Price leadership and volatility linkages between oil and renewable energy firms during the covid-19 pandemic

The COVID-19 pandemic is shaving a strong influence in all areas of society, like wealth, economy, travel, lifestyle habits, and, amongst many others, financial and energy markets. The influence in standard energies, like crude oil, and renewable energies markets has been twofold: from one side, the predictability of volatility has strongly decreased; secondly, the linkages of the price time series have been modified. In this paper, by using DCC-GARCH and Price Leadership Share method-ology, we can investigate the changes in the influences between standard energies and renewable energies markets by analyzing one-minute time series of West Texas Intermediate crude oil futures contract (WTI), the Brent crude oil futures contract (BRENT), the STOXX Europe 600 oil & gas index (SXEV), and the European renewable energy index (ERIX). Our results confirm volatility spillover between the time series. However, when assessing the accuracy of the predictability of the DCC-GARCH model, the results show that the model fails its prediction in the period of higher instability. Besides, we found that price leadership has been strongly influenced by the virus spreading stages. These results have been obtained by dividing the period between September 2019 and January 2021 into 6 subperiods according to the pandemic stages

A multivariate high-order markov model for the income estimation of a wind farm

The energy produced by a wind farm in a given location and its associated income depends both on the wind characteristics in that location—i.e., speed and direction—and the dynamics of the electricity spot price. Because of the evidence of cross-correlations between wind speed, direction and price series and their lagged series, we aim to assess the income of a hypothetical wind farm located in central Italy when all interactions are considered. To model these cross and auto-correlations efficiently, we apply a high-order multivariate Markov model which includes dependencies from each time series and from a certain level of past values. Besides this, we used the Raftery Mixture Transition Distribution model (MTD) to reduce the number of parameters to get a more parsimonious model. Using data from the MERRA-2 project and from the electricity market in Italy, we estimate the model parameters and validate them through a Monte Carlo simulation. The results show that the simulated income faithfully reproduces the empirical income and that the multivariate model also closely reproduces the cross-correlations between the variables. Therefore, the model can be used to predict the income generated by a wind farm

Incremental events in the construction of sambaquis, southeastern Santa Catarina.

Moundbuilding is a cross-cultural phenomenon of nearly world-wide scope. In this article some of the moundbuilding processes related to the sambaquis (shellmounds) from the coast of Santa Catarina State, Brasil, are examined, focusing on field research at the sambaqui Jaboticabeira II. By means of analysing the mounding up processes at that site, attention is drawn to its social and demographic corollaries, which speak of considerable social elaboration and territorial permanence in time.A construção de cômoros artificiais (mounds) é um fenômeno de amplo alcance em termos globais. Neste artigo são examinados alguns dos processos responsáveis pela construção destas estruturas no litoral sul de Santa Catarina, tomando-se como referência os trabalhos realizados no sambaqui Jaboticabeira II, município de Jaguaruna. Além da análise dos processos envolvidos na construção daquele sambaqui, procura-se chamar a atenção para os aspectos sociais e demográficos destes mesmos processos, evidenciando um sistema regional de considerável complexidade social e duração cronológica

Non-Standard Errors

In statistics, samples are drawn from a population in a data-generating process (DGP). Standard errors measure the uncertainty in estimates of population parameters. In science, evidence is generated to test hypotheses in an evidence-generating process (EGP). We claim that EGP variation across researchers adds uncertainty: Non-standard errors (NSEs). We study NSEs by letting 164 teams test the same hypotheses on the same data. NSEs turn out to be sizable, but smaller for better reproducible or higher rated research. Adding peer-review stages reduces NSEs. We further find that this type of uncertainty is underestimated by participants

Non-standard errors

In statistics, samples are drawn from a population in a data-generating process (DGP). Standard errors measure the uncertainty in estimates of population parameters. In science, evidence is generated to test hypotheses in an evidence generating process (EGP). We claim that EGP variation across researchers adds uncertainty: Non-standard errors (NSEs). We study NSEs by letting 164 teams test the same hypotheses on the same data. NSEs turn out to be sizable, but smaller for better reproducible or higher rated research. Adding peer-review stages reduces NSEs. We further find that this type of uncertainty is underestimated by participants

Entropy Measures for Credit Sovereign Ratings: The European Union Case

In this chapter, we analyze the main entropy measures applied to the sovereign credit rating data of the European Union. The dataset used for the investigation consists of ratings from four major rating agencies: Moody’s, S&P, Fitch, and DBRS, and it covers a 15-years period approximately which includes the great financial crisis of 2008-2011. This analysis allows us to compare the durations of the individual rating states among the agencies and to understand if those agencies really respond to the individual rating states with different durations. We perform the entire investigation considering the right censoring statistical problem

Midterm results from a multicenter registry on the treatment of infrainguinal critical limb ischemia using a heparin-bonded ePTFE graft

Objectives: To report midterm results of infrainguinal bypasses performed with a heparin-bonded expanded polytetrafluoroethylene (ePTFE) graft in patients presenting with critical limb ischemia. Methods: Over a 7-year period ending in 2008, 425 patients presenting with critical limb ischemia underwent infrainguinal revascularization using a heparin-bonded ePTFE graft in seven Italian vascular centers. Preoperative, intraoperative, and follow-up data were collected in a multicenter registry. Patients were predominantly male (79%) with a mean age of 73.5 years. Mean preoperative ankle brachial index (ABI) was 0.35 and 192 of the patients (45%) were diabetic. Intervention consisted of a femoral to below-knee bypass in 324 patients (76%), whereas the remaining 101 patients had a femoral to above-knee bypass. In patients with below-knee bypass, distal target vessels were the popliteal artery in 238 cases, the tibioperoneal trunk in 38 cases, and a tibial vessel in the remaining 48 cases (anterior tibial artery in 20 cases, posterior tibial artery in 23 cases, and peroneal artery in 5). Follow-up consisted of clinical and duplex scanning examinations within 3 months from the intervention and yearly thereafter. Early (< 30 day) results were analyzed in terms of deaths, graft thromboses, and amputations with univariate and multivariate (stepwise logistic regression) analysis. Follow-up results were evaluated in terms of primary and secondary graft patency, limb salvage, and survival rate with univariate and multivariate (Cox regression) analysis. Results: Thirteen perioperative deaths occurred (3.1%). Thirty-day primary graft patency was 92.5% and limb salvage was 95.8%. Follow-up was available in 98% of patients with a median duration of 25.5 months (SD, 17.6; range, 1-72). Cumulative estimated 36-month primary and secondary patency, limb salvage, and survival rates were 61%, 70%, 83%, and 83%, respectively. At univariate analysis, the factors associated with poorer limb salvage rates during follow-up were the presence of ischemic ulcers or gangrene (log-rank, 8.4; P = .004; 95% confidence interval [CI] 1.2-3.5; odds ratio [OR], 2.1), the presence of only one patent tibial vessel (log-rank, 41.3; P < .001; 95% CI, 3.1-10.8, OR, 5.8), redo surgery (log-rank, 12.4; P < .001; 95% CI, 1.4-4; OR, 2.4) and the postoperative treatment with antiplatelet therapy in comparison to oral anticoagulants (log-rank, 5.1; P = .02; 95% CI, 1.0-3.4; OR, 1.8). At multivariate analysis redo surgery (P = .02; 95% CI, 1.1-3.1; OR, 1.8), poor runoff score (P < .001; 95% CI, 2.5-9.1; OR, 4.7) and preoperative clinical status (P = .02; 95% CI, 1.1-3.1; OR, 1.8) were independently associated with decreased limb salvage rates. Conclusion: The use of a heparin-bonded ePTFE graft provides good early and midterm results, with low rates of late amputations. Primary and secondary patency made this graft an excellent alternative to autologous saphenous vein when it is absent, unsuitable, or of poor quality

Liver transplantation: expanding the donor pool.

No abstract availabl