Research in Nepal

Findings from University of Dayton geologist, Umesh Haritashya, after the deadly earthquake in Nepal April 25 will be published in a forthcoming article in Science, the leading journal on original scientific research

Capacitive electrodes for measuring bioelectric signals

Kapazitive Elektroden ermöglichen eine einfache Messung des Elektrokardiogramms (EKG) und Elektroenzephalogramms (EEG). Sie koppeln im Gegensatz zu herkömmlich verwendeten galvanischen Elektroden das Biosignal über einen isolierten kapazitiven Kontakt zum Körper aus. Der Fokus dieser Arbeit liegt auf der Charakterisierung des Übertragungsverhaltens dieser kapazitiven Elektroden und der praktischen Anwendung im Bereich der Routine-Diagnostik und spezieller Interface-Systeme am Beispiel des Brain-Computer Interfaces. Das im Rahmen dieser Arbeit entwickelte portable EKG-System ermöglicht die Messung mit 15 Elektroden, selbst durch Kleidung hindurch, und verbindet die klassische EKG-Messung mit einem einfachen Zugang zu komplexen räumlichen Darstellungen der Herzaktivität in Form von Body-Surface-Potential-Maps. Das Verfahren wird direkt mit etablierten Verfahren verglichen und anhand realer Patientendaten validiert. Dazu wurden Messungen in klinischer Umgebung durchgeführt. Die Ergebnisse zeigen eine gute Übereinstimmung der Messungen zwischen kapazitivem und galvanischem Aufbau. Durch die spezielle Anordnung der Elektroden im verwendeten System kann eine deutliche Vereinfachung der EKG-Messung realisiert werden. Die in dieser Arbeit durchgeführte elektrische Charakterisierung der Elektroden und die Beschreibung der Rauschprozesse ermöglicht ein besseres Verständnis der besonders für das EEG benötigten höheren Messempfindlichkeit. Um diese praktisch nachzuweisen, bzw. die Grenzen des Systems aufzuzeigen, wird der Aufbau eines kapazitiven 28-Kanal Helmsystems beschrieben, welches zusammen mit der ebenfalls entwickelten analogen und digitalen Signalverarbeitung EEG-Messungen ermöglicht. Gezeigt werden Messungen der Alpha-Aktivität und visuell evozierter Potentiale. Letztere Signale werden zusätzlich in einem speziellen Aufbau zur Realisierung eines kapazitiven Brain-Computer Interfaces verwendet und damit beispielhaft eine Steuerung eines Modellfahrzeugs demonstriert.Capacitive electrodes provide an easy access to bioelectric signals in the field of electrocardiography (ECG) and electroencephalography (EEG). They are based on a capacitive coupling between the electrode and the body; in contrast to the conventionally used galvanic electrodes they are isolated from the body. So capacitive electrodes do not require a direct electrical contact to the skin. This work focuses on the characterization of the transfer function and the noise behavior of the capacitive electrodes and the practical application of this measurement in routine diagnosis and specific interface systems, such as Brain-Computer Interfaces. The development of a portable ECG system is described, enabling the measurement of the ECG with 15 electrodes through clothing. This system combines the classical ECG measurement with complex spatial representations of the cardiac activity called body surface potential mapping. The procedure is directly compared with established systems and real patient data are presented. The results show a high correlation between measurements of the capacitive and galvanic system. The special arrangement of electrodes used in the system greatly simplifies the ECG measurement. The electrical characterization of the electrodes and in particular the description of the noise behavior is evaluated for measuring brain activity because the EEG needs a higher sensitivity. To demonstrate this in practice and also show the limitations of this approach, the construction of a capacitive 28-channel EEG helmet is described. In combination with a developed analog and digital signal processing unit, EEG measurements are possible with this helmet. Measurements of alpha activity and visually evoked potentials are presented. These visual evoked potentials are also used in a special system for the implementation of a capacitive Brain-Computer Interface. The control of a RC car is represented to demonstrate the function of this Brain-Computer Interface

Composition and luminescence studies of InGaN epilayers grown at different hydrogen flow rates

Indium gallium nitride (In(x)Ga(1-x)N) is a technologically important material for many optoelectronic devices, including LEDs and solar cells, but it remains a challenge to incorporate high levels of InN into the alloy while maintaining sample quality. A series of InGaN epilayers was grown with different hydrogen flow rates (0-200 sccm) and growth temperatures (680-750 °C) to obtain various InN fractions and bright emission in the range 390-480 nm. These 160-nm thick epilayers were characterized through several compositional techniques (wavelength dispersive x-ray spectroscopy, x-ray diffraction, Rutherford backscattering spectrometry) and cathodoluminescence hyperspectral imaging. The compositional analysis with the different techniques shows good agreement when taking into account compositional gradients evidenced in these layers. The addition of small amounts of hydrogen to the gas flow at lower growth temperatures is shown to maintain a high surface quality and luminescence homogeneity. This allowed InN fractions of up to ~16% to be incorporated with minimal peak energy variations over a mapped area while keeping a high material quality

Rapid Progression of Low-Grade Cervical Dysplasia into Invasive Cancer during Natalizumab Treatment for Relapsing Remitting Multiple Sclerosis

A 25-year-old patient treated for relapsing remitting multiple sclerosis (RRMS) with natalizumab had a rapid progression of a low grade squamous intraepithelial lesion to a FIGO stage 1B1 squamous cell carcinoma of the uterine cervix within 2 years. She was treated with radical hysterectomy and pelvic lymphadenectomy and subsequently developed a vault recurrence within 2 years. The recurrence was treated with definitive synchronous chemo-radiotherapy and she has been disease free for 7 years. This case and existing evidence on increased risk of developing cervical dysplasia under natalizumab show that MS patients under immunosuppressive therapy require close annual cervical screening with immediate investigation of abnormal test results

Ionizing radiation and inhibition of angiogenesis in a spontaneous mammary carcinoma and in a syngenic heterotopic allograft tumor model: a comparative study

BACKGROUND: The combined treatment modality of ionizing radiation (IR) with inhibitors of angiogenesis (IoA) is a promising treatment modality based on preclinical in vivo studies using heterotopic xeno- and allograft tumor models. Nevertheless reservations still exist to translate this combined treatment modality into clinical trials, and more advanced, spontaneous orthotopic tumor models are required for validation to study the efficacy and safety of this treatment modality. FINDINGS: We therefore investigated the combined treatment modality of IR in combination with the clinically relevant VEGF receptor (VEGFR) tyrosine kinase inhibitor PTK787 in the MMTV/c-neu induced mammary carcinoma model and a syngenic allograft tumor model using athymic nude mice. Mice were treated with fractionated IR, the VEGFR-inhibitor PTK787/ZK222584 (PTK787), or in combination, and efficacy and mechanistic-related endpoints were probed in both tumor models. Overall the treatment response to the IoA was comparable in both tumor models, demonstrating minimal tumor growth delay in response to PTK787 and PTK787-induced tumor hypoxia. Interestingly spontaneously growing tumors were more radiosensitive than the allograft tumors. More important combined treatment of irradiation with PTK787 resulted in a supraadditive tumor response in both tumor models with a comparable enhancement factor, namely 1.5 and 1.4 in the allograft and in the spontaneous tumor model, respectively. CONCLUSIONS: These results demonstrate that IR in combination with VEGF-receptor tyrosine kinase inhibitors is a valid, promising treatment modality, and that the treatment responses in spontaneous mammary carcinomas and syngenic allografts tumor models are comparable

MALDI Imaging Mass Spectrometry (MALDI-IMS)—Application of Spatial Proteomics for Ovarian Cancer Classification and Diagnosis

MALDI imaging mass spectrometry (MALDI-IMS) allows acquisition of mass data for metabolites, lipids, peptides and proteins directly from tissue sections. IMS is typically performed either as a multiple spot profiling experiment to generate tissue specific mass profiles, or a high resolution imaging experiment where relative spatial abundance for potentially hundreds of analytes across virtually any tissue section can be measured. Crucially, imaging can be achieved without prior knowledge of tissue composition and without the use of antibodies. In effect MALDI-IMS allows generation of molecular data which complement and expand upon the information provided by histology including immuno-histochemistry, making its application valuable to both cancer biomarker research and diagnostics. The current state of MALDI-IMS, key biological applications to ovarian cancer research and practical considerations for analysis of peptides and proteins on ovarian tissue are presented in this review

Platinum-resistance in epithelial ovarian cancer: an interplay of epithelial–mesenchymal transition interlinked with reprogrammed metabolism

Background: Epithelial ovarian cancer is the most lethal gynaecological cancer worldwide. Chemotherapy resistance represents a significant clinical challenge and is the main reason for poor ovarian cancer prognosis. We identified novel expression of markers related to epithelial mesenchymal transitions (EMT) in a carboplatin resistant ovarian cancer cell line by proteomics. This was validated in the platinum resistant versus sensitive parental cell lines, as well as platinum resistant versus sensitive human ovarian cancer patient samples. The prognostic significance of the different proteomics-identified marker proteins in prognosis prediction on survival as well as their correlative association and influence on immune cell infiltration was determined by public domain data bases. Methods: We explored the proteomic differences between carboplatin-sensitive OVCAR5 cells (parental) and their carboplatin-resistant counterpart, OVCAR5 CBPR cells. qPCR and western blots were performed to validate differentially expressed proteins at the mRNA and protein levels, respectively. Association of the identified proteins with epithelial–mesenchymal transition (EMT) prompted the investigation of cell motility. Cellular bioenergetics and proliferation were studied to delineate any biological adaptations that facilitate cancer progression. Expression of differentially expressed proteins was assessed in ovarian tumors obtained from platinum-sensitive (n = 15) versus platinum-resistant patients (n = 10), as well as matching tumors from patients at initial diagnosis and following relapse (n = 4). Kaplan–Meier plotter and Tumor Immune Estimation Resource (TIMER) databases were used to determine the prognostic significance and influence of the different proteomics-identified proteins on immune cell infiltration in the tumor microenvironment (TME). Results: Our proteomics study identified 2422 proteins in both cell lines. Of these, 18 proteins were upregulated and 14 were downregulated b

Indium clustering in a -plane InGaN quantum wells as evidenced by atom probe tomography

Atom probe tomography (APT) has been used to characterize the distribution of In atoms within non-polar a-plane InGaN quantum wells (QWs) grown on a GaN pseudo-substrate produced using epitaxial lateral overgrowth. Application of the focused ion beam microscope enabled APT needles to be prepared from the low defect density regions of the grown sample. A complementary analysis was also undertaken on QWs having comparable In contents grown on polar c-plane sample pseudo-substrates. Both frequency distribution and modified nearest neighbor analyses indicate a statistically non-randomized In distribution in the a-plane QWs, but a random distribution in the c-plane QWs. This work not only provides insights into the structure of non-polar a-plane QWs but also shows that APT is capable of detecting as-grown nanoscale clustering in InGaN and thus validates the reliability of earlier APT analyses of the In distribution in c-plane InGaN QWs which show no such clustering.The European Research Council has provided financial support under the European Community’s Seventh Framework Programme (FP7/2007-2013)/ERC Grant Agreement No. 279361 (MACONS). This work was also funded in part by the EPSRC (Grant Nos. EP/H047816/1, EP/H0495331 and EP/J003603/1).This is the author accepted manuscript. The final version is available via AIP at http://scitation.aip.org/content/aip/journal/apl/106/7/10.1063/1.4909514