Wave Packet Dynamics, Ergodicity, and Localization in Quasiperiodic Chains

In this paper, we report results for the wave packet dynamics in a class of quasiperiodic chains consisting of two types of weakly coupled clusters. The dynamics are studied by means of the return probability and the mean square displacement. The wave packets show anomalous diffusion in a stepwise process of fast expansion followed by time intervals of confined wave packet width. Applying perturbation theory, where the coupling parameter v is treated as perturbation, the properties of the eigenstates of the system are investigated and related to the structure of the chains. The results show the appearance of non-localized states only in sufficiently high orders of the perturbation expansions. Further, we compare these results to the exact solutions obtained by numerical diagonalization. This shows that eigenstates spread across the entire chain for v>0, while in the limit v->0 ergodicity is broken and eigenstates only spread across clusters of the same type, in contradistinction to trivial localization for v=0. Caused by this ergodicity breaking, the wave packet dynamics change significantly in the presence of an impurity offering the possibility to control its long-term dynamics.Comment: 10 pages, 9 figure

Light Transmission Through Metallic-Mean Quasiperiodic Stacks with Oblique Incidence

The propagation of s- and p-polarized light through quasiperiodic multilayers, consisting of layers with different refractive indices, is studied by the transfer matrix method. In particular, we focus on the transmission coefficient of the systems in dependency on the incidence angle and on the ratio of the refractive indices. We obtain additional bands with almost complete transmission in the quasiperiodic systems at frequencies in the range of the photonic band gap of a system with a periodic alignment of the two materials for both types of light polarization. With increasing incidence angle these bands bend towards higher frequencies, where the curvature of the transmission bands in the quasiperiodic stack depends on the metallic mean of the construction rule. Additionally, in the quasiperiodic systems for p-polarized light the bands show almost complete transmission near the Brewster's angle in contrast to the results for s-polarized light. Further, we present results for the influence of the refractive indices at the midgap frequency of the periodic stack, where the quasiperiodicity was found to be most effective.Comment: 10 pages, 7 figure

Charakterisierung und Isolierung von Glycosiden der Pflanze Stevia rebaudiana

Die vorliegende Diplomarbeit wurde im Rahmen eines Industrie-projektes am Department für Lebensmittelwissenschaften und –technologie der Universität für Bodenkultur, durchgeführt. Als Erste von vier Arbeiten, wurde hier die grundlegende „Analyse“ der Pflanze Stevia rebaudiana durchgeführt. Die Untersuchung der Proben (Blätter und bereits aufgereinigte, im Handel erhältliche Pulver) bestand aus vier Teilen. Einer grundle-genden chemischen Untersuchung auf Trockensubstanz, Asche-, Pro-tein- und Zuckergehalt folgte die Festlegung eines geeigneten Lö-sungsmittels für die Steviaglycoside. Danach erfolgte die Überprüfung einer geeigneten Methode zur Analyse mittels HPLC und eine grundlegende Prüfung von NIRS als Schnellmethode zur Untersuchung der Qualität von Wareneingang bzw. fertigem Produkt. Es wurden diverse Lösungsmittel und -methoden getestet [GEUNS 2008, Scaglianti et al., 2008 KOLB et al., 2001 und JECFA 2007], modifiziert und die bestgeeignete für weitere Analysen eruiert. Die Versuche wurden laut Anleitung durchgeführt bzw. bei Lösungsproblemen leicht abgewandelt (z.B.: durch zusätzliche Behandlung mittels Ultraschallbad). Die Untersuchungen und Vergleiche ergaben, dass sich Ethanol am besten als Lösungsmittel eignet. Weiters wurden aus der Literatur beschriebene Methoden zur Analyse des Glycosidgehalts mittels HPLC durchgeführt und ebenfalls abgewandelt. Durch Einstellung des pH-Wertes und Änderung des Drucks beim HPLC-Lauf gelang es, die HPLC-Analyse von zuerst 60 min auf 12 min zu kürzen. Als Laufmittel wurde ein Gemisch aus 80 % Acetonitril und 20 % Wasser für die Analysen mittels HPLC verwendet, welches dann aus einer Rohstoffknappheit von Acetonitril durch ein Laufmittel aus 92 % Methanol und 8 % Wasser ersetzt wurde. Zum Schluss wurden 32 teilweise im Handel gekaufte Pulver und Steviablätter mittels NIRS untersucht. Ziel dieser Untersuchung war es festzustellen, ob die Methode für dieses Pflanzenmaterial grund-sätzlich brauchbar ist, weil sie im Vergleich zur HPLC für große Pro-benmengen besser geeignet ist. Aufgrund der geringen Menge an unterschiedlichen Proben konnte hier nur eine positive Tendenz festgestellt werden. Um eine klare Aussage über die Eignung von NIRS zu treffen, wären mindestens doppelt so viele Proben notwendig.This diploma thesis was written in the context of a collaborative project on the Department of Food Sciences and Technology (University of Natural Ressources and Applied life sciences, Vienna). In this first of four diploma thesis which are part of this project, the basic “analysis” of Stevia rebaudiana was accomplished. The sample analysis (leaves and already cleaned powder, available in trade marked) consisted of four parts. An elementary chemical analysis of dry matter, ash-, protein- and sugar content was followed by the predefinition of a proper solvent for glycosides of stevia rebaudiana. After this an efficient method for HPLC analysis was determined and NIRS as a rapid method (for goods receipt, finished products) proved. Solvents and solvent methods were tested, modified and those most suitable for further analysis determined. Experiments were conducted according the instruction manual, respectively or adopted when solution problems occurred. The examinations and comparisons showed that Ethanol is the best solvent. Furthermore literarily described methods to analyse the glycosid content with HPLC were performed and also adopted accordingly (e.g. by adjusting the pH-value and changing the pressure level dur-ing the HPLC-run, the HPLC-analysis was successfully decreased from 60 minutes to 12 minutes). Initially a mixture of 80% Acetonitril and 20% water was used as mobile phase for HPLC analysis but was later replaced by 92% methanol and 8% water due to a shortage of resources. Finally 32 powders, partly buyable in the store, and Stevia leaves were analysed by NIRS. Goal of the analysis was to determine if the method is suitable for Stevia plant materials because NIRS is better qualified compared to the HPLC for huge amount of samples. Due to the fact of the small amount of different samples there could only a positive tendency be determined. At least twice as much samples would be necessary for a clear statement about the applicability of NIRS

Microvascular Impairment in Patients With Cerebral Small Vessel Disease Assessed With Arterial Spin Labeling Magnetic Resonance Imaging: A Pilot Study

In this pilot study, we investigated microvascular impairment in patients with cerebral small vessel disease (CSVD) using non-invasive arterial spin labeling (ASL) magnetic resonance imaging (MRI). This method enabled us to measure the perfusion parameters, cerebral blood flow (CBF), and arterial transit time (ATT), and the effective T1-relaxation time (T1eff) to research a novel approach of assessing perivascular clearance. CSVD severity was characterized using the Standards for Reporting Vascular Changes on Neuroimaging (STRIVE) and included a rating of white matter hyperintensities (WMHs), lacunes, enlarged perivascular spaces (EPVSs), and cerebral microbleeds (CMBs). Here, we found that CBF decreases and ATT increases with increasing CSVD severity in patients, most prominent for a white matter (WM) region-of-interest, whereas this relation was almost equally driven by WMHs, lacunes, EPVSs, and CMBs. Additionally, we observed a longer mean T1eff of gray matter and WM in patients with CSVD compared to elderly controls, providing an indication of impaired clearance in patients. Mainly T1eff of WM was associated with CSVD burden, whereas lobar lacunes and CMBs contributed primary to this relation compared to EPVSs of the centrum semiovale. Our results complement previous findings of CSVD-related hypoperfusion by the observation of retarded arterial blood arrival times in brain tissue and by an increased T1eff as potential indication of impaired clearance rates using ASL

Partitioning Schemes and Non-Integer Box Sizes for the Box-Counting Algorithm in Multifractal Analysis

We compare different partitioning schemes for the box-counting algorithm in the multifractal analysis by computing the singularity spectrum and the distribution of the box probabilities. As model system we use the Anderson model of localization in two and three dimensions. We show that a partitioning scheme which includes unrestricted values of the box size and an average over all box origins leads to smaller error bounds than the standard method using only integer ratios of the linear system size and the box size which was found by Rodriguez et al. (Eur. Phys. J. B 67, 77-82 (2009)) to yield the most reliable results.Comment: 10 pages, 13 figure

Pathways to Greener Pastures: Research Opportunities to Integrate Life Cycle Assessment and Sustainable Business Process Management Based on a Systematic Tertiary Literature Review

Sustainable Business Process Management (BPM) is a research field that aims to improve the sustainability performance of organizations’ operations. With its focus on business processes, it has the potential to bring sustainability considerations from external reporting to the core of organizations. We present a systematic tertiary literature study to provide a catalog of existing literature reviews and primary work and to give a consolidated overview of the state and research needs of the field. We find that Sustainable BPM research has focused on modeling approaches and most of the work so far is largely conceptual, with a limited sustainability perspective. Based on these findings, we propose an integration of BPM and Life Cycle Assessment (LCA), an established and rigorous method for sustainability analysis. We present research opportunities to show how both disciplines can synergize and leverage methods and techniques for business process automation and innovation to effectively improve the sustainability performance of organizations

DimLift: Interactive Hierarchical Data Exploration through Dimensional Bundling

The identification of interesting patterns and relationships is essential to exploratory data analysis. This becomes increasingly difficult in high dimensional datasets. While dimensionality reduction techniques can be utilized to reduce the analysis space, these may unintentionally bury key dimensions within a larger grouping and obfuscate meaningful patterns. With this work we introduce DimLift , a novel visual analysis method for creating and interacting with dimensional bundles . Generated through an iterative dimensionality reduction or user-driven approach, dimensional bundles are expressive groups of dimensions that contribute similarly to the variance of a dataset. Interactive exploration and reconstruction methods via a layered parallel coordinates plot allow users to lift interesting and subtle relationships to the surface, even in complex scenarios of missing and mixed data types. We exemplify the power of this technique in an expert case study on clinical cohort data alongside two additional case examples from nutrition and ecology.acceptedVersio

High-resolution nerve ultrasound abnormalities in POEMS syndrome: a comparative study

Background: High-resolution nerve ultrasound (HRUS) has been proven to be a valuable tool in the diagnosis of immune-mediated neuropathies, such as chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, M-protein, skin changes) is an important differential diagnosis of CIDP. Until now, there have been no studies that could identify specific HRUS abnormalities in POEMS syndrome patients. Thus, the aim of this study was to assess possible changes and compare findings with CIDP patients. Methods: We retrospectively analyzed HRUS findings in three POEMS syndrome and ten CIDP patients by evaluating cross-sectional nerve area (CSA), echogenicity and additionally calculating ultrasound pattern scores (UPSA, UPSB, UPSC and UPSS) and homogeneity scores (HS). Results: CIDP patients showed greater CSA enlargement and higher UPSS (median 14 vs. 11), UPSA (median 11.5 vs. 8) and HS (median 5 vs. 3) compared with POEMS syndrome patients. However, every POEMS syndrome patient illustrated enlarged nerves exceeding reference values, which were not restricted to entrapment sites. In CIDP and POEMS syndrome, heterogeneous enlargement patterns could be identified, such as inhomogeneous, homogeneous and regional nerve enlargement. HRUS in CIDP patients visualized both increased and decreased echointensity, while POEMS syndrome patients pictured hypoechoic nerves with hyperechoic intraneural connective tissue. Discussion: This is the first study to demonstrate HRUS abnormalities in POEMS syndrome outside of common entrapment sites. Although nerve enlargement was more prominent in CIDP, POEMS syndrome patients revealed distinct echogenicity patterns, which might aid in its differentiation from CIDP. Future studies should consider HRUS and its possible role in determining diagnosis, prognosis and treatment response in POEMS syndrome