bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrocardiograph signal denoising based on sparse decomposition
Authors: Zhu Junjiang , Li Xiaolu
Published: May 2017

Noise in ECG signals will affect the result of post‐processing if left untreated. Since ECG is highly subjective, the linear denoising method with a specific threshold working well on one subject could fail on another. Therefore, in this Letter, sparse‐based method, which represents every segment of signal using different linear combinations of atoms from a dictionary, is used to denoise ECG signals, with a view to myoelectric interference existing in ECG signals. Firstly, a denoising model for ECG signals is constructed. Then the model is solved by matching pursuit algorithm. In order to get better results, four kinds of dictionaries are investigated with the ECG signals from MIT‐BIH arrhythmia database, compared with wavelet transform (WT)‐based method. Signal–noise ratio (SNR) and mean square error (MSE) between estimated signal and original signal are used as indicators to evaluate the performance. The results show that by using the present method, the SNR is higher while the MSE between estimated signal and original signal is smaller.
Optimisation of throughput of two‐way buffer‐aided relaying networks with wireless‐assisted links
Authors: Kumar Rajeev , Hossain Ashraf
Published: May 2017

The authors propose protocols to optimise throughput of a relay in relaying networks where two users communicate only through buffer‐aided relay. Both the users randomly access finite size buffer of the relay. The protocols are developed on the basis of buffer state information (BSI) and channel state information (CSI). In their proposed scheme, half‐duplex decode‐and‐forward (DF) concept is used for improving the spectral efficiency of two‐way relaying networks. In this work, the authors derive maximum achievable relay throughput with fixed‐rate transmission which is in the form of linear‐fractional programming. For simplification, they transform the fractional programme into linear programme which is efficiently computed through the standard convex/linear numerical tool. The numerical results are performed with the assisted software such as CVX tool. They theoretically analyse the events to provide necessary performance endorsement. The BSI/CSI outperforms all the cases studied named as conventional relaying, BSI only, and CSI only.
One current adaptive switching strategy for DC/DC converter with spike limitation
Authors: Wu Qunfang , Wang Qin , Xu Zilong , He Peng , Li Jinbo
Published: May 2017

In this study, a new current adaptive switching strategy with the spike limitation applied in DC/DC converter is proposed. With this switching strategy, the switching speed of the power switch can be regulated adaptively with the change of the load. The turn‐on/turn‐off current is inversely proportional to the load. So, at the light load, the switching speed of the power switch is faster and the switching losses are lower. In addition, all of the control should be based on one principle that the current/voltage spike across power switch under a smaller load cannot exceed that under a rated load. The switching characteristics of power switch with the proposed switching strategy and the relationship between current/voltage spike, turn‐on/turn‐off current and power loop stray inductance during the switching transition is discussed in this study. Moreover, the drive circuit is designed in detail. Finally, a boost converter prototype with 200 V DC input voltage/380 V output voltage/1 kW output power is established to verify the proposed method. The tested results show that the efficiency of the converter adopted the proposed method rises by 1.5% comparing with that used a conventional switching strategy at the light load.
Copper(I)-Catalyzed Boryl Substitution of Allyl Aminals: Selective Synthesis of Linear γ-Aminoallylboronates
Authors: Ito Hajime , Takenouchi Yuta
Published: May 2017

A novel approach for the selective synthesis of α-substituted γ-aminoallylboronates through a copper(I)-catalyzed γ-boryl-substitution of allyl aminals is developed. The reaction proceeds with high yield (up to 88%) and good E/Z selectivity (up to >95:5). Subsequent aldehyde allylation using allylboronates affords (Z)-anti-1,2-amino alcohol derivatives with high stereoselectivity (up to 91% yield, and up to 17:83 E/Z).
Copper-Mediated sp
2 C–H Chlorination with Trichloroacetamide Using a Removable Directing Group
Authors: Li Jie , Lee Wan-Chen , Tehrani Arya
Published: May 2017

2-Aminophenyl-1H-pyrazole was discovered as a removable, bidentate directing group for copper-mediated aerobic oxidative sp
2 C–H bond chlorination employing trichloroacetamide as a new chlorine source. When Cu(OAc)2 was employed as the copper source, 1,1,3,3-­tetramethylguanidine (TMG) as an organic base, the reaction, optimally carried out overnight in DMSO at 80 °C in open air, produced a variety of mono- and dichlorinated products in moderate to excellent yields. This directing group can be removed oxidatively with cerium ammonium nitrate (CAN).
Prevalencia de lesiones por sobreuso en jugadores de las selecciones de rugby de Chile y Uruguay
Authors: Marsalli Michael , Santurio Marcelo , Garrido Cristián , Sepúlveda Oscar
Published: May 2017

Objetivo Determinar la prevalencia de lesiones por sobreuso en las selecciones de rugby adulta y juvenil de Chile y Uruguay. Objetivos secundarios: 1. Describir el impacto en el rendimiento, factores de riesgo y las diferencias entre adultos y juveniles; 2. Evaluar la definición de lesión según tiempo perdido para el estudio de las lesiones por sobreuso.

Metodología Grupo de estudio: selecciones adultas y juveniles de rugby de Chile y Uruguay (106 jugadores). Se utilizó el Oslo Sports Trauma Research Centre Overuse Injury Questionnaire, para el registro y la evaluación de las lesiones. Se definió lesión por sobreuso como todos los problemas articulares de origen no traumático, ocurridos hasta los 7 días previos al registro. Se registró la edad, peso, talla, posición de juego y volumen de entrenamiento para el análisis de factores de riesgo.

Resultados La prevalencia fue de un 31%. Solo el 6% requirió más de 24 horas de reposo deportivo. El principal factor de riesgo fue la edad (OR 1,12 IC 1,017–1,24), aumentando un 12% por cada año cumplido. Se observó una mayor prevalencia en los adultos y los juveniles presentaron un puntaje mayor de gravedad (23,2 versus 15,8 p = 0,03).

Conclusiones La prevalencia de lesiones por sobreuso en este grupo fue alta. El impacto en el rendimiento en la mayoría fue leve, siendo mayor en los juveniles. El principal factor de riesgo fue la edad. La definición de lesión según tiempo perdido fue insuficiente para el tamizaje de lesiones por sobreuso, pesquisando una minoría de los jugadores afectados.
Outcome after Hypospadias Repair: Evaluation Using the Hypospadias Objective Penile Evaluation Score
Authors: Krull Sarah , Krause Hardy , Mohnike Klaus , Roehl Friedrich-Wilhelm , Koehn Andrea , Hass Hans-Juergen , Rissmann Anke
Published: May 2017

Introduction The Hypospadias Objective Penile Evaluation Score (HOPE-Score) is a concise and reproducible way to describe hypospadias severity. We classified boys undergoing primary hypospadias repair to determine the correlation between the HOPE-Score and the severity of hypospadias first and the outcome after surgery second.

Materials and Methods Patients who underwent primary hypospadias repair from 2005 to 2014 were identified. An independent physician assessed retrospectively the HOPE-Score, using photographies of the patients before, after primary surgery, and after all necessary surgeries. The correlation between the HOPE-Score and the severity of hypospadias, on the one hand, and the outcome after surgery, on the other hand, were analyzed.

Results The HOPE-Score was assessed preoperatively for 79 boys, postoperatively for 66, and after all necessary surgeries for 21 patients. Mean HOPE-Score reached 30.2 ± 5.9 before surgery, 42.2 ± 6.1 after primary surgery, and 43.7 ± 3.4 after all necessary surgeries. A significant correlation between the HOPE-Score and the severity of hypospadias before surgery was observed. The boys with glanular hypospadias scored significantly higher (36.3 ± 5.4) than those with distal (29.6 ± 4.4) and proximal hypospadias (21.1 ± 3.5). Furthermore, a significant correlation between the HOPE-Score and the outcome after hypospadias repair was observed. Patients who needed no reintervention after primary hypospadias repair scored significantly higher postoperatively (45.1 ± 5.4) than those who needed a second (40.8 ± 4.2) or more than two surgeries (36.9 ± 7.4).

Conclusion The HOPE-Score is a good system to assess the severity of hypospadias and the cosmetic outcome after hypospadias repair.
The Increasing Genetic and Phenotypical Diversity of Congenital Myasthenic Syndromes
Authors: Abicht Angela , Evangelista Teresinha , Spendiff Sally , Lochmüller Hanns , McMacken Grace
Published: May 2017

The congenital myasthenic syndromes (CMS) are a diverse group of diseases, which result in an increasing range of phenotypes, but which are all due to inherited defects at the neuromuscular junction (NMJ). Although some patients remain genetically undiagnosed, our ability to identify the causative genes has shed new light on the role of previous uncharacterized proteins at the NMJ. Securing the genetic diagnosis can be challenging, but it is of critical importance to allow rational therapeutic intervention. In this review, we summarize the key clinical and pathologic features of the CMS subtypes, outline diagnostic clues, and challenges, and describe the recent advances that have highlighted the overlap between CMS and the muscular dystrophies and peripheral neuropathies.
MEGDEL Syndrome: Expanding the Phenotype and New Mutations
Authors: Rodrigues Márcia , Jacinto Sandra , Wevers Ron , Wortmann Saskia , Sequeira Sílvia
Published: May 2017

3-MEthylGlutaconic aciduria, Deafness, Encephalopathy, neuroradiological evidence of Leigh-like disease (MEGDEL syndrome) was initially described in four children with additional features of defective oxidative phosphorylation. Loss of functional variants in the SERAC1 gene was later reported in relation with this disorder of phospholipid remodeling. We describe a girl born after a pregnancy complicated by intrauterine growth retardation. In the neonatal period, she presented hypotonia, lethargy, weak reflexes, transient hypoglycemia, and elevated transaminases. Magnetic resonance imaging (MRI) performed at 12 days of life showed bilateral basal ganglia alterations suggestive of Leigh syndrome. She progressed with failure to thrive, severe delay of developmental milestones, axial hypotonia, spastic tetraparesis and dystonic movements. Investigations disclosed hyperlactacidemia, and the urinary organic acids revealed high levels mainly of 3-methylglutaconic acid. Muscle biopsy showed decreased activity of several complexes of the respiratory chain. Compound heterozygosity for two previously unreported variants in SERAC1 leads to the diagnosis of MEGDEL syndrome. Unlike other patients, this child presents very early MRI alterations and manifests no deafness.
Achievement of Body Mass Index Specific Weight Gain Recommendations: Impact on Preterm Birth in Twin Pregnancies
Authors: Newman Roger , Wojciechowski Barbara , Christensen Colleen , Greenan Candice
Published: May 2017

Objective To determine whether achievement of body mass index specific weight gain recommendations is associated with reduced preterm birth or neonatal morbidity among twin gestations.

Study Design This was a retrospective cohort study of twin gestations delivered at the Medical University of South Carolina from 2000 to 2010. In total, 588 women in all prepregnancy body mass index categories who delivered ≥24 weeks' gestation were included. Women were grouped as achieved or underachieved based on total weight gain and gestational age at delivery. Maternal and neonatal outcomes were compared between the groups.

Results Body mass index specific weight gain goals were achieved by 59.9% of women. The achieved group had a 1.5-fold reduction in the rate of preterm birth <32 weeks (18.8 vs. 30.5%; p = 0.001). Achievers had larger mean birthweights (2,146 ± 584 g vs. 1,859 ± 593 g; p < 0.001) and were significantly less likely to deliver either twin with a birthweight less than the 10th percentile for gestational age (larger twin 0.6 vs. 4.7%, p = 0.001; smaller twin 12.2 vs. 21.6%, p = 0.002). Composite neonatal morbidity, days on the respirator, length of hospital stay, and rate of neonatal intensive care unit admission were significantly decreased in the achieved group.

Conclusion Achievement of body mass index specific weight gain goals improves preterm birth rates, neonatal birthweights, and composite neonatal outcomes in women carrying twins.
Survivorship of Revision Wrist Replacement
Authors: Chee K. , Hayton M. , Murali S. , Talwalkar S. , Trail I. , Pinder E.
Published: May 2017

Purpose This study aims to report the 5-year survivorship of revision wrist arthroplasties and to report midterm clinical and radiological results.

Materials and Methods All patients receiving a revision wrist arthroplasty in our unit between January 1, 1997 and October 31, 2010 were identified, and clinical notes retrospectively analyzed for Quick Disabilities of the Arm, Shoulder and Hand (quickDASH), Patient Evaluation Method (PEM), Patient-Rated Wrist Evaluation (PRWE), the range of movement, and visual analog score (VAS). In cases where patient review had not occurred within the past year, they were invited for assessment, and this data was included in the analysis. Plain radiographs were analyzed for loosening of each component. The 5-year survival was plotted using Kaplan–Meier analysis.

Results Of the 19 patients identified, 1 was lost to follow-up and therefore excluded from all analyses. Mean age at revision wrist arthroplasty was 55.8 years and the mean time from primary to revision wrist arthroplasty was 6.7 years. At revision arthroplasty, 7 patients received the Biaxial implant (DePuy, Inc., Warsaw, IN) and 11 received the Universal II implant (Integra, Inc., Plainsboro, NJ). The 5-year implant revision survivorship was 83%. Depending on the variable of interest, clinical data were available for either three, four or five patients. At final follow-up (mean: 10.4 years), mean visual analog score was 2.9, mean quickDASH 57, mean PEM 49, mean PRWE 61, and mean arc of flexion/extension was 26 degrees. Radiological data were available for 12 patients, with evidence of gross loosening present in around 60% of the carpal components and 50% of the radial components at mean 6.7 years.

Conclusion Revision wrist replacement implant survival is acceptable, but the majority of the surviving implants are radiologically loose. It is not clear at this time whether they are better or worse than a fusion after a failed primary wrist arthroplasty.

Clinical Relevance It is reasonable to offer revision wrist arthroplasty in selective cases, but regular clinical and radiological follow-up is recommended.
Is the Correlation between Salivary Cortisol and Serum Cortisol Reliable Enough to Enable Use of Salivary Cortisol Levels in Preterm Infants?
Authors: Wynne-Edwards Katherine , Amin Parthiv , Zhou Ruokun , Sundaram Arun , Martinez-Soto Tania , Pacaud Danièle , Amin Harish
Published: May 2017

Background Newborn premature infants are susceptible to development of relative adrenal insufficiency following transition from fetal to extrauterine life. However, the best diagnostic test for adrenal insufficiency in neonates has yet to be developed.

Objectives and Methods The aim of this study was (1) to assess the feasibility of obtaining sufficient saliva sample to allow measurement of cortisol by liquid chromatography coupled to tandem mass spectrometry and (2) to assess the correlation, if any, between salivary and serum cortisol in preterm infants of ≤32 weeks' gestational age at birth.

Results Samples for 230 paired serum and saliva cortisol levels from 90 preterm infants were analyzed. 87.5% of samples collected had sufficient salivary volumes for measurement. Despite being statistically significant (p < 0.0001), the correlation (Spearman r = 0.674) between serum and salivary cortisol was not strong.

Conclusion Salivary free cortisol measurement is feasible but cannot be used to accurately reflect serum total cortisol. Further studies comparing salivary free cortisol to serum free cortisol and establishing normative data are needed before salivary cortisol can be used for diagnostic purposes.
Die Rolle von niedersächsischen Kommunen für die zukünftige ärztliche Versorgung – Eine Befragung der Bürgermeister und Landräte
Authors: Kuhn Bertolt , Steinhäuser Jost , Eberhard Sveja , Hufenbach Rolf , Amelung Volker
Published: May 2017

Hintergrund/Zielsetzung Die flächendeckende ambulante ärztliche Versorgung ist in ländlichen Regionen durch eine abnehmende Niederlassungsbereitschaft zunehmend bedroht. Kommunen sehen sich daher z. T. gefordert, ärztliche Niederlassungen mit eigenen Mitteln zu unterstützen. Ziel dieser Studie war es, die kommunale Perspektive auf die ambulante Versorgungssituation zu erheben und die Rolle und Einflussnahme der Kommunen zu untersuchen.

Methodik Die Bürgermeister (n=411) und Landräte (n=38) in Niedersachsen erhielten im September 2015 einen selbst entwickelten schriftlichen Fragebogen (Vollbefragung).

Ergebnisse Die Rücklaufquote des Fragebogens lag bei 72%. Die hausärztliche Versorgung schätzen 30% der Befragungsteilnehmer als ungenügend ein, 71% die sonstige fachärztliche Versorgung. Zwei Drittel sahen lokale Probleme mit der Nachbesetzung von Arztpraxen. 42% der Bürgermeister und 65% der Landräte gaben an, bereits Unterstützungsmaßnahmen für ambulante Ärzte geleistet zu haben. Zu den am häufigsten bisher durchgeführten Maßnahmen gehörten finanzielle Zuschüsse, Beratungsleistungen sowie der Aufbau von Kooperationen und Netzwerken. Das Modell eines MVZ in kommunaler Trägerschaft hielt ein Drittel für geeignet.

Schlussfolgerung Von den Kommunalverantwortlichen werden für ärztliche Niederlassungen verbreitet sowohl Nachbesetzungsprobleme als auch ein kommunaler Unterstützungsbedarf wahrgenommen. Ein beträchtlicher Anteil der Kommunen hat bereits unterschiedliche Unterstützungsmaßnahmen umgesetzt. Eine Beteiligung der Kommunen an der ambulanten Gesundheitsversorgung als Träger eines MVZ wird überwiegend kritisch bewertet.
Psychische Belastungen des Pflegepersonals im Krankenhaus: Effekte von Status und Organisationsstrukturen
Authors: Bär Stefan , Starystach Sebastian
Published: May 2017

Ziel der Studie Die Studie untersucht Effekte von Krankenhausarbeit auf die psychische Gesundheit von Pflegekräften. Mittels Querschnittsanalyse werden psychische Belastungen des Pflegepersonals durch dessen Arbeitsbedingungen an einem Großkrankenhaus differenziert nach organisationalen durch die Organisation bedingten Kategorien hinsichtlich Status- und Struktureffekten dargestellt.

Methodik Die Daten wurden standardisiert als Vollerhebung aller examinierten Pflegekräfte eines Großkrankenhauses der Maximalversorgung mithilfe des Impuls-Tests und eines kontextspezifischen Zusatzfragebogens erhoben. Die Analyse der Daten erfolgte anhand des Gratifikationskrisen- und Job-Demand-Control-Modells sowie einer Mittelwertberechnung der erhobenen 13 Dimensionen der Arbeitsbedingungen, die nach nominalen organisationalen Kategorien der Arbeitsorganisation unterscheidet.

Ergebnisse und Schlussfolgerungen Die Ergebnisse zeigen, dass psychische Belastungen von Pflegekräften nur unter Berücksichtigung von deren arbeitsorganisatorischen Einbindung und Verortung in der Organisation Krankenhaus sinnvoll verstanden werden können. Es lassen sich eindeutige Effekte daraufhin feststellen, welchem Arbeitszeitmodell Pflegekräfte unterworfen sind, welcher Organisationseinheit und Klinik sie angehören und insbesondere, ob sie eine Führungsposition innehaben oder nicht.
Neuberechnung der tabakattributablen Mortalität – Nationale und regionale Daten für Deutschland
Authors: Mons Ute , Kahnert Sarah
Published: May 2017

Einleitung Tabakkonsum ist weltweit jährlich für etwa 5 Mio. Todesfälle verantwortlich. Damit ist er das bedeutendste einzelne vermeidbare Gesundheitsrisiko. In diesem Beitrag werden Ergebnisse einer Neuberechnung der tabakattributablen Mortalität in Deutschland dargestellt und dabei geschlechtsspezifische und regionale Unterschiede aufgezeigt.

Daten und Methode Die Berechnung erfolgte auf Basis der Prävalenz der aktuellen und ehemaligen Raucher (Datenbasis: Mikrozensus 2013), der relativen Mortalitätsrisiken von aktuellen und ehemaligen Rauchern für Erkrankungen, bei denen durch Tabakkonsum ein erhöhtes Mortalitätsrisiko besteht, sowie der Anzahl der Todesfälle nach ICD-10-Diagnosen (Datenbasis: Todesursachenstatistik 2013). Erstmals wurden auch Darm- und Leberkrebs sowie Typ-2-Diabetes und Tuberkulose berücksichtigt.

Ergebniss Im Jahr 2013 sind 121 087 Todesfälle auf das Rauchen zurückzuführen, davon 84 782 Todesfälle bei Männern und 36 305 Todesfälle bei Frauen. Damit sind 13,5% aller Todesfälle dem Rauchen zuzuschreiben. Die tabakattributable Mortalitätsrate ist bei Männern höher als bei Frauen und regional besteht ein Nord-Süd-Gefälle.

Schlussfolgerung Die Anzahl der tabakbedingten Todesfälle ist beträchtlich und höher als bislang angenommen. Im Vergleich zum Jahr 2007 ist in absoluten Zahlen gesehen eine Zunahme zu verzeichnen, bei der tabakattributablen Mortalitätsrate hingegen ein leichter Rückgang. Aufgrund der demografischen Alterung der Bevölkerung wird die absolute Zahl tabakattributabler Todesfälle in den kommenden Jahren voraussichtlich weiterhin ansteigen.
Management des infizierten Implantats im Gesichts-/Schädelbereich
Authors: Weiser Julian , Lohse Christian , Kreutzer Kilian , Hennigsen Anders , Heiland Max , Gröbe Alexander
Published: May 2017

Durch die Möglichkeit der Implantation von Fremdmaterial wurden die medizinischen Therapiemöglichkeiten auch im Gesichtsschädelbereich zum Vorteil des Patienten substanziell erweitert. Neben den offensichtlichen Vorteilen der fehlenden Entnahmemorbidität und unbegrenzten Verfügbarkeit ist auf der anderen Seite als häufigste Komplikation die fremdmaterialassoziierte Infektion zu nennen. Der Gesichtsschädelbereich ist durch seine verbesserte Gewebeperfusion gegenüber anderen anatomischen Arealen privilegiert, daraus ergeben sich Auswirkungen auf den Verlauf und somit auch auf das Management von Infektionen in diesem Bereich. Dieser Artikel soll eine Übersicht über die Therapiemöglichkeiten von fremdmaterialassoziierten Infektionen sowohl dentaler Implantate, Osteosynthesematerial als auch im Rahmen der Kranioplastik liefern.
Bestandsaufnahme zu Zweitmeinungsverfahren in der Gesetzlichen Krankenversicherung (GKV)
Authors: Pieper Dawid , Heß Simone , Mathes Tim
Published: May 2017

Ziel der Studie Mit dem Versorgungsstärkungsgesetz wurde Mitte 2015 § 27 b SGB V die Zweitmeinung (ZM) in Deutschland gesetzlich verankert, auch wenn bislang die dabei zu berücksichtigenden Eingriffe vom Gemeinsamen Bundesausschuss (G-BA) noch nicht festgelegt worden sind. Unabhängig davon können die Krankenkassen jedoch den Versicherten eine ZM erstatten. Das Ziel ist eine Bestandsaufnahme der Angebote für ZM, die von den gesetzlichen Krankenkassen angeboten werden.

Methodik Im November 2016 sind die Webauftritte aller deutschen gesetzlichen Krankenkassen (KK, n=117) durchsucht worden. Recherchiert wurden Einträge zu Angeboten zu ZM für die Versicherten. Die Angaben wurden von einer Person extrahiert und von einer zweiten Person unabhängig davon qualitätsgesichert.

Ergebnisse Insgesamt konnten 78 ZM-Programme identifiziert werden. Die Hälfte der Krankenkassen (50%, n=59) hat mind. ein ZM-Programm, wovon die meisten dem Gebiet der Orthopädie (78%, n=61) und der Onkologie (58%, n=45) zugeschrieben werden konnten (Mehrfachnennungen jeweils möglich). Am häufigsten wird die ZM outgesourct (58%; n=44). Eine Vermittlung zu Gesundheitsdienstleitern, die über einen Vertrag mit der Krankenkasse verfügen erfolgt in 45% (n=34) der Fälle, während die ZM nur selten vom Krankenkassenpersonal erbracht wird (11%; n=8). Die Erbringung der ZM erfolgt in den meisten Fällen nach Aktenlage (63%; n=48), gefolgt vom persönlichen Kontakt (43%; n=33) und telefonischen Kontakt (14%; n=11). Das Erbringen der ZM dauert im Median 7 Tage, wobei die ZM nach Aktenlage (Median 7) schneller erbracht wird, als bei einem persönlichen Termin (Median 14 Tage).

Schlussfolgerung Die Möglichkeit eine ZM einzuholen, steht weiten Teilen der deutschen Bevölkerung offen. Das Angebot der einzelnen ZM-Programme muss als sehr heterogen beschrieben werden, was insgesamt zu einem sehr unübersichtlichen Angebot führt, das für den Patienten kaum zu durchschauen ist.
Implementierung eines laparoskopischen Simulationstrainings in der studentischen Lehre – das Lübecker Toolbox-Curriculum
Authors: Laubert Tilman , Thomaschewski Michael , Auerswald Paul , Zimmermann Markus , Brüheim Linda , Keck Tobias , Benecke Claudia
Published: May 2017

Hintergrund Simulationstraining in der minimalinvasiven Chirurgie (MIC) wird zunehmend relevant. Inwieweit das etablierte Lübecker Toolbox-Curriculum (LTB-Curriculum) zum Erlernen von MIC-Basisfertigkeiten die studentische Lehre in der Chirurgie ergänzen kann und mit welcher Akzeptanz, ist unklar.

Material und Methoden Seit 04/2015 haben Studierende der Humanmedizin an der Universität zu Lübeck die Möglichkeit, das hoch standardisierte und validierte LTB-Curriculum zu absolvieren. Dieses besteht inhaltlich aus 6 aufeinander aufbauenden Übungen mit definierten Zielvorgaben. Videotutorials erlauben das autodidaktische Training. Der individuelle Trainingsfortschritt wurde laufend dokumentiert wie im Curriculum vorgesehen. Es erfolgte die standardisierte Evaluation über ein für die Evaluation von Lehrveranstaltungen der Universität zu Lübeck etabliertes Onlineportal.

Ergebnisse Zwischen 04/2015 und 07/2016 durchliefen 63 Studierende das LTB-Curriculum. Das generelle Interesse an einer chirurgischen Fachdisziplin stieg von im Mittel 1,61 (Standardabweichung [SD] 0,78) vor dem Curriculum auf 1,12 nach dem Curriculum an. Die Anzahl der notwendigen Wiederholungen bis zum Erreichen der Zielvorgaben betrug für die Übungen 1 – 6 im Median 24 (6 – 79), 23 (5 – 61), 7 (5 – 33), 15 (5 – 59), 16 (5 – 50) und 18 (7 – 48). Keiner der 63 Studierenden brach das LTB-Curriculum vorzeitig ab. Im Durchschnitt wurden 4,35 (SD 1,58) Stunden pro Woche aufgewandt und im Mittel eine Gesamtdauer von 4,1 (SD 1,2) Wochen benötigt, um das LTB-Curriculum zu komplettieren. Die Evaluationsergebnisse ergaben eine Gesamtnote von 1,0 (SD 0,17). Der Lernzuwachs, die Didaktik und die Struktur des Trainingsprogramms wurden mit im Mittel 1,0 (SD 0,24), 1,14 (SD 0,36) und 1,0 (SD 0,24) bewertet. Die Relevanz des Curriculums für das weitere Studium und die zukünftige berufliche Tätigkeit wurde im Durchschnitt mit 1,2 (SD 0,45) angegeben.

Schlussfolgerung Das Angebot, das strukturierte Lübecker Toolbox-Curriculum zusätzlich zur regulären Lehre absolvieren zu können, wurde von zahlreichen Studierenden angenommen und sehr positiv evaluiert. Die Ergebnisse legen zudem nahe, dass das LTB-Curriculum das Interesse an einer chirurgischen Fachrichtung bei Studierenden steigert. In Zeiten, da die Chirurgie um Nachwuchs bemüht sein muss, erscheint dieser Aspekt relevant.
Mode transition in cooperative metamaterials at terahertz frequencies
Authors: Li Chun , Wu Jingbo , Zhang Caihong , Tan Wei , Jin Biaobing , Kang Lin , Xu Weiwei , Chen Jian , Wu Peiheng
Published: May 2017

By tailoring the intrinsic physical parameters of sub-resonators, we experimentally observe a mode transition in the cooperative metamaterials at terahertz frequencies. The transmission peak between the two lowest resonance modes experiences a non-monotonic change and the spectral response transforms from the V-type mode to the electromagnetically induced transparency-like state. Meanwhile, we employ a hybrid coupling model to theoretically study the influence of the near field coupling coefficient and the loss of resonators on their electromagnetic response and quantitatively analyze the transition of response. The calculation based on the model shows an excellent agreement with the simulated and experimental results. Our results not only provide a deep insight into the analogue of electromagnetically induced transparency but also offer an alternative approach to develop metamaterials-based devices such as slow light devices, switches, and filters in the terahertz region.
Correlative imaging across microscopy platforms using the fast and accurate relocation of microscopic experimental regions (FARMER) method
Authors: Huynh Toan , Daddysman Matthew K. , Bao Ying , Selewa Alan , Kuznetsov Andrey , Philipson Louis H. , Scherer Norbert F.
Published: May 2017

Imaging specific regions of interest (ROIs) of nanomaterials or biological samples with different imaging modalities (e.g., light and electron microscopy) or at subsequent time points (e.g., before and after off-microscope procedures) requires relocating the ROIs. Unfortunately, relocation is typically difficult and very time consuming to achieve. Previously developed techniques involve the fabrication of arrays of features, the procedures for which are complex, and the added features can interfere with imaging the ROIs. We report the Fast and Accurate Relocation of Microscopic Experimental Regions (FARMER) method, which only requires determining the coordinates of 3 (or more) conspicuous reference points (REFs) and employs an algorithm based on geometric operators to relocate ROIs in subsequent imaging sessions. The 3 REFs can be quickly added to various regions of a sample using simple tools (e.g., permanent markers or conductive pens) and do not interfere with the ROIs. The coordinates of the REFs and the ROIs are obtained in the first imaging session (on a particular microscope platform) using an accurate and precise encoded motorized stage. In subsequent imaging sessions, the FARMER algorithm finds the new coordinates of the ROIs (on the same or different platforms), using the coordinates of the manually located REFs and the previously recorded coordinates. FARMER is convenient, fast (3–15 min/session, at least 10-fold faster than manual searches), accurate (4.4 μm average error on a microscope with a 100x objective), and precise (almost all errors are <8 μm), even with deliberate rotating and tilting of the sample well beyond normal repositioning accuracy. We demonstrate this versatility by imaging and re-imaging a diverse set of samples and imaging methods: live mammalian cells at different time points; fixed bacterial cells on two microscopes with different imaging modalities; and nanostructures on optical and electron microscopes. FARMER can be readily adapted to any imaging system with an encoded motorized stage and can facilitate multi-session and multi-platform imaging experiments in biology, materials science, photonics, and nanoscience.
A novel signal acquisition platform of human cardiovascular information with noninvasive method
Authors: Chen Longcong , Cai Shaoxi , Li Bo , Jiang Qifeng , Ke Ming , Zhao Yi , Chen Sijia , Zou Misha
Published: May 2017

Cardiovascular diseases (CVDs) are considered the major cause of death worldwide, so more researchers pay more and more attention to the development of a non-invasive method to obtain as much cardiovascular information (CVI) as possible for early screening and diagnosing. It is known that considerable brain information could be probed by a variety of stimuli (such as video, light, and sound). Therefore, it is quite possible that much more CVI could be extracted via giving the human body some special interrelated stimulus. Based on this hypothesis, we designed a novel signal platform to acquire more CVI with a special stimulus, which is to give a gradual decrease and a different settable constant pressure to six air belts placed on two-side brachia, wrists, and ankles, respectively. During the stimulating process, the platform is able to collect 24-channel dynamic signals related with CVI synchronously. Moreover, to improve the measurement accuracy of signal acquisition, a high precision reference chip and a software correction are adopted in this platform. Additionally, we have also shown some collection instances and analysis results in this paper for its reliability. The results suggest that our platform can not only be applied on study in a deep-going way of relationship between collected signals and CVDs but can also serve as the basic tool for developing a new noninvasive cardiovascular function detection instrument and system that can be used both at home and in the hospital.
On the calculations of the static electronic dipole (hyper)polarizability for the free and spatially confined H−
Authors: Chołuj Marta , Bartkowiak Wojciech , Naciążek Paulina , Strasburger Krzysztof
Published: May 2017

The quality of the static electronic dipole (hyper)polarizabilities (α and γ) calculated using the coupled cluster with singles and doubles (CCSD) method and various basis sets for the isolated hydrogen anion (H−) was verified against highly accurate results obtained within the variation-perturbation scheme with the optimized explicitly correlated Gaussian functions. Moreover, the influence of spatial confinement on α and γ of H− was analyzed. The effect of confinement (orbital compression) was modeled by the spherically symmetric harmonic oscillator potential. Our results demonstrate that in order to obtain the value of α with a relative error less than 10% and correct order of magnitude of γ for the unconfined H− at the CCSD level of theory, at least triply augmented correlation consistent basis set (t-aug-cc-pVXZ, X = D,T,Q,5,6) has to be used. Furthermore, it was found that the spatial confinement significantly affects α and γ of H−.
Inhomogeneous fluid of penetrable-spheres: Application of the random phase approximation
Authors: Xiang Yan , Frydel Derek
Published: May 2017

The focus of the present work is the application of the random phase approximation (RPA), derived for inhomogeneous fluids [Frydel and Ma, Phys. Rev. E 93, 062112 (2016)], to penetrable-spheres. As penetrable-spheres transform into hard-spheres with increasing interactions, they provide an interesting case for exploring the RPA, its shortcomings, and limitations, the weak- versus the strong-coupling limit. Two scenarios taken up by the present study are a one-component and a two-component fluid with symmetric interactions. In the latter case, the mean-field contributions cancel out and any contributions from particle interactions are accounted for by correlations. The accuracy of the RPA for this case is the result of a somewhat lucky cancellation of errors.
Preface: Special Topic on Dynamics of Polymer Materials in Thin Films and Related Geometries
Authors: Ediger M. D. , Schweizer Kenneth S.
Published: May 2017

The last twenty years have seen a substantial effort to understand relaxation, mechanics, diffusion, and the glass transition in thin polymer films and related geometries. Recent progress in this field is highlighted in this special issue of The Journal of Chemical Physics on “Dynamics of Polymer Materials in Thin Films and Related Geometries.” With the goal of providing an entry point to these 35 papers for those not working in this field, we provide some background and perspective in this introduction to the special topic section.
Electrically driven terahertz radiation of 2DEG plasmons in AlGaN/GaN structures at 110 K temperature
Authors: Jakštas V. , Grigelionis I. , Janonis V. , Valušis G. , Kašalynas I. , Seniutinas G. , Juodkazis S. , Prystawko P. , Leszczyński M.
Published: May 2017

We experimentally observed a terahertz (THz) radiation of electrically driven 2D electron gas (2DEG) plasmons in AlGaN/AlN/GaN structures at T = 110 K. The grating with a period of 1.0 μm and a filling factor of 0.35 was used to couple electromagnetic radiation out from the plasmonic sample excited in a pulsed regime. The peak power radiated from ungated 2DEG plasmons at a frequency of 5.0 THz under an electric field of 450 V/cm was up to 940 nW. The intensity of the radiation was sufficient to measure spectra with a conventional far-infrared Fourier transform spectrometer. The analysis of the data revealed that the 2DEG plasmon radiation was superimposed with the black-body radiation of the sample and electroluminescence of the impurities. The strategy to reach higher powers of THz emission for practical applications is discussed.
Development of a programmable standard of ultra-low capacitance values
Authors: Khan M. S. , Séron O. , Thuillier G. , Thévenot O. , Gournay P. , Piquemal F.
Published: May 2017

A set of ultra-low value capacitance standards together with a programmable coaxial multiplexer (mux) have been developed. The mux allows the connection of these capacitances in parallel configuration and they together form the programmable capacitance standard. It is capable of producing decadic standard capacitances from 10 aF to at least 0.1 pF, which are later used to calibrate commercial precision capacitance bridges. This paper describes the realization and the characterization of this standard together with results obtained during the calibration of Andeen-Hagerling AH2700A bridges with a maximum uncertainty of 0.8 aF for all the capacitances generated ranging from 10 aF to 0.1 pF, at 1 kHz. These latter could be then integrated to functionalized AFMs or probe stations for quantitative capacitance measurements. Sources of uncertainties of the programmable capacitance standard, such as parasitic effects due to stray impedances, are evaluated and a method to overcome these hindrances is also discussed.
Measurement of low bit-error-rates of adiabatic quantum-flux-parametron logic using a superconductor voltage driver
Authors: Takeuchi Naoki , Suzuki Hideo , Yoshikawa Nobuyuki
Published: May 2017

Adiabatic quantum-flux-parametron (AQFP) is an energy-efficient superconductor logic. The advantage of AQFP is that the switching energy can be reduced by lowering operation frequencies or by increasing the quality factors of Josephson junctions, while keeping the energy barrier height much larger than thermal energy. In other words, both low energy dissipation and low bit error rates (BERs) can be achieved. In this paper, we report the first measurement results of the low BERs of AQFP logic. We used a superconductor voltage driver with a stack of dc superconducting-quantum-interference-devices to amplify the logic signals of AQFP gates into mV-range voltage signals for the BER measurement. Our measurement results showed 3.3 dB and 2.6 dB operation margins, in which BERs were less than 10−20, for 1 Gbps and 2 Gbps data rates, respectively. While the observed BERs were very low, the estimated switching energy for the 1-Gbps operation was only 2 zJ or 30kBT, where kB is the Boltzmann's constant and T is the temperature. Unlike conventional non-adiabatic logic, BERs are not directly associated with switching energy in AQFP.
Tunnel-injected sub-260 nm ultraviolet light emitting diodes
Authors: Zhang Yuewei , Krishnamoorthy Sriram , Akyol Fatih , Bajaj Sanyam , Allerman Andrew A. , Moseley Michael W. , Armstrong Andrew M. , Rajan Siddharth
Published: May 2017

We report on tunnel-injected deep ultraviolet light emitting diodes (UV LEDs) configured with a polarization engineered Al0.75Ga0.25 N/In0.2Ga0.8 N tunnel junction structure. Tunnel-injected UV LED structure enables n-type contacts for both bottom and top contact layers. However, achieving Ohmic contact to wide bandgap n-AlGaN layers is challenging and typically requires high temperature contact metal annealing. In this work, we adopted a compositionally graded top contact layer for non-alloyed metal contact and obtained a low contact resistance of ρc = 4.8 × 10−5 Ω cm2 on n-Al0.75Ga0.25 N. We also observed a significant reduction in the forward operation voltage from 30.9 V to 19.2 V at 1 kA/cm2 by increasing the Mg doping concentration from 6.2 × 1018 cm−3 to 1.5 × 1019 cm−3. Non-equilibrium hole injection into wide bandgap Al0.75Ga0.25 N with Eg>5.2 eV was confirmed by light emission at 257 nm. This work demonstrates the feasibility of tunneling hole injection into deep UV LEDs and provides a structural design towards high power deep-UV emitters.
Broadband terahertz pulse generation by optical rectification in GaP crystals
Authors: Aoki Katsuyoshi , Savolainen Janne , Havenith Martina
Published: May 2017

We demonstrate a broadband (0.3–7 THz) terahertz pulse generation using GaP generation and detection crystals with an 80-MHz-repetition-rate Ti:Sapphire laser. We also use simulations of cascaded terahertz generation to model the observed terahertz gain profiles. The efficient generation of the broadband terahertz pulses is based on optimizing the phase matching between the optical and terahertz pulses, which is achieved by tuning the wavelength of the laser. We observed further improvement in the generation efficiency due to a mismatching of the imaginary part of the complex wavevectors. Together, these effects allow the use of thicker crystals and thus lead to increased terahertz emission. Our results show that optical rectification by GaP can be used to generate broadband terahertz pulses with MHz-repetition-rate lasers up to a dynamic range that is comparable to commonly used sources like ZnTe and photo-conductive antennas.
Research Update: Van-der-Waals epitaxy of layered chalcogenide Sb2Te3 thin films grown by pulsed laser deposition
Authors: Hilmi Isom , Lotnyk Andriy , Gerlach Jürgen W. , Schumacher Philipp , Rauschenbach Bernd
Published: May 2017

An attempt to deposit a high quality epitaxial thin film of a two-dimensionally bonded (layered) chalcogenide material with van-der-Waals (vdW) epitaxy is of strong interest for non-volatile memory application. In this paper, the epitaxial growth of an exemplary layered chalcogenide material, i.e., stoichiometric Sb2Te3 thin films, is reported. The films were produced on unreconstructed highly lattice-mismatched Si(111) substrates by pulsed laser deposition (PLD). The films were grown by vdW epitaxy in a two-dimensional mode. X-ray diffraction measurements and transmission electron microscopy revealed that the films possess a trigonal Sb2Te3 structure. The single atomic Sb/Te termination layer on the Si surface was formed initializing the thin film growth. This work demonstrates a straightforward method to deposit vdW-epitaxial layered chalcogenides and, at the same time, opens up the feasibility to fabricate chalcogenide vdW heterostructures by PLD.
A first-principles study of carbon-related energy levels in GaN. II. Complexes formed by carbon and hydrogen, silicon or oxygen
Authors: Matsubara Masahiko , Bellotti Enrico
Published: May 2017

This work presents an in-depth investigation of the properties of complexes composed of hydrogen, silicon, or oxygen with carbon, which are the major unintentional impurities in undoped GaN. This manuscript is a complement to our previous work on carbon–carbon and carbon-vacancy complexes. We have employed a first-principles method using Heyd-Scuseria-Ernzerhof hybrid functionals within the framework of generalized Kohn-Sham density functional theory. Two H–C, four Si–C, and five O–C complexes in different charge states have been considered. After full geometry relaxations, formation energies, binding energies, and both thermal and optical transition levels were obtained. The calculated energy levels have been systematically compared with the experimentally observed carbon related trap levels. Furthermore, we computed vibrational frequencies for selected defect complexes and defect concentrations were estimated in the low, mid, and high carbon doping scenarios considering two different cases where electrically active defects: (a) only carbon and vacancies and (b) not only carbon and vacancies but also hydrogen, silicon, and oxygen. We confirmed that CN is a dominant acceptor in GaN. In addition to it, a substantial amount of SiGa–CN complex exists in a neutral form. This complex is a likely candidate for the unknown form of carbon observed in undoped n-type GaN.
Modeling of light-induced degradation due to Cu precipitation in p-type silicon. II. Comparison of simulations and experiments
Authors: Vahlman H. , Haarahiltunen A. , Kwapil W. , Schön J. , Inglese A. , Savin H.
Published: May 2017

The presence of copper impurities is known to deteriorate the bulk minority carrier lifetime of silicon. In p-type silicon, the degradation occurs only under carrier injection (e.g., illumination), but the reason for this phenomenon called copper-related light-induced degradation (Cu-LID) has long remained uncertain. To clarify the physics of this problem, a mathematical model of Cu-LID was introduced in Paper I of this article. Within the model, kinetic precipitation simulations are interlinked with a Schottky junction model for electric behavior of metallic precipitates. As this approach enables simulating precipitation directly at the minority carrier lifetime level, the model is verified in this second part with a direct comparison to the corresponding degradation experiments and literature data. Convincing agreement is found with different doping and Cu concentrations as well as at increased temperature, and in the dark, both simulated degradation and measured degradation are very slow. In addition, modeled final lifetimes after illumination are very close to experimental final lifetimes, and a correlation with the final precipitate size is found. However, the model underestimates experimentally observed differences in the degradation rate at different illumination intensities. Nevertheless, the results of this work support the theory of Cu-LID as a precipitate formation process. Part of the results also imply that heterogeneous nucleation sites play a role during precipitate nucleation. The model reveals fundamental aspects of the physics of Cu-LID including how doping and heterogeneous nucleation site concentrations can considerably influence the final recombination activity.
Evidence of reward production and pollination by Centris in Encyclia (Orchidaceae: Laeliinae): the reproductive biology of Encyclia mapuerae
Authors: Krahl A. H. , Krahl D. R. P. , Valsko J. J. , Webber A. C. , Pansarin E. R.
Published: May 2017

Encyclia is a neotropical orchid genus distributed from Florida to South Brazil and comprises ~120 taxa, including Encyclia mapuerae (Huber) Brade & Pabst. Besides its diversity and wide distribution, conclusive data on pollinators and reproductive biology of this orchid genus is scarce. Furthermore, nothing is known about the production of floral reward in Encyclia but the pollinators of their species are assumed to be attracted through food deception. Based on data on phenology, floral morpho-anatomy, histochemistry, pollinators, pollination mechanisms, and breeding system, the reproductive biology of E. mapuerae was studied in a nature reserve at Central Amazonia, Brazil. The flowers of E. mapuerae show longitudinal lines on the labellum that act as a nectar guide. The secretory epidermis has papillae whose cells are covered by an ornamented cuticle. The subtended tissue is composed of a tree-layered collenchyma. The flowers attract several species of Hymenoptera. However, a single species of Centris was recorded as pollinator. The bees collect the nectar produced inside the cuniculus. When the bees leave the flower the pollinarium is attached to their heads. Encyclia mapuerae is self-compatible and pollinator-dependent. The reproductive success in natural conditions is low because of deficient pollen transference due to the scarcity of pollinators. As far we know this is the first study that reports and production of floral reward in Encyclia. This discovery provides new insights on the function of the cuniculus in Laeliinae, and sheds light on the evolution of floral rewards and pollination mechanisms within this diverse group of Neotropical orchids.