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    Wyświetlanie 1-6 z 6
    Tytuł:
    African stock markets’ connectedness: Quantile VAR approach
    Autorzy:
    Yaya, OlaOluwa
    Adenikinju, Olayinka
    Olayinka, Hammed A.
    Powiązania:
    https://bibliotekanauki.pl/articles/36095676.pdf
    Data publikacji:
    2024
    Wydawca:
    Fundacja Naukowa Instytut Współczesnych Finansów
    Tematy:
    Quantile dynamic connectedness
    Market phases
    Vector autoregression
    portfolio management
    normal market condition
    lower quantile of returns
    African stocks markets
    Opis:
    The present paper investigates African stock markets’ linkages by considering stocks in the continent’s largest economies, specifically Egypt, Kenya, Morocco, Nigeria, South Africa, and Tunisia. Using a dataset that spanned November 25, 2008, to September 18, 2023, the quantile connectedness approach of Chatziantoniou et al. (2021) is employed, and the results unfold these interesting dynamics of African market connectivity: (i) In the bearish market phase, South African stock dominated the entire network, transmitting shocks to the remaining stocks, while Moroccan and Kenyan stocks played similar role mildly. (ii) In the bullish market phase, Nigerian stock dominated the market as a major net transmitter of shock supported by South African and Kenyan stock markets. (iii), The Egyptian and Tunis stock markets are net shock receivers in both the bear and bull market phases. (iv), At the median quantile value, stocks become less riskier and the Kenyan stock market becomes the most vulnerable while Nigerian, Egyptian, and South African stock markets are influenced by other stock markets when markets are calm. (v), Though, African stocks are underperforming, interested portfolio managers will learn from the trading strategies to be adopted to maximize their returns. These findings will benefit portfolio managers, international stakeholders, and regulators.
    Źródło:
    Modern Finance; 2024, 2, 1; 51-68
    2956-7742
    Pojawia się w:
    Modern Finance
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Health expenditure in sub-Saharan Africa: Is it mean reversion? A Fourier unit root test approach
    Wydatki na zdrowie w Afryce Subsaharyjskiej a zdolność powrotu do wartości średniej. Zastosowanie testu pierwiastka jednostkowego Fouriera
    Autorzy:
    Olalude, Gbenga A.
    Olayinka, Hammed A.
    Ojo, Oluwadare O.
    Powiązania:
    https://bibliotekanauki.pl/articles/1015437.pdf
    Data publikacji:
    2021-04-30
    Wydawca:
    Główny Urząd Statystyczny
    Tematy:
    mean reversion
    health expenditure
    healthcare
    Fourier unit root test
    sub-Saharan Africa
    zdolność powrotu do wartości średniej
    wydatki na zdrowie
    służba zdrowia
    test pierwiastka jednostkowego Fouriera
    Afryka Subsaharyjska
    Opis:
    The aim of the paper is to examine the mean reversion in health expenditure of 45 sub-Saharan African countries. The series on current health expenditure (percent of GDP in total), obtained from the World Development Indicators, each spanned the years 2000–2017. We employed the Fourier unit root test, which allows modelling structural breaks, to deal with any such breaks that could arise as a result of a small sample size (18 years) of data available on health expenditure of the selected countries. The results showed evidence of mean reversion in the health spending pattern of 27 sub-Saharan African countries. There is evidence of nonmean reversion in the health expenditure pattern of the remaining 18 countries considered. We further investigate the link between health expenditure and health outcome, using infant mortality rate and under-five mortality rate as health outcome variables. An inverse association could be observed between the infant mortality rate and health expenditure and between the under-five mortality rate and health expenditure in 24 sub-Saharan African countries. On the other hand, in 13 other sub-Saharan African countries we observed a positive association between the variables. The findings of this study could be of great importance to healthcare delivery programmes in the studied countries.
    Celem pracy jest zbadanie zdolności powrotu do wartości średniej (ang. mean reversion) w wydatkach na zdrowie w 45 krajach Afryki Subsaharyjskiej. Analizowany jest szereg czasowy odnoszący się do bieżących wydatków na zdrowie (w procentach nominalnego PKB) w okresie 2000–2017. Dane pozyskano z bazy światowych wskaźników rozwoju prowadzonej przez Bank Światowy. Ze względu na prawdopodobieństwo wystąpienia skoków strukturalnych spowodowane stosunkowo krótkim szeregiem czasowym (18 lat) oraz potencjalnymi lukami w dostępnych danych zastosowano test pierwiastka jednostkowego Fouriera, pozwalający na modelowanie skoków w danych. Wyniki analizy pozwoliły stwierdzić zdolność powrotu do wartości średniej wydatków na zdrowie w 27 spośród badanych krajów. W przypadku pozostałych 18 krajów nie stwierdzono takiej zdolności. Za pomocą dwóch wskaźników: umieralności niemowląt oraz śmiertelności dzieci poniżej piątego roku życia przeanalizowano również związek między wydatkami na zdrowie a skutecznością ochrony zdrowia. Negatywną zależność zaobserwowano w 24 krajach, a pozytywną – w 13. Wyniki niniejszego badania mogą mieć duże znaczenie dla programów opieki zdrowotnej w badanych krajach.
    Źródło:
    Wiadomości Statystyczne. The Polish Statistician; 2021, 66, 4; 25-44
    0043-518X
    Pojawia się w:
    Wiadomości Statystyczne. The Polish Statistician
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Use of high spatial resolution satellite data for monitoring and characterization of drought conditions in the Northwestern Algeria
    Autorzy:
    Abbes, M.
    Hammed, A.
    Lafrid, A.
    Mahi, H.
    Nehal, L.
    Powiązania:
    https://bibliotekanauki.pl/articles/89204.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Wrocławska. Wydział Geoinżynierii, Górnictwa i Geologii. Instytut Górnictwa
    Tematy:
    drought
    Northwestern Algeria
    SPI
    NDVI
    linear regression
    satellite imagery
    Opis:
    Over the last decades, Algeria has witnessed intense and persistent drought periods characterized by a significant rainfall deficit. The Northwestern Algeria, such as the most south Mediterranean regions, is marked by alternating wet and dry periods and mixing between Atlantic and Mediterranean airs. In a climate context increasingly disturbed by anthropogenic activities, it is essential to analyze the dry episodes at spatial and temporal scales. In order to understand this problem, this work aims to use the potential of Landsat satellite imagery for monitoring drought conditions in the Cheliff watershed in the northwestern Algeria. As known, the behavior of vegetation is strongly related to climate changes. On this basis, a comparison of the variations in the standardized normalized difference vegetation index (NDVI) and those of the drought indices calculated from meteorological data was implemented. In fact, the rainfall series from fifty meteorological stations were analyzed. The standardized precipitation index (SPI) was calculated for the years 1987, 2000, 2006, 2011 and 2015, corresponding to the acquisition dates of Landsat images. Similarly, an extraction of the NDVI values was performed for each meteorological station. The linear regression between SPI and NDVI showed a good correlation. Thus, the obtained results enabled establishing a new drought index based essentially on satellite data. This index represents the advantage for monitoring spatially the drought phenomena and can solve the problem of climatic data lack.
    Źródło:
    Mining Science; 2018, 25; 71-99
    2300-9586
    2353-5423
    Pojawia się w:
    Mining Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Household expenditure in Africa: evidence of mean reversion
    Autorzy:
    Olalude, Gbenga A.
    Yaya, OlaOluwa S.
    Olayinka, Hammed A.
    Jimoh, Toheeb A.
    Adebiyi, Aliu A.
    Adesina, Oluwaseun A.
    Powiązania:
    https://bibliotekanauki.pl/articles/19233453.pdf
    Data publikacji:
    2023-06-13
    Wydawca:
    Główny Urząd Statystyczny
    Tematy:
    household expenditure
    poverty level
    mean reversion
    Africa
    Opis:
    This paper investigates the mean reversion in household consumption expenditure in 38 African countries; the expenditure series used were the percentage of nominal Gross Domestic Product (GDP), each spanning 1990 to 2018. Due to a small sample size of time series of household expenditure, with possible structural breaks, we used the Fourier unit root test approach, which enabled us to model both smooth and instantaneous breaks in the expenditure series. The results showed non-mean reversion in the consumption expenditure pattern of Egypt, Madagascar and Tunisia, while mean reversion was detected in the remaining 35 countries. Thus, the majority of African countries are on the verge of recession once shocks that affect the growth of GDP are triggered. Findings in this paper are of relevance to policymakers on poverty alleviation programmes in those selected countries.
    Źródło:
    Statistics in Transition new series; 2023, 24, 3; 171-186
    1234-7655
    Pojawia się w:
    Statistics in Transition new series
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Elastohydrodynamic analysis of a journal bearing with different grade oils considering thermal and cavitation effects using CFD-FSI
    Autorzy:
    Kadhim, Zainab H.
    Hammed, Lekaa
    Rahima, Fatima A.
    Ridha, Ali Mohammed
    Powiązania:
    https://bibliotekanauki.pl/articles/2203641.pdf
    Data publikacji:
    2023
    Wydawca:
    Polska Akademia Nauk. Polskie Towarzystwo Diagnostyki Technicznej PAN
    Tematy:
    journal bearing
    hydrodynamic lubrication
    thermal effect
    elastic deformation
    cavitation effect
    CFD
    smarowanie hydrodynamiczne
    efekt cieplny
    odkształcenie sprężyste
    łożysko
    Opis:
    This paper investigates a three-dimensional CFD analysis of hydrodynamic journal bearing performance for two different available types of lubricants, SEA 10W50 and SEA 15W40, considering thermal, elastic deformation, and cavitation effects. A 3-dimensional CFD model founded on continuity, momentum, energy, in addition elasticity equations has been implemented. The analysis is performed for a bearing with different journal speeds (1000-3000rpm) and eccentricity ratios (0.1-0.9). The cavitation effect was considered using the model of Zwart-Gerber-Balamri multiphase flow model. The bearing material elastic deformation was considered by implementing the two-way FSI technique through ANSYS-FLUENT 2019 R2. A comparative study of the oil film temperature, thermal pressure, also the load capacity by the bearing has been performed. By comparing the current work's oil film temperature results with those obtained by Ferron et al (1983), with a maximum deviation between the results not exceeding 3 percent, the mathematical model was validated. The findings demonstrate that, once the cavitation consequence is taken into account, the lubricant film pressure decreases. Furthermore, at what time the bearing rotates at greater eccentricity ratios and rotational speeds, more deformation material of the bearing is seen. The current research may help in predicting the bearing performance parameters in real-world situations.
    Źródło:
    Diagnostyka; 2023, 24, 2; art. no. 2023213
    1641-6414
    2449-5220
    Pojawia się w:
    Diagnostyka
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Morphology analysis and microbial diversity in novel anaerobic baffled reactor treating recycled paper mill wastewater
    Autorzy:
    Zwain, Haider M.
    Al-Marzook, Farah A.
    Nile, Basim K.
    Jeddoa, Zuhair Mohammed Ali
    Atallah, Aqeel H.
    Dahlan, Irvan
    Hassan, Waqed Hammed
    Powiązania:
    https://bibliotekanauki.pl/articles/2073763.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    anaerobic digestion
    AD
    novel anaerobic baffled reactor
    NABR
    recycled paper mill wastewater
    RPMW
    microbial diversity
    microbial morphology
    Opis:
    The profile of microbial diversity in a NABR digesting RPMW was investigated using phylogenetic analysis of partial 16S rRNA sequences by a neighbor-joining-tree, supported by microbial morphology analysis by SEM. The results showed that microorganism inside NABR consisted of dominant Bacillus (25 strains) and Bacterium (1 strain) which were isolated from the settled sludge at the bottom of the reactor, whilst Bacillus (2 strains), Pseudomonas (2 strain) and Chryseobacterium (2 strain) were isolated from the biofilm formed on the packing material. It revealed that the microbial community strains, function, and structure changed simultaneously throughout the reactor system. The microscopic results showed rich biofacies, while the dominant microorganisms have various morphologies in every compartment of the system. It consisted of a long rod-shaped and filamentous bacterium composed majorly of bacilli of different sizes. Although the study successfully analyzed the microbial diversity and morphology in the system, the microbial communities reported in this study were different from other similar studies. This may be caused by the application of a culture-based technique that usually provides limited information due to the number of barely cultivated or uncultured strains.
    Źródło:
    Archives of Environmental Protection; 2021, 47, 4; 9--17
    2083-4772
    2083-4810
    Pojawia się w:
    Archives of Environmental Protection
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-6 z 6

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