100 research outputs found
Advanced manufacturing techniques for X-ray and VHE gamma-ray astronomical mirrors.
No full textThe main theme of this thesis is on the development of the technologies for the future X-ray astronomy telescopes and specifically for the New Hard X-ray Mission and eROSITA (Spectrum-RG) missions. Other important next future X-ray missions, currently under advanced study and/or manufacturing are NuSTAR (USA), ASTRO-H (Japan) and GEMS (USA).
The New Hard X-ray Mission (NHXM) is being developed in Italy as an evolution of the original HEXIT-SAT project and is now the hard x-ray project of reference for the Italian high energy community. NHXM is meant to provide a real breakthrough on a number of hot astrophysical issues, by exploiting the most advanced technology in broad-band (0.2 – 80 keV) high angular resolution (<20 arc seconds HEW) grazing incidence mirrors and spectroscopic detectors, together with the use of a high efficiency imaging polarimeter. Such issues can be summarized in two main headings:
● making the census of the population of black holes in the Universe and probing the physics of accretion in the most diverse conditions;
● investigating the particle acceleration mechanisms at work in different contexts, and the effects of radiative transfer in highly magnetized plasmas and strong gravitational fields.
These topics were identified as top priority in the study commissioned by the Italian Space Agency (ASI) in 2004 to the Italian scientific community with contracts involving Thales-Alenia Space Italy (TAS-I, Turin), the Media Lario Technologies (MLT, Lecco) company and the INAF institution. NHXM benefits from the phase A study of the canceled French-Italian-German SIMBOL-X mission (2007-2008) and has been recently subjected to a scientific phase B study financed by ASI. Media Lario Technologies company received a contract from ASI in 2009 for a Technology Development Program (ASI-TDP) aiming at improving the technology readiness level with also in-house adoption of hardware for the metrology/manufacturing of the multilayer x-ray optics.
Spectrum-RG is a Russian - German x-ray astrophysical observatory scheduled for lunch in 2013. German Space Agency (DLR) is responsible for the development of the key mission instrument - the x-ray grazing incident mirror telescope eROSITA. The second experiment is ART-XC - an x-ray mirror telescope with a harder response than eROSITA, which is being developed by Russia (IKI, Moscow and VNIIEF, Sarov). The name eROSITA stands for extended Roentgen Survey with an Imaging Telescope Array. The general design of the eROSITA x-ray telescope is derived from that of ABRIXAS: a bundle of 7 mirror modules with short focal lengths make up a compact telescope which is ideal for survey observations. Similar designs had been proposed for the missions DUO and ROSITA but were not realized. Compared to those, however, the effective area in the soft x-ray band has now much increased by adding 27 additional outer mirror shells to the original 27 ones of each mirror module. The requirement on the on-axis resolution has also been confined, namely to 15 arc seconds HEW. For these reasons the prefix “extended” to the original name “ROSITA” had been added. The scientific motivation for this extension is founded in the ambitious goal to detect about 100000 clusters of galaxies which trace the large scale structure of the Universe in space and time.
The main scientific goals are:
● to detect the hot intergalactic medium of 50-100 thousand galaxy clusters and groups and hot gas in filaments between clusters to map out the large scale structure in the Universe for the study of cosmic structure evolution;
● to detect systematically all obscured accreting Black Holes in nearby galaxies and many (up to 3 Million) new, distant active galactic nuclei;
● to study in detail the physics of galactic x-ray source populations, like pre-main sequence stars, supernova remnants and x-ray binaries.
Max-Planck-Institute für extraterrestrische Physik (MPE) is the scientific institute responsible for the eROSITA Payload. Media Lario Technologies (MLT) is the industrial enabler for the manufacturing of the Optical Payload for eROSITA - including the flight quality mandrels, and it is currently in the C/D Phase of the project.
The research activity described in this thesis has been carried out at Media Lario Technologies company and at the Brera Astronomical Observatory under the supervision of INAF-OAB researchers Dott. Giovanni Pareschi and Dott. Gianpiero Tagliaferri. The research activity of the author of this thesis is focused on the development of an advance polishing technique for the mandrels to be used as masters in the mirrors replication by electroforming. The goal is to implement a process where the mandrels can be manufactured with a high accuracy (< 6 arc seconds HEW) and low roughness (< 0.2 nm rms) within a consistent short time. In the contest of the eROSITA and NHXM (projects currently running in MLT) the author participated as technical/scientific responsible, investigating innovative mandrels manufacturing technologies (e.g. Single Point Diamond Turning, shape corrective polishing) representing an evolution of the standard approach used so far. In this frame the author has also contributed to the adoption of a customized deterministic polishing machine and a customized 3D metrology device for the mandrel geometrical characterization.
An additional research activity, performed by the author at Media Lario Technologies company and at the Brera Astronomical Observatory, is focused on the development of lightweight glass mirrors manufactured via cold-slumping technique for Imaging Atmospheric Cherenkov Telescopes (IACT). Very High Energy (VHE) gamma rays, with photon energies in the TeV range, can be detected by ground based experiments. In fact, such high energy photons interact high in the upper atmosphere and generate an air shower of secondary particles. These particles emit the so-called Cherenkov light, a faint blue light. The mirror elements here developed have a sandwich-like structure where the reflecting and backing facets are composed by glass sheets with an interposed honeycomb aluminum core. This effort found application at the world’s largest IACT, the 17m MAGIC II telescope (currently operating in Roque de los Muchachos - La Palma, Canary Islands), where 112 mirrors (~ 1 squared meter each), manufactured with the newly developed cold-slumping technique here described, are installed
The regime switching evidence of financial-economic-political risk in Turkey
No full textIn recent time, Turkey could be said to have experienced different levels of Economic Risk, Financial Risk, and Political Risk from low- to high-level. This study investigates the linkage between country risks, namely Financial Risk, Economic Risk, and Political Risk (FEP risk) in Turkey for the period 1984Q1 to 2019Q1 by using threshold cointegration, Markow-switching regression (given the nonlinearity and structural breaks observed in the time series variables), and frequency domain causality approaches. The empirical findings of this study reveal that (i) nonlinear cointegration between Economic Risk, Financial Risk, and Political Risk in Turkey is statistically significant given the evidence of threshold cointegration test, which determines the structural breaks endogenously; (ii) there is positive linkage among the component of country risk at different volatility periods; (iii) there is a significant Granger causal linkage between Economic Risk, Financial Risk and Political Risk at the different frequency levels. The study is likely to open debate about the literature since the study concludes with a discussion on short-run and long-run implications for economic, political, and financial stabilises, thus offering policy suggestions for the policymakers in Turkey.© The Author(s) 2022. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly
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Time-frequency dependency of financial risk and economic risk: Evidence from Greece
No full textThis study aims to shed some light on the one of the most popular phenomena in the economics and finance literature-nexus between economic growth and financial development-for the case of Greece over 1990Q1 to 2018Q4 within the framework of risk. In other words, this study investigates the causal link between financial risk and economic risk in Greece using wavelet coherence tests while answering the following questions: (i) does financial risk lead to economic risk in Greece and/or does economic risk lead to financial risk in Greece, and (ii) if so, why? The wavelet coherence approach allows the study to capture the long-run and short-run causal linkages among the time series variables since the approach combines time and frequency domain causalities. The findings from wavelet coherence supports the Schumpeter hypothesis since the findings proves that there is unidirectional causality from financial risk to economic risk in Greece (i) between 1995 and 1998; (ii) between 2003 and 2013; (iii) between 2013 and 2017 at different frequency levels. The findings clearly reveal how financial risk is important predictor for economic risk in Greece over the period of 1990-2018
Does political risk matter for economic and financial risks in Venezuela?
No full textIn this paper, the time-frequency dependency of political risk as well as economic and financial risks is explored in Venezuela using quarterly data from 1984Q1 to 2018Q4. The present study uses the wavelet coherence technique, which allows the investigation of both the long and short-term causal relationships between political risk and economic and financial risks in Venezuela. The findings of this study indicate that: (i) significant vulnerabilities in political risk, economic risk, and financial risk are observed at different time periods and different frequency levels; (ii) political risk has a strong power for explaining economic risk from 1995 to 2005 in the long run, while between 1984 and 2010, economic risk and political risk are positively correlated at different frequency levels; (iii) in the long run, changes in political risk significantly lead to changes in financial risk in Venezuela
Foreign Direct Investment in the Banking Sector: Empirical Evidence from Turkey
No full textMultinational bank activities have gradually risen in developing countries since the beginning of the globalisation process. Rising foreign bank activities in developing countries have motivated researchers to investigate foreign banks, comprehensively. Turkey is a typical example of a developing country that achieved a tremendous growth rate in foreign bank asset, especially throughout the last decade. The aim of this thesis is to examine two-way linkage; (1) between foreign bank penetration (FBP) and banking variables; (2) between FBP and country risk and (3) between FBP, foreign direct investment (FDI) and foreign portfolio investment (FPI) in Turkey. Therefore, this thesis is constructed by three empirical sections. Moreover the pattern of FDI inflow and outflow in the world and in Turkey has been analysed, chronologically. In addition, the theory of FDI is taken into account and existing FDI theories has been criticised.
In the first empirical work – Chapter 3 - the short run and long run relationship, if it exits, between FBP and determinants of bank performance (namely, domestic bank assets, domestic credit and banking profitability) in Turkey was investigated after controlling DGDP and 2001 financial crisis (DUM2001). The outcome of the Granger causality test indicates that there was unilateral causality which runs from DDB to DFBP . Moreover, I also found feedback causality between DFBP and DCREDIT . By employing impulse response functions, I found that there is positive relationship between DFBP and DCREDIT as I expected. Moreover, the response of DFBP to one standard deviation shock in domestic bank assets is initially statistically significant and positive. The reverse effect is statistically significant and positive. In the final model, the response of DFBP to one standard deviation shock in profitability (PRO) is significant and positive at 3rd quarter. The reverse effect is surprisingly positive but not statistically significant.
Specifically, what has not been also investigated deeply in the empirical literature is the two-way linkage between foreign bank penetration and risk such as political, financial and economic. Thus, in chapter 4, linkage between FBP and country risk (namely, political risk, economic risk and financial risk) was examined in Turkey using quarterly data from 1994Q1 to 2009Q4. My finding indicated that I found one error correction term significant and positive in bivariate vector error correction in model 1 and 2, implying that in the long run, foreign bank penetration has contributed to economic and political risk. Moreover, short run causality based on VAR approach between DFBP and financial risk is investigated but I failed to find any significant causality in the VAR model after controlling DGDP and 2001 financial crisis, even at the 10% level. By analysing impulse response functions, I could not detect any significant relationship between DFBP and host country risk variables in the short run. This is because adding control variables (DGDP and DUM2001) make the relationship between host country risk variables and DFBP statistically insignificant.
Finally, I investigated two-way linkage between FBP, FPI and FDI in Turkey after controlling DGDP and 2001 financial crisis. The finding from the VAR based block exogeneity wald test indicated that changes in DFBP significantly lead to changes in DFDI and there is also unilateral causality which runs from FPI to DFBP. Moreover, using the variance decomposition technique I found that DFDI and FPI have little explanatory power for the evolution of DFBP in Turkey. The contribution of DFBP to the variability of DFDI is more than that of FPI. The contribution of DFDI to FPI variability ranges between 0.000% and 9.122% throughout 12 quarter periods whilst the contribution of DFBP to FPI variability ranges between 0.000% and 7.611%
Co‐Movement of Political Risk and Sovereign Credit Risk: A Wavelet Coherence Analysis for Argentina, Brazil, and Venezuela
No full textEconomic risk linkages between Israel and middle east countries
No full textThis study analyses the economic risk relationship between seven of the top economies in the Middle East and Israel. Our findings are of great interest and likely to begin a new debate in the Middle East region. The results of a block exogeneity Wald test reveal that economic stability in Israel does Granger-cause economic stability in Lebanon, Oman, Qatar and the UAE. Reverse causality has been validated for Lebanon and Bahrain only. We also find that there is a positive impact on Israel’s economic stability over the stability of Bahrain, Kuwait and the UAE with different seasonal patterns. In the reverse direction, in response to a shock to Israel’s economic stability, the stability of the UAE, Saudi Arabia, Oman, and Kuwait are also found to be positive and significant with different seasonal frequencies
The Impact of Political Stability on Environmental Quality in the Long Run: The Case of Turkey
No full textIn the 21st century, environmental problems are considered the biggest challenges. Turkey is one of the emerging markets that need to improve the quality of their environment. In the literature, how political risk affects the environment in Turkey has not been studied. In order to contribute to the issue, this study aims to determine the impact of political stability on the quality of the environment in Turkey. The present study investigates the effect of political stability on environmental quality, taking into account the critical role of economic growth, environmental regulation, patents in environmental technologies, and renewable energy consumption in Turkey from 1990 to 2019. The present study used nonlinear autoregressive distributed lag (NARDL) and dynamic ordinary least square (DOLS) models to investigate the effect of political stability on environmental quality in Turkey. The empirical findings show that political stability in Turkey reduces environmental deregulation by declining CO2 emissions. Similarly, patents in environmental technologies and renewable energy consumption positively contribute to the environmental quality in Turkey by decreasing CO2 emissions. On the other hand, economic growth has a significant positive effect on CO2 emissions. This study suggests that political stability is an important indicator of environmental quality in Turkey. In order to ensure the continuity of Turkey’s environmental sustainability, political tension in the country should be controlled by politicians, and it is recommended that Turkey should turn to and invest in renewable energy sources by following technological innovation
Innovation capacity, business sophistication and macroeconomic stability: empirical evidence from OECD countries
No full textThe main aim of this study is to explore the linkages between innovation capacity, business sophistication, and macroeconomic stability within OECD countries. In order to obtain information regarding the relationship between time series variables, the Pedroni cointegration, Kao cointegration, fully modified ordinary least square, dynamic ordinary least square, Granger causality, and Dumitrescu Hurlin causality tests are employed. The empirical results reveal that improvement in business sophistication triggers innovation capacity and support macroeconomic stability. Innovation capacity would also need to be expanded in the long-run, which positively leads to advanced business sophistication that has a cyclical effect. If policymakers intend to accelerate business sophistication, then their attention should be directed towards maximizing the economic indicators in the long-run. To the best of our knowledge, the linkage between innovation capacity, business sophistication and macroeconomic stability in OECD countries has not been comprehensively explored through the use of a single dataset. Thus, the findings of this study could lead to a new debate regarding the concept
Sustainable development and investment in artificial intelligence in the USA
No full textAbstract Business practices and government policies are rapidly being reshaped by artificial intelligence (AI) in today’s world. However, it is still unclear whether AI will accelerate or hinder progress on sustainable development goals. Within this perspective, the present study aims to capture the asymmetric effect of investment in AI on the sustainable development goals (SDGs) index in the USA while taking into account green electricity and gross domestic product. Using newly developed estimators, the study explores this relationship by considering non-linearity. The results point to the fact that (i) there is a long-run asymmetric linkage between AI, SDGs, GDP, and green electricity; (ii) AI investment contributes to sustainable development positively in the USA; (iii) green electricity contributes to sustainable development in a positive way; (iv) SDGs index is negatively affected by economic growth
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