473 research outputs found
Has Automation Changed the Response of Unemployment Rate to GDP Growth?
Debate over the effect of technology and automation on job creation or job destruction has been an ongoing debate in economics for some time. The recent developments in automation and the speed with which machine is replacing labor in some industries has worried many economists (Krugman, 2013, Graetz, G & G Michaels, 2015). While a number of recent studies present evidence on the negative effect of automation on employment by occupations (Oschinski M & R Wyonchi, 2017), none presents empirical evidence on the effect of automation on jobs at the macroeconomics level. This study utilizes the traditional model of the relationship between the real GDP growth and unemployment rate, estimated for US economy in 1962 and publicized as Okun’s Law. The relationship implies that a one percent increase in GDP growth above the normal growth of GDP results in .4 percent decrease in unemployment rate. Although the relationship between GDP growth and unemployment rate may be affected by other economic variables in the short-run, a variable that may result in structural change in this relationship in the long-run is technology and its effect on unemployment. Technological advancement may lead to substitution of capital for labor, resulting in less response of GDP growth to unemployment rate than what Okun’s law proposed. The main objective of this paper is to test whether such a structural change in the relationship has occurred or not. Using data for the last sixty years for eight industrialized countries, this paper compares the average response of unemployment rate to real GDP growth in three decades of 1955-1985, with the recent three decades of 1986-201
Dentin bonding agent with improved bond strength to dentin through incorporation of sepiolite nanoparticles
The study aims to investigate the effect of incorporation of sepiolite nanoparticles on the microtensile bond strength of an experimental dentin bonding to the human dentin. The sepiolite nanoparticles were incorporated into an experimental methacrylate-based dentin bonding system in concentrations of 0.0, 0.2, 1.0, 2.0, and 5.0 weight percents. The specimens were then ultrasonicated to finely disperse the nanoparticles in the adhesive matrix. The coronal enamel of 30 intact human premolars was cut to expose dentin. Having etched, rinsed, and blot dried the experimental bonding agents were applied to dentin surface. Adper Single Bond was used as control group according to the manufactor?s instruction. Then all the teeth were built up by composite and sectioned in stick form for microtensile test. The fracture surface was observed using SEM. The data were analyzed by ANOVA and Tukey?s post-Hoc test. The results indicated that the incorporation of the nanofiller, improved the bond strength to dentin with the highest values obtained at 1 w% sepiolite nanoparticle content. Sepiolite nanoparticles can be considered as novel fillers to improve the mechanical properties of dentin bonding agents
Application of Quantitative Software in Economics and Decision Science
Mathematics is often used to facilitate a clear and organized presentation of economic theories and problems. It provides a simplified approach for setting up models, making explicit assumptions about the models, finding optimal solutions, and extending the results by varying the parameters and assumptions of the models. Many economists would agree that a large gain in clarity and economy of effort can be achieved by incorporating mathematics into economic teaching. What limits the use of mathematics in teaching economics is inadequate preparation of students in quantitative methods. In addition, some mathematical manipulations and calculations turn out to be time consuming and tedious for class presentations. This paper argues that both of these problems can be overcome by using modern mathematical software in teaching economics
Enhanced Gas Recovery with Carbon Dioxide Sequestration in a Water-drive Gas Condensate Reservoir: a Case Study in a Real Gas Field
Gas reservoirs usually have high recovery due to high mobility and low residual gas saturation, although some of them producing under water-drive mechanism have low recovery efficiency. Encroachment of water into these reservoirs traps considerable amount of gas and increases the maximum residual gas saturation, which results in the reduction of gas and condensate production. Generally, the recoveries of water-drive gas reservoirs vary between 35-75%, whereas depletion-drive reservoirs exhibit recoveries near 85%. In this work, a method was proposed for reducing water encroachment, sweeping reservoir gas content effectively, and enhancing the hydrocarbon recovery consequently. To this end, a condensate gas reservoir model, located in the south of Iran, was chosen to study the process. The injection was performed above the bottom-up aquifer from two horizontal wells, and the base gas was produced by four vertical wells. Three cases of inactive aquifer (Case I), active aquifer (Case II), and active aquifer with CO2 injection (Case III) were studied subsequently. The proposed gas-gas displacement method increases the recovery of reservoir especially the recovery of heavier components composing the main part of the condensate. Moreover, the injection of a huge volume of CO2 without significant CO2 production can be interesting from an environmental point of view and can be considered as a CO2 sequestration process
Determination of Effect of Oral Vitamin D to Improve Ventilatory Threshold in Healthy Young Adults with Vitamin D Deficiency
Background: Many studies have shown a high prevalence of vitamin D deficiency in different communities. Due to multiple roles of vitamin D in the body, this study was aimed to determine the effect of oral vitamin D3 on ventilatory threshold-1 in a condition of vitamin D deficiency.Materials and Methods: Recent study performed on 25 healthy young adults with the serum levels of 25 Hydroxyvitamin D3 lower than 20 ng/ml, had referred to the sports medicine clinic of Taleghani Hospital of Tehran, in a one-year period (2016-2017). After primary evaluation, baseline ventilatory threshold-1 were determined by cardiopulmonary exercise testing (CPET). Then persons were treated with 50,000 IU/week of oral vitamin D3 for 8 weeks, and one week after the completion of treatment, ventilator threshold-1 was measured again, similar to the beginning conditions of the study, and its changes were studied.Results: The mean baseline ventilatory threshold-1 of participants before any intervention was 22.46 ± 6.45 (ml/kg/min), and after 8 weeks of treatment by 50000 IU/week of oral vitamin D3, increased to 26.79 ± 5.33 (ml/kg/min) at the end of study, which there was a statistically significant increase in ventilatory threshold-1 (p<0.001).Conclusion: Recent study showed that proper treatment of the vitamin D deficiency, improves ventilatory threshold-1 in healthy young adults
Comparative Outcomes of Pulpotomy in Mature Molars with Irreversible Pulpitis: A Non-Randomized Trial Evaluating Calcified and Non-Calcified Pulp Chambers
Introduction: This non-randomized clinical trial investigated the outcomes of full pulpotomy in adult molars with irreversible pulpitis, comparing those with calcified and non-calcified pulp chambers over 6 and 12 months. Materials and Methods: A total of 101 adult permanent molars with irreversible pulpitis, in individuals over 12 years old, were categorized based on pulp chamber calcification observed in radiographic images by two endodontists. Subsequently, full pulpotomy procedures were performed, achieving hemostasis, and applying a 2 mm layer of calcium-enriched mixture (CEM) cement as a pulp covering agent. After 48 hours, the setting of the CEM cement was verified, followed by the application of a layer of resin-modified glass-ionomer. The tooth was then restored using amalgam. Clinical and radiographic evaluations were conducted at 6-month and 1-year follow-ups by blinded endodontists. Success rates were compared using Fisher's exact test and logistic regression tests with a significance level of 0.05. Results: Among the 97 patients with 6-month and 1-year follow-ups, all achieved clinical success. Radiographic success rates were 99% at 6 months and 96.9% at 1 year, regardless of pulp calcification. In the 6-month follow-up, success rates were 98.07% for non-calcified pulp chambers and 100% for calcified pulp chambers. At the 1-year follow-up, success rates were 96.1% and 97.8%, respectively. Statistical analysis showed no significant difference in radiographic success rate between the two groups at both follow-ups (P>0.05). Conclusions: Full pulpotomy using CEM cement is a successful treatment for adult permanent teeth with calcified and non-calcified pulp chambers presenting signs and symptoms of irreversible pulpitis up to a 1-year follow-up. This study provides compelling evidence that vital pulp therapy can be effectively employed in the pulpotomy of calcified teeth, at least in the short term
In silico characterization of competing endogenous RNA network in glioblastoma multiforme with a systems biology approach
Glioblastoma multiforme (GBM) is the most frequent malignant type of primary brain cancers and is a malignancy with poor prognosis. Thus, it is necessary to find novel therapeutic modalities based on molecular events occur at different stages of tumor progression. We used expression profiles of GBM tissues that contained long non-coding RNA (lncRNA), microRNA (miRNA) and mRNA signatures to make putative ceRNA networks. Our strategy led to identification of 1080 DEmRNAs, including 777 downregulated DEmRNAs (such as GJB6 and SLC12A5) and 303 upregulated DEmRNAs (such as TOP2A and RRM2), 19 DElncRNAs, including 16 downregulated DElncRNAs (such as MIR7-3HG and MIR124-2HG) and 3 upregulated DElncRNAs (such as CRNDE and XIST) and 49 DEmiRNAs, including 10 downregulated DEmiRNAs (such as hsa-miR-10b-5p and hsa-miR-1290) and 39 upregulated DEmiRNAs (such as hsa-miR-219a-2-3p and hsa-miR-338-5p). We also identified DGCR5, MIAT, hsa-miR-129-5p, XIST, hsa-miR-128-3p, PART1, hsa-miR-10b-5p, LY86-AS1, CRNDE, and DLX6-AS1 as 10 hub genes in the ceRNA network. The current study provides novel insight into molecular events during GBM pathogenesis. The identified molecules can be used as therapeutic targets for GBM
Expression pattern of non-coding RNAs in non-functioning pituitary adenoma
Non-functioning pituitary adenoma (NFPA) is a benign tumor arising from the adenohypophyseal cells. They can be associated with symptoms arising from mass effect. Although these tumors are regarded to be benign tumors, they are associated with increased comorbidity and mortality. Several studies have indicated abnormal expression of genes in these tumors. In the current study, we have used existing methods to identify differentially expressed genes (DEGs) including DE long non-coding RNAs (DElncRNAs) and DE microRNAs (DEmiRNAs) in NFPAs compared with normal samples. Then, we have assessed the relation between these genes and important signaling pathways. Our analyses led to identification of 3131 DEGs, including 189 downregulated DEGs (such as RPS4Y1 and DDX3Y) and 2898 upregulated DEGs (such as ASB3 and DRD4), and 44 DElncRNAs, including 8 downregulated DElncRNAs (such as NUTM2B-AS1 and MALAT1) and 36 upregulated DElncRNAs (such as BCAR4 and SRD5A3-AS1). GnRH signaling pathway, Tight junction, Gap junction, Melanogenesis, DNA replication, Nucleotide excision repair, Mismatch repair and N-Glycan biosynthesis have been among dysregulated pathways in NFPAs. Taken together, our study has revealed differential expression of several genes and signaling pathways in this type of tumors
Coordination of recognition and disclosure decisions in uncertainties reporting: investigating the relationship between conditional conservatism and risk disclosu
Accounting Conservatism and risk disclosure are two information policies that managers can use to transfer business uncertainties to external users. Managers are expected to coordinate their reporting and disclosure choices by considering the cost and benefit of these two choices when making financial reporting decisions and coordinate or trade off the two options of conservatism and risk disclosure. This study investigated the relationship between conditional conservatism and risk disclosure. It also analyzed the effect of the factors of the level of debt financing needs and the manager's overconfidence by using a multiple regression model based on the sample of 87 companies listed on the Tehran stock exchange for the period of 2011 to 2020. The results indicate that managers use conditional conservatism and risk disclosure as two complementary information policies to reduce information asymmetry and agency costs. By applying more Conditional conservatism, managers improve the level of risk disclosure in proportion to the level of uncertainty perceived through risk disclosure by users to maintain consistency between quantitative and qualitative information. The debt financing needs has a negative and significant effect, and the overconfidence characteristic of managers has no significant effect on the relationship between the level of conditional conservatism and the level of risk disclosure of firms. Companies with a higher debt financing needs use more conditional conservatism than risk disclosure to reduce debt Costs. The results show that the relative costs and benefits of conservative reporting and risk disclosure affect financial reporting policies regarding risks and uncertainties. Introduction The relationship between accounting conservatism and risk disclosure is included under the relationship between recognition and disclosure decisions. The level of accounting conservatism is important in deciding the optimal level of disclosure, and Earnings Attributes are related to companies' voluntary disclosure decisions (Francis et al., 2008). Based on contractual and litigation incentives, conditional conservatism and risk disclosure are two alternative tools to reduce information asymmetry about uncertainties and reduce agency costs. As a result, managers may coordinate between these two options by considering the costs and limited benefits of each. The way managers make decisions in choosing the level of accounting conservatism and disclosure, such as earnings forecasting, has been investigated in previous studies, but no research has investigated the relationship between the level of accounting conservatism and risk disclosure as one of the types of qualitative disclosure. Hence, the question arises as to how managers coordinate the decisions of choosing the level of conservatism and risk disclosure. The purpose of this research is to explore how managers' decisions are coordinated in the two choices of conditional accounting conservatism and risk disclosure, under the influence of the debt financing needs and management characteristics in companies listed on the Tehran Stock Exchange. To cover the objectives of the research, three hypotheses including (1) the existence of a significant relationship between conditional conservatism and risk disclosure, (2) the effect of the company's debt financing needs, and (3) managers' overconfidence on the relationship between the level of conditional conservatism and the level of risk disclosure have been described and tested.MethodsResearch hypotheses have been examined by using a multivariable regression model and based on the sample of 87 companies listed on the Tehran stock exchange for the period of 2011 to 2020. The data needed for the research has been extracted from the financial statements, explanatory notes, the Management Discussion and Analysis, and the directors’ reports.The first research hypothesis is tested using equation (1).Equation (1) where RDit (the dependent variable) is the level of risk disclosure, which has been measured using the content analysis of the explanatory notes, the Management Discussion and Analysis, and the directors’ reports. Conservit (the independent variable) is conditional conservatism calculated using khan and Watts’ (2009) C-Score. Controlk,it are the control variables of the level of risk disclosure that have been selected and measured based on previous studies.The second hypothesis is tested using equation (2).Equation (2) where FIN_Needs is the variable of the need to finance through debt, which is calculated using the financing deficit criterion according to Deng et al. (2018).To test the third hypothesis, equation (3) is used to examine the effect of management overconfidence on the relationship between conservatism and risk disclosure:Equation (3) where OverConf is the manager's overconfidence variable, which is calculated based on investment-based overconfidence according to Ahmed and Duellman (2013). FindingsThere is a significant positive relationship between the level of conditional conservatism and the level of risk disclosure. The need to finance through debt has a negative and significant effect, and the overconfidence characteristic of managers has no significant effect on the relationship between the level of conditional conservatism and the level of risk disclosure of firms. Conclusion & Result The results show that managers use conditional conservatism and risk disclosure as two complementary information policies. The result conflicts with the results of Hui et al. (2009), Wang (2019), D'Augusta and DeAngelis (2020), Asadi and Bayat (2014), Nikbakht and Hajiazimi (2013) and AsadiMashizi et al. (2020). Based on the contractual and litigation demand, when companies face higher uncertainty and risk, they use more conservative accounting in their financial reporting (Dai & Ngo, 2021؛ Haque et al., 2019؛ Hsieh et al., 2019؛ Hejranijamil et al., 2020) and disclose higher risk to reduce agency costs, including the cost of debt and the possibility of lawsuits.This can be justified based on the argument of D'Augusta and DeAngelis (2020) about investors' understanding of the differences between quantitative and qualitative information. Conservatism conveys business uncertainties quantitatively and risk disclosure qualitatively conveys uncertainties to users. With a greater level of accounting conservatism, managers improve the level of risk disclosure in proportion to the level of uncertainty perceived through risk disclosure by users to maintain consistency between quantitative and qualitative information. The result is consistent with the results of Huang et al. (2014) and Nagar et al. (2019). Also, it can be explained with the assumption that the existence of reporting and risk disclosure requirements limits managers to trade-off risk disclosure and the level of conservatism, especially from the perspective of increased costs from the benefits of disclosure. Moreover, the results are consistent with the argument of Linsley and Shrives (2006) in support of mandatory risk disclosure and the research results of Dyer et al. (2017).Based on the contractual theory, companies with a higher need to finance through debt use a more conditional conservatism level than risk disclosure to reduce debt. The results show that the relative costs and benefits of conservative reporting and risk disclosure affect financial reporting policies regarding risks and uncertainties. This is consistent with the research results of Deng et al. (2018) and Michels (2017).Also, unlike previous studies (such as Ahmed and Duellman (2013) and Ramsheh and Molanzari (2014)), the results indicate that managers with overconfidence characteristics have higher risk tolerance and also provide higher levels of voluntary disclosure.Finally, the results of the research indicate that the users of financial statements should consider the financial reporting policies of a company in interpreting the information of financial reports about risks and uncertainties, because each of these policies and reporting choices in different conditions such as the need to finance through debt may affect how information is disclosed
Investigating the Privatization of Iran's Oil Refinery Industries with DID (Fuzzy) Approach
In recent years, privatization in the downstream industries of oil and gas , has been one of the most important measures taken to change and improve the business environment and remove barriers of production, as well as to implement of the general policies of Article 44 of the Constitution. This study intends to check out eleven variables related to the performance of six companies: Isfahan Oil Refinery, Bandar Abbas Oil Refinery, Tehran Oil Refinery, Lavan Oil Refinery, Shiraz Oil Refinery and Tabriz Oil Refinery by DID (fuzzy) method and compare it with control groups in order to Assess the privatization status of these companies. The results of this study show that two variables out of the eleven variables -, the ratio of general administrative and sales costs to revenues and the number of staff before and after the transfer, were significant for the control group. In other words, the employment situation and general administrative and sales costs in the companies under review were more unsatisfactory than the control group and in this regard, they had poor performance. This shows that in practice, the transfer of these companies has not affected the employment situation, positively
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