Open Photoacoustic Cell for Blood Sugar Measurement: Numerical Calculation of Frequency Response

A new approach for continuous and non-invasive monitoring of the glucose concentration in human epidermis has been suggested recently. This method is based on photoacoustic (PA) analysis of human interstitial fluid. The measurement can be performed in vitro and in vivo and, therefore, may form the basis for a non-invasive monitoring of the blood sugar level for diabetes patients. It requires a windowless PA cell with an additional opening that is pressed onto the human skin. Since signals are weak, advantage is taken of acoustic resonances of the cell. Recently, a numerical approach based on the Finite Element (FE) Method has been successfully used for the calculation of the frequency response function of closed PA cells. This method has now been adapted to obtain the frequency response of the open cell. Despite the fact that loss due to sound radiation at the opening is not included, fairly good accordance with measurement is achieved

Photoacoustics Modelling using Amplitude Mode Expansion Method in a Multiscale T-cell Resonator

The photoacoustic (PA) effect consisting of the generation of an acoustic signal based on the absorption of light has already demonstrated its potential for various spectroscopic applications for both gaseous and solid samples. The signal produced during photoacoustic spectroscopy (PAS) measurement is, however, usually weak and needs to be amplified. This is achieved by using a photoacoustic cell resonator where acoustic resonances are utilized to significantly boost the signal. Therefore, a PA resonator has a significant role in PAS measurement set-ups. When designing or optimizing a new PA resonator, numerical methods are generally used to simulate the photoacoustic signal generation. In this paper, the amplitude mode expansion (AME) method is presented as a quick and accurate simulation tool. The method is used to simulate the photoacoustic signal in a multi-scale T-cell resonator over a wide frequency range. The AME method is based on eigenmode expansion and introduction of losses by quality factors. The AME simulation results are compared and analyzed against the results from the viscothermal method. Reasonably good agreement is obtained between the two methods. However, small frequency shifts in the resonances of the AME method are noted. The shifts are attributed to the location of the dominant mode within the T-cell. The viscothermal method is considered the most accurate method for simulating the photoacoustic signal in small resonators. However, it is computationally very demanding. The AME method provides a much faster simulation alternative. This is particularly useful in the design and optimization of photoacoustic resonators where numerical methods are preferred over experimental measurements due to their speed and low cost.Comment: Comsol Conference 201

Zur tariflichen Umsetzung des steuerlichen Existenzminimums

Das Bundesverfassungsgericht erklärte in zwei Entscheidungen, 1990 den Kinderfreibetrag und 1992 den Grundfreibetrag des deutschen Einkommensteuergesetzes für zu niedrig und damit im Widerspruch zum Grundgesetz. In der vorliegenden Arbeit werden die international üblichen tarifpolitischen Instrumente zur Steuerfreistellung eines haushaltsbezogenen Existenzminimums hinsichtlich ihrer Verfassungskonformität sowie ihrer distributiven und fiskalischen Konsequenzen untersucht. Neben der reinen Tarifanalyse werden auch die quantitativen Wirkungen spezieller Tarifalternativen auf Durchschnittshaushalte sowie auf eine prognostizierte Verteilung von Lohnsteuerpflichtigen für das Jahr 1990 studiert, wobei jeweils ein Existenzminimum im Ausmaß des Sozialhilfeniveaus steuerfrei belassen wird.The child tax allowance and the basic tax allowance of the German income tax system have been declared by the Federal Constitutional Court as too low and thus unconstitutional. Against this background this paper provides a survey of tax instruments in OECD countries which secure tax-exemption for low-income earners. These instruments are analysed with respect to their constitutional feasability as well as their distributional and fiscal effects. Three alternative income tax schedules are compared. These use a basic allowance, a basic credit and a minimum threshold which leave the subsistence level tax free but retain the marginal tax rate pattern of the 1986/88/90 income tax reform. The quantative implications of these tax policy alternatives are examined for average employee households and for an estimated distribution of wage income in 1990

Backcoupling of acoustic streaming on the temperature field inside high-intensity discharge lamps

Operating high-intensity discharge lamps in the high frequency range (20-300 kHz) provides energy-saving and cost reduction potentials. However, commercially available lamp drivers do not make use of this operating strategy because light intensity fluctuations and even lamp destruction are possible. The reason for the fluctuating discharge arc are acoustic resonances in this frequency range that are excited in the arc tube. The acoustic resonances in turn generate a fluid flow that is caused by the acoustic streaming effect. Here, we present a 3D multiphysics model to determine the influence of acoustic streaming on the temperature field in the vicinity of an acoustic eigenfrequency. In that case a transition from stable to instable behavior occurs. The model is able to predict when light flicker can be expected. The results are in very good accordance with accompanying experiments

High-Intensity Discharge Lamp and Duffing Oscillator - Similarities and Differences

The processes inside the arc tube of high-intensity discharge lamps are investigated by finite element simulations. The behavior of the gas mixture inside the arc tube is governed by differential equations describing mass, energy and charge conservation as well as the Helmholtz equation for the acoustic pressure and the Navier-Stokes equation for the flow driven by the buoyancy and the acoustic streaming force. The model is highly nonlinear and requires a recursion procedure to account for the impact of acoustic streaming on the temperature and other fields. The investigations reveal the presence of a hysteresis and the corresponding jump phenomenon, quite similar to a Duffing oscillator. The similarities and, in particular, the differences of the nonlinear behavior of the high-intensity discharge lamp to that of a Duffing oscillator are discussed. For large amplitudes the high-intensity discharge lamp exhibits a stiffening effect in contrast to the Duffing oscillator.Comment: 14 pages, 8 figure

Neue Funde von Lepthyphantes geniculatus in Sachsen-Anhalt (Araneae, Linyphiidae)

Vorkommen desselten gefundenen Lepthyphantes geniculatus KULCZYNSKI, 1898 sind aus Deutschland bisher nur vom Gipskarstgebiet des Kyffhäusers (N-Thüringen) bekannt. 1964 und 1965 wurden dort auf zwei Gipshügeln in der Umgebung von Bad Frankenhausen insgesamt 4 männliche und 2 weibliche in Bodenfallen nachgewiesen (v. BROEN 1965, 1966)

Politik und Wirtschaft im Zeichen des Bürgerprotestes: Das Beispiel des Frankfurter Flughafens

Innovation, Dynamik und eine gewisse Veränderungsbereitschaft der Bürger sind unerlässliche Faktoren für die Reformfähigkeit eines Staates, der stetiges Wachstum sowie Wohlstand generiert. Doch immer häufiger kommt es vor allem bei öffentlichen Infrastrukturprojekten zum Phänomen des "Wutbürgers", der jeglichen Reformvorschlägen kritisch gegenübersteht und Veränderungen kompromisslos ablehnt. Laut einer Befragung der Gegner des Frankfurter Flughafenausbaus ist eine Kultur der Misstrauensgesellschaft entstanden, die es vorher so nicht gegeben hat. Die von den Politologen Prof. Dr. Eike-Christian Hornig und Jan-Bernd Baumann, beide Justus-Liebig-Universität Gießen, erstellte Studie auf Basis einer durch das Institut infratest dimap durchgeführten Umfrage deutet auf eine geringe gesamtgesellschaftliche Repräsentativität der Protestierenden hin: Die Demonstranten sind neuerdings älter, formal überdurchschnittlich gebildet und verfügen über ein großes Zeitbudget.Bisher hat man gerade in dieser Gesellschaftsschicht eine tragende Säule der Demokratie vermutet. Statt sich jedoch für andere - beispielsweise mit der Forderung nach Minderheiten- oder Artenschutz - einzusetzen, dominiert bei dieser Protestbewegung das Eigeninteresse. Die dadurch aufkommende Frage nach einer Krise der repräsentativen Demokratie vor dem Hintergrund der demographischen Entwicklung bildet den theoretischen Rahmen für die wissenschaftliche Diskussion

Determining the most suitable spectral range for TDLS – a quantitative approach

We present a mathematical method which allows determination of an optimal spectral range for gas mixture analysis based on theoretical absorption spectra. The resulting center wavelength is particularly suited for tunable diode laser spectroscopy (TDLS). The procedure contains several steps of numerical calculations which can easily be implemented in almost any programming language. We apply our method to three exemplary mixtures of hydrocarbons and present and validate the individual results.Hochschule für Angewandte Wissenschaften HamburgBundesministerium für Umwelt, Naturschutz, Nukleare Sicherheit und VerbraucherschutzPeerReviewe

On the Necessity for High-availability Data Center Backends in a Distributed Wireless System

When business processes depend on the processing capabilities within a data center, the typical system architecture use a high-availability setup to maintain a high level of service. Faced with a specific machine-to-machine system consisting of many endpoints that collect and forward data to the data center we argue that the dependability of the overall system does not necessitate a high level of service for the data center components. Taking an existing discrete event simulation model of a distributed technical system we investigate and discuss the effects of prolonged outages of the data center on the major business processes of the system