Impact of the COVID-19 pandemic on return and risk transmission between oil and precious metals: Evidence from DCC-GARCH model

It is frequently discussed in the literature that the correlation between low-correlation assets under ordinary market conditions may increase during crisis periods. To contribute to the ongoing debates, this paper empirically examines risk transmission between oil and precious metal markets induced by the COVID-19 pandemic using the DCC-GARCH model. The findings reveal evidence of a significant risk transmission between oil prices and precious metal prices, particularly during the onset of the COVID-19 pandemic. The findings point out that the negative relationship between oil and all precious metals returns in the pre-COVID-19 period has changed with the effect of the pandemic. In this process, it is revealed that the negative relationship between oil and gold has strengthened, but the negative relationship between oil and silver has weakened. In addition, the correlations between oil and platinum and palladium turn positive. The empirical findings imply that investors and portfolio managers seeking portfolio diversification and hedging opportunities in a high-risk environment such as the COVID-19 pandemic should consider gold and silver assets for investment

Investigation of entamoeba gingivalis and trichomonas tenax in periodontitis or gingivitis patients in Kayseri

Amaç: Bu çalışmada periodontitis ve gingivitis hastalarında E. gingivalis ve T. tenax yaygınlığının araştırılması amaçlanmıştır. Yöntem: Çalışmamıza 107 periodontitis hastası ve 68 gingivitis hastası alınmıştır. Ağzında tespit edilen mevcut mikrobiyal dental plaklar ka zınmış ve kazınan plak parçaları, içerisinde % 0,9 serum fizyolojik bulunan tüplere konulmuştur. Örnekler ışık mikroskobu altında incelenmiştir. Ayrıca T. tenax için aynı örnekten bir miktar da besiyerine ekilmiş ve 37°C’de inkübe edilmiştir. Bulgular: Periodontitis hastalarının 38’inde E. gingivalis, üçünde T. tenax ve ikisinde hem E. gingivalis hem de T. tenax birlikte tespit edilmiş tir. Gingivitis hastalarının ise 22’sinde E. gingivalis, 2’sinde T. tenax, 1’inde ise E. gingivalis ve T. tenax birlikte bulunmuştur. Sonuç: Çalışmamızda periodontitis ve gingivitis hastalarında oral protozoonlar yüksek oranda bulunmuştur. Yeni yapılacak çalışmalarla E. gingivalis ve T. tenax prevalansının belirlenmesi ve özellikle korunma prensiplerine uyulması gerektiği kanısındayı

An assessment of the relationship between peri-implant status and dental anxiety and oral health-related quality of life

Background: The purpose of this study is to evaluate the relationship between peri-implant diseases and dental anxiety and oral health-related quality of life. Methods: In a total of 101 subjects (44 females, 57 males, mean age 56.9 ± 12.1), 325 implants were examined using modified plaque index, modified sulcus bleeding index, probing depth, bleeding on probing, clinical attachment level, suppuration, and keratinized mucosa width. The Oral Health Impact Profile (OHIP- 14) was used to measure the impact of oral health-related quality of life. For the purpose of assessing the dental anxiety level, Corah’s Dental Anxiety Scale (DAS) was performed. In addition to dental implant measurements, the periodontal status of the participants' natural teeth was assessed by the Community Periodontal Index (CPI) of the World Health Organization. Results: All created groups as peri-implantitis, peri-implant mucositis, and peri-implant healthy were compatible with each other in terms of gender, age, income level, smoking status, and oral hygiene practices (p>0.05). A statistically significant correlation was found indicating that the peri-implant condition worsened as the education level decreased (p=0.033). There was no statistically significant difference between study groups in terms of DAS, OHIP-14, and CPI. There was a significant correlation between the scores of DAS and OHIP-14 (p<0.001). Conclusion: No relationship was found between peri-implant diseases and dental anxiety and quality of life. It was determined that as the anxiety levels of the participants increased, their quality of life decreased

The effects of orthognathic surgery on periodontal status

The aim of this study was to investigate the effects of orthognathic surgery on periodontium in the 3rd and 6th months after the operation. Methods: In a total of 10 orthognathic surgery patients (7 females, 3 males, mean age 23.2 ± 4.83), full mouth clinical periodontal measurements such as plaque index (PI), gingival index (GI), probing depth (PD), bleeding on probing (BOP), clinical attachment level (CAL), and mobility (M) were performed before the surgical procedure (T0) at all teeth except the third molars. Six of these patients underwent double jaw orthognathic surgery, 2 patients sagittal split ramus osteotomy, and 2 patients Le Fort I osteotomy. The same full mouth clinical periodontal measurements were repeated in the 3rd (T1) and 6th (T2) months after surgery. Results: There was no statistically significant difference between the T0 and T1 and T2 values in any of the parameters (PI, GI, PD, BOP, CAL, and M) at any of the regions measured (maxillary teeth, mandibular teeth, or full mouth). Conclusion: Within the limits of this study, it has been observed that orthognathic surgical treatments do not have a significant effect on periodontal status. However, further studies are needed before final conclusions can be provided

Evaluation of the morphology of the canalis sinuosus using cone-beam computed tomography in patients with maxillary impacted canines

WOS: 000416318900001PubMed ID: 28680842Purpose: The nasopalatine canal is a well-known, important anatomical structure in the anterior maxilla, but this region contains many accessory canals. The canalis sinuosus (CS) is one of these canals; it contains the anterior superior alveolar nerve, along with veins and arteries. The purpose of this study was to evaluate the CS using cone-beam computed tomography (CBCT) in patients with maxillary impacted canines. Materials and Methods: A total of 111 patients admitted to the Istanbul Medipol University School of Dentistry for the exposure, orthodontic treatment, and/or extraction of an impacted canine were included in this study. CBCT images were obtained for these patients under standard conditions. Axial, coronal, and sagittal sections were evaluated to assess the prevalence of CS, the direction and diameter of the canal, its relation with the impacted canine, and its distance from the alveolar crest. Further, possible correlations with patient gender and age were analyzed. Results: The CS could be detected bilaterally in all the evaluated tomography images. The mean canal diameter was significantly larger in males than in females (P =. 001). The CS ran significantly closer to the impacted canine when the canal was located horizontally (P =. 03). Variations of the canal, such as accessory canals, were identified in 6 patients. Conclusion: CS is an anatomical entity that may resemble periapical lesions and other anatomical structures. Evaluation with CBCT prior to surgical procedures in the anterior maxilla will help to prevent overlooking such anatomical structures and to decrease possible surgical complications

The nonlinear effects of environmental innovation on energy sector-based carbon dioxide emissions in OECD countries

This paper empirically investigates the impact of environmental innovation on energy sector-based CO2 emissions using a large dataset for 32 OECD countries covering the period 1997-2018. To detect the nonlinear relationship between variables, this paper adopts a panel smooth transition regression (PSTR) model, which can estimate both the threshold level endogenously and the smoothness of the transition from one regime to another. The findings indicate that environmental innovation has a reducing effect on CO2 emissions from the energy sector up to a certain level of innovation is insignificant (1st regime), then it has a reducing effect (2nd regime), and above this level environmental innovation has an increasing effect on carbon emissions (3rd regime), suggesting the existence of a rebound effect. These findings point out that environmental innovations alone are not a solution to struggle environmental problems and should be supported by environmental policies to reveal their environmental reflections. This paper not only makes an important contribution to the empirical literature, but also reveals important policy implications, particularly to achieve climate change targets

Pollute less or tax more? Asymmetries in the EU environmental taxes - Ecological balance nexus

This paper examines the impact of environmentally related taxes on environmental performance in the EU-15 countries during the period of 1995–2016 by utilizing an innovative non-linear model, which is the panel smooth transition regression (PSTR) model. Although the effectiveness of environmental taxes has been discussed before, the potential effects of these taxes on ecological balance sheets as a measure to reflect human pressures on the environment/ecosystem have not been fully investigated. This paper, therefore, deals with total ecological balance and its main components, which are based on the major types of ecologically productive areas such as cropland, grazing land, forest area, and fishing grounds. The results indicate that revenues from environmentally-related taxes as a share of GDP significantly lower the ecological deficits after exceeding a certain threshold level, but not cropland balance accounts. Thus, well-designed environmental taxes on the optimal level have the potential to reduce environmental problems/ ecological imbalance, if not implemented in conjunction with policies such as tax exemptions, refunds or tax allowances that limit their impact. © 2021The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper

Threshold effects of economic growth on water stress in the Eurozone

This paper empirically examines the environmental Kuznets curve (EKC) hypothesis using a country’s water stress as an indicator of the pressure on renewable water resources. The sample consists of 9 European countries by covering the period 1995–2013. The paper adopts a panel threshold regression model which can predict the threshold level endogenously to analyze whether income per person has an impact on water stress. The empirical findings strongly demonstrate the existence of a threshold beyond which environmental pressures of GDP (real) per capita growth on renewable water resources tend to increase. The growth below the threshold levels has no statistically significant effect on water stress, while the growth rate above the threshold increases stress on water resources. The available empirical findings obtained, albeit limited, tend not to support the EKC hypothesis, which postulates an inverted-U-shaped relationship. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature

The relationship between periodontal disease severity and state-trait anxiety level

Objective: To determine the relationship between the paroxysm related to periodontal disease and the state-trait anxiety level in patients attending a periodontology clinic in Turkey. Methods: The cross-sectional study involved 141 patients > or = 18 years old attending the periodontology clinic at the Dental Faculty of Erciyes University, Turkey, between January and March 2009. A questionnaire developed by the researchers, the State-Trait Anxiety Inventory Index and the Community Periodontal Index were used for data collection. SPSS 15, chi square test and unpaired students' t test were used for statistical analysis. Results: Gingivitis was present in 101 (71.6%) patients, while periodontitis was found in 40 (28.4%). The mean age of periodontal patients was significantly higher than those of gingivitis patients (p < 0.05). Graduates were less likely to develop periodontitis than those who had only primary education (p < 0.05). Gingivitis was seen to be significantly higher in patients having poor oral hygiene (p < 0.05). State-Trait Anxiety Inventory scores of periodontal patients was significantly higher than those of gingivitis patients (p < 0.05). Patients with high state anxiety scores were more likely to have periodontitis. The most important variables associated with periodontitis and gingivitis were age, State-Trait Anxiety Inventory, income level and needs for treatment, respectively. Conclusion: Periodontal treatment will improve if anxiety is diagnosed and relieved by different methods