CIs’ resilience research. This paper provides a state-of-the-art review on the approaches that have a complete qualitative dimension, or that can be used as entry points for semi-quantitative analyses. The study aims to uncover the usage of qualitative research methods through a systematic review based on PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses). The paper identifies four principal dimensions of resilience referred to CIs (i.e., techno-centric, organisational, community, and urban) and discusses the related qualitative methods. Besides many studies being focused on energy and transportation systems, the literature review allows to observe that interviews and questionnaires are most frequently used to gather qualitative data, besides a high percentage of mixed-method research. The article aims to provide a synthesis of literature on qualitative methods used for resilience research in the domain of CIs, detailing lessons learned from such approaches to shed lights on best practices and identify possible future research directions

    Learning from incidents: A supply chain management perspective in military environments

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    Supply chain management (SCM) represents a crucial role in the military sector to ensure operation sustainability. Starting from the NATO handbook for military organizational learning, this paper aims at investigating the link between technical inconveniences and sustainable supply chain operations. Taking advantage of the learning from incidents (LFI) models traditionally used in the risk and safety management area, this paper proposes an information management system to support organizational learning from technical inconveniences in a military supply chain. The approach is discussed with reference to the Italian context, in line with international and national standards for technical inconvenience reporting. The results of the paper show the benefits of adopting a systematic LFI system for technical inconveniences, providing related exemplar business intelligence dashboards. Further implications for the generalization of the proposed information management system are presented to foster a healthy and effective reporting environment in military scenarios

    Sexuality and Politics. Lady Morgan and the Morality of the Italians

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    A study of the book "Italy" published by lady Morgan in 1821, with particular reference to the problem of the sexual morality and of the family life of the Italian

    Unmanned aerial systems: Status and Forthcoming challenges for Safety Risk Management

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    Urban Air Mobility (UAM) promises a revolution in urban transportation: for the first time ever, cities will be able to use the third dimension for their mobility needs. The traditional aviation industry and high-tech newcomers alike are making huge investments to make this - still unproven - technology a reality. Although Unmanned Aerial Systems (UAS) have now for some time been used in segregated airspace where separation from other air traffic can be assured, potential users have interests to deploy UAS in non-segregated airspaces. Recent technological and operational improvements give reason to believe that UAS safety and performance capabilities are maturing. However, there is still the need for establishing a systematic agreement between UAS safety policies with commonly accepted UAS Safety Risk Management processes. This agreement is needed to show that the risks related to UAS operations in all the different airspace classes can be adequately controlled in a way that would not jeopardize current safety levels and safety mitigations effectiveness. This study aims to investigate the current status of UAS operations and future concepts of operations with specific interest in the management of safety risk. This manuscript aims to summarize some of regulatory aspects currently available linked to safety investigation and reporting of drone operations and consequently draw some potential lines for future research
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