The Statistics of Superdirective Beam Patterns

Superdirective arrays have been extensively studied because of their considerable potential accompanied, unfortunately, by a high sensitivity to random errors that affect the responses and positions of array elements. However, the statistics of their actual beam pattern (BP) has never been systematically investigated. This paper shows that the Rician probability density function (PDF), sometimes adopted to study the impact of errors in conventional arrays, is a valid approximation for superdirective BP statistics only where some mathematical terms are negligible. The paper also shows that this is the case for all linear end-fire arrays considered. A similar study is proposed concerning the correlation between BP lobes, showing that for the superdirective arrays considered the lobes, especially non-adjacent ones, are almost independent. Furthermore, knowledge of the PDF of the actual BP allows one to define quantile BP functions, whose probability of being exceeded, at any point, is fixed. Combining the lobes' independence with quantile BP functions, an empirical equation for the probability that the entire actual BP will not exceed a quantile function over an interval larger than a given size is obtained. This new knowledge and these tools make it possible to devise new methods to design robust superdirective arrays via optimization goals with clearer and more relevant statistical meaning

A data extraction system for underwater particle holography

Pulsed laser holography is an extremely powerful technique for the study of particle fields as it allows instantaneous, noninvasive high-resolution recording of substantial volumes. By replaying the real image one can obtain the size, shape, position and - if multiple exposures are made - velocity of every object in the recorded field. Manual analysis of large volumes containing thousands of particles is, however, an enormous and time-consuming task, with operator fatigue an unpredictable source of errors. Clearly the value of holographic measurements also depends crucially on the quality of the reconstructed image: not only will poor resolution degrade size and shape measurements, but aberrations such as coma and astigmatism can change the perceived centroid of a particle, affecting position and velocity measurements. For large-scale applications of particle field holography, specifically the in situ recording of marine plankton with 'HoloCam,' we have developed an automated data extraction system that can be readily switched between the in-line and off-axis geometries and provides optimised reconstruction from holograms recorded underwater. As a videocamera is automatically stepped through the 200 by 200 by 1000mm sample volume, image processing and object tracking routines locate and extract particle images for further classification by a separate software module

Towards a new seismic short-term prediction methodology for critical service operators and manufacturing companies against earthquake

This paper is concerned with the novel short-term and operational-term seismic hazard assessment approach within the critical service operators and the manufacturing industry. The Cosmetecor earthquake prediction methodology has been tested and validated in the recent two decades. A prototype, Kuznetsov method, for exploring the Earth's interior has been used to create global monitoring network, which automatically detects spatial-temporal clusters and identifies electric potential anomalies. Research team developed the mathematical modelling of proton migration in terms of the fundamental Vlasov-Maxwell equation to convert original time series into visualization of electromagnetic wave. A 2-layer neural network model is used to fine-grained classification. Further, the statistical and scaling laws of seismicity have been exploited to present case of earthquake seasonality, i.e., a dataset of abnormal seismic scenarios for machine learning task. Finally, authors evaluated results in terms of reliability and accuracy of earthquake warnings at M5.2 threshold in Kamchatka: 17% of all warning represent missed alerts, and 83% represent correct alerts where events occurred in a 10-year time horizon. Common outcome in almost every case is mean lead time (time horizon) of 11.62 days. The dispersion is 6.7 days. Further, a non-random sample of the Italian companies assessed new benefits of methodology during survey. The stakeholders confirmed that they will be able to activate business continuity plan to mitigate earthquake consequences in a specific time frame. It is anticipated the emergence of new risk management practices on the Cosmetecor-based high technology of the 21st century, and the replacement of the long-term, one-in-a-hundred-year return period, assessment with a short-term, seasonal, seismic risk assessment

Evolution of space programs governance

This chapter discusses the evolution of space programs governance from the “Old Space” paradigm to the “New Space” one. For both paradigms, we discuss archetypical governance models, rationale, pros and cons. Ultimately, we explain the driving forces underpinning the evolution of program governance models. We show three governance archetypes. Traditionally program architectures and governance models were quite homogeneous and mostly government-led (archetype 1), while in the “New Space” paradigm, programs may also include partnerships with private actors (archetype 2) or being directly led and owned by private actors (archetype 3)

What is value in the New Space Economy? The end-users’ perspective on satellite data and solutions

New industrial dynamics are disrupting the space sector. New stakeholders bringing in capital, technologies, and knowledge from other industries are developing next-generation space infrastructures and services. Both commercial and institutional space projects have to be valuable for a wider set of end-users, asking not only for economic returns but also social and environmental benefits. Space organizations urge understanding and fostering value in the New Space Economy ecosystem. Indeed, end-users are still struggling to enact the expected value of satellite data and solutions for their business. This paper aims to investigate the expected value and the level of adoption (enacted value) of satellite data and satellite-based solutions in the New Space Economy ecosystem from end-users’ perspective. We interviewed 21 managers from end-user organizations in different sectors (i.e., Insurance & Finance, Energy & Utility, Transportation & Logistics). Value is deeply discussed in general management literature, and we identify Value Theory as the theoretical lens with the most explanatory power for the phenomenon under examination. From the end-users’ perspective, we frame the expected value and the enacted value in taking strategic and tactical decisions regarding their activities, services and products, laying the foundations for further studies of value mechanisms in the New Space ecosystem. Our research set a theoretical and conceptual foundation on value in the New Space ecosystem. It also delineates the blurred boundaries of the New Space ecosystem, the main stakeholders involved, and their perception of value. Insights and implications for strategic and innovation management are also provided. Practitioners may exploit our research results and leverage the end-users-oriented framework to develop next-generation space projects in the New Space ecosystem. We also discuss the limitations and further developments of this research

Evidence for engraftment of human bone marrow cells in non-lethally irradiated baboons

Background. Prior to organ harvesting, an attempt was made to modulate the donor's immune responses against prospective xenogeneic recipients by infusion of 'recipient-type' bone marrow. Methods. For this purpose, baboons conditioned with total lymphoid irradiation were given 6x108 unmodified human bone marrow cells/kg body weight with no subsequent treatment. Results. Animals survived until they were euthanized at 18 months. Using primers specific for human chorionic gonadotrophin gene, the presence of human DNA was confirmed by polymerase chain reaction in the blood of one animal for up to 18 months after cell transplantation; in the other animal, xenogeneic chimerism became undetectable in the blood at 6 months after bone marrow infusion. However, tissue samples obtained from both animals at the time they were euthanized bad evidence of donor (human) DNA. Additionally, the presence of donor DNA in individually harvested colonies of erythroid and myeloid lineages suggested that infused human bone marrow cells had engrafted across the xenogeneic barrier in both baboons. Conclusions. Bone marrow transplantation from human to baboon leads to establishment of chimerism and modulation of donor-specific immune reactivity, which suggests that this strategy could be reproducibly employed to crease 'surrogate' tolerogenesis in prospective donors for subsequent organ transplantation across xenogeneic barriers

Multistationary and Oscillatory Modes of Free Radicals Generation by the Mitochondrial Respiratory Chain Revealed by a Bifurcation Analysis

The mitochondrial electron transport chain transforms energy satisfying cellular demand and generates reactive oxygen species (ROS) that act as metabolic signals or destructive factors. Therefore, knowledge of the possible modes and bifurcations of electron transport that affect ROS signaling provides insight into the interrelationship of mitochondrial respiration with cellular metabolism. Here, a bifurcation analysis of a sequence of the electron transport chain models of increasing complexity was used to analyze the contribution of individual components to the modes of respiratory chain behavior. Our algorithm constructed models as large systems of ordinary differential equations describing the time evolution of the distribution of redox states of the respiratory complexes. The most complete model of the respiratory chain and linked metabolic reactions predicted that condensed mitochondria produce more ROS at low succinate concentration and less ROS at high succinate levels than swelled mitochondria. This prediction was validated by measuring ROS production under various swelling conditions. A numerical bifurcation analysis revealed qualitatively different types of multistationary behavior and sustained oscillations in the parameter space near a region that was previously found to describe the behavior of isolated mitochondria. The oscillations in transmembrane potential and ROS generation, observed in living cells were reproduced in the model that includes interaction of respiratory complexes with the reactions of TCA cycle. Whereas multistationarity is an internal characteristic of the respiratory chain, the functional link of respiration with central metabolism creates oscillations, which can be understood as a means of auto-regulation of cell metabolism. © 2012 Selivanov et al