TY - JOUR A1 - Harris, Isaac A1 - Kleefeld, Andreas T1 - The inverse scattering problem for a conductive boundary condition and transmission eigenvalues JF - Applicable Analysis N2 - In this paper, we consider the inverse scattering problem associated with an inhomogeneous media with a conductive boundary. In particular, we are interested in two problems that arise from this inverse problem: the inverse conductivity problem and the corresponding interior transmission eigenvalue problem. The inverse conductivity problem is to recover the conductive boundary parameter from the measured scattering data. We prove that the measured scatted data uniquely determine the conductivity parameter as well as describe a direct algorithm to recover the conductivity. The interior transmission eigenvalue problem is an eigenvalue problem associated with the inverse scattering of such materials. We investigate the convergence of the eigenvalues as the conductivity parameter tends to zero as well as prove existence and discreteness for the case of an absorbing media. Lastly, several numerical and analytical results support the theory and we show that the inside–outside duality method can be used to reconstruct the interior conductive eigenvalues. KW - Transmission eigenvalues KW - Conductive boundary condition KW - Inverse scattering Y1 - 2018 U6 - https://doi.org/10.1080/00036811.2018.1504028 SN - 1563-504X VL - 99 IS - 3 SP - 508 EP - 529 PB - Taylor & Francis CY - London ER - TY - JOUR A1 - Frauenrath, Tobias A1 - Hezel, Fabian A1 - Renz, Wolfgang A1 - de Geyer d'Orth, Thibaut A1 - Dieringer, Matthias A1 - von Knobelsdorf-Brenkenhoff, Florian A1 - Prothmann, Marcel A1 - Schulz-Menger, Jeanette A1 - Niendorf, Thoralf T1 - Acoustic cardiac triggering: a practical solution for synchronization and gating of cardiovascular magnetic resonance at 7 Tesla JF - Journal of Cardiovascular Magnetic Resonance N2 - Background To demonstrate the applicability of acoustic cardiac triggering (ACT) for imaging of the heart at ultrahigh magnetic fields (7.0 T) by comparing phonocardiogram, conventional vector electrocardiogram (ECG) and traditional pulse oximetry (POX) triggered 2D CINE acquisitions together with (i) a qualitative image quality analysis, (ii) an assessment of the left ventricular function parameter and (iii) an examination of trigger reliability and trigger detection variance derived from the signal waveforms. Results ECG was susceptible to severe distortions at 7.0 T. POX and ACT provided waveforms free of interferences from electromagnetic fields or from magneto-hydrodynamic effects. Frequent R-wave mis-registration occurred in ECG-triggered acquisitions with a failure rate of up to 30% resulting in cardiac motion induced artifacts. ACT and POX triggering produced images free of cardiac motion artefacts. ECG showed a severe jitter in the R-wave detection. POX also showed a trigger jitter of approximately Δt = 72 ms which is equivalent to two cardiac phases. ACT showed a jitter of approximately Δt = 5 ms only. ECG waveforms revealed a standard deviation for the cardiac trigger offset larger than that observed for ACT or POX waveforms. Image quality assessment showed that ACT substantially improved image quality as compared to ECG (image quality score at end-diastole: ECG = 1.7 ± 0.5, ACT = 2.4 ± 0.5, p = 0.04) while the comparison between ECG vs. POX gated acquisitions showed no significant differences in image quality (image quality score: ECG = 1.7 ± 0.5, POX = 2.0 ± 0.5, p = 0.34). Conclusions The applicability of acoustic triggering for cardiac CINE imaging at 7.0 T was demonstrated. ACT's trigger reliability and fidelity are superior to that of ECG and POX. ACT promises to be beneficial for cardiovascular magnetic resonance at ultra-high field strengths including 7.0 T. KW - Interval Time Series KW - Image Quality Score KW - Image Quality Assessment KW - Sound Pressure Level KW - Cardiovascular Magnetic Resonance Y1 - 2010 U6 - https://doi.org/10.1186/1532-429X-12-67 SN - 1532-429X VL - 12 IS - 1 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Martin, Conrad A1 - Frauenrath, Tobias A1 - Özerdem, Celal A1 - Renz, Wolfgang A1 - Niendorf, Thoralf T1 - Development and evaluation of a small and mobile Magneto Alert Sensor (MALSE) to support safety requirements for magnetic resonance imaging JF - European Radiology N2 - Objective The purpose of this study is to (i) design a small and mobile Magnetic field ALert SEnsor (MALSE), (ii) to carefully evaluate its sensors to their consistency of activation/deactivation and sensitivity to magnetic fields, and (iii) to demonstrate the applicability of MALSE in 1.5 T, 3.0 T and 7.0 T MR fringe field environments. Methods MALSE comprises a set of reed sensors, which activate in response to their exposure to a magnetic field. The activation/deactivation of reed sensors was examined by moving them in/out of the fringe field generated by 7TMR. Results The consistency with which individual reed sensors would activate at the same field strength was found to be 100% for the setup used. All of the reed switches investigated required a substantial drop in ambient magnetic field strength before they deactivated. Conclusions MALSE is a simple concept for alerting MRI staff to a ferromagnetic object being brought into fringe magnetic fields which exceeds MALSEs activation magnetic field. MALSE can easily be attached to ferromagnetic objects within the vicinity of a scanner, thus creating a barrier for hazardous situations induced by ferromagnetic parts which should not enter the vicinity of an MR-system to occur. KW - MRI KW - MR safety KW - Magneto alert sensor KW - High field MRI KW - Uktrahigh field MRI Y1 - 2011 U6 - https://doi.org/10.1007/s00330-011-2153-z SN - 1432-1084 VL - 21 SP - 2187 EP - 2192 PB - Springer CY - Berlin, Heidelberg ER - TY - JOUR A1 - Gaigall, Daniel T1 - Test for Changes in the Modeled Solvency Capital Requirement of an Internal Risk Model JF - ASTIN Bulletin N2 - In the context of the Solvency II directive, the operation of an internal risk model is a possible way for risk assessment and for the determination of the solvency capital requirement of an insurance company in the European Union. A Monte Carlo procedure is customary to generate a model output. To be compliant with the directive, validation of the internal risk model is conducted on the basis of the model output. For this purpose, we suggest a new test for checking whether there is a significant change in the modeled solvency capital requirement. Asymptotic properties of the test statistic are investigated and a bootstrap approximation is justified. A simulation study investigates the performance of the test in the finite sample case and confirms the theoretical results. The internal risk model and the application of the test is illustrated in a simplified example. The method has more general usage for inference of a broad class of law-invariant and coherent risk measures on the basis of a paired sample. KW - Bootstrap KW - Empirical process KW - Functional Delta Method KW - Hadamard differentiability KW - Paired sample Y1 - 2021 U6 - https://doi.org/10.1017/asb.2021.20 SN - 1783-1350 VL - 51 IS - 3 SP - 813 EP - 837 PB - Cambridge Univ. Press CY - Cambridge ER - TY - JOUR A1 - Dersch, Jürgen A1 - Geyer, Michael A1 - Herrmann, Ulf A1 - Jones, Scott A. A1 - Kelly, Bruce A1 - Kistner, Rainer A1 - Ortmanns, Winfried A1 - Pitz-Paal, Robert A1 - Price, Henry T1 - Trough integration into power plants—a study on the performance and economy of integrated solar combined cycle systems JF - Energy : the international journal Y1 - 2004 U6 - https://doi.org/10.1016/S0360-5442(03)00199-3 SN - 0360-5442 N1 - SolarPACES 2002, Zürich, Switzerland, 4–6 September 2002 VL - 29 IS - 5-6 (Special Issue SolarPaces) SP - 947 EP - 959 ER - TY - JOUR A1 - Puppe, Michael A1 - Giuliano, Stefano A1 - Frantz, Cathy A1 - Uhlig, Ralf A1 - Schumacher, Ralph A1 - Ibraheem, Wagdi A1 - Schmalz, Stefan A1 - Waldmann, Barbara A1 - Guder, Christoph A1 - Peter, Dennis A1 - Schwager, Christian A1 - Teixeira Boura, Cristiano José A1 - Alexopoulos, Spiros A1 - Spiegel, Michael A1 - Wortmann, Jürgen A1 - Hinrichs, Matthias A1 - Engelhard, Manfred A1 - Aust, Michael T1 - Techno-economic optimization of molten salt solar tower plants JF - AIP Conference Proceedings art.no. 040033 N2 - In this paper the results of a techno-economic analysis of improved and optimized molten salt solar tower plants (MSSTP plants) are presented. The potential improvements that were analyzed include different receiver designs, different designs of the HTF-system and plant control, increased molten salt temperatures (up to 640°C) and multi-tower systems. Detailed technological and economic models of the solar field, solar receiver and high temperature fluid system (HTF-system) were developed and used to find potential improvements compared to a reference plant based on Solar Two technology and up-to-date cost estimations. The annual yield model calculates the annual outputs and the LCOE of all variants. An improved external tubular receiver and improved HTF-system achieves a significant decrease of LCOE compared to the reference. This is caused by lower receiver cost as well as improvements of the HTF-system and plant operation strategy, significantly reducing the plant own consumption. A novel star receiver shows potential for further cost decrease. The cavity receiver concepts result in higher LCOE due to their high investment cost, despite achieving higher efficiencies. Increased molten salt temperatures seem possible with an adapted, closed loop HTF-system and achieve comparable results to the original improved system (with 565°C) under the given boundary conditions. In this analysis all multi tower systems show lower economic viability compared to single tower systems, caused by high additional cost for piping connections and higher cost of the receivers. REFERENCES Y1 - 2019 U6 - https://doi.org/10.1063/1.5067069 VL - 2033 IS - Issue 1 PB - AIP Publishing CY - Melville, NY ER - TY - JOUR A1 - Penner, Crystal A1 - Usherovich, Samuel A1 - Niedermeier, Jana A1 - Bélanger-Champagne, Camille A1 - Trinczek, Michael A1 - Paulßen, Elisabeth A1 - Hoehr, Cornelia T1 - Organic Scintillator-Fibre Sensors for Proton Therapy Dosimetry: SCSF-3HF and EJ-260 JF - electronics N2 - In proton therapy, the dose from secondary neutrons to the patient can contribute to side effects and the creation of secondary cancer. A simple and fast detection system to distinguish between dose from protons and neutrons both in pretreatment verification as well as potentially in vivo monitoring is needed to minimize dose from secondary neutrons. Two 3 mm long, 1 mm diameter organic scintillators were tested for candidacy to be used in a proton–neutron discrimination detector. The SCSF-3HF (1500) scintillating fibre (Kuraray Co. Chiyoda-ku, Tokyo, Japan) and EJ-260 plastic scintillator (Eljen Technology, Sweetwater, TX, USA) were irradiated at the TRIUMF Neutron Facility and the Proton Therapy Research Centre. In the proton beam, we compared the raw Bragg peak and spread-out Bragg peak response to the industry standard Markus chamber detector. Both scintillator sensors exhibited quenching at high LET in the Bragg peak, presenting a peak-to-entrance ratio of 2.59 for the EJ-260 and 2.63 for the SCSF-3HF fibre, compared to 3.70 for the Markus chamber. The SCSF-3HF sensor demonstrated 1.3 times the sensitivity to protons and 3 times the sensitivity to neutrons as compared to the EJ-260 sensor. Combined with our equations relating neutron and proton contributions to dose during proton irradiations, and the application of Birks’ quenching correction, these fibres provide valid candidates for inexpensive and replicable proton-neutron discrimination detectors Y1 - 2022 U6 - https://doi.org/10.3390/electronics12010011 SN - 2079-9292 N1 - This article belongs to the Special Issue "Applications of Optical Fiber Sensors" VL - 12 IS - 1 PB - MDPI CY - Basel ER - TY - JOUR A1 - Matoni, Georg A1 - Berndt, Heinz T1 - Thermal synthesis of the optical pure pentapeptide derivative Z-(L)-Ala-(L)-Phe-Gly-(L)-Phe-Gly-OMe JF - Tetrahedron letters Y1 - 1980 U6 - https://doi.org/10.1016/S0040-4039(00)93618-9 SN - 0040-4039 VL - 21 IS - 1 SP - 37 EP - 40 ER - TY - JOUR A1 - Eilmann, Britta A1 - Zweifel, Roman A1 - Buchmann, Nina A1 - Fonti, Patrick A1 - Rigling, Andreas T1 - Drought-induced adaptation of the xylem in Scots pine and pubescent oak JF - Tree Physiology Y1 - 2009 U6 - https://doi.org/10.1093/treephys/tpp035 SN - 0829-318X (Print) SN - 1758-4469 (Online) VL - 29 IS - 8 SP - 1011 EP - 1020 PB - Heron CY - Victoria, BC ER - TY - JOUR A1 - El Bergui, Omnia A1 - Abouabdillah, Aziz A1 - Bourioug, Mohamed A1 - Schmitz, Dominik A1 - Biel, Markus A1 - Aboudrare, Abdellah A1 - Krauss, Manuel A1 - Jomaa, Ahlem A1 - Romuli, Sebastian A1 - Müller, Joachim A1 - Fagroud, Mustapha A1 - Bouabid, Rachid T1 - Innovative solutions for drought: Evaluating hydrogel application on onion cultivation (Allium cepa) in Morocco JF - Water N2 - Throughout the last decade, and particularly in 2022, water scarcity has become a critical concern in Morocco and other Mediterranean countries. The lack of rainfall during spring was worsened by a succession of heat waves during the summer. To address this drought, innovative solutions, including the use of new technologies such as hydrogels, will be essential to transform agriculture. This paper presents the findings of a study that evaluated the impact of hydrogel application on onion (Allium cepa) cultivation in Meknes, Morocco. The treatments investigated in this study comprised two different types of hydrogel-based soil additives (Arbovit® polyacrylate and Huminsorb® polyacrylate), applied at two rates (30 and 20 kg/ha), and irrigated at two levels of water supply (100% and 50% of daily crop evapotranspiration; ETc). Two control treatments were included, without hydrogel application and with both water amounts. The experiment was conducted in an open field using a completely randomized design. The results indicated a significant impact of both hydrogel-type dose and water dose on onion plant growth, as evidenced by various vegetation parameters. Among the hydrogels tested, Huminsorb® Polyacrylate produced the most favorable outcomes, with treatment T9 (100%, HP, 30 kg/ha) yielding 70.55 t/ha; this represented an increase of 11 t/ha as compared to the 100% ETc treatment without hydrogel application. Moreover, the combination of hydrogel application with 50% ETc water stress showed promising results, with treatment T4 (HP, 30 kg, 50%) producing almost the same yield as the 100% ETc treatment without hydrogel while saving 208 mm of water. KW - water economy KW - yield KW - deficit irrigation KW - hydrogel KW - onion Y1 - 2023 U6 - https://doi.org/10.3390/w15111972 VL - 15 IS - 11 PB - MDPI CY - Basel ER -