63 research outputs found

    On dynamics and stability of thin periodic cylindrical shells

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    The object of considerations is a thin linear-elastic cylindrical shell having a periodic structure along one direction tangent to the shell midsurface. The aim of this paper is to propose a new averaged nonasymptotic model of such shells, which makes it possible to investigate free and forced vibrations, parametric vibrations, and dynamical stability of the shells under consideration. As a tool of modeling we will apply the tolerance averaging technique. The resulting equations have constant coefficients in the periodicity direction. Moreover, in contrast with models obtained by the known asymptotic homogenization technique, the proposed one makes it possible to describe the effect of the period length on the overall shell behavior, called a length-scale effect

    IDENTIFICATION OF THE MASS INERTIA MOMENT IN AN ELECTROMECHANICAL SYSTEM BASED ON WAVELET–NEURAL METHOD

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    This paper presents the results of testing of a complex electromechanical system model. These results have been obtained for accepted in simu-lations the method of identifying an inertia moment of reduced masses on shaft of induction motor drive during the changes of a backlash zone width. The effectiveness of correct diagnostic conclusions enables coefficients anal-ysis of testing signals wavelet expansion as well as weights of a supervised learning neural network. The earlier fault detection of five important state variables, which describe physical quantities of chosen complex electro-mechanical system has been verified for its correctness during the backlash zone width monitoring in the early stage of its gradual rise. The proposed here algorithm with mass inertia moment changes has proved to be an effective diagnostic method in the area of system changeable dynamic conditions and this has been shown in the resulting changes of backlash zone width

    IDENTIFICATION OF A BACKLASH ZONE IN AN ELECTROMECHANICAL SYSTEM CONTAINING CHANGES OF A MASS INERTIA MOMENT BASED ON A WAVELET–NEURAL METHOD

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    In this article a new method of identification of a backlash zone width in a structure of an electromechanical system has been presented. The results of many simulations in a tested model of a complex electromechanical system have been taken while changing a value of a reduced masses inertia moment on a shaft of an induction motor drive. A wavelet analysis of tested signals and analysis of weights that have been obtained during a neural network supervised learning - have been applied in a diagnostic algorithm. The proposed algorithm of detection of backlash zone width, represents effective diagnostic method of a system at changing dynamic conditions, occurring also as a result of mass inertia moment changes

    Neonatal survival in complex humanitarian emergencies: setting an evidence-based research agenda.

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    BACKGROUND: Over 40% of all deaths among children under 5 are neonatal deaths (0-28 days), and this proportion is increasing. In 2012, 2.9 million newborns died, with 99% occurring in low- and middle-income countries. Many of the countries with the highest neonatal mortality rates globally are currently or have recently been affected by complex humanitarian emergencies. Despite the global burden of neonatal morbidity and mortality and risks inherent in complex emergency situations, research investments are not commensurate to burden and little is known about the epidemiology or best practices for neonatal survival in these settings. METHODS: We used the Child Health and Nutrition Research Initiative (CHNRI) methodology to prioritize research questions on neonatal health in complex humanitarian emergencies. Experts evaluated 35 questions using four criteria (answerability, feasibility, relevance, equity) with three subcomponents per criterion. Using SAS 9.2, a research prioritization score (RPS) and average expert agreement score (AEA) were calculated for each question. RESULTS: Twenty-eight experts evaluated all 35 questions. RPS ranged from 0.846 to 0.679 and the AEA ranged from 0.667 to 0.411. The top ten research priorities covered a range of issues but generally fell into two categories- epidemiologic and programmatic components of neonatal health. The highest ranked question in this survey was "What strategies are effective in increasing demand for, and use of skilled attendance?" CONCLUSIONS: In this study, a diverse group of experts used the CHRNI methodology to systematically identify and determine research priorities for neonatal health and survival in complex humanitarian emergencies. The priorities included the need to better understand the magnitude of the disease burden and interventions to improve neonatal health in complex humanitarian emergencies. The findings from this study will provide guidance to researchers and program implementers in neonatal and complex humanitarian fields to engage on the research priorities needed to save lives most at risk

    Response to a DNA vaccine against the H5N1 virus depending on the chicken line and number of doses

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    Background Avian influenza virus infections cause significant economic losses on poultry farms and pose the threat of a possible pandemic outbreak. Routine vaccination of poultry against avian influenza is not recommended in Europe, however it has been ordered in some other countries, and more countries are considering use of the avian influenza vaccine as a component of their control strategy. Although a variety of such vaccines have been tested, most research has concentrated on specific antibodies and challenge experiments. Methods We monitored the transcriptomic response to a DNA vaccine encoding hemagglutinin from the highly pathogenic H5N1 avian influenza virus in the spleens of broiler and layer chickens. Moreover, in layer chickens the response to one and two doses of the vaccine was compared. Results All groups of birds immunized with two doses of the vaccine responded at the humoral level by producing specific anti-hemagglutinin antibodies. A response to the vaccine was also detected in the spleen transcriptomes. Differential expression of many genes encoding noncoding RNA and proteins functionally connected to the neuroendocrine-immune system was observed in different immunized groups

    The core genome multi-locus sequence typing of Mycoplasma anserisalpingitidis

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    Abstract Background: Mycoplasma anserisalpingitidis is a waterfowl pathogen that mainly infects geese, can cause significant economic losses and is present worldwide. With the advance of whole genome sequencing technologies, new methods are available for the researchers; one emerging methodology is the core genome Multi-Locus Sequence Typing (cgMLST). The core genome contains a high percentage of the coding DNA sequence (CDS) set of the studied strains. The cgMLST schemas are powerful genotyping tools allowing for the investigation of potential epidemics, and precise and reliable classification of the strains. Although whole genome sequences of M. anserisalpingitidis strains are available, to date, no cgMLST schema has been published for this species. Results: In this study, Illumina short reads of 81 M. anserisalpingitidis strains were used, including samples from Hungary, Poland, Sweden, and China. Draft genomes were assembled with the SPAdes software and analysed with the online available chewBBACA program. User made modifications in the program enabled analysis of mycoplasmas and provided similar results as the conventional SeqSphere+ software. The threshold of the presence of CDS in the strains was set to 93% due to the quality of the draft genomes, resulting in the most accurate and robust schema. Three hundred thirty-one CDSs constituted our cgMLST schema (representing 42,77% of the whole CDS set of M. anserisalpingitidis ATCC BAA-2147), and a Neighbor joining tree was created using the allelic profiles. The correlation was observed between the strains’ cgMLST profile and geographical origin; however, strains from the same integration but different locations also showed close relationship. Strains isolated from different tissue samples of the same animal revealed highly similar cgMLST profiles. Conclusions: The Neighbor joining tree from the cgMLST schema closely resembled the real-life spatial and temporal relationships of the strains. The incongruences between background data and the cgMLST profile in the strains from the same integration can be because of the higher probability of contacts between the flocks. This schema can help with the epidemiological investigation and can be used as a basis for further studies. Keywords: cgMLST, chewBBACA, Genotyping, Mycoplasma anserisalpingitidis, Waterfowl, Whole genome sequencin

    COVID-19: cross-border contact tracing in Germany, February to April 2020

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    Since January 2020, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has rapidly spread to become a global pandemic [1]. Active case finding, early detection and isolation of cases and their contacts are essential for breaking transmission chains. A modelling study showed that 70% of contacts should be traced in order to control the outbreak, assuming a baseline reproduction rate of 2.5 [2]. Early warning systems for the serious cross-border spread of infectious pathogens include the International Health Regulations (IHR) 2005 and the Early Warning and Response System (EWRS) for the European Union/European Economic Area (EU/EEA) countries [3,4]. Within Germany, communication channels have been established in accordance with the German Infection Protection Act (Infektionsschutzgesetz; IfSG). Cross-border contact tracing at the national level is operated by the Robert Koch Institute (RKI), the federal public health institute in Germany. The first cases of coronavirus disease 2019 (COVID-19) in Germany occurred in Bavaria at the end of January 2020 [5]. The first SARS-CoV-2 cluster also led to cross-border contacts and exposures on flights since close contacts and suspected cases travelled to Austria and Spain after exposure. This required intensive international communication to identify and share the information on contacts with the responsible health authorities. An international communication and contact tracing team (RKI IC-Team) was rapidly created in the RKI COVID-19 Emergency Operations Centre (EOC) including members of all units of the department for infectious disease epidemiology and other departments at the RKI. The core task of the team was to collect and communicate information on confirmed COVID-19 cases and their contacts to other countries in the event of cross-border relevance. In addition, incoming information on German citizens exposed abroad was communicated through the federal state health authorities to the responsible local health authorities in Germany. The spread of SARS-CoV-2 in Germany triggered the introduction of various measures: (i) mass gatherings with more than 1,000 participants were banned after calendar week 10, (ii) schools and public places were closed in several federal states, (iii) physical distancing measures of at least 1.5 m to another person were recommended, (iv) it was recommended to cancel non-essential travel and (v) quarantine measures for travellers from high risk areas entering Germany were introduced in calendar week 15. Because of the federal structure in Germany, the measures and their implementation varied between the states. This work aimed to describe the extent and course of activities resulting from information on COVID-19 exposure events with a cross-border context. Further, we discuss the challenges experienced and possible workflow improvements.Peer Reviewe

    An analytic perspective of a mixed methods study during humanitarian crises in South Sudan: translating facility- and community-based newborn guidelines into practice.

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    BACKGROUND: In South Sudan, the civil war in 2016 led to mass displacement in Juba that rapidly spread to other regions of the country. Access to health care was limited because of attacks against health facilities and workers and pregnant women and newborns were among the most vulnerable. Translation of newborn guidelines into public health practice, particularly during periods of on-going violence, are not well studied during humanitarian emergencies. During 2016 to 2017, we assessed the delivery of a package of community- and facility-based newborn health interventions in displaced person camps to understand implementation outcomes. This case analysis describes the challenges encountered and mitigating strategies employed during the conduct of an original research study. DISCUSSION: Challenges unique to conducting research in South Sudan included violent attacks against humanitarian aid workers that required research partners to modify study plans on an ongoing basis to ensure staff and patient safety. South Sudan faced devastating cholera and measles outbreaks that shifted programmatic priorities. Costs associated with traveling study staff and transporting equipment kept rising due to hyperinflation and, after the July 2016 violence, the study team was unable to convene in Juba for some months to conduct refresher trainings or monitor data collection. Strategies used to address these challenges were: collaborating with non-research partners to identify operational solutions; maintaining a locally-based study team; maintaining flexible budgets and timelines; using mobile data collection to conduct timely data entry and remote quality checks; and utilizing a cascade approach for training field staff. CONCLUSIONS: The case analysis provides lessons that are applicable to other humanitarian settings including the need for flexible research methods, budgets and timelines; innovative training and supervision; and a local research team with careful consideration of sociopolitical factors that impact their access and safety. Engagement of national and local stakeholders can ensure health services and data collection continue and findings translate to public health action, even in contexts facing severe and unpredictable insecurity
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