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Stress state rock mass monitoring ahead of longwall No. II/501/C, Mine Staszic-Wujek, PGG, Poland -Project RFCS DD-MET
Waclawik, Petr; Kukutsch, Radovan; Staš, Lubomír; Souček, Kamil; Vavro, Leona; Vavro, Martin; Kubina, Lukáš; Schuchová, Kristýna
2022 - English
For designing precisely the reinforcement of mine gate and reinforcing underground structures in general, knowing stress and deformation states in the rock massive in the immediate vicinity of these mine works as precisely as possible is absolutely decisive. In order to verify the rock mass stress state and its changes induced by longwall mining, the monitoring of rock mass stress changing in connection with the mine out of the coal seam No. 501, longwall face No. II/501/C in the Mine Staszic-Wujek, Poland, was suggested. The aim of the contractual research was the realisation and interpretation of the rock stress state monitoring using the CCBO (Compact Conical ended Borehole Overcoring method) and CCBM (Compact Conical ended Borehole Monitoring method) probes in the forefield of mentioned longwall face within geotechnical station. To verify stress monitoring, the survey of the state of the longwall gate was carried out using a pulse 3D scanner. The purpose was to capture deformation changes ahead of the advancing longwall face, specifically, at five stages in the ± 20 m section on each side from the installed geotechnical station.
Keywords:
pre-mining stress; induced stress; 3D laser scanning
Available at various institutes of the ASCR
Stress state rock mass monitoring ahead of longwall No. II/501/C, Mine Staszic-Wujek, PGG, Poland -Project RFCS DD-MET
For designing precisely the reinforcement of mine gate and reinforcing underground structures in general, knowing stress and deformation states in the rock massive in the immediate vicinity of these ...
Do pessimistic expectations about discrimination make minorities withdraw their effort? Causal evidence
Korlyakova, Darya
2022 - English
There is a long-standing concern that expected discrimination discourages minorities from exercising effort to succeed. Effort withdrawal could contribute to confirming negative stereotypes about minorities’ productivity and enduring disparities. This paper extends the findings of correlational research by exogenously manipulating individuals’ beliefs about discrimination against their group and exploring a causal link between perceived discrimination and individuals’ labor market behavior. For this purpose, we conduct an online experiment in the US with a diverse sample of 2,000 African Americans. We randomly assign individuals to two groups and inform one group about the frequency of discrimination against African Americans in a previous survey. To study the information effects on effort, we subsequently measure participants’ results on a math task. We document that most individuals initially overestimate discrimination against African Americans. The overestimation decreases strongly and significantly as a result of information provision. At the same time, treated individuals, males in particular, attempt and solve correctly fewer math problems compared to untreated individuals. Hence, our findings do not support the common concern that minorities’ inflated expectations about discrimination induce them to underperform.
Keywords:
perceived discrimination; racial minorities; effort
Fulltext is available at external website.
Do pessimistic expectations about discrimination make minorities withdraw their effort? Causal evidence
There is a long-standing concern that expected discrimination discourages minorities from exercising effort to succeed. Effort withdrawal could contribute to confirming negative stereotypes about ...
Information, perceived returns and college major choices
Kudashvili, Nikoloz; Todua, Gega
2022 - English
Students may hold inaccurate beliefs about earnings and employment opportunities when making their education decisions. This paper analyzes the effects of information provision on student’s intended and actual college major choices in Georgia. Secondary school students in our experiment systematically overestimated the earnings and unemployment rates of college graduates. We find that 10 percent more students who received information on actual earnings and unemployment changed their actual college major choices than others. The changes in their majors are partly driven by differences in the perceived and actual unemployment rates, whereas the earning differences do not appear to play a role. We also estimate spillover effects on students who do not receive information directly, and show that they matter, but only for older students who are closer to high school graduation. Importantly, we find that the immediate changes in the intended choices are not linked to the final major choices, suggesting that measuring the effects of information on immediately expressed intentions may not be sufficient to understand how information affects actual real-life decisions. We find that both direct and indirect information provision have sizable effects on student college major choices.
Keywords:
college major; perceived unemployment; perceived earnings
Fulltext is available at external website.
Information, perceived returns and college major choices
Students may hold inaccurate beliefs about earnings and employment opportunities when making their education decisions. This paper analyzes the effects of information provision on student’s intended ...
Social networks and surviving the Holocaust
Bělín, M.; Jelínek, T.; Jurajda, Štěpán
2022 - English
Survivor testimonies link survival in deadly POW camps, Gulags, and Nazi concentration camps to the formation of close friendships with other prisoners. We provide statistical evidence consistent with these fundamentally selective testimonies. We study the survival of the 140 thousand Jews who entered the Theresienstadt ghetto, where 33 thousand died and from where over 80 thousand were sent to extermination camps. We ask whether an individual’s social status prior to deportation, and the availability of potential friends among fellow prisoners influenced the risk of death in Theresienstadt, the ability to avoid transports to the camps, and the chances of surviving Auschwitz. Pre-deportation social status protected prisoners in the self-administered society of the Theresienstadt ghetto, but it was no longer helpful in the extreme conditions of the Auschwitz-Birkenau concentration camp. Relying on multiple proxies of pre-existing social networks, we uncover a significant survival advantage to entering Auschwitz with a group of potential friends.
Keywords:
social status; social networks; Holocaust survival
Fulltext is available at external website.
Social networks and surviving the Holocaust
Survivor testimonies link survival in deadly POW camps, Gulags, and Nazi concentration camps to the formation of close friendships with other prisoners. We provide statistical evidence consistent with ...
Proximity to help matters: the effect of access to centers of legal aid on bankruptcy rates
Hrehová, Kristína; Domonkos, Š.
2022 - English
Personal bankruptcy aims to provide a fresh start to debtors. While bankruptcy is often the only solution to financial distress, large spatial distance to affordable legal services may result in its underuse by eligible debtors. Using a large administrative dataset of personal bankruptcies, we study the impact of spatial distance from public Centers for Legal Aid (CLAs) on the regional incidence of personal bankruptcy in Slovakia. We avoid endogeneity by focusing on the increased availability of legal aid controlling for the expected distance from the nearest CLA, which serves as the first contact point in the process of filing for personal bankruptcy in the Slovak Republic. Distance from these legal aid centers has a significant impact on personal bankruptcy rates: the closer the nearest CLA is, the larger the prevalence of personal bankruptcy is in a given municipality. We quantify the impact of service access on personal bankruptcy rates, showing that improved access to free legal aid has both a statistically and substantively significant impact on the use of personal bankruptcy by the public. At the end of the almost 3-year-long period analyzed, municipalities with good access to CLAs had 3.3 bankruptcies more per 1,000 inhabitants than municipalities with weak access to CLAs. This effect is significant, as the average national bankruptcy rate until December 2019 reached 6.3 bankruptcies per 1,000 persons.
Keywords:
personal bankruptcy; insolvency; policy analysis
Fulltext is available at external website.
Proximity to help matters: the effect of access to centers of legal aid on bankruptcy rates
Personal bankruptcy aims to provide a fresh start to debtors. While bankruptcy is often the only solution to financial distress, large spatial distance to affordable legal services may result in its ...
Is longer maternal care always beneficial? The impact of a four-year paid parental leave
Bičáková, Alena; Kalíšková, Klára
2022 - English
We study the impact of an extension of paid family leave from 3 to 4 years on child long-term outcomes. Using a difference-in-differences design and comparing the first-affected with the last-unaffected cohorts of children, we find that an additional year of maternal care at the age of 3, which primarily crowded out enrollment into public kindergartens, had an adverse effect for children of loweducated mothers on human capital investments and labor-market attachment in early adulthood. The affected children were 12 p.p. more likely not to be in education, employment, or training (NEET) at the age of 21-22. The impact on daughters was larger and driven by a lower probability of attending college and higher probability of home production. Sons of low-educated mothers, on the other hand, were less likely to be employed. The results suggest that exposure to formal childcare may be more beneficial than all-day maternal care at the age of 3, especially for children with a lower socio-economic background.
Keywords:
family leave; maternal care; subsidized childcare
Fulltext is available at external website.
Is longer maternal care always beneficial? The impact of a four-year paid parental leave
We study the impact of an extension of paid family leave from 3 to 4 years on child long-term outcomes. Using a difference-in-differences design and comparing the first-affected with the ...
Setting interim deadlines to persuade
Senkov, Maxim
2022 - English
This paper studies the optimal design of self-reporting on the progress of a project by a rent-seeking agent reporting to a principal who is concerned with accomplishing the project before an exogenous deadline. The project has two stages: completing the first stage serves as a milestone and completing the second stage accomplishes the project. I show that if the project is sufficiently promising ex ante, then the agent commits to provide only the good news that the project is accomplished. If the project is not promising enough ex ante, the agent persuades the principal to start the funding by committing to provide not only good news but also the bad news that the milestone of the project has not been reached by an interim deadline.
Keywords:
dynamic Bayesian persuasion; informational incentives; interim deadline
Fulltext is available at external website.
Setting interim deadlines to persuade
This paper studies the optimal design of self-reporting on the progress of a project by a rent-seeking agent reporting to a principal who is concerned with accomplishing the project before an ...
TM03000027-V6: ESC 3 - Posouzení vlivu na přesnost navigačních systémů GNSS - Evaluation of factors influencing the GNSS positioning accuracy
Urbář, Jaroslav; Suchánek, P.; Chum, Jaroslav
2022 - English
Technická zpráva o vlivu na přesnost navigačních systémů GNSS. Získaná data k ověření vlivu na přesnost navigačních systémů GNSS při výskytu MSTID v ionosféře. \n\nTechnical report analyzing the effect of MSTIDs on an accuracy of GNSS based positioning. The analysis should be performed based on experimentally obtained data.\n
Keywords:
medium-scale traveling ionospheric disturbances (MSTIDs); Global Navigation Satellite System (GNSS); GADIOD; GNSS
Available on request at various institutes of the ASCR
TM03000027-V6: ESC 3 - Posouzení vlivu na přesnost navigačních systémů GNSS - Evaluation of factors influencing the GNSS positioning accuracy
Technická zpráva o vlivu na přesnost navigačních systémů GNSS. Získaná data k ověření vlivu na přesnost navigačních systémů GNSS při výskytu MSTID v ionosféře. \n\nTechnical report analyzing the ...
Annular impinging jets and an active control of hysteretic effects
Devani, Yogendrasasidhar; Antošová, Zuzana; Trávníček, Zdeněk
2022 - English
An annular air jet with and without flow control was studied experimentally using flow visualization and measurements of the wall pressure and flow velocity by the Pitot and Prandtl probes and the hot-wire anemometer. To investigate flow control swirling effects, eight synthetic jets were generated from the annular nozzle center body.The experiments cover Reynolds numbers 4000–10000 (evaluated from the outer exit diameter of the annular nozzle). For Re<9000, the bistability and hysteresis were identified and two different flow field patterns (A and B) were found under the same boundary conditions. For A pattern, a small recirculation area (bubble) of separated flow is attached to the nozzle center body. For B pattern, a large recirculation area of separated flow bridges entire nozzle-to-wall distance. For higher Re > 9000, the bistability and hysteresis were not found.Flow control swirling effects causes suppression of the hysteresis. Moreover, weak flow control causes that the entire annular jet is forced into a precessing motion.
Keywords:
annular jet; impinging jet; bistability; hysteresis
Available at various institutes of the ASCR
Annular impinging jets and an active control of hysteretic effects
An annular air jet with and without flow control was studied experimentally using flow visualization and measurements of the wall pressure and flow velocity by the Pitot and Prandtl probes and the ...
Sequential sampling beyond decisions? A normative model of decision confidence
Rehák, Rastislav
2022 - English
We study informational dissociations between decisions and decision confidence. We explore the consequences of a dual-system model: the decision system and confidence system have distinct goals, but share access to a source of noisy and costly information about a decision-relevant variable. The decision system aims to maximize utility while the confidence system monitors the decision system and aims to provide good feedback about the correctness of the decision. In line with existing experimental evidence showing the importance of post-decisional information in confidence formation, we allow the confidence system to accumulate information after the decision. We aim to base the post-decisional stage (used in descriptive models of confidence) in the optimal learning theory. However, we find that it is not always optimal to engage in the second stage, even for a given individual in a given decision environment. In particular, there is scope for post-decisional information acquisition only for relatively fast decisions. Hence, a strict distinction between one-stage and two-stage theories of decision confidence may be misleading because both may manifest themselves under one underlying mechanism in a non-trivial manner.
Keywords:
decision; confidence; sequential sampling
Fulltext is available at external website.
Sequential sampling beyond decisions? A normative model of decision confidence
We study informational dissociations between decisions and decision confidence. We explore the consequences of a dual-system model: the decision system and confidence system have distinct goals, but ...
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