323,030 research outputs found
Studium diradikálů multireferenčními metodami spřažených klastrů s explicitní korelací
No full textNázev práce: Studium diradikálů multireferenčními metodami spřažených klastrů Autor: Matej Švaňa Katedra: Katedra fyzikální a makromolekulární chemie Vedoucí diplomové práce: Mgr. Jiří Pittner, Dr. rer. nat., Ústav fyzikální chemie J. Heyrovského Abstrakt: Tematem diplomové práce je studium isomerizace cyklopropánu přes trimetylénový/propylidénový diradikál pomocí jednak konvenční a jed- nak multireferenční metody vázaných klastrů. Hlavním cílem bylo srovnat konvergenci získaných energií s velikostí použité báze pro konvenční a explic- itně korelované MRCC výpočty. Podle očekávání výsledky ukázaly, že explic- itní korelace vede k výraznému zlepšení konvergence (cca o jedno kardinální číslo), což umožňuje výrazné úspory výpočetního času. Navíc výpočty po- mocí MkCCSD(T)-F12/QZ a BWCCSD(T)-F12/QZ metod patří mezi ty ne- jsofistikovanejší, jaké kdy byli na výpočet relativní energií cyklopropánu a trimetylénu/propylidénu použity. Klíčová slova: explicitně korelované, spřažené klastry, multireferenční, isomerizace cyclopropánu, trimetylén, propylidén 1Title: Study of Diradicals by Explicitly Correlated Multireference Coupled Cluster Methods Author: Matej Švaňa Department: Department of Physical and Macromelecular Chemistry Supervisor: Mgr. Jiří Pittner, Dr. rer. nat., J. Heyrovský Institute of Physical Chemistry Abstract: Total energies of cyclopropane, trimethylene, and propylidene were calculated with conventional post-HF CCSD(T), BWCCSD(T), MkCCSD(T) methods and their explicitly correlated alternatives. Main aims of the the- sis were to compare the basis set convergence of total energies and relative energies between cyclopropane and trimethylene/propylidene, both at the conventional and the explicitly correlated levels. It was shown that use of explicit correlation accelerates the convergence of the total energy by one or- der of basis set quality, resulting in considerable savings in computational times. Also, the MkCCSD(T)-F12/QZ and the BWCCSD(T)-F12/QZ calcula- tions belong to the most sophisticated approaches employed for estimation of the relative energies of cyclopropane and trimethylene/propylidene to date. Keywords: explicitly correlated, coupled cluster, multi-reference, cyclopropane isomerisation, trimethylene, propylidene 1Katedra fyzikální a makromol. chemieDepartment of Physical and Macromolecular ChemistryPřírodovědecká fakultaFaculty of Scienc
Fiscal stimuli during the COVID-19 crisis
No full textPričujoče diplomsko delo obravnava krizo covid-19, s posebnim poudarkom na fiskalnih intervencijah, implementiranih v gospodarstvih G7. Začnemo s pregledom učinkov pandemije covida-19, ki ga nadaljujemo z obravnavo značilnosti fiskalnih intervencij v gospodarstvih skupine G7. Države so v boju proti zdravstvenim in ekonomskim posledicam koronavirusne krize reagirale s fiskalnimi paketi, ki so po obsegu in strukturi heterogeni in neprimerljivi z dosedanjimi krizami. Pregled empirične literature kaže, da so se države na pandemično recesijo ustrezno odzvale. Spričo primerjalne analize na osnovi izbranih makroekonomskih indikatorjev ugotavljamo, da je presoja uspešnosti soočanja s koronavirusno krizo odvisna od opazovanega indikatorja in se ta med gospodarstvi G7 razlikuje. Zaradi signifikantnega vpliva fiskalnih spodbud na javne finance posebno pozornost posvečamo javnofinančnim pozicijam držav EU v postcovidnem obdobju, s poudarkom na fiskalnih pravilih in morebitnih scenarijih, v katerih bi se članice Unije lahko znašle v prihodnosti.The present thesis provides an assessment of the COVID-19 crisis, with a special emphasis on the fiscal interventions implemented in the G7 economies. We begin with an overview of the effects caused by the COVID-19 pandemic, and continue with an examination of the characteristics of fiscal interventions in the G7 economies. In the fight against the health and economic consequences of the coronavirus crisis, countries have reacted with fiscal packages, heterogenous by scope and size and incomparable to previous crises. An empirical literature review shows that countries have responded to the pandemic recession accordingly. In the light of comparative analysis based on chosen macroeconomic indicators, we find that the assessment of success in dealing with the coronavirus crisis depends on the observed indicator and it varies among G7 countries. Due to the significant impact of fiscal stimuli on public finances, we dedicate special attention to public finance positions of EU countries in the postcovid era, underlining fiscal rules and possible scenarios member states may be facing in the future
Analysis of the fiscal sustainability of the G20 economies
No full textZagotavljanje zdravih javnih financ postaja v okolju naraščajočih obrestnih mer in javnih dolgov vse pomembnejše za nosilce fiskalne politike, ki s svojim delovanjem opravljajo pomembne funkcije alokacije resursov, redistribucije dohodkov in stabilizacije gospodarstva. Vsled naraščajočih demografskih izzivov, potrebe po financiranju zelene in digitalne transformacije in ob prisotnosti geopolitičnih trenj je zagotavljanje fiskalne vzdržnosti in oblikovanje zadostnih fiskalnih rezerv v nekriznih časih ključnega pomena za učinkovito spopadanje z izzivi in stabilizacijo gospodarstva v času gospodarskih kriz. Zato v magistrskem delu s panelnimi testi stacionarnosti in kointegracije empirično testiramo fiskalno vzdržnost gospodarstev skupine G7 in gospodarstev G20 brez držav skupine G7, pri čemer prvi panel vključuje analizo za obdobje med leti 1950 in 2022, drugi panel pa za obdobje med leti 1998 in 2022. Članice G7 in G20 obravnavamo zaradi njihove vloge pri sooblikovanju globalnega gospodarskega okolja in spodbujanju mednarodnega gospodarskega sodelovanja ter usklajevanja med geografsko, kulturno in politično različnimi državami. Analizo pričnemo s pregledom teoretičnih izhodišč s področja javnih financ, primerjave pogledov različnih ekonomskih šol, opredelitve medčasovne proračunske omejitve in pomena zagotavljanja fiskalne vzdržnosti. Teoretična izhodišča dopolnjujemo z empirično evidenco, ki izkazuje mešane rezultate. Medtem ko konvencionalne metode ne beležijo toliko rezultatov za potrditev vzdržnosti javnih financ, panelne študije ponujajo več dokazov v prid fiskalne vzdržnosti, ki je potrjena tudi za gospodarstva G7. Nadaljujemo s pregledom javnofinančnih agregatov članic G20, ki jih nato uporabljamo v empirični analizi. V empiričnem delu testiramo stacionarnost državnih prihodkov, državnih izdatkov, primarnega salda in javnega dolga, pri čemer stacionarnost javnega dolga testiramo le v prvi diferenci. Kointegracijo testiramo v treh parih, in sicer (1) med državnimi prihodki in državnimi izdatki, (2) med primarnim saldom in odloženim javnim dolgom in (3) med javnim dolgom in odloženim primarnim saldom. Stacionarnost smo izvajali s testi prve in druge generacije, natančneje z LLC testom, IPS testom, Breitungovim testom, Fisherjevim-ADF in Fisherjevim-PP testom ter s Pesaran CIPS testom. Kointegracijo smo izvedli s Pedronijevim testom. Empirična analiza ponuja dokaze v prid fiskalne vzdržnosti gospodarstev v skupini G20.In an environment of rising interest rates and public debt, ensuring sound public finances is becoming increasingly important for fiscal policy makers, whose actions perform the important functions of resource allocation, income redistribution and economic stabilisation. In the face of growing demographic challenges, the need to finance green and digital transformation, and in the presence of geopolitical tensions, ensuring fiscal sustainability and building sufficient fiscal buffers in non-crisis times is crucial to effectively address challenges and stabilise the economy in times of economic downturns. Therefore, in this master’s thesis, we empirically test the fiscal sustainability of the G7 and G20 economies excluding the G7 using panel tests of stationarity and cointegration, with the first panel including an analysis for the period 1950-2022 and the second panel for the period 1998-2022. We consider the G7 and G20 members because of their role in co-shaping the global economic environment and promoting international economic cooperation and coordination between geographically, culturally and politically diverse countries. We begin the analysis by reviewing the theoretical background of public finance, comparing the views of different schools of economic thought, defining the intertemporal fiscal constraint and the importance of ensuring fiscal sustainability. The theoretical background is complemented by empirical evidence, which shows mixed results. While conventional methods do not record as many results to confirm the sustainability of public finances, panel studies offer more evidence in favour of fiscal sustainability, which is also confirmed for the G7 economies. We proceed with an overview of the fiscal aggregates of G20 members, which are then used in the empirical analysis. In the empirical work, we test for stationarity of government revenues, government expenditures, the primary balance and government debt, with stationarity of government debt tested only in first difference. We test for cointegration in three pairs, namely (1) between government revenues and government expenditures, (2) between the primary balance and lagged government debt, and (3) between government debt and lagged primary balance. Stationarity was tested using first- and second generation tests, specifically the LLC test, the IPS test, the Breitung test, the Fisher-ADF, the Fisher-PP tests and the Pesaran CIPS test. Cointegration was performed with the Pedroni test. The empirical analysis provides evidence in favour of fiscal sustainability of the G20 economies
Black esophagus in forensic autopsies: impressive finding and cause of death?
No full textBlack esophagus (BE) is characterized by a discoloration of the esophageal mucosa, commonly arising from acute esophageal necrosis. The underlying pathogenesis of BE is poorly understood though it is frequently associated with comorbidities, such as diabetes mellitus, alcohol abuse, infections. Determining the cause of death in cases involving BE at autopsy can be particularly challenging. The report presents the case of a 45-year-old man with a history of alcohol abuse. Autopsy revealed extensive BE along with bilateral pneumonia. Cause of death was determined to be severe pneumonia in combination with acute esophageal necrosis, against a background of chronic alcohol abuse. This case underscores the importance of a thorough forensic investigation, including anamnestic information, autopsy findings and histopathological examination, in order to accurately establish the cause of death, even in presence of dramatic findings such as BE
Process, eventuality and wieder/again
No full textThis paper argues for a scopal explanation of the readings of the adverb wieder (‘again’). It is the syntactic entity that wieder is related to which determines whether the repetitive or the restitutive reading obtains. If it is adjoined to the minimal verbal domain, it relates to a situation-internal state thus producing a restitutive interpretation, if adjoined to a higher verbal projection, it relates to an eventuality resulting in a repetitive interpretation. Proceeding from the assumption that adverbial adjuncts have base positions which reflect their semantic relations to the rest of the sentence, repetitive wieder is shown to belong to the class of eventuality adverbs that minimally c-command the base positions of all arguments, whereas restitutive wieder has many properties in common with process (manner) adjuncts that minimally c-command the verb in clause-final base position
Optimalizované simulace kvantových systémů a metoda DMRG
No full textV této práci studujeme kvantové simulace na klasických počítačích z pohledu kvantové teorie informace. Zaměřujme se zejména na silně korelované mnohočásticové vlnové funkce. Ukazujeme, jak je možné pomocí ztrátové kvantové komprese zredukovat množství dat potřebných pro datovou reprezentaci stavu a zkoumáme strukturu entanglementu silně korelovaných chemických systémů. Pro tento účel popisujeme různé míry entanglementu pro metodu DMRG ( metoda Density Matrix Renormalization Group). V rámci DMRG metody implementujeme výpočet zobecnění vzájemné informace (mutual information) pro systém rozdělený na tři části. Uvádíme několik způsobů jak optimalizovat výpočet základního stavu v rámci DMRG. Teoretické závěry jsou podpořeny numerickou simulatcí molekuly diboranu, jenž vykazuje chemicky zajímavou elektronovou strukturu, jako např. 3-centrové 2-elektronové vazby. V teoretické části uvádíme do problematiky kvantové teorie informace v souvislosti s kvantově chemickými systémy, vysvětlujeme motivaci, jenž stojí za naším výběrem toho systému a prezentujeme výsledky svých vlastních výpočtů tříčásticové vzájemne informace (tripartite mutual information). Powered by TCPDF (www.tcpdf.org)Title: Optimizing quantum simulations and the DMRG method Author: Jan Brandejs Department: Department of Chemical Physics and Optics Supervisor: doc. Dr. rer. nat. Jiří Pittner, DSc., J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences Abstract: In this work, we explore the quantum information theoretical aspects of simulation of quantum systems on classical computers, in particular the many- electron strongly correlated wave functions. We describe a way how to reduce the amount of data required for storing the wavefunction by a lossy compression of quantum information. For this purpose, we describe the measures of quantum entanglement for the density matrix renormalization group method. We imple- ment the computation of multi-site generalization of mutual information within the DMRG method and investigate entanglement patterns of strongly correlated chemical systems. We present several ways how to optimize the ground state calculation in the DMRG method. The theoretical conclusions are supported by numerical simulations of the diborane molecule, exhibiting chemically interest- ing electronic structure, like the 3-centered 2-electron bonds. In the theoretical part, we give a brief introduction to the principles of the DMRG method. Then we explain the quantum informational...Institute of Theoretical PhysicsÚstav teoretické fyzikyMatematicko-fyzikální fakultaFaculty of Mathematics and Physic
Diffusive author(s), cohesive author: Analysis of S/N (1994)
No full textThis study indicates the ways in which various aspects of the author(s) are brought forth in Dumb type’s performance art, the S/N production. Previous research has suggested a non-hierarchical organization of Dumb type and the absence of a “privileged author” in Dumb type’s collaborative work, S/N. However, the results that I have investigated from member’s interviews on the creative process of S/N along with my analysis of the recorded images of S/N, indicate a different aspect of the author(s). First, S/N was created through, so to speak, the collective ideas of the members of Dumb type. Further, S/N has at least nine quotations from previous performances, installations, and printed writings, besides the work-in-progress technique. Explicating one of the “author functions” as given by Michel Foucault, each text has plural subjects of the author. However, it has been revealed from members’ interviews that Teiji Furuhashi had a decision-making role in selecting the members’ ideas within the performance. Since then, S/N has had plural subjects of creation; however, Furuhashi is one of the subjects of creation along with the “privileged author.” S/N has plural authors (diffusive authors) yet at the same time, it has a “privileged author,” Teiji Furuhashi (cohesive author)
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
A field study to evaluate PMI estimation methods for advanced decomposition stages
No full textEstimating the postmortem interval (PMI) is one of the major tasks and a continuous challenge in forensic pathology. It is often an exclusion process of available methods, which ultimately can lead to an unsatisfactory outcome due to poor reliability. This problem is most acute in the late PMI, when decomposition proceeds and some methods (such as rigor, livor, and algor mortis) are no longer applicable. Several methods, such as forensic entomology, skeletal muscle protein degradation, and the study of body decomposition by application of a morphological scoring, are expected to provide further information; however, all have certain limitations and weaknesses. Availability of a tool-box of methods allows a case-specific selection of the most appropriate one(s), or eventually provides improvements in the overall accuracy and precision of the PMI estimation by merging and combining methods. To investigate practical (field) application, eventual interferences, and/or synergetic effects, as well as the robustness of these methods towards specific influencing factors, a field study was conducted, using eight pig cadavers of different body weights and physical coverage, left to decompose under natural conditions for 16 days. Morphological changes during decomposition were assessed using the total body score (TBS), muscle samples were collected to analyze protein degradation, and insect colonization was evaluated. The results reveal strengths and current limitations of all tested methods, as well as promising synergistic effects, and thus, provide a baseline for targeted future research
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