Spelling suggestions: "subject:"accident"" "subject:"occident""
751 |
The manufacture and characterisation of composite nuclear fuel for improved in-reactor performanceBuckley, James January 2017 (has links)
Fuel for nuclear reactors with an increased thermal conductivity offers the potential for lower fuel operating temperatures and reduced fission gas release rates. Uranium dioxide (UO2) based composites offer a method of achieving a higher thermal conductivity. Silicon carbide (SiC) and molybdenum (Mo) have been identified as potential candidates for use in a composite fuel material. Uranium dioxide composites were manufactured with the inclusion of whiskers and granules of SiC up to a 30 vol% loading. The manufacturing route used was based on the current process employed to commercially manufacture UO2 fuel, by reductive sintering. Composites containing Mo were manufactured via spark plasma sintering and included loadings of up to 10 vol% Mo. The composites were characterised on their microstructural properties and where appropriate the thermal conductivity was determined by laser flash analysis. The composites containing SiC achieved low densities, 95%TD. The microstructure contained channel like structures of Mo, due to the use of an agglomerated UO2 precursor powder. An increased thermal conductivity was determined for the molybdenum composites. At the maximum measurement temperature of 800°C the increase was found to be 68% in the 10 vol% composites compared to UO2.
|
752 |
Analyse par graphes de la connectivité fonctionnelle de repos par IRM : vers de nouveaux biomarqueurs de la récupération fonctionnelle dans l'AVC / Functional connectivity in resting state MRI. Graph analysis : new biomarkers of functional recovery in strokeTermenon Conde, Maite 15 December 2016 (has links)
L'auteur n'a pas fourni de résumé en français / L'auteur n'a pas fourni de résumé en anglais
|
753 |
Psychosociální poradenství pro účastníky dopravních nehod v Českých Budějovicích / Psychosocial counselling for the participants of traffic accidents in České BudějoviceUHŘÍČEK, Jan January 2008 (has links)
This dissertation focuses on the field of psychosocial counselling intended for the people involved in traffic accidents. Traffic accidents often result in considerable whole-society damages and significant reduction in the life quality of affected individuals or their relatives. Traffic accidents may often represent nerve-racking, traumatic events which significantly go beyond the scope of common human experience. People involved in traffic accidents may suffer from mental problems which might impair an area of their social functioning. As a result, traffic accidents have significant impact not only to the lives of persons directly involved, but also to their relatives. Victims´ self-help may fail and, without the expert intervention, may lead to the whole-life misery. One of possible ways of how to help the people involved in the traffic accident is the psychosocial counselling which is the subject of this dissertation. This thesis, among others, aims to analyse the offer of psychosocial consulting services intended for traffic accident participants in the town of České Budějovice. To this end, the combination of qualitative and quantitative data collection techniques, questionnaire survey of experts and organizations and semi-standardized interviews with experts operating in České Budějovice were carried out. Other goals of the thesis included mapping of public awareness concerning the possible utilization of psychosocial counselling for traffic accident participants in České Budějovice, as well as, mapping the interest in using such services on the public{\crq}s part in this town. A public questionnaire survey was performed to reach these objectives. The findings revealed that there is a public demand for services of an organization providing the people involved in traffic accidents with psychosocial counselling. The public awareness of the possibility of using psychosocial counselling in this area, however, proved to be low in České Budějovice. The survey has also shown that the offer of psychosocial counselling focused on traffic accident participants does exist in this town. The dissertation may contribute to higher awareness of not only the professional employees who provide the assistance (psychologists, social workers, non-profit organization employees, physicians, police officers, fire fighters), students of humanities and volunteers involved in giving psychosocial assistance to the victims of disasters, but also of those people involved in traffic accidents whom anyone of us may become.
|
754 |
Flight deck engineering : impact of flight deck crew alerting and information systems on English as a second language flight crewmembers performance in airline flight operationsSevillian, Dujuan Brandez January 2017 (has links)
There are many pieces of flight deck research on general use of written English language technical information and problem solving using technical documentation. Contributory causes of aircraft accidents have been due to misunderstandings of crew alerts and procedural divergence by English as-a-second language flight crewmembers (ESL). Research was conducted to understand impact of written English language technical information on ESL flight crewmembers’ performance. Two types of systems were evaluated, technical documentation and crew alerting systems that contain technical information, with respect to their impact on ESL flight crewmember performance. Preliminary analysis results indicated written English language technical information can be confusing, difficult to read and interpret, and leads to misunderstandings by ESL flight crewmembers during aircraft nonnormal conditions. English as-a-second language flight crewmembers indicated they often experience problems executing written English language technical procedures after outset of crew alerts. Conversely, experimental trials revealed ESL flight crewmembers did not experience many cognitive performance issues with use of crew alerting systems and technical information designed with an English language emphasis. English as-a second language flight crewmembers’ English language proficiency, background knowledge, and use of use of metacognitive strategies to read and comprehend written English language on crew alerting and information systems, indicated they utilized written English technical information with ease. Particularly, ESL flight crewmembers’ workload was low, they had fast response times to system faults, and they experienced minimal procedural deviations. On the contrary, when ESL flight crewmembers utilized written English language technical procedures translated into their native language during non-normal conditions, they experienced several cognitive performance challenges. English as-a second language flight crewmembers’ background knowledge of written English language technical information translated into their native language, use of metacognitive strategies to read and comprehend written English language translated into their native language, indicated they experienced difficulties with reading and comprehending translated technical information on information systems. Particularly, ESL flight crewmembers were challenged cognitively when they responded to crew alerts through execution of decision-making processes. They indicated translation of written English language technical information into their native language was a pre-cursor to procedural deviation, long response times to system issues, as well as high workload during experimental trials. It is recommended that further research focus on design and use of written English language technical documentation by ESL flight crewmembers during non-normal conditions. It is also recommended that if deemed practical by the aviation industry, further research should focus on design, integration, and utilization of technical documentation in a language(s) other than English, and measurement of ESL flight crewmembers performance on the flight deck.
|
755 |
Simulovaná havárie vozidla převážejícího vybranou chemickou látku ve vybraném městě / Simulated accident of car lifting defined chemical substance in defined cityTLUŠŤÁK, Kamil January 2016 (has links)
The aim of this diploma thesis is to simulate a road accident of a vehicle carrying a chosen dangerous chemical substance in a chosen city. We chose a crash site based on statistical inquiry of the number of road accidents. We chose a chemical substance by analyzing substances used in the vicinity of the chosen city. Through the use of simulation, we described and created a proposition of solving the arose extraordinary event, for the components of Emergency Service units. After completing these objectives, it will be possible to answer the research question: What kind of jeopardy does the leakage of a chosen chemical substance represent, during transportation in a chosen town? The theoretical part firstly focuses on basic terms that we worked with in the thesis. Basic legislative fixing point of dangerous objects and substances is described. Also, European and interstate regulations about transportation of these things is described. European agreement ADR is separately described further away. In the next part, manipulation with dangerous substances and mixtures is described as it is shown in Enactment EP and Council No. 1272/2008/ES, or the enactment of CLP. The characteristics determining their hazardousness, the way of evaluation and classification of dangerous substances and mixtures into corresponding categories is also described. Separately described are ways of packaging and numbering these substances. In the last part, we described the making of a safety list about chemical substances and mixtures, with an emphasis on the information about their transportation. In the next part we described the transportation of dangerous objects and substances on the highway. Further away we described appropriateness and demands for transportation of dangerous substances, for example demands on choosing vehicle personnel, the transportation itself and the equipment that every vehicle must have. We described the risks related with transportation and planning routes for transporting dangerous substances and objects. The aim of the assessments and precautions above are to minimalize risks related to transportation of dangerous substances and thus make it relatively safe. Unfortunately, this is not absolutely possible. This was also found to be true in the empirical part of the thesis, in which we carried out an analysis of the statistics of road accidents of vehicles in the ADR mode, and we found that the human factor is indeed the cause of these accidents. It was proven that 94% of all the road accidents of vehicles in the ADR mode was caused by the driver of the vehicle.Further away, the number of Emergency Service units interferences in cases of dangerous substance leakage and procedures carried out during those interferences, are described. In the empirical part of the thesis, we described methods of choosing the crash site and the dangerous substance. As a crash site we chose highway I/49 in Zlín county, that is evaluated as a highway of medium risk of road accidents, on the road risk map of Czech Republic. More accurately, cross-road of Třída Tomáše Bati and Březnická street in Zlín. When choosing the right substance we conducted an analysis of chemical substance usage in Zlín county. Subsequently we chose aqueous solution of ammoniac, which is being transported on the highway I/49 by two companies. It is prepared in IBC containers with the volume of 1000 liters. Acquired data was used for simulation, evaluation of the extraordinary event and for choosing the number of individuals in jeopardy.The simulation was executed using the TerEx software. Subsequently, the proposal for dealing with the extraordinary event by the Emergency Service units was developed. Based on the executed simulation, it is possible to assess that transportation of dangerous substances and mixtures constitutes a great danger in the residential area with a high number of habitable and administrative buildings.
|
756 |
A vigilância epidemiológica de agravos decorrentes de acidentes de trânsito em Porto Alegre : caracterização das fontes de dados existentesLivi, Karla Lindorfer January 2013 (has links)
A dissertação tem por objetivo caracterizar as fontes de dados sobre acidentes de trânsito existentes em um município de grande porte (Porto Alegre-RS) visando o desenvolvimento e a implantação de um sistema de vigilância epidemiológica de lesões e mortes no trânsito. Para tanto, foi elaborado um modelo conceitual a partir da definição de Acidentes de Transporte Terrestre (ATT) e seus fatores determinantes, de modo a identificar oportunidades de registro das informações. Foram considerados aspectos relacionados à estrutura, processos, fluxos de informações geradas, e atores envolvidos na produção e utilização das mesmas. Partindo deste modelo e da definição de sistemas de vigilância epidemiológica, as fontes de dados foram descritas quanto as variáveis: lugar, pessoa e tempo, definição de caso, objetivos, descrição de componentes e funcionamento (população alvo, forma, método e tempo de coleta, armazenamento e transferência de dados); frequência de análise dos dados; a quem são destinadas e a forma de divulgação das informações; as intervenções às quais estão vinculadas e a possibilidade de identificação dos fatores de risco para acidentes de trânsito. Além disto, partindo do referencial teórico para estruturação de sistemas de vigilância epidemiológica de acidentes da OMS/CDC, foram identificadas potencialidades e limitações dos dados disponíveis nas diferentes fontes para vigilância de ATT. Foram estudadas seis fontes de dados: Sistema de Informação Sobre Mortalidade, Sistema de Internação Hospitalar Descentralizado, Inquérito de Violências e Acidentes em Serviços Sentinela de Urgência e Emergência da Vigilância de Violências e Acidentes, Sistema de Atendimento Pré-Hospitalar do Serviço de Atendimento Móvel de Urgência, Cadastro de Acidentes de Trânsito da Empresa Pública de Transporte e Circulação de Porto Alegre, e Sistema de Informações Policiais da Secretaria de Segurança Pública do Estado do Rio Grande do Sul. A coleta de dados foi realizada por meio de entrevistas semiestruturadas com os responsáveis técnicos pelas bases de dados e análise de material documental disponível. O artigo descreve a forma de processamento, análise e divulgação dos dados, a utilidade e vinculação das informações em relação a processos decisórios e a identificação de fatores de risco para acidentes de trânsito. A descrição operacional das fontes dados, a caracterização das variáveis e a identificação de potencialidades e limitações para vigilância de ATT foram apresentadas como detalhes metodológicos adicionais. O estudo demonstrou que a coleta de dados primários ou secundários depende da oportunidade de acesso ao evento e o processamento, análise e divulgação das informações obedecem a atribuições e objetivos setoriais. Quanto à utilidade das informações e a vinculação dessas com processos decisórios, no setor saúde, estão voltadas para o planejamento e a gestão dos serviços. Nos órgãos de segurança e trânsito, para a segurança pública e viária, planejamento educação e engenharia de trânsito. Há escassez de dados relacionados à cena do acidente e a trajetória da vítima. A totalidade das informações produzidas pelas fontes estudadas caracteriza parcialmente os eventos, muitas vezes, não apontando a dinâmica do evento, quem foram os envolvidos e os fatores de risco associados de forma a auxiliar na determinação e causalidade e direcionar medidas de prevenção e controle. Tais resultados indicam a importância da qualificação dos dados primários coletados na cena do acidente e a padronização dos dados em relação a conceitos e terminologias. Para auxiliar na determinação de causalidade, apontar fatores de risco e subsidiar a tomada de decisão em saúde é fundamental à integração, relacionamento e compartilhamento de dados bem como análise multidisciplinar dos eventos. / The aim of this thesis is to characterize the sources of data on existing traffic accidents in a large municipality (Porto Alegre, Brazil) in order to develop and implement a system of epidemiological surveillance of injuries and deaths from traffic accidents. To do so, a conceptual model from the definition of Land Transport Accidents (LTAs) and its determining factors were prepared in order to identify opportunities of information records. Aspects related to structure, processes, generated information flows, and actors involved in their production were considered. On the basis of this model and the definition of epidemiological surveillance systems, the sources of data were described according to the variables: place, person, and time; definition of case; objectives; description of components and functioning (target population, form, methods, and time of collection, storage, and transfer of data); frequency of analysis of data; to whom the information is addressed as well as its form of dissemination; interventions to which the information is linked; and the possibility of identifying the risk factors for road traffic accidents. In addition, based on the theoretical framework for organization of systems of epidemiological surveillance of accidents of WHO/CDC, both potentialities and limitations on the data available in the different sources for surveillance of LTAs were identified. Six sources of data were studied: Mortality Information System, Decentralized Hospitalization System, Investigation of Acts of Violence and Accidents in the Sentinela (Sentinel) Urgency and Emergency Services of VIVA (Surveillance System for Acts of Violence and Accidents), System of Pre-Hospital Care of SAMU (Mobile Emergency Care Service), Records of Traffic Accidents of EPTC (Government-owned Corporation for Transport and Traffic in Porto Alegre), and System of Police Information of the Secretariat for Public Security in the State of Rio Grande do Sul. Data were collected by means of both semi-structured interviews with technicians responsible for the databases and documented material available. The article describes the form of processing, analysis and dissemination of data, utility and linking of information in relation to the processes of decision-making, and the identification of risk factor for road traffic accidents. The operational description of the source of data, the characterization of variables, and the identification of potentialities as well as the limitations on the surveillance of LTAs were presented as additional methodological details. The study showed that the collection of primary or secondary data depends on the opportunity to access the event and the processing, analysis and dissemination of information obey tasks and sectorial objectives. The usefulness of the information and its relation to the processes of decision-making in the health sector are related to the planning and management of services. In the agencies for security and traffic, they are related to public and road safety, planning, education, and traffic engineering. There is shortage of data related to the scene of the accident and the victim's course. All information produced by the study partially characterizes the events, often not pointing the dynamics of the event, who the involved were, and the associated risk factors, in order to help in determination and causality, and to direct both prevention and control measures. These results indicate the importance of the classification of the primary data collected at the scene of the accident and the standardization of data regarding concepts and terminology. In order to help determine causality, identify risk factors, and support the decision-making in health, record linkage, and data sharing as well as the multidisciplinary analysis of the events are essential to integration.
|
757 |
Surveillance bakteriální kmenů produkujících širokospektrou beta-laktamázu. / Surveillance of bacterial strains producing broad-spectrum beta-lactamase.VLASOVÁ, Martina January 2013 (has links)
In the first part of my thesis I focus on mapping problems associated with antibiotic therapy and subsequent development of antibiotic resistance. Tracking resistance is based primarily on data collection and evaluation of the results set sensitivity from around the world. Antibiotic resistance is a natural phenomenon that can be observed in the evolution of microbes as one of the mechanisms of adaptation to new conditions in the environment. For this work I have chosen the following research questions. Do the incidence of ESBL strains in the České Budějovice Hospital a.s. increase over time? Are these values comparable to those achieved in another region, namely in Moravian hospitals the University Hospital of Olomouc, Ostrava University Hospital and Regional University Hospital of T. Bata in Zlin? The data collection I made in collaboration with the laboratory technicians and doctors at Hospital?s Bacteriology Laboratory in České Budějovice. Bacteries tested for the detection of ESBL production originated from biological materials, witch came from patients of hospital in České Budějovice. The first objective was to compare the results achieved in the České Budějovice Hospital in the period of 2007 to 2012. If we look at the total number of ESBL strains that have been isolated since 2007, values have upward trend. While in 2007 there were only 64 strains a year later, the number more than doubled. In 2010, the value soared to 281 tribes and in the year 2012, the number was 321 tribes. The incidence of ESBL strains in 2007 increased about five times. In the long term we can say the numbers have increasing tendency and the range of each species in the production of ESBL has significantly changed. In 2007, it was K. pneumoniae strains that dominated the statistics, but over time the strains of E. coli came forefront. Values of 2012 suggest that the presence of ESBL strains of K. pneumoniae is again almost equal to the number of E. coli strains. The second objective was to compare the results of the 2012 with study of the Prevalence of ESBL-positive Enterobacteriaceae in large Moravian hospitals. In the general overview of ESBL producers values in Hospital České Budějovice (5.23%) are comparable to those in Ostrava (4.9%) and in Zlín (4.3%). Number of strains in the Hospital in Olomouc (11.8%) is about twice as high as the numbers in České Budějovice. In this comparison the České Budějovice Hospital is one of the hospitals with a lower incidence of ESBL producers. The České Budějovice Hospital is below the national average, which originate from an elaborate system of care for patients with colonization or infection with ESBL strains, and from therapy control system using antibiotic center. These results may serve to the Hospital in České Budějovice for statistical purposes, and also for proposals for improving patient care. In the discussion, I pointed out the danger of the spread of resistant strains of bacteria in the community and also the associated risks that mentioned bacteria mean for patients injured in mass accidents or disasters. In these cases, number of infections including ESBL producers can penetrate through open wounds into the affected body. Unlike conventional sensitive bacteria those strains are resistant to commonly used antibiotics and thereby endanger the lives of people affected by the accident.
|
758 |
Neodkladná a následná opatření v případě úniku chlóru - Simulovaná havárie vozidla přepravujícího chlór / The urgent and follow-up precautions in case of leakage of chlorine - Simulated accident of vehicle carrying chlorineKADIČ, Milan January 2013 (has links)
The goal of this diploma thesis is to introduce urgent and follow-up precautions in case of leakage of chlorine - simulated accident of vehicle transporting chlorine. The major objective of this study is to analyse the risk of chlorine-transport for people with the aid of available simulation programme and to specify urgent and follow-up precautions. The next part of this study is to investigate the knowledgeability of people. The theoretical part of this study is systematical structured into a number of chapters and worked out on the basis of available legislative regulations, literature and internet sources. At first basic legislation of transport of dangerous substances is described, from the european, as well as national perspective. The next chapter deals with transport of dangerous substances, danger classes of these substances, their labeling in transport, as well as labeling of transport units. The following chapter is devoted to aspects of an accident in case of transporting of dangerous substances. This chapter demonstrates an accident with leakage of dangerous substance, its impact, escape of this substance and its spread. Further the sources and risks of transportation of dangerous substances and accident rate in this transport are described. The next chapter deals with the specific dangerous substance - chlorine. It is aimed at physico-chemical characters of chlorine, its history and its current utilisation, its effect on human health, on environment and first aid in case of contact. At the end urgent and follow-up precautions in case of an accident inkl. leakage of chlorine. The empirical part of this study is devoted to two basic research questions. Qualitative, as well as quantitative methods of research were used to answers these questions. The empirical part is devided into two major chapters. The primary purpose of this study is to simulate an accident of vehicle transporting chlorine with the aid of the programme TerEx and to determine its impact on people and surrounding. The first question was to analyse the potential dangerous for people and surroundings in case of an accident with chlorine. For this purpose the town České Budějovice was used. First the transport of liquid chlorine in small containers in the Czech Republic was analysed focusing on the southbohemian region and especially the regional city. Thereafter input data were entered. On the basis of obtained outputs were determined threats, that arise from the transport of dangerous chlorine and on the basis of simulation were characterized activities carried out by Integrated Rescue System using appropriate urgent and follow-up precautions. Part of this work was also the second research question - the level of knowledge of people located close to the simulated accident about this problem. This survey was aimed at the risk of chlorine, its transport and characteristics and impact on human health as well as protection against its adverse effects. For this purpose a group of second-year students of the local gymnasium located close to the place of simulated accident was chosen. The data were collected through a questionnaire, which contained a group of questions relating to this problem. The obtained data were evaluated using basic methods of elemental statistical analysis and graphic processing. Findings resulting from the analysis of transporting of chlorine and from the simulation using the programme TerEx show, that the danger to the population of České Budějovice in case of an accident with chlorine is significant. The issue of chlorine-transport and its risks is additionally complicated by insufficient regulation. Another negative factor of transporting of these substances is the complicated traffic situation in the country town. Based on the results of the questionary can be stated, that these students have average knowledge in this issue.
|
759 |
Studie připravenosti zdravotnické záchranné služby na mimořádnou událost s velkým počtem raněných a obětí - dopravní nehoda autobusu / Study of emergency medical service preparedness for large number of injuries and casualties - bus accidentPRUDEL, Ondřej January 2013 (has links)
This diploma thesis deals with problematic of emergency medical service preparedness in the Czech Republic, in the place of disaster and during this situation especially in bus accident with large number of injuries and casualties. Bus accident can create high risk of forming mass disaster due to many people transported in small area with low safety components. High risk of many injuries and casualties with chaotic first call make hard decision to activate plans to solve this situation for emergency services. Theoretical part of diploma thesis maps transformation of Czech paramedic system organization from districts to regions and new legislations for emergency medical service that solve preparedness, organization and duties during large incidents. Due to this new legislations were formed offices for emergency preparedness which ensure this preparedness. Practical part of diploma thesis is analysis of Czech paramedic preparedness that solve bus accidents as disaster. For this analysis were used data from regional emergency medical service headquarters (EMS HQ) - bus accident reports, drills for staff and special material equipments. But only 3 EMS HQ provided acceptable data and 1 EMS HQ partly acceptable data. Aim of this study is assessment in preparedness change for disaster during examined time (2000 - 2011) and comparison of real event to training drills. This part of thesis is supplied by statistic data (transformed into graphs) of bus accidents with injuries and casualties from department of Transportation Police of the Czech republic and Fire Rescue Service Directorate. Whole practical part is made by analysis of primary (documents, EMS HQ personal visits) and secondary information (information servers, journals). Within this analysis was made evaluation of Czech emergency medical preparedness for bus accidents with large number of injuries and casualties. This analysis shows that in area of the Czech Republic is missing central directorate for Czech paramedic system. Which is shown in varying material, drill and whole preparedness for disaster situation. This problem is also made by new legislation that were not here before (law for emergency medical system and law notices). High variation of equipments and procedures in solving disasters can cause difficulties during accident intervention on the borders of paramedic regions. For comparison to other countries preparedness is in this thesis mentioned Poland - special training course for specialist in disaster management, USA - Medical Alert Center (MAC) and Israel - control system for disaster drills.
|
760 |
Vliv dopravně technického stavu silnice I. třídy č. 3 v rámci okresu Český Krumlov na předcházení mimořádných událostí v silničním provozu / Influences of the technical condition of road no 3 in the district of Czech Krumlov at preventing incidents on the road.ONDRUŠKA, Jiří January 2014 (has links)
The creation of the safe traffic zone is a long term issue requiring often significant investments, which municipalities or regional governments are not able to cover within their own budget. Despite complex programs to initiate measures on increasing of the road safety have not been launched yet. One of significant parameters of the safe traffic zone is occurrence of solid obstacles in the immediate vicinity of a road (such as tall trees, billboards placed without a permit etc.), which afterwards influence the seriousness of consequences of the accident. The content and the aim of this diploma written assignment is to find out the actual impact of the transport and technical conditions of the first-class road No. 3 in the Český Krumlov District on the occurrence of incidents in the road traffic which can be found out by analysis of the causes and the effects of the incidents in the specific accidents sites and mapping of the current transport and technical conditions of this relatively loaded road due to heavy traffic. To fulfill the aim of the written assignment, the method of critical analysis, which studies the problem in more complex way and is not satisfied with the simple explanation, was used. With its application I tried to find an answer to the question whether the mentioned road fulfills the forgiving and the self-explanatory road function in all aspects and at those to propose an optimal solution to prevent eventually to mitigate of incidents. In case that the achieved goals of this diploma written assignment will be by the owner of the mentioned road respectively the property administrator and the competent road administration office used to make certain measures leading to lowering of the amount of accidents then the elaboration has fulfilled its purpose. By my opinion every driver has a right to move in the safe traffic zone. Duration and development of the state that we live in will not do without a functioning road system and that is why the current system should be first of all maintained by the state, renewed, expanded and made to perfection because feeling safe on roads is a right and a responsibility of each and one of us.
|
Page generated in 0.0851 seconds