Kariesprophylaktische Wirksamkeit von elmex® Kariesschutz Zahnpasta und elmex® Kariesschutz Zahnspülung bei Patienten in kieferorthopädischer Behandlung mit herausnehmbaren Apparaturen: eine klinisch-mikrobiologische Studie

Kieferorthopädische Apparaturen schaffen zusätzliche Retentionsstellen für Mutans-Streptokokken (SM) und erhöhen das Kariesrisiko während der Behandlung. Ob dieses Risiko durch die Verwendung der elmex® Kariesschutz Zahnspülung (ZSP) reduziert werden kann, sollte in der vorliegenden Studie überprüft werden. 48 Patienten mit herausnehmbaren Apparaturen wurden nach ihrem Kariesbefall (DMFT/S: 3/7), dem Approximalraum-Plaque-Index (API: 72%), Papillen-Blutungs-Index (PBI: 22 %) sowie der SM-Speichelkeimzahlen (SM 2) homogen einer Test- (TG) und einer Kontrollgruppe (KG) zugeteilt. Alle Patienten putzten ihre Zähne morgens und abends mit der elmex® Kariesschutz Zahnpasta; Patienten der TG spülten zusätzlich nach jedem Zähneputzen mit der ZSP. Ein Jahr lang wurden alle drei Monate der API, PBI und die SM-Keimzahlen erhoben. Zu Studienabschluss wurden der DMFT/S und initialkariöse Läsionen (IS) wiederholt erfasst. Alle Probanden wiesen im Beobachtungsjahr eine mittelschwere Zahnfleischentzündung (PBI: TG 17,6% ± 14,2; KG 20,9% ± 15,7) und eine mäßige Mundhygiene (API: TG 64,9% ± 21,6; KG 70,1% ± 20,9) auf; Unterschiede zwischen den Probandengruppen lagen nach einem Jahr nicht vor. Ein Zuwachs initial kariöser und/oder kariöser Läsionen wurde nicht registriert. In der TG stieg durch die Verwendung der ZSP der Anteil der Probanden mit niedrigen SM-Keimzahlen (SM 0 und SM 1) von 34,6% auf 58,4% an. Bei den Probanden der KG erhöhte sich der entsprechende Anteil von 22,7% auf 33,3%. Bei Patienten in kieferorthopädischer Behandlung kann ein Zuwachs initial kariöser und kariöser Läsionen durch Verwendung fluoridhaltiger Zahnpasta vermieden werden. Eine zusätzliche ZSP sollte kieferorthopädischen Patienten als fester Bestandteil der Mundhygiene empfohlen werden

Die Glättung räumlicher Datensätze auf administrativen Flächen: Eine Fallstudie mit Berliner Wahldaten

Composite spatial data on administrative area level are often presented by maps. The aim is to detect regional differences in the concentration of subpopulations, like elderly persons, ethnic minorities, low-educated persons, voters of a political party or persons with a certain disease. Thematic collections of such maps are presented in different atlases. The standard presentation is by Choropleth maps where each administrative unit is represented by a single value. These maps can be criticized under three aspects: the implicit assumption of a uniform distribution within the area, the instability of the resulting map with respect to a change of the reference area and the discontinuities of the maps at the borderlines of the reference areas which inhibit the detection of regional clusters. In order to address these problems we use a density approach in the construction of maps. This approach does not enforce a local uniform distribution. It does not depend on a specific choice of area reference system and there are no discontinuities in the displayed maps. A standard estimation procedure of densities are Kernel density estimates. However, these estimates need the geo-coordinates of the single units which are not at disposal as we have only access to the aggregates of some area system. To overcome this hurdle, we use a statistical simulation concept. This can be interpreted as a Simulated Expectation Maximisation (SEM) algorithm of Celeux et al (1996). We simulate observations from the current density estimates which are consistent with the aggregation information (S-step). Then we apply the Kernel density estimator to the simulated sample which gives the next density estimate (E-Step). This concept has been first applied for grid data with rectangular areas, see Groß et al (2017), for the display of ethnic minorities. In a second application we demonstrated the use of this approach for the so-called “change of support” (Bradley et al 2016) problem. Here Groß et al (2020) used the SEM algorithm to recalculate case numbers between non-hierarchical administrative area systems. Recently Rendtel et al (2021) applied the SEM algorithm to display spatial-temporal clusters of Corona infections in Germany. Here we present three modifications of the basic SEM algorithm: 1) We introduce a boundary correction which removes the underestimation of kernel density estimates at the borders of the population area. 2) We recognize unsettled areas, like lakes, parks and industrial areas, in the computation of the kernel density. 3) We adapt the SEM algorithm for the computation of local percentages which are important especially in voting analysis. We evaluate our approach against several standard maps by means of the local voting register with known addresses. In the empirical part we apply our approach for the display of voting results for the 2016 election of the Berlin parliament. We contrast our results against Choropleth maps and show new possibilities for reporting spatial voting results.Räumliche Daten auf der Ebene administrativer Flächeneinheiten werden häufig über Karten dargestellt. Das Ziel ist es dabei regionale Unterschiede für interessierenden Bevölkerungsgruppen aufzudecken. Dies betrifft beispielsweise ältere Personen, ethnische Minderheiten, Personen mit geringer Bildung aber auch Wähler einer politischen Partei sowie Personen, die sich mit einer bestimmten Krankheit infiziert haben. Die Zusammenfassung derartiger Karten wird in Atlanten präsentiert. Eine Standarddarstellung benutzt Choroplethen, wo jede administrative Einheit durch einen einzigen Wert repräsentiert wird. Diese Karten können unter drei Aspekten kritisiert werden: Die implizite Annahme einer gleichmäßigen Verteilung innerhalb der Fläche der Einheit, die Instabilität der Darstellung beim Wechsel der administrativen Einheit sowie die Sprünge an den Grenzlinien der Einheiten, die das Aufdecken von regionalen Clustern erschweren. Um diese Probleme zu beseitigen, verwenden wir eine Kartenkonstruktion auf der Basis von Dichten. Dieser Ansatz vermeidet eine zwangsläufige gleichmäßige Dichte innerhalb der Referenzflächen. Er ist unabhängig von der Wahl eines spezifischen Referenzsystems und vermeidet Sprungstellen. Ein Standardverfahren würde Kerndichteschätzer verwenden. Allerdings werden hierfür die Geokoordinaten der einzelnen Einheiten benötigt. Diese stehen aber nicht zur Verfügung sondern lediglich die Aggregate der jeweiligen Flächeneinheit. Um diese Hürde zu umgehen, verwenden wir ein statistisches Simulationskonzept. Es kann als Simulierter EM (SEM) Algorithmus von Celeux et al (1996) beschrieben werden. Auf Basis der gegenwärtigen Dichteschätzung simulieren wir Beobachtungen, die mit der Aggregatsinformation konsistent sind (S-Schritt). Dann wenden wir den Kerndichteschätzer auf die simulierte Stichprobe an, die die nächste Dichteschätzung liefert (E-Schritt). Dieses Konzept wurde erstmals für Gitterdaten auf Rechtecken zur Darstellung von ethnischen Minderheiten angewendet, Groß et al (2017). Eine weitere Anwendung fand dieser Ansatz beim sogenannten „Change of Support“ Problem, (Bradley et al 2016). Hier nutzten Groß et al (2020) den SEM Algorithmus bei der Umrechnung von Fallzahlen zwischen nicht-hierarchischen Flächensystemen. Jüngst haben Rendtel et al (2021) den SEM Algorithmus für die Darstellung räumlich-zeitlicher Konzentrationen von Corona Infektionen in Deutschland verwendet. Hier präsentieren wir drei Modifikationen des SEM Algorithmus: 1) Wir führen eine Randkorrektur ein, die die Unterschätzung der Kerndichteschätzung an den Grenzen der Population beseitigt. 2) Wir berücksichtigen unbewohnte Bereiche wie Parks, Seen und Industriegebiete bei der Berechnung der Kerndichteschätzung. 3) Wir passen den SEM Algorithmus für die Berechnung lokaler Prozentsätze an, die insbesondere für Wahlanalysen interessant sind. Wir evaluieren unseren Ansatz gegen verschiedene Standardkarten auf Basis eines lokalen Wählerregisters mit bekannten Adressen. Im empirischen Teil wenden wir unseren Ansatz auf die Darstellung von Wahlergebnissen zur Wahl des Berliner Abgeordnetenhauses 2016 an. Wir vergleichen unsere Ergebnisse mit Choroplethenkarten und zeigen neue Möglichkeiten zur Berichterstattung räumlicher Wahlergebnisse

Comparison of LLRF Control Approaches for High Intensity Hadron Synchrotrons: Design and Performance

A usual and effective way to realize closed-loop controllers is to use cascaded SISO feedback and to rely on some kind of linear PID structure with parameters adjusted manually in simulations or experiments. Such a control may not reach optimal performance if the system is coupled or non-linear. Regarding intense beams, longitudinal beam loading can be compensated by detuning. But the coupling between phase and amplitude (or I and Q component) highly depends on the tuning, that is on the resonant frequency of the cavity. It is derived that cavity and beam dynamics thus show bi-linear nature, i.e. belong to a well investigated class of non-linear systems with appropriate control strategies available. Different controller designs are compared in terms of performance but also design transparency, the need of previous knowledge like the expected magnitude of beam loading and adaptability to different conditions, e.g. during acceleration or if applied to the full range of ion species as at GSI. The performance evaluation is based on macro-particle tracking simulations. In particular avail and limits of an optimal (quadratic cost) MIMO controller for bi-linear systems are shown

Simulated geo-coordinates as a tool for map-based regional analysis

Map-based regional analysis is interested to detect areas with a large concentration of certain populations. Here kernel density estimates (KDE) offer advantages over classical choropleth maps. However, kernel density estimation needs exact geo-coordinates. In a recent paper Groß et al. (2017) have proposed a measurement error model which uses local aggregates for kernel density estimation. Their algorithm simulates "exact" geo-coordinates which reflect the information on the aggregates. In this article we suggest two extensions of this approach. First, we consider boundary constraints, which are usually ignored in the KDE framework. This concerns not only the outer limits of a municipality but also unsettled regions within a city like parks, lakes and industrial areas. Without a boundary correction standard KDEs underestimate the density in the vicinity of boundaries. Here we propose a modification of the original algorithm which uses rescaled kernel functions. Regional maps often display local percentages, for example, voters for a special party among all voters in each voting district. Here we derive a smooth representation of percentages which is based on the ratio of two densities. Again, the original algorithm is modified to cope with the estimation of a ratio of two densities. Our empirical examples refer to voting results from Berlin. It is shown that the proposed methodology reveals a lot of regional insight which is not produced by standard choropleth maps

Modeling longitudinal bunched beam dynamics in hadron synchrotrons using scaled fourier-hermite expansions

To devise control strategies and to analyze the stability of systems with feedback, a set of few ordinary differential equations (ODEs) describing the underlying dynamics is required. It is deduced by combining two approaches not used in that context before: (I) Numerical Fourier-Hermite solutions of the Vlasov equation have been studied for over fifty years [1, 2]. The idea to expand the distribution function in Fourier series in space and Hermite functions in velocity is transferred to the dynamics of bunched beams in hadron synchrotrons in this contribution. The Hermite basis is a natural choice for plasmas with Maxwellian velocity profile as well as for particle beams with Gaussian momentum spread. The Fourier basis used for spatially nearly uniform plasmas has to be adapted to bunched beams where the beam profile is not uniform in phase. (II) This is achieved analogously to the deduction of the three term recursion relations to construct orthogonal polynomials, but applied to Fourier series with the weight function taken from the Hamiltonian. The resulting system of ODEs for the expansion coefficients of desired order - dependent on the number of functions retained - is roughly checked against macro particle tracking simulations

Impact of Simplified Stationary Cavity Beam Loading on the Longitudinal Feedback System for SIS100

The main synchrotron SIS100 of the Facility for Antiproton and Ion Research (FAIR) will be equipped with a bunch-by-bunch feedback system to damp longitudinal beam oscillations. In the basic layout, one three-tap finite impulse response (FIR) filter will be used for each single bunch and oscillation mode. The detected oscillations are used to generate a correction voltage in dedicated broadband radio frequency (RF) cavities. The digital filter is completely described by two parameters, the feedback gain and the passband center frequency, which have to be defined depending on the longitudinal beam dynamics. In earlier works, the performance of the closed loop control with such an FIR-filter was analyzed and compared to simulations and measurements with respect to the damping of coherent dipole and quadrupole modes, the first modes of oscillation. This contribution analyzes the influence of cavity beam loading on the closed loop performance and the choice of the feedback gain and passband center frequency to verify future high current operation at FAIR

Test Setup for Automated Barrier Bucket Signal Generation

For sophisticated beam manipulation several ring accelerators at FAIR and GSI like the main synchrotron SIS100 and the ESR will be equipped with barrier bucket systems. Hence, the associated LLRF has to be applicable to different RF systems, with respect to the cavity layout and the power amplifier used, as well as to variable repetition rates and amplitudes. Since already the first barrier bucket pulse of a long sequence has to meet certain minimum demands, an open-loop control on the basis of calibration data is foreseen. Closed-loop control is required to improve the signal quality during a sequence of pulses and to adapt to changing conditions like temperature drifts. A test setup was realized that allows controlling the signal generator, reading out the oscilloscope as well as processing the collected data. Frequency and time domain methods can be implemented to approach the dynamics of the RF system successively and under operating conditions, i.e. generating single sine pulses. The setup and first results from measurements are presented as a step towards automated acquisition of calibration data and iterative improvement of the same

Input Signal Generation for Barrier Bucket RF Systems at GSI

At the GSI facility in Darmstadt, Germany, Barrier Bucket RF systems are currently designed for the SIS 100 synchrotron (part of the future FAIR facility) and the Experimental Storage Ring (ESR). The purpose of these systems is to provide single sine voltage pulses at the cavity gap. Due to the high requirements regarding the gap signal quality, the calculation of the pre-distorted input signal plays a major role in the system development. A procedure to generate the input signal based on the dynamic properties in the linear region of the system has been developed and tested at a prototype system. It was shown that this method is able to generate single sine gap signals of high quality in a wide voltage range. As linearity can only be assumed up to a certain magnitude, nonlinear effects limit the quality of the output signal at very high input levels. An approach to overcome this limit is to extend the input signal calculation to a nonlinear model of the system. In this contribution, the current method to calculate the required input signal is presented and experimental results at a prototype system are shown. Additionally, first results in the nonlinear region are presented

Prototype Results of the ESR Barrier-Bucket System

The experimental storage ring (ESR), operated at the GSI facility in Darmstadt, Germany, allows experiments with a variety of ion species. In combination with the existing electron cooler, its RF cavities have been used to demonstrate longitudinal beam accumulation in order to increase the beam intensity. Limitations of the existing narrow-band cavities led to the development of a magnetic alloy (MA) based broad-band cavity for the generation of Barrier-Bucket signals. The application of a pre-distortion method demands high linearity of the driver amplifier and highlights the importance of its selection process. In this contribution, the cavity and amplifier system design is described and data measured at a prototype system are presented

Status of the Barrier-Bucket system for the ESR

In combination with beam cooling, Barrier-Bucket operation allows an intensity increase of particle beams by concentrating particles in one bucket, while creating an empty bucket for the next injection (“longitudinal stacking”). This can be achieved by generation of two RF voltage single-sine waves as barrier pulses, of which one is shifted in time to compress the beam (Fig. 1)