75 research outputs found
Discretional political budget cycles and separation of powers
No full textIn contrast to previous empirical work on electoral cycles, which implicitly assumes the executive has full discretion over fiscal policy, this paper contends that under separation of powers an unaligned legislature may have a moderating role. Focusing on the budget surplus, we find that stronger effective checks and balances explain why cycles are weaker in developed and established democracies. Once the discretional component of executive power is isolated, there are significant cycles in all democracies. Whether the political system is presidential or parliamentary, or the electoral rules are majoritarian or proportional, does not change the basic results.political budget cycles, asymmetric information, discretion, separation of powers, checks and balances, veto players, rule of law
Polyoxometalate-based nanocarbon composite materials as lithium ion battery electrodes
No full textNowadays, a dependence on coal, oil and natural gas has created severe air pollution and global warming with alarming consequences. Solar energy, wind power, nuclear energy, as well as geothermal energy represent sustainable energy sources which are however “uncontrollable” in dimensions of time and space. The electricity grid, which is powerful in accumulating and re-distributing all the power generated from the above ways, requires high financial investments and infrastructural built-up. Therefore, the whole society’s concerns are concentrating attention once again on portable chemical energy storage systems. The lithium ion battery provides the portability of chemical energy and at the same time delivers this energy as electricity with high conversion efficiency and without pollution. With the fast- increasing development of electric vehicles, the research and development of low-cost, safe, highly efficient rechargeable Li batteries is becoming a priority on the agenda of material scientists. As such, the large-scale fundamental implementation of lithium batteries (or other rechargeable batteries) can not only benefit the stationary storage of electricity connected with the grid, but also provide convenient power usage for portable electric products including vehicles.
Polyoxometalate (POM) chemistry, features a large group of earth-abundant, redox active metal oxide clusters and provides material scientists with infinite possibilities to develop POM-based novel battery materials. POMs are ideal components for molecular cluster batteries (MCBs) which exhibit excellent features including multi-electron storage, where the transition metals provide empty d orbitals that can host excess electrons in order to realize the Li-interaction within molecular structure. The nanocarbon family, including various dimensional carbon allotropes, offers great conductive pathways and architectural building blocks which can incorporate POMs to construct a wide range of POM/nanocarbon hybrid/composite supramolecular structures.
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In this PhD thesis, a state-of-the-art of the POM/nanocarbon energy materials is summarized and the research works that have been contributed by the author during his PhD studies are discussed. The linkage of POMs and various dimensional nanocarbon allotropes can be generally classified into covalent binding, non-covalent attachment and electrostatic assembly. On the other hand, the architectural built-up can be summarized by the topological characteristics of nanocarbon substrates, including 0D graphene quantum dots, 1D carbon nanotubes, 2D graphene and graphene oxide as well as 3D porous carbon matrix. In this context, according to the author and his collaborators’ own contribution, four different types of POM based superstructures are critically investigated which are:
1) Sonication-driven-growth of POM nanocrystals on 1D single-walled carbon nanotubes;
2) Self-assembly of POM clusters and 0D graphene quantum dots into nanorod-like composites;
3) Immobilization of POM clusters on 3D hierarchical porous polymers;
4) Incorporation of polyoxovanadates into 3D metal organic framework followed by pyrolysis to form alloyed cobalt vanadium oxide/carbon hierarchical composites
THE MATERIALITY AND SPATIALITY OF GRAVES AND GRAVE MARKERS IN THE BORDER REGION BETWEEN LUXEMBOURG AND GERMANY
No full textThis PhD thesis is the partial result of the research project entitled "Material Culture and Spaces of Remembrance – A Study of Cemeteries in Luxembourg in the Context of the Greater Region", under the coordination and supervision of Dr. Thomas Kolnberger and Associate Professor Sonja Kmec at the University of Luxembourg, and funded by the Fonds National de la Recherche (FNR).
Building on prior, seminal research, this thesis aims to address the following questions concerning a specific, predefined region between Luxembourg and Germany, and selected cemeteries:
• Does the research approach demonstrated from Anglo-American literature also apply to the sample in the border region between Luxembourg and Germany?
• Does the analysis of materiality within its spatial context provide indications of a neighbouring effect, i.e. do material characteristics appear in spatial clusters?
• With regards to the materiality that can be observed at the selected cemeteries, what might explain the specific appearance of, especially, graves and grave markers; i.e. what factors, such as cemetery regulations or stonemasons, might have had an influence?
Based on a pilot project at Walferdange (Luxembourg) cemetery, as well as a specifically developed and designed data collection approach and tool, the author of this thesis collected the data from full populations of grave and grave marker material culture at three additional, selected cemeteries in Luxembourg and Germany, i.e. Wormeldange, Wincheringen and Konz, in order to allow an analysis of the present assemblage, reaching back into the late 19th century. The data gained thus were analysed using statistical and geo-spatial methods.
The results of this data collection and analysis indicate the following: similar methods compared to, for example, work in the Anglo-American context, can generally be applied; since materiality of funeral culture shows a certain level of fluctuation and volatility over time in this specific research context, the researcher has to be careful in order to ensure appropriate dating; results in a chronologically limited data set in which also accurate spatiality cannot be ensured. Whileclusters of materiality can be identified visually, they do not in all instances produce stable results during statistical testing. Thus, a neighbouring effect cannot in all cases be supported and needs to be critically questioned in the face of different tactical confidence intervals.
Moreover, potential cultural differences and differences in cemetery management, manifested for example in cemetery regulations, are not enough to explain the actual materiality and spatiality that can be found on the researched cemeteries. The author uses additional literature from business studies and economics in order to highlight a different approach in historical archaeological research in understanding grave monument genesis, their explanatory power and studying related phenomena in the future, hypothesizing about business related aspects in the interrelationship between stonemasons and their customers
Usefulness of N-terminal-pro B-type natriuretic peptide as a heart failure marker in patients undergoing percutaneous left atrial appendage occlusion
No full textBackground: The left atrial appendage is involved in secretion of N-terminal-pro B-type natriuretic peptide (NT-proBNP). Percutaneous left atrial appendage occlusion (LAAO) for prevention of stroke may cause variations in NT-proBNP release.
Aim: This study aimed to assess the diagnostic value of NT-proBNP after LAAO.
Methods: The study group comprised 53 patients in whom LAAO was performed. The patients with heart failure (HF) and reduced ejection fraction (EF) were allocated to group I (n = 16) whereas patients with no HF symptoms and EF > 40% were allocated to group II (n = 37). The symptomatic patients with EF > 40% were excluded. NT-proBNP values were measured prior to LAAO, at one–two days, and at three-month follow-up. EF, six-minute walk test (6MWT), and peak oxygen consump¬tion (VO2max) were assessed 24 h prior to LAAO and after three months.
Results: Prior to LAAO the NT-proBNP level was higher in group I, when compared to group II (3084.74 ± 559.53 pg/mL vs. 808.02 ± 115.83 pg/ml, p < 0.01). In both groups there was a nonsignificant increase in NT-proBNP level at one–two days after LAOO (3100.14 ± 690.08 pg/mL in group I and 1012.09 ± 166.71 pg/mL in group II). At the three-month follow-up a fur¬ther increase of NT-proBNP level in group I (3852.73 ± 1025.78 pg/mL) and a decrease in group II (855.03 ± 107.49 pg/mL) was observed. The pairwise comparison between the means of 6MWT and VO2max showed no significant changes during follow-up. At baseline, NT-proBNP level of 988 pg/mL presented 87.5% sensitivity and 75.7% specificity for prediction of HF. Three months after LAAO, it increased to 1358 pg/mL (sensitivity 81.2%, specificity 78.4%).
Conclusions: When diagnosing HF in atrial fibrillation patients, the higher cut-off value of NT-proBNP should be used. NT-proBNP remains an appropriate diagnostic marker of HF in patients after LAAO.Wstęp: Uszko lewego przedsionka bierze udział w sekrecji N-końcowego fragmentu propeptydu natriuretycznego typu B (NT-proBNP). Zabiegi przezskórnej eliminacji uszka lewego przedsionka (LAAO) w celu profilaktyki udaru mózgu u chorych z migotaniem przedsionków mogą mieć wpływ na uwalnianie NT-proBNP.
Cel: Celem niniejszej pracy było określenie przydatności oznaczeń NT-proBNP po zabiegach LAAO.
Metody: Grupę badaną stanowiło 53 chorych poddanych LAAO. Pacjenci z niewydolnością serca (HF) i obniżoną frakcją wyrzutową lewej komory (EF) stanowili grupę I (n = 16), natomiast pacjenci bez HF i z EF > 40% — grupę II (n = 37). Pacjenci, u których występowały objawy, z EF > 40% nie byli włączeni do badania. NT-proBNP oznaczano przed zabiegiem LAAO, 1–2 dni po LAAO oraz po 3 miesiącach od zabiegu. Test 6-minutowego marszu (6MWT), ocena EF i maksymalnego zużycia tlenu (VO2max) były przeprowadzane 24 godziny przed LAAO oraz po 3 miesiącach.
Wyniki: Przed zabiegiem stężenie NT-proBNP wynosiło 1495 ± 1703 pg/ml. Stwierdzono nieznamienny wzrost stężenia NT-proBNP po 1–2 dniach od LAAO (1642,45 ± 1961,21 pg/ml, p = 0,44) oraz w obserwacji 3-miesięcznej (1759,99 ± 2661,33 pg/ml, p = 0,62). Porównanie parami wyników 6MWT i VO2max nie wykazało istotnych różnic. Wyjściowo stężenie NT-proBNP 988 pg/ml cechowała czułość wynosząca 87,5% i specyficzność wynosząca 75,7% w rozpoznawaniu HF. W obserwacji 3-miesięcznej wartość ta wzrosła do 1358 pg/ml (czułość — 81,2%, specyficzność — 78,4%).
Wnioski: W przebiegu migotania przedsionków należy stosować wyższe wartości odcięcia NT-proBNP w celu rozpoznania HF. NT-proBNP pozostaje właściwym markerem HF u pacjentów, u których wykonano zabieg LAAO
Wady wielozastawkowe — złożony problem wymagający indywidualizacji diagnostyki i leczenia
No full text16-28: Residual leaks after left atrial appendage closure in correlation to the shape of ostium and lending zone
No full textThe Extended Utility of CHA2DS2VASc and HAS-BLED Scores in the Selection for Transcutaneous Left Atrial Appendage Closure
No full textBackground and purpose: Left atrial appendage closure (LAAC) is an option for stroke prevention in atrial fibrillation patients. Randomized studies have demonstrated the effectiveness and safety of LAAC but included patients with an average risk of stroke and bleeding complications. The current study aimed to assess the extended utility of CHA2DS2VASc (congestive heart failure; hypertension; age ≥75 years [doubled]; type 2 diabetes; previous stroke, transient ischemic attack, or thromboembolism [doubled]; vascular disease; age 65 to 75 years; and sex category) and HAS-BLED (hypertension; abnormal renal/liver function; stroke; bleeding history or predisposition; labile INR, elderly, drugs/alcohol concomitantly) scores for qualification and prognosis after LAAC. Methods: The study population comprised 270 patients aged 72.8 ± 8.78 years. The occluders used were the Amplatzer Amulet (N = 205), Amplatzer Cardiac Plug (N = 53), and Watchman device (N = 12). The prognosis after LAAC was analyzed for different cohorts of patients distinguished based on different CHA2DS2VASc and HAS-BLED scores. The mean duration of follow-up was 21.6 ± 10.3 months. Results: The observed rates of ischemic stroke and bleeding were much lower than that expected (2.2% vs. 5.6%, and 0.76% vs. 6.05%, respectively). The mortality rate did not differ concerning the CHA2DS2CVASc score. It was significantly lower (8.3%) for HAS-BLED < 3, and it raised to 17.9% for HAS-BLED = 3 and to 25.9% for HAS-BLED > 3. Significant differences (p = 0.003) occurred for Kaplan–Meier curves for extreme HAS-BLED subgroups. A composite endpoint was most often found in high/very high risk of bleeding patients. Conclusions: HAS-BLED, but not CHA2DS2CVASc score, may be a useful tool to predict the prognosis of patients after LAAC. Qualification for LAAC based on the risk of stroke should not differ from qualification for anticoagulation. Despite the worse prognosis of patients with the highest bleeding risk, this group is likely to experience the greatest benefit from reducing the bleeding risk from LAAC
The intracardiac concentrations of the N-terminal-pro B-type natriuretic peptide (NT-proBNP) and the determinants of its secretion in patients with atrial fibrillation
No full textBackground: N-terminal-pro B-type natriuretic peptide (NT-proBNP) is elevated not only in heart failure (HF) but also in atrial fibrillation (AF). The role and secretion pattern of NT-proBNP in AF is still undetermined.
Aim: The study aimed to assess NT-proBNP concentrations in patients with and without preserved left ventricular ejection fraction (LVEF) depending on the type of AF. It was also intended to define the main source of NT-proBNP production within the heart. In addition, it aimed to study the relation of NT-proBNP with some echocardiographic parameters reflecting the stretch of heart chambers as well as with the chosen parameters of physical capacity.
Methods: Blood samples were collected from the right atrium (RA), left atrium (LA), and femoral artery (FA) in 53 patients referred for occlusion of the LA appendage. Thirty patients were assigned into Group I (LVEF ≥ 50%, no HF symptoms) and the remaining 23 patients to Group II (LVEF < 50%, HF symptoms). NT-proBNP concentrations were determined using the ELISA test.
Results: In Group I, the lowest NT-proBNP level was found in RA (460.47 ± 723.15 pg/mL and 1097.72 ± 851.42 pg/mL for paroxysmal and permanent AF, respectively), higher in LA (481.5 ± 724.56 pg/mL and 1188.06 ± 851.42 pg/mL for paroxysmal and permanent AF), and the highest values in FA (537.77 ± 808.49 pg/mL and 1188.04 ± 798.28 pg/mL for paroxysmal and permanent AF). In Group II the NT-proBNP values were significantly higher compared to Group I (p < 0.01), but similarly values in RA were the lowest (183.47 ± 1826.08 pg/mL and 2141.68 ± 1801.69 pg/mL for paroxysmal and permanent AF), intermediate values were observed in LA (1857.57 ± 2221.39 pg/mL and 2386.81 ± 2067.2 pg/mL for paroxysmal and permanent AF), and the highest were seen in FA (1936.27 ± 2149.85 and 2437.33 ± 1999.37 pg/mL for paroxysmal and permanent AF, respectively). In Group I, NT-proBNP from LA best correlated with LA area (r = 0.56) and RA area (r = 0.56). In Group II, the strongest correlations were found between NT-proBNP from LA and left ventricular end-systolic dimension (r = 0.57) and volume (r = 0.6).
Conclusions: NT-proBNP is markedly elevated in the majority of patients with AF even in the absence of HF. LA secretion of NT-proBNP is an important contributor to the overall increase of NT-proBNP also in HF patients. In AF patients, the concentration of NT-proBNP correlates with the remodelling of heart chambers, but not with physical capacity.Wstęp: Stężenie N-końcowego peptydu natriuretycznego typu B (NT-proBNP) wzrasta nie tylko w niewydolności serca (HF), ale także w migotaniu przedsionków (AF). Patofizjologia sekrecji NT-proBNP w migotaniu przedsionków wciąż nie jest w pełni wyjaśniona.
Cel: Celem badania była ocena wewnątrzsercowych stężeń NT-proBNP u pacjentów z prawidłową bądź obniżoną frakcją wyrzutową lewej komory serca w zależności od typu AF. Ponadto celem było określenie głównego źródła wydzielania NT-proBNP w obrębie jam serca oraz związku jego wydzielania z echokardiograficznymi wykładnikami rozciągania włókien mięśniowych oraz wybranymi parametrami wydolności fizycznej.
Metody: U 53 pacjentów poddawanych zabiegom przezskórnego zamknięcia uszka lewego przedsionka pobrano próbki krwi z prawego przedsionka (RA), lewego przedsionka (LA) oraz tętnicy udowej (FA). Pacjenci z frakcją wyrzutową lewej komory (LV-EF) &gt; 50% i brakiem klinicznych objawów HF stanowili Grupę I, natomiast chorzy z LV-EV&lt;50% i objawami HF stanowili Grupę II. NT-proBNP oznaczano w pobranych próbkach krwi testem ELISA.
Wyniki: U pacjentów w Grupie II stwierdzono znamiennie wyższe wartości NT-proBNP (P<0,01). Współwystępowanie utrwalonego migotania przedsionków wiązało się niezależnie od LV-EF z wyższymi wartościami NT-proBNP (P<0,01). Analiza wariancji ANOVA dla powtarzanych pomiarów NT-proBNP nie wykazała istotnych różnic w próbkach krwi pobranych z różnych jam serca.
Wnioski: Stężenie NT-proBNP jest istotnie podwyższone u większości pacjentów z migotaniem przedsionków niezależnie od rozpoznania HF. Wydzielanie NT-proBNP w lewym przedsionku ma znaczący udział w całkowitej sekrecji NT-proBNP u pacjentów z HF. U pacjentów z AF stężenie NT-proBNP koreluje z remodelingiem jam serca, natomiast nie ma związku z ich wydolnością fizyczną
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