Reconstruction Of Events Research Articles

Бурят-Монгольский ученый комитет (1922–1929 гг.): этапы становления и организация первых научных исследований

The article aims at shedding light on the history of the Buryat-Mongolian Scientific Committee: stages of its growth, contributions of its staff members in the organization of research and its implementation. Materials and methods. Both published and unpublished documents kept in the Center for Oriental Manuscripts and Xylographs of the Institute for Mongolian, Buddhist, and Tibetan Studies of the Siberian Branch of the Russian Academy of Sciences and in the State Archive of the Republic of Buryatia were used as the main sources for the reconstruction of the past events while the data analysis was based on the main scientific principles of historicism, systematicity, and objectivity; the paper’s comprehensive approach was implemented via the method of system analysis, problem-chronological and historical-comparative methods, and local history. Results. The Buryat-Mongolian Scientific Committee (Buruchkom), established in July 1922, was designed to promote the national-cultural construction in Buryat-Mongolia while focusing on research and educational tasks. It had to begin its operation under far from favorable conditions, such as poor funding, illiteracy of the population, a shortage of personnel, and practically non-existent printing and publishing, especially in the Buryat-Mongolian language. Nevertheless, Buruchkom organized the studies of Buryat history, archaeology, spiritual and material culture, language and religion, and started field work as well. A significant portion of its activities was initially directed towards translation of educational and socio-political literature into the Buryat language, related terminological and lexical studies, preparation and publication of teaching materials, such as textbooks and teaching manuals for Buryat-Mongolian schools. The academic environment was enhanced with establishing a library and museum, which were of much relevance for future scientific work. Buruchkom’s final success was due to its fruitful cooperation with the central scientific institutions of the country and the Mongolian Scientific Committee. Conclusion. Despite that its team of researchers was not numerous, Buruchkom managed to organize, as well as conduct research projects in the fields of history, archaeology, ethnography, and linguistics. Having accomplished an important objective of laying the foundations of science in the region, it has now become a leading academic center of the Republic, known for its research in the arts and humanities.

Kommunikationsstörungen in ukrainisch- und deutschsprachigen Star-Interviews aus der Perspektive des Interviewten

The aim of the article is to determine and analyze the characteristics of communication failures in star interviews from the point of view of the respondents, i.e. the interviewees. The empirical research base consists of Ukrainian and Germanlanguage video interviews from 2010 to 2019, which were either broadcast on television or produced for YouTube. The research process includes the integrated application of methods and techniques from communicative linguistics, in particular discourse analysis. A new methodological basis was developed for the investigation of these communication failures, namely for the reconstruction of a single event in two discursive environments, the determination of the communicative context and the communication situation in interviews in comparable languages. The results of the study made it possible to identify the characteristic features of communication failures in star interviews on three levels of the communicative genre: on the external structural, internal structural, and situational levels. Both common features of communication failures and differences in the Ukrainian and German-language interviews were determined. The results of the study show that the types of communication failures in interviews with celebrities in Ukrainian and German are universal, but they reflect national and cultural specificities given the characteristics of both languages and each language culture and their realities, norms, conventions, and maxims of communication. In both languages, communicative failures are a typical and often unavoidable component of interviews. 

Reconstruction of the last cretaceous anoxic event in the Tarfaya Laayoune basin (South of Morocco): Biostratigraphy and Paleoenvironment of the Oum Debaa Formation

Abstract The Tarfaya-Laayoune coastal basin developed in a stable passive margin, where sedimentation occurred in shallow bays. During the Late Cretaceous, bituminous and phosphatic series were deposited in the shallow depression such as Sebkha Oum Debaa. In this work, the age of these Cretaceous layers are refined using a palynological approach and their paleoenvironments are described using organic geochemistry. Based on quantitative and qualitative palynological analyses, the sediments revealed a rich and diverse dinoflagellate cyst assemblage (65 taxa); among them 9 important biostratigraphic markers: Andalusiella inflata, Andalusiella ivoirensis, Andalusiella mauthei, Cerodinium diebelii, Cerodinium speciosum, Dinogymnium acuminatum, Odontochitina porifera, Trichodinium castanea, and Trithyrodinium evittii. According to the reported stratigraphic dinoflagellate taxa distribution, an age range of late Campanian to early Maastrichtian is herein proposed for the Oum Debaa Formation. This biostratigraphy update has been correlated to the Tethyan and Sub-Boreal domains. On the paleoenvironmental level, geochemical proxies have displayed an anoxic lagoon depositional which is dominated by an intermediate climate between hot / humid and arid with an often low paleoproductivity regime which induces redox conditions.

Processing and analysis of botanical micro-and macroobjects using computer vision technologies

This article discusses the problems of automation of processing and analysis of botanical micro-and macroobjects. The problem is a comprehensive interdisciplinary research aimed at recognizing and searching for botanical micro-and macroobjects using computer vision technologies. Computer vision is an area of artificial intelligence that deals with the analysis and extraction of information from images (in this case, the fern dispute). The purpose of this study is to solve a number of applied and fundamental problems in the biosystematics of botanical objects and the study of microevolutionary processes. The results of the research are stored in a specially developed database “Spore morphology of ferns of the Pteridaceae family”. The database implements a set of queries relevant to biometrics tasks. The database is based on images and biometric data on the morphology of fern spores obtained in the form of measurements of systematically important signs of spores, as well as data on the shape and surface of the studied objects. The diagnostic characters of taxa of the Pteridaceae family have been standardized for solving the research problems. In the course of the study, fundamentally new knowledge was obtained that will supplement the natural classification of the Pteridaceae family, as well as test hypotheses about the relationship of a number of taxa represented on the continents of Eurasia and Africa, for an objective reconstruction of events of past geological periods. Processing and analysis of botanical micro-and macro-objects and the development of specialized software are carried out in the Python programming language using an integrated development environment for Python - PyCharm. When developing the graphical interface of the program, we used the sets of Python libraries PyQt5 and a visual tool for designing and creating graphical user interfaces (GUI) from Qt components - Qt Designer.

Measurement of the 136-Xe ββ2υ half-life in NEXT-White

The NEXT (Neutrino Experiment with a Xenon TPC) collaboration searches for the neutrino-less double beta decay (0υββ) of 136Xe at the Laboratorio Subterráneo de Canfranc (LSC). A first large-scale prototype of a high-pressure Xenon gas electroluminescent TPC, NEXT-White, operated at the LSC from 2016 to 2021. In this analysis, the measurement of the half-life of the two-neutrino mode of the double beta decay (2νυβ) will be presented. For this measurement, two novel techniques in the field have been used: a highly refined topological reconstruction of events that improves the background rejection, and a direct subtraction of the ββ backgrounds, measured with 136Xe-depleted data. These techniques allow for background-model-dependent and background-model-independent results, demonstrating the robustness of the 2νυβ half-life measurement and the unique capabilities of NEXT. The final value presented corresponds to a half-life of T-2υ 1/2 = 2.34+0’®0 (stat)-0’37(sys) x 1021 year. After the completion of the NEXT-White programme, the NEXT-100 apparatus will start its commissioning at the second half of 2022. Holding 100 kg of 136Xe at 15 bar, this detector will perform the first competitive 0νυβ search within the NEXT roadmap. As validated with NEXT-White, NEXT- 100 will set a limit in m-ββ of 70-130 meV after 5 years of data taking.

Multi-Dimensional Remote Sensing Analysis Documents Beaver-Induced Permafrost Degradation, Seward Peninsula, Alaska

Beavers have established themselves as a key component of low arctic ecosystems over the past several decades. Beavers are widely recognized as ecosystem engineers, but their effects on permafrost-dominated landscapes in the Arctic remain unclear. In this study, we document the occurrence, reconstruct the timing, and highlight the effects of beaver activity on a small creek valley confined by ice-rich permafrost on the Seward Peninsula, Alaska using multi-dimensional remote sensing analysis of satellite (Landsat-8, Sentinel-2, Planet CubeSat, and DigitalGlobe Inc./MAXAR) and unmanned aircraft systems (UAS) imagery. Beaver activity along the study reach of Swan Lake Creek appeared between 2006 and 2011 with the construction of three dams. Between 2011 and 2017, beaver dam numbers increased, with the peak occurring in 2017 (n = 9). Between 2017 and 2019, the number of dams decreased (n = 6), while the average length of the dams increased from 20 to 33 m. Between 4 and 20 August 2019, following a nine-day period of record rainfall (>125 mm), the well-established dam system failed, triggering the formation of a beaver-induced permafrost degradation feature. During the decade of beaver occupation between 2011 and 2021, the creek valley widened from 33 to 180 m (~450% increase) and the length of the stream channel network increased from ~0.6 km to more than 1.9 km (220% increase) as a result of beaver engineering and beaver-induced permafrost degradation. Comparing vegetation (NDVI) and snow (NDSI) derived indices from Sentinel-2 time-series data acquired between 2017 and 2021 for the beaver-induced permafrost degradation feature and a nearby unaffected control site, showed that peak growing season NDVI was lowered by 23% and that it extended the length of the snow-cover period by 19 days following the permafrost disturbance. Our analysis of multi-dimensional remote sensing data highlights several unique aspects of beaver engineering impacts on ice-rich permafrost landscapes. Our detailed reconstruction of the beaver-induced permafrost degradation event may also prove useful for identifying degradation of ice-rich permafrost in optical time-series datasets across regional scales. Future field- and remote sensing-based observations of this site, and others like it, will provide valuable information for the NSF-funded Arctic Beaver Observation Network (A-BON) and the third phase of the NASA Arctic-Boreal Vulnerability Experiment (ABoVE) Field Campaign.

Annular distribution patterns of .357 Magnum fragments in soft tissue simulants after striking hard material that prevented the bullet from exiting

The distribution of bullet fragments inside the body can provide information for the reconstruction of events in shooting incidents. The formation of an annular distribution pattern of bullet fragments was recently presented in a case report. The fragments were scattered radially around an exit-re-entrance wound resulting from collision of the bullet with a floor tile immediately after perforating the body. Such an annular distribution pattern of bullet fragments around an exit-re-entrance wound would indicate that a body was in close contact with hard material, for instance, lying on hard ground or leaning against a concrete wall, when the shot was fired. The aim of this experimental study was to investigate the formation and reproducibility of the annular distribution pattern of bullet fragments. It was assumed that the distribution pattern would be formed when hard material blocks a bullet from exiting a soft tissue simulant. Furthermore, the dependency of this distribution pattern on the impact angle was assessed. For this purpose, .357 Magnum bullets were fired at ballistic soap blocks with a steel plate at the rear end of the soap block. Six shots were performed at an impact angle of 90° (experiment 1), and six shots were performed at an impact angle of 45° (experiment 2). The distribution pattern of the fragments inside the individual soap blocks was examined via computed tomography (CT). In experiment 1, the bullets burst, and large fragments formed annular distribution patterns with a radial extent of approximately 4.9 cm and a maximum depth of approximately 2.3 cm. In experiment 2, the bullets ricocheted from the steel plate, and tiny fragments formed small annular distribution patterns at the points of ricochet with a radial extent of approximately 1.5 cm and a maximum depth of approximately 1.2 cm. The end position of the large main fragments was approximately 9.7 cm distant from the point of ricochet at a mean depth of 2.7 cm. The mean kinetic energy of the bullets at the time of impact was 580 J in experiment 1 and 394 J in experiment 2. Distribution patterns of bullet fragments in the body may provide information not only on the impact angle of a bullet but also on whether the body was in contact with a hard material that blocked the bullet from exiting the body. CT proved to be an appropriate imaging method for such investigations.

Simulation-based reconstruction of traffic incidents from moving vehicle mono-camera

Video recordings from digital cameras implemented in road vehicles present a valuable source of data concerning various dangerous traffic situations, i.e., road accidents or near-miss incidents. This data is readily available and numerous methods for forensic reconstruction of traffic situations from vehicle video were presented in the past. New alternative method for reconstruction of traffic situations from vehicle video is presented in this article. The method is based on the fusion of kinetic vehicle trajectory simulation within 3D laser scanner point cloud, projective geometry, and processing of video footage from moving vehicle camera. The method offers accurate reconstruction of general vehicle motion within relevant time domain whereby in-depth technical information about traffic incident can be quantitatively extracted from video footage. The result is physics-based 3D projection of simulated vehicle motion on the motion of real vehicle recorded by moving monocular camera. The method was validated within performed experimental test runs with respect to vehicle speed, distance travelled, acceleration/deceleration and directional quantities (yaw rate, yaw angle). The method was further applied in the reconstruction of real-world traffic events.

Geohazards Monitoring and Assessment Using Multi-Source Earth Observation Techniques

Geological disasters are responsible for the loss of human lives and for significant economic and financial damage every year. Considering that these disasters may occur anywhere—both in remote and/or in highly populated areas—and anytime, continuously monitoring areas known to be more prone to geohazards can help to determine preventive or alert actions to safeguard human life, property and businesses. Remote sensing technology—especially satellite-based—can be of help due to its high spatial and temporal coverage. Indeed, data acquired from the most recent satellite missions is considered suitable for a detailed reconstruction of past events but also to continuously monitor sensitive areas on the lookout for potential geohazards. This work aims to apply different techniques and methods for extensive exploitation and analysis of remote sensing data, with special emphasis given to landslide hazard, risk management and disaster prevention. Multi-temporal SAR (Synthetic Aperture Radar) interferometry, SAR tomography, high-resolution image matching and data modelling are used to map out landslides and other geohazards and to also monitor possible hazardous geological activity, addressing different study areas: (i) surface deformation of mountain slopes and glaciers; (ii) land surface displacement; and (iii) subsidence, landslides and ground fissure. Results from both the processing and analysis of a dataset of earth observation (EO) multi-source data support the conclusion that geohazards can be identified, studied and monitored in an effective way using new techniques applied to multi-source EO data. As future work, the aim is threefold: extend this study to sensitive areas located in different countries; monitor structures that have strategic, cultural and/or economical relevance; and resort to artificial intelligence (AI) techniques to be able to analyse the huge amount of data generated by satellite missions and extract useful information in due course.

REVIEW. Khapizov Sh.M., Shekhmagomedov M.G. Ibrahim-Haji from Urada (1701-1770) and his era: studies on history and life. Makhachkala, 2021. ISBN 978-5-6045929-0-8

The present review discusses the collective monograph “Ibrahim-Haji from Urada (1701-1770) and his era: studies on history and life” (Makhachkala, 2021), which is a significant contribution to Caucasian studies. Given the fact that in recent years in historical science there has been an increased interest in the personality of Ibrahim-Haji al-Uradi, the comprehensive monograph sheds light on many aspects of the life and work of the outstanding scholar and expert in Islamic law and grammar of the Avar language, author of poems in Avar, theologian, one of the ideologists of the struggle between the Dagestanis and Nadir Shah, Qadi of Gidatl. The authors of the collective monograph, using a rich documentary base, carry out a scrupulous reconstruction of political events in the Caucasus of the period under study, and against this background analyze the life and work of Ibrahim-Haji al-Uradi. For the first time in modern Caucasian studies, the authors have introduced a number of Georgian, Turkish and Iranian primary sources, which help to reveal a more complete picture of the events in the Eastern Caucasus and the entire Caucasian region as a whole in the second half of the 18th century. Moreover, the authors attracted Arabic-language sources from private manuscript collections from Gidatl and the contents of the collections from the Collection of Oriental Manuscripts of the Institute of Archeology and Ethnography of the DFRC RAS. In addition to that, it is necessary to mention the private and mosque manuscript collections of Dagestan. In total, the authors have attracted more than 2000 works in their work. This study undoubtedly occupies a worthy place along with other works devoted to the life and work of Ibrahim-Hajji al-Uradi.

Short and Long Time Bloodstains Age Determination by Colorimetric Analysis: A Pilot Study.

Bloodstains found at crime scenes represent a crucial source of information for investigative purposes. However, in forensic practice, no technique is currently used to estimate the time from deposition of bloodstains. This preliminary study focuses on the age estimation of bloodstains by exploiting the color variations over time due to the oxidation of the blood. For this purpose, we used a colorimetric methodology in order to easily obtain objective, univocal and reproducible results. We developed two bloodstain age prediction algorithms: a short-term and a long-term useful model for the first 24h and 60 days, respectively. Both models showed high levels of classification accuracy, particularly for the long-term model. Although a small-scale study, these results improve the potential application of colorimetric analysis in the time-line reconstruction of violent criminal events.

Struck down in the marketplace: Bioarchaeological analysis of an individual recovered from the earthquake complex at Kourion

This article details the excavation and osteobiography of a single individual from the Earthquake Complex at the late Roman site of Kourion on the island of Cyprus. The Earthquake Complex consists of two structures, the Earthquake House and Market Building, that were damaged and then destroyed by a series of earthquakes in the fourth century CE. Originally found in 1987 during excavations of the Earthquake Complex, this individual was excavated en bloc and removed to the Episkopi museum. Continued excavations of the individual and osteological analysis were completed in 2015. Detailed here are the recovery and reconstruction of events surrounding the individual’s death. This individual died during one of the fourth century CE earthquakes that affected life throughout the eastern Mediterranean. Kourion suffered multiple earthquakes in this time frame; this snapshot archaeological deposit provides an opportunity to understand a single individual’s experience within this destructive episode.

The largest nuclear accident in the history of the nuclear fleet. Reconstruction of events and analysis of the accident consequences to assess the risks and hazards of small nuclear power facilities

The article presents the results of studies related to the reconstruction and assessment of the radiation consequences of the largest nuclear accident in the history of the USSR/Russia and the world's nuclear fleets, corresponding to the fifth (5th) hazard level according to the International INES scale, which occurred on a nuclear submarine in 1985 in Chazhma Bay. The event recovery methodology includes the collection, generalization, analysis of disparate data, modeling and retrospective forecasting using modern methods in order to restore the events and assess the consequences at the normative and background levels. The refined data of the release of dose-forming radionuclides from the submarine reactor into the surface layer of the atmosphere are given, the trajectory of the radioactive cloud transfer, the trace formation and the fallout of radioactive substances up to 400 km from the accident site are determined. The authors have estimated the time of contact with the moving cloud, the density of the fallout of radionuclides; the equivalent dose rate, the dose load from the cloud and the dose during long-term residence of the population in the contaminated area. External and internal exposure they determined by individual and cumulative exposure to 131-135I, 137Cs, 90Sr and 60Co. They considered the territories of the shipyard where the accident occurred and the adjacent areas – the Dunai Peninsula, Ussuri Bay, Primorskii Krai and the border province of Heilongjiang (China). It was extremely important to analyze the damaging factors initiated by an uncontrolled self-sustaining chain reaction at the early and subsequent stages of the nuclear accident on the power installation, carrier, support infrastructure, settlements and the environment for a more complete understanding of the existing risks and dangers of using new nuclear power facilities – mobile small nuclear power stations.

B-event statements as vehicles for two interactional practices in police interactions with suspects/witnesses

B-events are matters which are better known to listeners than to speakers. This paper studies the detectives’ use of B-event statements in two different environments in their interactions with suspects/witnesses. The first type of environment are relatively co-operative sequences during which the aim is the reconstruction of events and constructing the record; here, B-event statements are realised as confirmation seeking questions. The second type of environment, a hostile interactional environment, is composed of argumentative sequences in which detectives aim to determine who are the perpetrators of crimes; in these sequences, the detectives’ B-event statements are realised as accusations. While performing the two activities, the detectives signal different epistemic levels and stances at the turn level. Thus, the former B-event statements are mostly epistemically downgraded, while the latter are mostly upgraded, in order to facilitate undertaking these different activities during police questioning.

Developing the future of gamma-ray astrophysics with monolithic silicon pixels

This paper explores the potential of AstroPix, a project to develop Complementary Metal Oxide Semiconductor (CMOS) pixels for the next generation of space-based high-energy astrophysics experiments. Multimessenger astrophysics is a rapidly developing field whose upcoming missions need support from new detector technology such as AstroPix. ATLASPix, a monolithic silicon detector optimized for the ATLAS particle detector at CERN, is the beginning of the larger AstroPix project. Energy resolution is a driving parameter in the reconstruction of gamma-ray events, and therefore the characterization of ATLASPix energy resolution is the focus of this paper. The intrinsic energy resolution of the detector exceeded our baseline requirements of <10% at 60 keV. The digital output of ATLASPix results in energy resolutions insufficient to advance gamma-ray astronomy. However, the results from the intrinsic energy resolution indicate the digital capability of the detector can be redesigned, and the next generation of pixels for the larger AstroPix project have already been constructed. Iterations of AstroPix-type pixels are an exciting new technology candidate to support new space-based missions.

High-resolution reconstruction of typhoon events since ~1850 CE based on multi-proxy sediment records in a coastal lagoon, South China

Coastal lagoon sediments provide continuous and high-resolution records of the activity of past typhoons. In this study, multiple proxies were analyzed with a core taken from Pinqing Lagoon located on the northeast margin of the South China Sea. Based on 210Pb dating, grain sizes and other geophysical/geochemical analyses, a total of seven typhoon-induced layers covering the past ~170 years were identified and compared with observational and historical records of typhoons. The layers were characterized by a higher sand fraction, lower loss-on-ignition, decreased magnetic susceptibility, and increased element ratios of Sr/Fe, Sr/Ba, Ca/Ti, and Ca/K. We found reduced sensitivity of the sedimentary response to typhoons due to the coastal geomorphological evolution, such as sand spit growth, which emphasizes the value of using a multiple-proxy approach. The typhoon activity revealed by both sedimentary proxies and observational/historical records in Shanwei was closely related to the variations of the El Niño/Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), and to sunspot activity, providing useful clues for reconstructing the long-term typhoon history in the lagoon in order to decipher the patterns and mechanisms of typhoons in South China.

Deep learning reconstruction in ANTARES

ANTARES is currently the largest undersea neutrino telescope, located in the Mediterranean Sea and taking data since 2007. It consists of a 3D array of photo sensors, instrumenting about 10Mt of seawater to detect Cherenkov light induced by secondary particles from neutrino interactions. The event reconstruction and background discrimination is challenging and machine-learning techniques are explored to improve the performance. In this contribution, two case studies using deep convolutional neural networks are presented. In the first one, this approach is used to improve the direction reconstruction of low-energy single-line events, for which the reconstruction of the azimuth angle of the incoming neutrino is particularly difficult. We observe a promising improvement in resolution over classical reconstruction techniques and expect to at least double our sensitivity in the low-energy range, important for dark matter searches. The second study employs deep learning to reconstruct the visible energy of neutrino interactions of all flavors and for the multi-line setup of the full detector.

Communicative deviations of respondents in political video interviews in Ukrainian and German

The research has the objective to establish the peculiarities of communicative deviations as a cognitive and at the same time discursive phenomenon in Ukrainian- and German-language video interviews from the viewpoint of respondents. The procedure of the research involves the integrated application of methods and techniques of pragmatics, deviatology and communicative linguistics. A new methodological basis has been developed for the reconstruction of communicative deviations using discourse analysis, namely for the reconstruction of a single event in two discursive environments, determining the communicative context and communication of interview in compared languages. The results of the research allow us to identify the features of communicative deviations in political interviews at the external, internal structural levels and at the situational level. The conclusions of the research indicate that the types of communicative deviations in political video interviews are universal in Ukrainian and German, but reflect national and cultural specifics given the peculiarities of both languages and each linguoculture, as well as existing realias, norms, conventions, maxims and rules of communication.

АЛИМЕНТНЫЕ ПРИТЯЗАНИЯ ФАКТИЧЕСКИХ ВОСПИТАТЕЛЕЙ РЕБЕНКА: ПРОЦЕССУАЛЬНЫЕ ОСОБЕННОСТИ СУДЕБНОГО РАЗРЕШЕНИЯ

This article is devoted to theoretical research problems of interaction and correlation material-legal and procedural components in the structure of such a phenomenon as the actual upbringing of a child and the legal consequences that it entails. The “semilegal” regime of this type of relationship, associated with the legislative non-obviousness of their subjects, as well as the criteria for the occurrence of legal consequences of such education, introduces significant features to procedural relations. The authors make one of the few scientific attempts to investigate these features. The subject of theoretical analysis involves essential signs of relationships for the actual upbringing of a child and tools judicial knowledge of this category of cases: logic for the purpose of establishing the content reliability of the studied post-facts, reception reconstruction of past events in the relations of the disputing parties; judicial interpretation, judicial discretion, analogy of the law. In conclusion, the idea is put forward that the problem of proper child-rearing should not be covered by the problem of evaluative concepts. This problem is more of a methodological one, and its effective resolution should start not so much from a protective cross-section of the topic of childhood, where there is room for parental delinquency and the destructive notion of “inappropriate child-rearing” with its extreme cases of infringement of children’s rights and interests, but from a positive-regulative aspect.

Explosive nosocomial outbreak of SARS-CoV-2 in a rehabilitation clinic: the limits of genomics for outbreak reconstruction

BackgroundNosocomial outbreaks of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) are frequent despite implementation of conventional infection control measures. An outbreak investigation was undertaken using advanced genomic and statistical techniques to reconstruct likely transmission chains and assess the role of healthcare workers (HCWs) in SARS-CoV-2 transmission.MethodsA nosocomial SARS-CoV-2 outbreak in a university-affiliated rehabilitation clinic was investigated, involving patients and HCWs, with high coverage of pathogen whole-genome sequences (WGS). The time-varying reproduction number from epidemiological data (Rt) was estimated, and maximum likelihood phylogeny was used to assess genetic diversity of the pathogen. Genomic and epidemiological data were combined into a Bayesian framework to model the directionality of transmission, and a case–control study was performed to investigate risk factors for nosocomial SARS-CoV-2 acquisition in patients.FindingsThe outbreak lasted from 14th March to 12th April 2020, and involved 37 patients (31 with WGS) and 39 employees (31 with WGS), 37 of whom were HCWs. Peak Rt was estimated to be between 2.2 and 3.6. The phylogenetic tree showed very limited genetic diversity, with 60 of 62 (96.7%) isolates forming one large cluster of identical genomes. Despite the resulting uncertainty in reconstructed transmission events, the analyses suggest that HCWs (one of whom was the index case) played an essential role in cross-transmission, with a significantly greater fraction of infections (P<2.2e-16) attributable to HCWs (70.7%) than expected given the number of HCW cases (46.7%). The excess of transmission from HCWs was higher when considering infection of patients [79.0%; 95% confidence interval (CI) 78.5–79.5%] and frail patients (Clinical Frailty Scale score >5; 82.3%; 95% CI 81.8–83.4%). Furthermore, frail patients were found to be at greater risk for nosocomial COVID-19 than other patients (adjusted odds ratio 6.94, 95% CI 2.13–22.57).InterpretationThis outbreak report highlights the essential role of HCWs in SARS-CoV-2 transmission dynamics in healthcare settings. Limited genetic diversity in pathogen genomes hampered the reconstruction of individual transmission events, resulting in substantial uncertainty in who infected whom. However, this study shows that despite such uncertainty, significant transmission patterns can be observed.