Radiation reaction in curved space-time: local method

Although consensus seems to exist about the validity of equations accounting for radiation reaction in curved space-time, their previous derivations were criticized recently as not fully satisfactory: some ambiguities were noticed in the procedure of integration of the field momentum over the tube surrounding the world-line. To avoid these problems we suggest a purely local derivation dealing with the field quantities defined only {\em on the world-line}. We consider point particle interacting with scalar, vector (electromagnetic) and linearized gravitational fields in the (generally non-vacuum) curved space-time. To properly renormalize the self-action in the gravitational case, we use a manifestly reparameterization-invariant formulation of the theory. Scalar and vector divergences are shown to cancel for a certain ratio of the corresponding charges. We also report on a modest progress in extending the results for the gravitational radiation reaction to the case of non-vacuum background.Comment: 10 pages, ws-procs9x6, published in "Gravitation and Astrophysics", Proceedings of the VII Asia-Pacific International Conference National Central University, Taiwan 23 - 26 November 2005, ed. J.M. Nester, C.-M. Chen, J.-P. Hsu. World Scientific, 2006, pp. 345-35

Petrological and geochemical characteristics of Palaeogene low-rank coal on the Faroe Islands: restricted effects of alteration by basaltic lava flows

The first combined petrographic and geochemical investigation of coal from the Faroe Islands was performed as a case study to understand thermal effects from basaltic lavaflows on immature coal. The samples were divided into two distinct groups:“normal”coal (xylite and detroxylite) and“altered organic matter”(charcoal and organic particles dispersed in samples rich in altered clastic mineral components or enriched via hydrothermal fluids). The“normal”coal consists primarily of huminite-group material dominated by ulminite. The proportions of material from inertinite and liptinite groups vary from sample to sample. The studied macerals are anisotropic with no observed reaction rims or vacuoles. According to the mean ulminite reflectance in combination with ultimate and proximate analyses, the coal reached the lignite and subbituminous stages. The maceral compositions together with coal palynology indicate a predominance of gelified wood-derived tissues and demonstrate that the coal evolved in wet forest swamps under limno-telmatic to telmatic conditions. Alteration effects on immature coals from overlying basalt flows were relatively limited. Due to relatively rapid heat loss from the basaltic lava, as verified by the presence of volcanic glass (tachylyte), its imposed thermal effects resulted only in development of a thin“anthracite-like”crust on samples with no elevated coal rank. Associated hydrothermal fluids induced coal hydrofracturing with subsequent mineral precipitation and decomposition of the ambient feldspar-rich volcaniclastic sediments. Altered organic matter is enriched in SiO2, Al2O3 and FeOtot, as well as in trace elements such as Ni and Cr. In contrast, these samples are depleted in Hg (<10 ppb).Jedná se o první kombinovaný petrografický a geochemický výzkum uhlí na Faerských ostrovech, který byl proveden jako klíčová studie k pochopení termálního efektu výlevů bazaltových láv v blízkosti slojí nevyzrálého uhlí. Vzorky byly rozděleny do dvou odlišných skupin: „normální“ uhlí (xylit a detroxylit) a „alterovaná organická hmota“ (dřevěné uhlí a organické částice rozptýlené ve vzorcích bohatých na alterované klastické minerální komponenty nebo obohacených hydrotermálními fluidy). „Normální“ uhlí je tvořeno převážně macerály huminitové skupiny, z nichž dominuje ulminit. Zastoupení macerálů skupiny inertinitu a liptinitu je variabilní. Studované macerály jsou anizotropní, bez pozorovaných reakčních lemů či vakuol. Na základě světelné odraznosti ulminitu a chemicko-technologických parametrů vykazuje uhlí nízký stupeň prouhelnění. Macerálové složení společně s palynologií indikují převahu dřevních pletiv a ukazují na vývoj uhlí v prostředí občasně zaplavovaných lesních mokřadů. Efekt alterace nevyzrálého uhlí nadložními bazaltovými výlevy byl poměrně omezený. Vzhledem k relativně rychlému zchladnutí bazaltové lávy, prokázanému přítomností vulkanického skla (tachylytu), se termální efekt projevil pouze vyvinutím tenké vrstvičky antracitového vzhledu na vzorcích bez celkového zvýšení stupně prouhelnění. Hydrotermální fluida spojená s vulkanickou aktivitou způsobila mechanickou desintegraci uhlí a následné vysrážení minerálů doprovázené rozkladem okolních vulkanoklastických sedimentů bohatých na živce. Alterovaná organická hmota je obohacena jednak o SiO2, Al2O3 a FeOtot, jednak o stopové prvky, jako například Ni a Cr. Naopak, tyto vzorky jsou ochuzeny o Hg (<10 ppb)

Evaluation of 3D Printing Use for Multinational Armed Forces Logistic Processes in Crisis Situations

3D printing technology could be an option for the delivery of spare parts in a multinational army supply process, especially in crisis situations, when specific spare parts need to be available as soon as possible. The article deals with the selection of fused filament fabrication as an appropriate method for that purpose by comparing its advantages and disadvantages, as well as the best material (Nylon CF15 Carbon) based on important mechanical properties using the comparative and Saaty\u27s methods. Several samples were made to be exposed to UV radiation in a climate chamber (Q-LAB Q-SUN-Xe3 equipped with a DAYLIGHT-Q filter) and tested according to the ASTM D2565 and ASTM D4459 standards. To compare the mechanical properties of the samples exposed to UV radiation with those of the unexposed ones, a tensile test was done according to the CSN EN ISO 527-2 standard. Finally, the specific spare part was designed and 3D printed, and the delivery times of the standard supply period were compared with those of the 3D printing technology

Nine-amino-acid transactivation domain: Establishment and prediction utilities

AbstractHere we describe the establishment and prediction utilities for a novel nine-amino-acid transactivation domain, 9aa TAD, that is common to the transactivation domains of a large number of yeast and animal transcription factors. We show that the 9aa TAD motif is required for the function of the transactivation domain of Gal4 and the related transcription factors Oaf1 and Pip2. The 9aa TAD possesses an autonomous transactivation activity in yeast and mammalian cells. Using sequence alignment and experimental data we derived a pattern that can be used for 9aa TAD prediction. The pattern allows the identification of 9aa TAD in other Gal4 family members or unrelated yeast, animal, and viral transcription factors. Thus, the 9aa TAD represents the smallest known denominator for a broad range of transcription factors. The wide occurrence of the 9aa TAD suggests that this domain mediates conserved interactions with general transcriptional cofactors. A computational search for the 9aa TAD is available online from National EMBnet-Node Austria at http://www.at.embnet.org/toolbox/9aatad/

L/F-CIPS: Collaborative indoor positioning for smartphones with lateration and fingerprinting

The demand for indoor location-based services and the wide availability of mobile devices have triggered research into new positioning systems able to provide accurate indoor positions using smartphones. However, accurate solutions require a complex implementation and long-term maintenance of their infrastructure. Collaborative systems may help to alleviate these drawbacks. In this paper, we propose a smartphone-based collaborative architecture using neural networks and received signal strength, which exploits the built-in wireless communication technologies in smartphones and the collaboration between devices to improve traditional positioning systems without additional deployment. Experiments are carried out in two real-world scenarios, demonstrating that our proposed architecture enhances the position accuracy of traditional indoor positioning systems.The authors gratefully acknowledge funding from European Union’s Horizon 2020 RIA programme under the Marie Skłodowska Curie grant agreement No. 813278 (A-WEAR: A network for dynamic wearable applications with privacy constraints) and No. 101023072 (ORIENTATE: Low-cost Reliable Indoor Positioning in Smart Factories). The associate editor coordinating the review of this article and approving it for publication was Prof. Name Surname (Corresponding authors: J. Torres-Sospedra and S. Casteleyn)

L/F-CIPS: collaborative indoor positioning for smartphones with lateration and fingerprinting

The demand for indoor location-based services (LBS) and the wide availability of mobile devices have triggered research into new positioning systems able to provide accurate indoor positions using smartphones. However, accurate solutions require a complex implementation and long-term maintenance of their infrastructure. Collaborative systems may help alleviate these drawbacks. In this article, we propose a smartphone-based collaborative architecture using neural networks and received signal strength (RSS), which exploits the built-in wireless communication technologies in smartphones and the collaboration between devices to improve the traditional positioning systems without additional deployment. Experiments are carried out in two real-world scenarios, demonstrating that our proposed architecture enhances the position accuracy of the traditional indoor positioning systems (IPSs)

Collaborative Indoor Positioning Systems: A Systematic Review

Research and development in Collaborative Indoor Positioning Systems (CIPSs) is growing steadily due to their potential to improve on the performance of their non-collaborative counterparts. In contrast to the outdoors scenario, where Global Navigation Satellite System is widely adopted, in (collaborative) indoor positioning systems a large variety of technologies, techniques, and methods is being used. Moreover, the diversity of evaluation procedures and scenarios hinders a direct comparison. This paper presents a systematic review that gives a general view of the current CIPSs. A total of 84 works, published between 2006 and 2020, have been identified. These articles were analyzed and classified according to the described system’s architecture, infrastructure, technologies, techniques, methods, and evaluation. The results indicate a growing interest in collaborative positioning, and the trend tend to be towards the use of distributed architectures and infrastructure-less systems. Moreover, the most used technologies to determine the collaborative positioning between users are wireless communication technologies (Wi-Fi, Ultra-WideBand, and Bluetooth). The predominant collaborative positioning techniques are Received Signal Strength Indication, Fingerprinting, and Time of Arrival/Flight, and the collaborative methods are particle filters, Belief Propagation, Extended Kalman Filter, and Least Squares. Simulations are used as the main evaluation procedure. On the basis of the analysis and results, several promising future research avenues and gaps in research were identified

Resilience of critical infrastructure elements and its main factors

Resilience in a critical infrastructure system can be viewed as a quality that reduces vulnerability, minimizes the consequences of threats, accelerates response and recovery, and facilitates adaptation to a disruptive event. In this context, comprehensive knowledge of the environment and of the main factors whereby resilience is determined, limited, and affected can be said to represent the fundamental precondition for strengthening the resilience of critical infrastructure elements. Based on this idea, the article defines the initial and functional conditions for building and strengthening the resilience of critical infrastructure elements, i.e., the resilience concept in a critical infrastructure system. Subsequently, factors determining the resilience of these elements are identified, both in terms of technical resilience (i.e., robustness and recoverability) and organizational resilience (i.e., adaptability). In the final part of the article, these factors are presented in greater detail in the context of case studies focused on the electricity, gas, information and communications technology, and road transport sectors. Determination of these factors is examined with regard to the intensity of a disruptive event and the performance of the respective critical infrastructure element.Web of Science62art. no. 2