465 research outputs found

    Der EU-Erweiterungsprozess und die Gretchenfrage: Ist Demokratie käuflich?

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    Inhalt: Problemstellung; Demokratieförderung – was steckt dahinter?; Demokratie; Demokratieförderung und externe Akteure; Konsolidierung; Konditionalität; Zusammenfassung; Motive des Handelns – Rationalität oder Überzeugung?; Der Weg zur EU-Mitgliedschaft; Neumitglieder in der EU – durch und durch demokratisch?; Konditionalität versus Sozialisierung; Die Bedeutung von Opportunitätskosten; Zusammenfassung; Konditionalität – eine Strategie stößt an ihre Grenzen; Fazit: Demokratische Überzeugung ist nicht käuflich; Literaturverzeichni

    Einfluss von Oberflächeneigenschaften auf die thermoelektrischen Transporteigenschaften einzelner einkristalliner Nanodrähte

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    Diese Arbeit demonstriert die vollständige thermoelektrische Charakterisierung einzelner einkristalliner Bismuttellurid- und Silbernanodrähte und deren anschließende lokale strukturelle und chemische Charakterisierung mittels analytischer Transmissionselektronenmikroskopie. Die lokale strukturelle, chemische und morphologische Charakterisierung entlang der Nanodrähte trägt essentiell zum Verständnis des thermoelektrischen Transportes bei und bestätigt die Korrelation zwischen Oberflächen- und den thermoelektrischen Eigenschaften. Für durchmesservariierte Bismuttelluridnanodrähte wird der Einfluss der Morphologie auf die Wärmeleitfähigkeit bei Raumtemperatur quantifiziert. Im Vergleich zu einem glatten Referenznanodraht zeigt der durchmesservariierte Nanodraht gleicher Zusammensetzung und Kristallorientierung eine Reduktion der Wärmeleitfähigkeit um 55 %. Diese Reduktion kann durch Phononenrückstreuung an der eingekerbten Oberfläche erklärt werden. Die elektrische Leitfähigkeit und der Seebeckkoeffizient der Bismuttelluridnanodrähte deuten auf einen topologischen Oberflächenzustand hin. Für Silbernanodrähte werden die elektrische Leitfähigkeit und die Wärmeleitfähigkeit im Temperaturbereich von 1,4 K bis 300 K gemessen. Mit fallender Temperatur steigt die relative Reduktion der Wärmeleitfähigkeit im Verhältnis zur elektrischen Leitfähigkeit stärker, sodass die Lorenzzahl die klassische Wiedemann-Franz-Relation nicht erfüllt und eine Funktion der Temperatur darstellt. Der Temperaturverlauf der Lorenzzahl der Silbernanodrähte entspricht der 1938 von Makinson aufgestellten Theorie für hochreine Metalle und ist im Tieftemperaturbereich um bis zu zwei Größenordnungen zum Sommerfeldwert reduziert.This work demonstrates the full thermoelectric characterisation of individual single crystalline bismuth telluride and silver nanowires and their subsequent local structural and chemical characterisation via analytical transmission electron microscopy along the whole nanowires. Therefore, the correlation between the structure, in particular the surface morphology, and the thermoelectric transport properties is unambiguously shown. For diameter varied bismuth telluride nanowires the influence of the morphology on the thermal conductivity is quantified at room temperature. The diameter varied nanowire shows a reduction of 55 % with respect to the smooth nanowire of the same chemical composition and structural orientation. This reduction can be explained by phonon backscattering at the indents. The electrical conductivity and the Seebeck coefficient indicate the presence of a topological surface state. For silver nanowires the electrical and thermal conductivity are determined in the temperature range between 1.4 K and 300 K. With decreasing temperature the relative reduction of the thermal conductivity is higher than the reduction of the electrical conductivity resulting in a temperature-dependent Lorenz number, so that the classical Wiedemann-Franz relation is not fulfilled. The temperature characteristic of the silver nanowires'' Lorenz number is in agreement with the theory Makinson established for highly pure metals in 1938 and is reduced by two orders of magnitude with respect to the Sommerfeld value in the low temperature regime

    Epidemiology, Symptoms, and Treatment Characteristics of Hyponatremic Psychiatric Inpatients

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    Hyponatremia is a common phenomenon in psychiatry occurring as an adverse effect to drugs or following polydipsia. We performed a retrospective in-depth analysis of hyponatremia cases in a large unselected population of psychiatric inpatients. During a 3-year period, all cases of hyponatremia were identified among patients admitted to a large psychiatric state and university hospital by the institution's electronic laboratory database. Demographic, treatment-related, and laboratory data were obtained by consecutive chart review, respectively. Hyponatremia occurred in 347 (4.9%) of 7113 cases, of which the majority (78%) displayed only a mild manifestation. Symptoms were recorded in 28.8% of cases, already occurred in mild forms, and comprised gait impairment (45%, including falls), confusion (30%), sedation (26%), and dyspepsia (41%). Age, female sex, nonpsychiatric drug polypharmacy-particularly with thiazides and/or angiotensin-converting enzyme inhibitors-and diagnosis of a mood disorder were associated with more severe hyponatremia, respectively. The proportion of hyponatremic patients treated with venlafaxine, trazodone, carbamazepine, oxcarbazepine, and first-generation antipsychotics, respectively, was significantly higher in the hyponatremia sample than in the normonatremic population. This was, surprisingly, not the case with selective serotonin reuptake inhibitors or any other antidepressant drug class. We found prescription with second-generation antipsychotics to be significantly associated with less severe hyponatremia. Hyponatremia may be mainly attributed to the syndrome of inappropriate antidiuretic hormone secretion, as indicated by decreased serum osmolarity in our sample. Besides old age and female sex, treatment with certain drugs-rather than whole drug classes-carries a substantially increased risk

    Epidemiology, Symptoms, and Treatment Characteristics of Hyponatremic Psychiatric Inpatients

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    Hyponatremia is a common phenomenon in psychiatry occurring as an adverse effect to drugs or following polydipsia. We performed a retrospective in-depth analysis of hyponatremia cases in a large unselected population of psychiatric inpatients. During a 3-year period, all cases of hyponatremia were identified among patients admitted to a large psychiatric state and university hospital by the institution's electronic laboratory database. Demographic, treatment-related, and laboratory data were obtained by consecutive chart review, respectively. Hyponatremia occurred in 347 (4.9%) of 7113 cases, of which the majority (78%) displayed only a mild manifestation. Symptoms were recorded in 28.8% of cases, already occurred in mild forms, and comprised gait impairment (45%, including falls), confusion (30%), sedation (26%), and dyspepsia (41%). Age, female sex, nonpsychiatric drug polypharmacy-particularly with thiazides and/or angiotensin-converting enzyme inhibitors-and diagnosis of a mood disorder were associated with more severe hyponatremia, respectively. The proportion of hyponatremic patients treated with venlafaxine, trazodone, carbamazepine, oxcarbazepine, and first-generation antipsychotics, respectively, was significantly higher in the hyponatremia sample than in the normonatremic population. This was, surprisingly, not the case with selective serotonin reuptake inhibitors or any other antidepressant drug class. We found prescription with second-generation antipsychotics to be significantly associated with less severe hyponatremia. Hyponatremia may be mainly attributed to the syndrome of inappropriate antidiuretic hormone secretion, as indicated by decreased serum osmolarity in our sample. Besides old age and female sex, treatment with certain drugs-rather than whole drug classes-carries a substantially increased risk

    Physical inactivity causes endothelial dysfunction

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    ЭНДОТЕЛИЙ /ПОВРЕЖДЭПИТЕЛИЙ /ПОВРЕЖДДВИГАТЕЛЬНАЯ НАГРУЗКА, МЕТОДЫ ИССЛЕДОВАНИЯФИЗИЧЕСКОЕ НАПРЯЖЕНИ

    Flexible CO<sub>2</sub> sensor architecture with selective nitrogen functionalities by one-step laser-induced conversion of versatile organic ink

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    Nitrogen-doped carbons (NC) are a class of sustainable materials for selective CO2 adsorption. We introduce a versatile concept to fabricate flexible NC-based sensor architectures for room-temperature sensing of CO2 in a one-step laser conversion of primary coatings cast from abundant precursors. By the unidirectional energy impact in conjunction with depth-dependent attenuation of the laser beam, a layered sensor heterostructure with porous transducer and active sensor layer is formed. Comprehensive microscopic and spectroscopic cross-sectional analyses confirm the preservation of a high content of imidazolic nitrogen in the sensor. The performance was optimized in terms of material morphology, chemical composition, and surface chemistry to achieve a linear relative resistive response of up to ∆R/R0 = -14.3% (10% of CO2). Thermodynamic analysis yields ΔadsH values of -35.6 kJ·mol-1 and 34.1 kJ·mol-1 for H2O and CO2, respectively. The sensor is operable even in humid environments (e.g., ∆R/R0,RH=80% = 0.53%) and shows good performance upon strong mechanical deformation

    Synthesis of organic inorganic hybrids based on the conjugated polymer P3HT and mesoporous silicon

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    Organic inorganic hybrids are a class of functional materials that combine favorable properties of their constituents to achieve an overall improved performance for a wide range of applications. This article presents the synthesis route for P3HT porous silicon hybrids for thermoelectric applications. The conjugated polymer P3HT is incorporated into the porous silicon matrix by means of melt infiltration. Gravimetry, sorption isotherms and energy dispersive X ray spectroscopy EDX mapping indicate that the organic molecules occupy more than 50 of the void space in the inorganic host. We demonstrate that subsequent diffusion based doping of the confined polymer in a FeCl3 solution increases the electrical conductivity of the hybrid by five orders of magnitude compared to the empty porous silicon hos

    Resolving electron and hole transport properties in semiconductor materials by constant light-induced magneto transport

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    The knowledge of minority and majority charge carrier properties enables controlling the performance of solar cells, transistors, detectors, sensors, and LEDs. Here, we developed the constant light induced magneto transport method which resolves electron and hole mobility, lifetime, diffusion coefficient and length, and quasi-Fermi level splitting. We demonstrate the implication of the constant light induced magneto transport for silicon and metal halide perovskite films. We resolve the transport properties of electrons and holes predicting the material’s effectiveness for solar cell application without making the full device. The accessibility of fourteen material parameters paves the way for in-depth exploration of causal mechanisms limiting the efficiency and functionality of material structures. To demonstrate broad applicability, we further characterized twelve materials with drift mobilities spanning from 10–3 to 103 cm2V–1s–1 and lifetimes varying between 10–9 and 10–3 seconds. The universality of our method its potential to advance optoelectronic devices in various technological fields
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