The before-after study is still the most popular method used by traffic engineers and transportation safety analysts for evaluating the effects of an intervention. However, this kind of study may be plagued by important methodological limitations, which could significantly alter the study outcome. They include the regression-to-the-mean (RTM) and site-selection effects. So far, most of the research on these biases has focused on the RTM. Hence, the primary objective of this study consists of presenting a method that can reduce the site-selection bias when an entry criterion is used in before-after studies for continuous (e.g. speed, reaction times, etc.) and count data (e.g. number of crashes, number of fatalities, etc.). The proposed method documented in this research provides a way to adjust the Naive estimator by using the sample data and without relying on the data collected from the control group, since finding enough appropriate sites for the control group is much harder in traffic-safety analyses. In this study, the proposed method, a.k.a. Adjusted method, was compared to commonly used methods in before-after studies. The study results showed that among all methods evaluated, the Naive is the most significantly affected by the selection bias. Using the CG, the ANCOVA, or the EB method based on a control group (EBCG) method can eliminate the site-selection bias, as long as the characteristics of the control group are exactly the same as those for the treatment group. However, control group data that have same characteristics based on a truncated distribution or sample may not be available in practice. Moreover, site-selection bias generated by using a dissimilar control group might be even higher than with using the Naive method. The Adjusted method can partially eliminate site-selection bias even when biased estimators of the mean, variance, and correlation coefficient of a truncated normal distribution are used or are not known with certainty. In addition, three actual datasets were used to evaluate the accuracy of the Adjusted method for estimating site-selection biases for various types of data that have different mean and sample-size values.

Darbo tikslas. Įvertinti greitosios medicinos pagalbos pasirengimą ekstremalių situacijų atvejais. Darbo uždaviniai: 1. Įvertinti VšĮ Kėdainių PSPC GMP skyriaus pasirengimą veikti ekstremalių situacijų atvejais kitų panašias paslaugas teikiančių įstaigų kontekste. 2. Įvertinti VšĮ Kėdainių PSPC GMP skyriaus pasirengimo veiklai ES atveju pokyčius 2013-2014m., įdiegus pasirengimo veiklai ir planavimo ES metodiką. 3. Ištirti įstaigos operatyvumo rodiklių pokyčius įdiegus naują GMP kvietimo valdymo sistemą. 4. Įstaigos patirties veikti ekstremaliose situacijose analizė. Darbo metodika: GMP įstaigų vadovų struktūrizuota apklausa. Tiesioginis Kėdainių GMP pasirengimo veikti ekstremaliose situacijose vertinimas. Įstaigos operatyvumo rodiklių pokyčių analizė. Kėdainių GMP skyriaus darbuotojų, dalyvavusių teikiant pagalbą masinių nelaimių atvejais struktūrizuotas interviu. Rezultatai: Tyrime dalyvavusių įstaigų bendrasis saugumo indeksas skirtingų dydžių GMP tarpe pasiskirstė tolygiai. Daugumos vadovų nuomone, jų įstaigų bendrasis saugumo indeksas yra pakankamas (72 proc. – 91proc.). VšĮ Kėdainių PSPC, GMP skyriuje, vertinant 2013 – 2014m. pasirengimo veiklai ES atveju, įvyko teigiami pokyčiai. Bendras saugomo indeksas nuo 0,78 išaugo iki 0,93. Įdiegus GMP iškvietimų ir pajėgų valdymo sistemą, operatyvumo rodikliai tapo tikslesni. Lyginant 2012m. ir 2013m. iškvietimų, neatitinkančių minimalių laiko kriterijų, skaičius mieste padidėjo nuo 3,9 iki 5,3 proc. (p=0,002). 2013m. pirmajame... [toliau žr. visą tekstą] / Aim of the study: to assess disaster preparedness of health care institutions providing emergency medical services (EMS). Objectives: 1. To assess disaster preparedness of Kėdainiai EMS in context of other similar institutions. 2. To evaluate changes of disaster preparedness of Kedainiai EMS after implementation of guidelines for disaster preparedness and planning in 2013-2014. 3. To evaluate changes of operative performance indicators after implementation of the new dispatch and ambulances’ management system in Kedainiai EMS. 4. To analyze experience of Kėdainiai EMS in recent disasters. Methods:Structured interview of EMS institutions managers. Direct measurement of Kėdainiai EMS preparedness to respond in emergency situations. Analysis of changes of operative performance indicators. Structured interview of Kėdainiai EMS staff who had experience in recent disasters. Results: In opinion of the majority of managers, their institutions safety index is sufficient (72% - 91%). There were positive changes in disaster preparedness in Kedainiai EMS in 2013-2014: Overall safety index increased from 0,78 to 0,93. Operative performance indicators became more accurate after installation of dispatch and ambulance management system. Proportion of calls, when ambulance response time that does not meet minimum arrival time requirements, increased from 3.9% to 5.3% in the year 2012 – 2013 (p=0,002). In the first quarter of 2013 right after installation of the system, this performance... [to full text]

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The safety performance of nuclear power reactors is a very important factor in evaluating nuclear energy sustainability. Improving the safety performance of nuclear reactors can enhance nuclear energy sustainability as it will improve the environmental indicator used to evaluate the overall sustainability of nuclear energy. Great interest is given now to advanced nuclear reactors especially those using passive safety components. Investigation of the improvement in nuclear safety using advanced reactors was done by comparing the safety performance of a conventional reactor which uses active safety systems, such as Pressurized Water Reactor (PWR), with an advanced reactor which uses passive safety systems, such as AP1000, during a design basis accident, such as Loss of Coolant Accident (LOCA), using the PCTran as a simulation code. To assess the safety performance of PWR and AP1000, the “Global Safety Index” GSI model was developed by introducing three indicators: probability of accident occurrence, performance of safety system in case of an accident occurrence, and the consequences of the accident. Only the second indicator was considered in this work. A more detailed model for studying the performance of passive safety systems in AP1000 was developed. That was done using SCDAPSIM/RELAP5 code as it is capable of modelling design basis accidents (DBAs) in advanced nuclear reactors.