From a Heavenly Arabic Poem to an Enigmatic Judeo-Arabic Astrolabe

Since the sole surviving astrolabe with engraving in Judaeo-Arabic came to light at an auction in 1988 the inscription on the rim has troubled researchers for it appeared to make little sense. We show here that the inscription is a corrupt version of a 10th-century poem compiled by the astronomer-mathematician-poet Abū Isfāq Ibrāhīm al-Sābi' for the ruler 'Adud al-Dawla when the scholar presented him with an astrolabe; this poem appeared in several manifestations between Baghdad and al-Andalus over the centuries, of which our astrolabe presents the most distorted version. There is also a problem with the plates, the latitudes underlying the markings often being at variance with what is stated on them. The difficulty of dating the astrolabe and assigning it to either of al-Andalus or the Maghrib is discussed

MyPyPSA-Ger: Introducing CO2 taxes on a multi-regional myopic roadmap of the German electricity system towards achieving the 1.5 ◦C target by 2050

This paper will introduce the open-source model MyPyPSA-Ger, a myopic optimization model developed to represent the German energy system with a detailed mapping of the electricity sector, on a highly disaggregated level, spatially and temporally, with regional differences and investment limitations. Furthermore, this paper will give new outlooks on the German federal government 2050 emissions goals of the electricity sector to become greenhouse gas neutral by proposing new CO2 allowance strategies. Moreover, the regional differences in Germany will be discussed, their role and impact on the energy transition, and which regions and states will drive the renewable energy utilization forward. Following a scenario-based analysis, the results point out the major keystones of the energy transition path from 2020 to 2050. Solar, onshore wind, and gas-fired power plants will play a fundamental role in the future electricity systems. Biomass, run of river, and offshore wind technologies will be utilized in the system as base-load generation technologies. Solar and onshore wind will be installed almost everywhere in Germany. However, due to the nature of Germany’s weather and geographical features, the southern and northern regions will play a more important role in the energy transition. Higher CO2 allowance costs will help achieve the 1.5-degree-target of the electricity system and will allow for a rapid transition. Moreover, the more expensive, and the earlier the CO2 tax is applied to the system, the less it will cost for the energy transition, and the more emissions will be saved throughout the transition period. An earlier phase-out of coal power plants is not necessary with high CO2 taxes, due to the change in power plant’s unit commitment, as they prioritize gas before coal power plants. Having moderate to low CO2 allowance cost or no clear transition policy will be more expensive and the CO2 budget will be exceeded. Nonetheless, even with no policy, renewables still dominate the energy mix of the future. However, maintaining the maximum historical installation rates of both national and regional levels, with the current emissions reduction strategy, will not be enough to reach the level of climate-neutral electricity system. Therefore, national and regional installation requirements to achieve the federal government emission reduction goals are determined. Energy strategies and decision makers will have to resolve great challenges in order to stay in line with the 1.5-degree-target

Achieving 100% renewable power system in Germany

Most recently, the federal government in Germany published new climate goals in order reach climate neutrality by 2045. This paper demonstrates a path to a cost optimal energy supply system for the German power grid until the year 2050. With special regard to regionality, the system is based on yearly myopic optimization with the required energy system transformation measures and the associated system costs. The results point out, that energy storage systems (ESS) are fundamental for renewables integration in order to have a feasible energy transition. Moreover, the investment in storage technologies increased the usage of the solar and wind technologies. Solar energy investments were highly accompanied with the installation of short-term battery storage. Longer-term storage technologies, such as H2, were accompanied with high installations of wind technologies. The results pointed out that hydrogen investments are expected to overrule short-term batteries if their cost continues to decrease sharply. Moreover, with a strong presence of ESS in the energy system, biomass energy is expected to be completely ruled out from the energy mix. With the current emission reduction strategy and without a strong presence of large scale ESS into the system, it is unlikely that the Paris agreement 2° C target by 2050 will be achieved, let alone the 1.5° C

The Determinants Of Capital Flight: Evidence From MENA Countries

This paper examines the determinants of capital flight in seven Middle East and North Africa (MENA) countries during the period of 1981-2008. The results are robust to four econometrics techniques: Ordinary least Squares, Fixed effects, Random Effects, and Seemingly Unrelated Regression Model. The empirical findings indicate that the capital flight in MENA countries is driven mainly by lag capital flight, external debt, foreign direct investment, real GDP growth rate and uncertainty. Based on these results, the paper recommends that governments in these countries should manage their external debt efficiently, and stabilize their monetary and macroeconomic policies in order to staunch capital flight

Diversification and hedging strategies of green bonds in financial asset portfolios during the COVID-19 pandemic

In this paper, we investigate whether investors can reap potential diversification or hedging benefits from holding green bonds in a portfolio containing a conventional financial asset during the COVID-19 pandemic. Using data from 6 November 2014 to 5 November 2020, we estimate corrected dynamic conditional correlation between between green bonds and four major asset classes: stocks, corporate bonds, commodities, and clean energy. We extend our analysis by using these correlations to examine hedging, optimal portfolio weights, and naïve strategies and evaluate their implications for investors by calculating hedging effectiveness and utility gain improvement. Results reveal that across the full sample, pre-COVID-19, and during-COVID-19 periods, optimal portfolio weights represent an ideal strategy to realize the greatest risk reduction and risk-adjusted return. Further, green bonds could add substantial diversification benefits for investors holding assets in clean energy, global stocks, and commodities

Time domain homogenisation of elastic and viscoelastic metamaterials

The mechanical behaviour of metamaterials typically depends on their microstructural configuration and composition, in addition to their relative density. The design of these materials requires extensive experiments or complex finite element models which tend to be numerically demanding. In order to understand, control and optimise the macroscopic mechanical behaviour, in this paper numerical homogenisation is applied to a simple square unit cell with a single inclusion using a combination of elastic and viscoelastic responses on the micro level. Through a systematic analysis of unit cell behaviour with increasingly complex microstructural configurations, it is shown how certain macroscale constitutive laws can be obtained in a controlled and controllable manner

Endoscopic treatment of cavum vergae cyst: case report and review

A 3.5-year-old boy was admitted with febrile convulsion for the first time. The patient had a medical history of in vitro fertilization (IVF) and premature delivery in the 21st week of pregnancy. Further, he suffered from neonatal germinal matrix hemorrhage and intraventricular hematoma (IVH). The patient was treated in the pediatric intensive care unit. Cranial magnetic resonance imaging (MRI) showed resorption of the hematoma with the presence of cavum vergae (CV) variation. The new brain MRI revealed progression of the cavum to a large CV cyst compared with the previous imagings, causing pressure upon both lateral ventricles. Endoscopic fenestration of the lateral walls of the cyst with lateral ventricles was performed. The postoperative period was uneventful and the patient was discharged the next day. Followup MRI one year after surgery showed normal ventricle size, shrinkage of the cyst and cerebrospinal fluid (CSF) flow between the cyst and the lateral ventricles. This is an interesting demonstration of the progression over years of a CV anatomical variation to a large CV cyst in a premature birth case that experienced germinal matrix hemorrhage