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Abstract

Self-control is a complex and multifaceted construct that can be regarded as an individual trait that follows its own developmental trajectory. In the presented study we used NAS-50 for the assessment of self-control in adolescents and young adults. Since the questionnaire has not been used before in underage participants we tested its reliability in adolescent and adult samples. We also investigated possible age and gender differences in self-control abilities as well as relations between NAS-50 and behavioral measures of cognitive control and impulsivity. Although the sample was quite small, the reliability of the questionnaire was similar to the results achieved by its authors. According to the predictions in the literature we did not find relations between NAS-50 and behavioral measures of cognitive control and impulsivity. We also did not observe significant age differences in the assessment of self-control abilities. The theoretical relevance of our results is discussed.

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Authors and Affiliations

Joanna Fryt
Tomasz Smoleń
Karolina Czernecka
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Abstract

The article focuses on selected problems which have now appeared and fall under the ideas “industry 4.0” and “society 5.0”, namely on anthropological issues. Changes in the relationships between man and technology based on trust lead to an increase of the role of the technological factor in these relations. Other aspects of the analyzed changes concern the new requirements of the responsibility and changes of human subjectivity and rationality. The future of man appears to be an area of uncertainty related to inter alia the conditions of functioning and living in the order of the post-digital world.

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Andrzej Kiepas
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Abstract

On 7 April 1968 the Club of Rome was established. In 1972 D.H. Meadows, D.L. Meadows, J. Randers and W.W. Behrens published The Limits to Growth as the first report to the Club of Rome – describing various scenarios for world development to 2100. Since that time the Club of Rome has developed in the world wide apolitical movement.

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Leszek Kuźnicki
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Abstract

The aim of this study was to assess the effects of two flocculants that are often used to overcome activated sludge bulking problems - aluminium chloride, AlCl3, and aluminium sulphate, Al2(SO4)3 - on Lecaneinermis (Rotifera, Monogononta) at three different temperatures: 8, 15 and 20°C. The mean EC50 value (effective concentration, mg dm-3) calculated for the 24 h mortality test was 0.012 mg Al3+dm-3. Next, the effects of low concentrations of the Al-salts on the population development from single individuals (parthenogenetic females) were tested in a 21-day experiment. At concentrations as low as EC4.8 and EC0.48, both Al-salts affected rotifer population negatively. However, temperature was the most pronounced factor that modified the toxicity of the Al-salts to the rotifers. On the 12th day of the experiment, there were significant interactions between temperature and the Al-salts, indicating that the chemicals were more toxic to the rotifers at 20°C than at lower temperatures. The weaker rotifers sensitivity to Al-salts (especially to AlCl3) in temperatures below 15°C, when the biggest problems associated with sludge bulking occurs,may means use both rotifers and chemicals reasonable and effective.

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Authors and Affiliations

Beata Klimek
Edyta Fiałkowska
Janusz Fyda
Wioleta Kocerba-Soroka
Agnieszka Pajdak-Stós
Łukasz Sobczyk
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Abstract

Multiple anthropogenic agents have turned Lake Maracaibo into a hypereutrophic environment. Heavy metals resulting from the steel and oil industry augment pollution in the lake. There is a lack of research on the ecotoxicological effect of heavy metals in protozoa. To evaluate the ecotoxicological effect of Cr3+, Cr6+, Cd2+, Pb2+ and Ni2+ on free-living ciliated protozoa and to identify suitable ciliated protozoa candidates for bioindicators of water quality; we estimated the lethal concentration for 50% of the protozoa population (LC50) in samples from two stations (S1: narrow of Maracaibo and S2: South of the lake) using ecotoxicological tests in the Sedgewick–Rafter chamber and Probit analysis. The general toxicity patterns obtained for S1 protozoa (Euplotes sp. and Oxytricha sp.) were Cr3+ > Cd2+ > Pb2+ > Cr6+ > Ni2+; and those corresponding to S2 (Coleps sp. and Chilodonella sp.) were Cr6+ > Cr3+ > Cd2+ > Pb2+ > Ni2+. We found statistically significant difference (p < 0.05) in the LC50 of protozoa exposed to Cr3+, Cr6+, Ni2+ and Pb2+ when comparing the two sampling stations. The differences observed in toxicity patterns are probably the result of various kinds of protozoa adaptation, possibly induced by various sources, levels and incidents of exposure to heavy metals contamination of the protozoa studied and to the physicochemical conditions prevailing in the two selected stations. The levels of tolerance observed in the present study, allow us to infer that S2 ciliates are the most susceptible to the contaminants studied and can be used as possible microbiological indicators that provide early warning in studies of contamination by heavy metals in Lake Maracaibo.
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Authors and Affiliations

Fernando Luis Castro Echavez
1
Julio César Marín Leal
2

  1. University of La Guajira, Faculty of Engineering, Environmental Engineering Program, PICHIHÜEL Research group, km 5 vía a Maicao, 440002, Riohacha, Colombia
  2. University of Zulia, Faculty of Engineering, School of Civil Engineering, Department of Sanitary and Environmental Engineering (DISA), Maracaibo, Venezuela
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Abstract

AM50/Mg2Si composites containing 5.7 wt. % and 9.9 wt. %. of Mg2Si reinforcing phase were prepared successfully by casting method. The microstructure of the cast AM50/Mg2Si magnesium matrix composites was investigated by light microscopy and X-ray diffractometry (XRD). The microstructure of these composites was characterized by the presence of α-phase (a solid solution of aluminium in magnesium), Mg17Al12 (γ-phase), Al8Mn5 and Mg2Si. It was demonstrated that the Mg2Si phase was formed mainly as primary dendrites and eutectic.

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Authors and Affiliations

M.A. Malik
K. Majchrzak
K.N. Braszczyńska-Malik
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Abstract

The paper presents the probabilistic model of fibrillation currents containing two components with different frequencies. An analysis was conducted of the threat of ventricular fibrillation which occurs in consequence of the electric shock with the highest permissible contact shocking voltage of the network frequency (50 Hz), taking into account the threat caused by the second component of the voltage which has the frequency higher than the network frequency. The sample results of calculations apply to the probability of the ventricular fibrillation in case of a shock caused by the highest permissible contact shocking voltage, for the defined time of shock duration, without and with the participation of an additional voltage component with higher frequency. The formula has been presented for the calculation of the highest permissible contact shock voltages with taking into account the voltage component of the frequency higher than the network frequency. The results of calculations indicate that a considerable reduction of the highest permissible contact shock voltage is necessary in order to compensate for a growth of the ventricular fibrillation threat caused by the presence of an additional component with the frequency other the network frequency. This applies in particular to the long shock duration times and low frequencies (up to 500 Hz) of an additional component of the shocking voltage.

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Authors and Affiliations

Włodzimierz Korniluk
Dariusz Sajewicz
Edward Anderson

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