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Wyświetlanie 1-9 z 9
Tytuł:
Statistical and Econometric Analysis of Selected Effects of COVID-19 Pandemic
Autorzy:
Kempa, Wojciech
Rydarowska-Kurzbauer, Joanna
Halama, Marzena
Smuda, Elżbieta
Biel, Maciej
Powiązania:
https://bibliotekanauki.pl/articles/2064569.pdf
Data publikacji:
2021
Wydawca:
STE GROUP
Tematy:
cluster analysis
COVID-19 pandemic
GDP
regression
unemployment
Opis:
The paper examines the impact of the COVID-19 pandemic on macroeconomic activity in the selected European countries. The studies are based on monthly and quarterly indicators of GDP, unemployment rates and key indicators of the tourism sector. To present how COVID-19 has affected these macroeconomic variables, statistic data from the three periods are compared. Namely, data are collected from the pre-pandemic period, i.e. the fourth quarter of 2019 as the reference period, the second period covers the first quarter of 2020 and means the beginning of the pandemic, and the third one covers second quarter of 2020, during which the pandemic has spread to all the analyzed countries. The following statistical techniques are used in the research: regression analysis, the hierarchical grouping of agglomerations, k-means method, and selected non-parametric tests (Kruskal-Wallis test for a selected group of countries and Kolmogorov-Smirnov test for a selected pair of countries). The results show the significant impact of the pandemic on the level of gross domestic product, unemployment rate and turism sector. In most cases, a correlation between incidence of COVID-19 infections, unemployment rate and GDP is observed. The statistical techniques also allow to demonstrate the similarities and differences in the response of the economies to the COVID-19 pandemic. Central Statistical Offices of the selected countries are the main data source and for all calculations Statistica version 13.3. is used.
Źródło:
Multidisciplinary Aspects of Production Engineering; 2021, 4, 1; 395--407
2545-2827
Pojawia się w:
Multidisciplinary Aspects of Production Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Queueing systems with random volume customers and a sectorized unlimited memory buffer
Autorzy:
Tikhonenko, Oleg
Ziółkowski, Marcin
Kempa, Wojciech M.
Powiązania:
https://bibliotekanauki.pl/articles/2055163.pdf
Data publikacji:
2021
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
queueing system
random volume customers
sectorized memory buffer
total volume vector
Laplace transform
Laplace–Stieltjes transform
multivariate L’Hospital rule
system kolejkowania
wektor objętości
transformata Laplace'a
transformata Laplace'a-Stieltjesa
Opis:
In the present paper, we concentrate on basic concepts connected with the theory of queueing systems with random volume customers and a sectorized unlimited memory buffer. In such systems, the arriving customers are additionally characterized by a non-negative random volume vector. The vector’s indications can be understood as the sizes of portions of information of a different type that are located in the sectors of memory space of the system during customers’ sojourn in it. This information does not change while a customer is present in the system. After service termination, information immediately leaves the buffer, releasing its resources. In analyzed models, the service time of a customer is assumed to be dependent on his volume vector characteristics, which has influence on the total volume vector distribution. We investigate three types of such queueing systems: the Erlang queueing system, the single-server queueing system with unlimited queue and the egalitarian processor sharing system. For these models, we obtain a joint distribution function of the total volume vector in terms of Laplace (or Laplace-Stieltjes) transforms and formulae for steady-state initial mixed moments of the analyzed random vector, in the case when the memory buffer is composed of two sectors. We also calculate these characteristics for some practical case in which the service time of a customer is proportional to the customer’s length (understood as the sum of the volume vector’s indications). Moreover, we present some numerical computations illustrating theoretical results.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2021, 31, 3; 471--486
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On departure process in the batch arrival queue with single vacation and setup time
Autorzy:
M. Kempa, Wojciech
Powiązania:
https://bibliotekanauki.pl/articles/764146.pdf
Data publikacji:
2010
Wydawca:
Uniwersytet Marii Curie-Skłodowskiej. Wydawnictwo Uniwersytetu Marii Curie-Skłodowskiej
Źródło:
Annales Universitatis Mariae Curie-Skłodowska. Sectio AI, Informatica; 2010, 10, 1
1732-1360
2083-3628
Pojawia się w:
Annales Universitatis Mariae Curie-Skłodowska. Sectio AI, Informatica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ocena stanu wiedzy ratowników medycznych na temat zasad udzielania pierwszej pomocy w warunkach pola
Assessment of the status of knowledge of paramedics about principles for granting first aid in conditions of battlefield
Autorzy:
Łaskawiec, Daria
Nycz, Blanka
Trzepizur, Magdalena
Statowski, Wojciech
Kempa, Joanna
Powiązania:
https://bibliotekanauki.pl/articles/2201490.pdf
Data publikacji:
2019
Wydawca:
Politechnika Śląska. Katedra Biomechatroniki
Tematy:
medycyna pola walki
pierwsza pomoc
ratownictwo medyczne
battlefield medicine
first aid
professional soldiers
Opis:
Ratownictwo taktyczne jest definiowane poprzez szereg czynności mających na celu ratować poszkodowanego, ograniczyć śmiertelność na polu walki, odpowiedzieć na reakcję ogniową oraz wykonać zadanie taktyczne. W tym celu ważna jest znajomość wytycznych TCCC, które opisują schematy działań na polu walki. Celem pracy była ocena stanu wiedzy ratowników medycznych na temat zasad udzielania pierwszej pomocy w warunkach pola walki. W badaniu uczestniczyło 213 ratowników medycznych, którzy uzupełniali autorski kwestionariusz anonimowej ankiety internetowej.
Tactical rescue is defined by a series of activities aimed at rescuing a wounded soldier, reducing mortality on the battlefield, responding to a fire reaction and performing a tactical task. To this purpose, it is important to know the TCCC guidelines, which describe the schemes of action on the battlefield. The aim of this work was to evaluate the status of knowledge of paramedics about principles for granting first aid in conditions of battlefield. In this research 213 paramedics took part who supplemented the questionnaire of anonymous online survey.
Źródło:
Aktualne Problemy Biomechaniki; 2019, 18; 21--28
1898-763X
Pojawia się w:
Aktualne Problemy Biomechaniki
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
In vitro culture of white lupin embryos as a stage for SSD technique
Autorzy:
Ogrodowicz, Piotr
Mikołajczak, Krzysztof
Kuczyńska, Anetta
Kaczmarek, Zygmunt
Ćwiek-Kupczyńska, Hanna
Surma, Maria
Adamski, Tadeusz
Święcicki, Wojciech
Barzyk, Paweł
Trzeciak, Renata
Kempa, Michał
Powiązania:
https://bibliotekanauki.pl/articles/2148491.pdf
Data publikacji:
2021-03-31
Wydawca:
Instytut Uprawy Nawożenia i Gleboznawstwa – Państwowy Instytut Badawczy
Tematy:
embryo development
single seed descent technique
survival rate
temperature regimes
type of growth
white lupin
Opis:
White lupin is an important source of proteins, the content of which amounts to 36–40% in its seeds. Breeding of new varieties usually takes several years. The present study aimed to shorten the breeding cycle by applying the single-seed descent technique together with in vitro culture of embryos dissected from immature seeds. The effects of temperature on embryo development were studied in indeterminate vs. determinate varieties in in vitro culture using the following temperature regimes:(1) 8 °C; (2) 16 °C in the first week, then 8 °C; (3) 20 °C in the first week, then 20/18 °C; and (4) 16 °C throughout the culture period. The embryos were cultured on the standard Murashige and Skoog medium. The observed growth rate of plantlets as well as the survival of plants ex vitro showed that at lower temperatures (8–16 °C) the plants developed slowly, but their ex vitro survival rate was higher compared to those grown at a higher temperature (20 °C). In addition, the results indicated that the in vitro embryo development rate of determinate varieties is significantly lower than that of indeterminate varieties.
Źródło:
Polish Journal of Agronomy; 2021, 44; 9-14
2081-2787
Pojawia się w:
Polish Journal of Agronomy
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-9 z 9

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