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Neutron-induced reaction cross sections are important for a wide variety of research fields ranging from the study of nuclear level densities, nucleosynthesis to applications of nuclear technology like design, and criticality and safety assessment of existing and future nuclear reactors, radiation dosimetry, medical applications, nuclear waste transmutation, accelerator-driven systems and fuel cycle investigations. Simulations and calculations of nuclear technology applications largely rely on evaluated nuclear data libraries. The evaluations in these libraries are based both on experimental data and theoretical models. CERN’s neutron time-of-flight facility n_TOF has produced a considerable amount of experimental data since it has become fully operational with the start of its scientific measurement programme in 2001. While for a long period a single measurement station (EAR1) located at 185 m from the neutron production target was available, the construction of a second beam line at 20 m (EAR2) in 2014 has substantially increased the measurement capabilities of the facility. An outline of the experimental nuclear data activities at n_TOF will be presented.
The accurate knowledge of the neutron-induced fission cross-sections of actinides and other isotopes involved in the nuclear fuel cycle is essential for the design of advanced nuclear systems, such as Generation-IV nuclear reactors. Such experimental data can also provide the necessary feedback for the adjustment of nuclear model parameters used in the evaluation process, resulting in the further development of nuclear fission models. In the present work, the 240Pu(n,f) cross-section was measured at CERN's n_TOF facility relative to the well-known 235U(n,f) cross section, over a wide range of neutron energies, from meV to almost MeV, using the time-of-flight technique and a set-up based on Micromegas detectors. This measurement was the first experiment to be performed at n_TOF's new experimental area (EAR-2), which offers a significantly higher neutron flux compared to the already existing experimental area (EAR-1). Preliminary results as well as the experimental procedure, including a description of the facility and the data handling and analysis, are presented.
We have measured the radiative neutron-capture cross section and the total neutron-induced cross section of one of the most important isotopes for the s process, the 25Mg. The measurements have been carried out at the neutron time-of-flight facilities n_TOF at CERN (Switzerland) and GELINA installed at the EC-JRC-IRMM (Belgium). The cross sections as a function of neutron energy have been measured up to approximately 300 keV, covering the energy region of interest to the s process. The data analysis is ongoing and preliminary results show the potential relevance for the s process.
Above 1 MeV of incident neutron energy the fission fragment angular distribution (FFAD) has generally a strong anisotropic behavior due to the combination of the incident orbital momentum and the intrinsic spin of the fissioning nucleus. This effect has to be taken into account for the efficiency estimation of devices used for fission cross section measurements. In addition it bears information on the spin deposition mechanism and on the structure of transitional states. We designed and constructed a detection device, based on Parallel Plate Avalanche Counters (PPAC), for measuring the fission fragment angular distributions of several isotopes, in particular 232Th. The measurement has been performed at n_TOF at CERN taking advantage of the very broad energy spectrum of the neutron beam. Fission events were recognized by back to back detection in coincidence in two position-sensitive detectors surrounding the targets. The detection efficiency, depending mostly on the stopping of fission fragments in backings and electrodes, has been computed with a Geant4 simulation and validated by the comparison to the measured case of 235U below 3 keV where the emission is isotropic. In the case of 232Th, the result is in good agreement with previous data below 10 MeV, with a good reproduction of the structures associated to vibrational states and the opening of second chance fission. In the 14 MeV region our data are much more accurate than previous ones which are broadly scattered.
Ziele: Das Ziel dieser offiziellen Leitlinie, die von der Deutschen Gesellschaft für Gynäkologie und Geburtshilfe (DGGG) und der Deutschen Krebsgesellschaft (DKG) publiziert und koordiniert wurde, ist es, die Früherkennung, Diagnostik, Therapie und Nachsorge des Mammakarzinoms zu optimieren.
Methoden: Der Aktualisierungsprozess der S3-Leitlinie aus 2012 basierte zum einen auf der Adaptation identifizierter Quellleitlinien und zum anderen auf Evidenzübersichten, die nach Entwicklung von PICO-(Patients/Interventions/Control/Outcome-)Fragen, systematischer Recherche in Literaturdatenbanken sowie Selektion und Bewertung der gefundenen Literatur angefertigt wurden. In den interdisziplinären Arbeitsgruppen wurden auf dieser Grundlage Vorschläge für Empfehlungen und Statements erarbeitet, die im Rahmen von strukturierten Konsensusverfahren modifiziert und graduiert wurden.
Empfehlungen: Der Teil 1 dieser Kurzversion der Leitlinie zeigt Empfehlungen zur Früherkennung, Diagnostik und Nachsorge des Mammakarzinoms: Der Stellenwert des Mammografie-Screenings wird in der aktualisierten Leitlinienversion bestätigt und bildet damit die Grundlage der Früherkennung. Neben den konventionellen Methoden der Karzinomdiagnostik wird die Computertomografie (CT) zum Staging bei höherem Rückfallrisiko empfohlen. Die Nachsorgekonzepte beinhalten Untersuchungsintervalle für die körperliche Untersuchung, Ultraschall und Mammografie, während weiterführende Gerätediagnostik und Tumormarkerbestimmungen bei der metastasierten Erkrankung Anwendung finden.
Purpose: The aim of this official guideline coordinated and published by the German Society for Gynecology and Obstetrics (DGGG) and the German Cancer Society (DKG) was to optimize the screening, diagnosis, therapy and follow-up care of breast cancer.
Methods: The process of updating the S3 guideline dating from 2012 was based on the adaptation of identified source guidelines which were combined with reviews of evidence compiled using PICO (Patients/Interventions/Control/Outcome) questions and the results of a systematic search of literature databases and the selection and evaluation of the identified literature. The interdisciplinary working groups took the identified materials as their starting point to develop recommendations and statements which were modified and graded in a structured consensus procedure.
Recommendations: Part 1 of this short version of the guideline presents recommendations for the screening, diagnosis and follow-up care of breast cancer. The importance of mammography for screening is confirmed in this updated version of the guideline and forms the basis for all screening. In addition to the conventional methods used to diagnose breast cancer, computed tomography (CT) is recommended for staging in women with a higher risk of recurrence. The follow-up concept includes suggested intervals between physical, ultrasound and mammography examinations, additional high-tech diagnostic procedures, and the determination of tumor markers for the evaluation of metastatic disease.
n this paper we report on the investigation of baryonic resonance production in proton-proton collisions at the kinetic energies of 1.25 GeV and 3.5 GeV, based on data measured with HADES. Exclusive channels npπ+ and ppπ0 as well as ppe+e− were studied simultaneously in the framework of a one-boson exchange model. The resonance cross sections were determined from the one-pion channels for Δ(1232) and N(1440) (1.25 GeV) as well as further Δ and N* resonances up to 2 GeV/c2 for the 3.5 GeV data. The data at 1.25 GeV energy were also analysed within the framework of the partial wave analysis together with the set of several other measurements at lower energies. The obtained solutions provided the evolution of resonance production with the beam energy, showing a sizeable non-resonant contribution but with still dominating contribution of Δ(1232)P33. In the case of 3.5 GeV data, the study of the ppe+e− channel gave the insight on the Dalitz decays of the baryon resonances and, in particular, on the electromagnetic transition form-factors in the time-like region. We show that the assumption of a constant electromagnetic transition form-factors leads to underestimation of the yield in the dielectron invariant mass spectrum below the vector mesons pole. On the other hand, a comparison with various transport models shows the important role of intermediate ρ production, though with a large model dependency. The exclusive channels analysis done by the HADES collaboration provides new stringent restrictions on the parameterizations used in the models.
his contribution aims to give a basic overview of the latest results regarding the production of resonances in different collision systems. The results were extracted from experimental data collected with HADES that is a multipurpose detector located at the GSI Helmholtzzentrum, Darmstadt. The main points discussed here are: the properties of the strange resonances Λ(1405) and Σ(1385), the role of Δ’s as a source of pions in the final state, the production dynamics reflected in form of differential cross sections, and the role of the ϕ meson as a source for K− particles.
We present the results of two-pion production in tagged quasi-free np collisions at a deutron incident beam energy of 1.25 GeV/c measured with the High-Acceptance Di-Electron Spectrometer (HADES) installed at GSI. The specific acceptance of HADES allowed for the first time to obtain high-precision data on π+π− and π−π0 production in np collisions in a region corresponding to large transverse momenta of the secondary particles. The obtained differential cross section data provide strong constraints on the production mechanisms and on the various baryon resonance contributions (∆∆, N(1440), N(1520), ∆(1600)). The invariant mass and angular distributions from the np → npπ+π −and np → ppπ−π0 reactions are compared with different theoretical model predictions.
Sleep is regulated in a time-of-day dependent manner and profits working memory. However, the impact of the circadian timing system as well as contributions of specific sleep properties to this beneficial effect remains largely unexplored. Moreover, it is unclear to which extent inter-individual differences in sleep-wake regulation depend on circadian phase and modulate the association between sleep and working memory. Here, sleep electroencephalography (EEG) was recorded during a 40-h multiple nap protocol, and working memory performance was assessed by the n-back task 10 times before and after each scheduled nap sleep episode. Twenty-four participants were genotyped regarding a functional polymorphism in adenosine deaminase (rs73598374, 12 G/A-, 12 G/G-allele carriers), previously associated with differences in sleep-wake regulation. Our results indicate that genotype-driven differences in sleep depend on circadian phase: heterozygous participants were awake longer and slept less at the end of the biological day, while they exhibited longer non rapid eye movement (NREM) sleep and slow wave sleep concomitant with reduced power between 8–16 Hz at the end of the biological night. Slow wave sleep and NREM sleep delta EEG activity covaried positively with overall working memory performance, independent of circadian phase and genotype. Moreover, REM sleep duration benefitted working memory particularly when occurring in the early morning hours and specifically in heterozygous individuals. Even though based on a small sample size and thus requiring replication, our results suggest genotype-dependent differences in circadian sleep regulation. They further indicate that REM sleep, being under strong circadian control, boosts working memory performance according to genotype in a time-of-day dependent manner. Finally, our data provide first evidence that slow wave sleep and NREM sleep delta activity, majorly regulated by sleep homeostatic mechanisms, is linked to working memory independent of the timing of the sleep episode within the 24-h cycle.
The neutron sensitivity of the C6D6 detector setup used at n_TOF facility for capture measurements has been studied by means of detailed GEANT4 simulations. A realistic software replica of the entire n_TOF experimental hall, including the neutron beam line, sample, detector supports and the walls of the experimental area has been implemented in the simulations. The simulations have been analyzed in the same manner as experimental data, in particular by applying the Pulse Height Weighting Technique. The simulations have been validated against a measurement of the neutron background performed with a natC sample, showing an excellent agreement above 1 keV. At lower energies, an additional component in the measured natC yield has been discovered, which prevents the use of natC data for neutron background estimates at neutron energies below a few hundred eV. The origin and time structure of the neutron background have been derived from the simulations. Examples of the neutron background for two different samples are demonstrating the important role of accurate simulations of the neutron background in capture cross-section measurements.
The neutron capture cross section of 58Ni was measured at the neutron time of flight facility n_TOF at CERN, from 27 meV to 400 keV neutron energy. Special care has been taken to identify all the possible sources of background, with the so-called neutron background obtained for the first time using high-precision GEANT4 simulations. The energy range up to 122 keV was treated as the resolved resonance region, where 51 resonances were identified and analyzed by a multilevel R-matrix code SAMMY. Above 122 keV the code SESH was used in analyzing the unresolved resonance region of the capture yield. Maxwellian averaged cross sections were calculated in the temperature range of kT = 5 – 100 keV, and their astrophysical implications were investigated.
Recent studies suggest that synaptic lysophosphatidic acids (LPAs) augment glutamate-dependent cortical excitability and sensory information processing in mice and humans via presynaptic LPAR2 activation. Here, we studied the consequences of LPAR2 deletion or antagonism on various aspects of cognition using a set of behavioral and electrophysiological analyses. Hippocampal neuronal network activity was decreased in middle-aged LPAR2−/− mice, whereas hippocampal long-term potentiation (LTP) was increased suggesting cognitive advantages of LPAR2−/− mice. In line with the lower excitability, RNAseq studies revealed reduced transcription of neuronal activity markers in the dentate gyrus of the hippocampus in naïve LPAR2−/− mice, including ARC, FOS, FOSB, NR4A, NPAS4 and EGR2. LPAR2−/− mice behaved similarly to wild-type controls in maze tests of spatial or social learning and memory but showed faster and accurate responses in a 5-choice serial reaction touchscreen task requiring high attention and fast spatial discrimination. In IntelliCage learning experiments, LPAR2−/− were less active during daytime but normally active at night, and showed higher accuracy and attention to LED cues during active times. Overall, they maintained equal or superior licking success with fewer trials. Pharmacological block of the LPAR2 receptor recapitulated the LPAR2−/− phenotype, which was characterized by economic corner usage, stronger daytime resting behavior and higher proportions of correct trials. We conclude that LPAR2 stabilizes neuronal network excitability upon aging and allows for more efficient use of resting periods, better memory consolidation and better performance in tasks requiring high selective attention. Therapeutic LPAR2 antagonism may alleviate aging-associated cognitive dysfunctions.
The production of Σ0 baryons in the nuclear reaction p (3.5 GeV) + Nb (corresponding to sNN=3.18 GeV) is studied with the detector set-up HADES at GSI, Darmstadt. Σ0s were identified via the decay Σ0→Λγ with subsequent decays Λ→pπ− in coincidence with a e+e− pair from either external (γ→e+e−) or internal (Dalitz decay γ⁎→e+e−) gamma conversions. The differential Σ0 cross section integrated over the detector acceptance, i.e. the rapidity interval 0.5<y<1.1, has been extracted as ΔσΣ0=2.3±(0.2)stat±(−0.6+0.6)sys±(0.2)norm mb, yielding the inclusive production cross section in full phase space σΣ0total=5.8±(0.5)stat±(−1.4+1.4)sys±(0.6)norm±(1.7)extrapol mb by averaging over different extrapolation methods. The Λall/Σ0 ratio within the HADES acceptance is equal to 2.3±(0.2)stat±(−0.6+0.6)sys. The obtained rapidity and momentum distributions are compared to transport model calculations. The Σ0 yield agrees with the statistical model of particle production in nuclear reactions. Keywords: Hyperons, Strangeness, Proton, Nucleus.
The design and operation of innovative nuclear systems requires a better knowledge of the capture and fission cross sections of the Pu isotopes. For the case of capture on 242Pu, a reduction of the uncertainty in the fast region down to 8-12% is required. Moreover, aiming at improving the evaluation of the fast energy range in terms of average parameters, the OECD NEA High Priority Request List (HPRL) requests high-resolution capture measurements with improved accuracy below 2 keV. The current uncertainties also affect the thermal point, where previous experiments deviate from each other by 20%. A fruitful collaboration betwen JGU Mainz and HZ Dresden-Rossendorf within the EC CHANDA project resulted in a 242Pu sample consisting of a stack of seven fission-like targets making a total of 95(4) mg of 242Pu electrodeposited on thin (11.5 μm) aluminum backings. This contribution presents the results of a set of measurements of the 242Pu(n, γ) cross section from thermal to 500 keV combining different neutron beams and techniques. The thermal point was determined at the Budapest Research Reactor by means of Neutron Activation Analysis and Prompt Gamma Analysis, and the resolved (1 eV - 4 keV) and unresolved (1 - 500 keV) resonance regions were measured using a set of four Total Energy detectors at the CERN n_TOF-EAR1.
The experimental area 2 (EAR-2) at CERNs neutron time-of-flight facility (n_TOF), which is operational since 2014, is designed and built as a short-distance complement to the experimental area 1 (EAR-1). The Parallel Plate Avalanche Counter (PPAC) monitor experiment was performed to characterize the beam pro↓le and the shape of the neutron 'ux at EAR-2. The prompt γ-flash which is used for calibrating the time-of-flight at EAR-1 is not seen by PPAC at EAR-2, shedding light on the physical origin of this γ-flash.
Der vorliegende Band dokumentiert die Erhebungsinstrumente der dritten Phase des BilWiss-Forschungsprogramms BilWiss-UV1 ("Ertrag und Entwicklung des universitären bildungswissenschaftlichen Wissens - Validierung eines Kompetenztests für Lehrkräfte") zu wissenschaftlichen Zwecken. Ziel dieser letzten Projektphase ist die Weiterentwicklung und Verbesserung des in den Vorgängerprojekten "BilWiss" und "BilWiss-Beruf" entwickelten Kompetenztests zur Erfassung des bildungswissenschaftlichen Wissens bei Lehramtsstudierenden und -absolvent(inn)en. Dieses Skalenhandbuch dokumentiert ausschlieÿlich den im Rahmen von BilWiss-UV erhobenen Studierendenlängsschnitt (LSII) der vorwiegend der Frage nachgeht, inwieweit sich bildungswissenschaftliches Wissen als Folge der Instruktion im Lehramtsstudium verändert. Ziel des Studierendenlängsschnittes ist es, eine Verteilung der Studierenden über den kompletten Studienverlauf abzubilden, da davon ausgegangen wird, dass je nach Fortschritt im Studium ein unterschiedlicher Bildungswissenschaftlicher Wissensstand zu erwarten ist. Das Projekt wird im Rahmen des BMBF-Förderprogramms "KoKoHS - Kompetenzmodelle und Instrumente der Kompetenzerfassung im Hochschulsektor-Validierung und methodische Innovationen" gefördert. Das Forschungsprogramm ist ein Verbundprojekt der Goethe-Universität Frankfurt (Prof. Dr. Mareike Kunter, Koordination), der Universität Duisburg-Essen (Prof. Dr. Detlev Leutner) sowie der Technischen Universität München (Prof. Dr. Tina Seidel). Das gesamte Programm zielt darauf ab, zu untersuchen, inwieweit angehende Lehrkräfte durch das Studium der Bildungswissenschaften unterstützt werden, mit den vielfältigen Herausforderungen ihres Berufs professionell umzugehen. Die zentrale Annahme dabei ist, dass konzeptuelles Wissen über bildungswissenschaftliche Inhalte die professionelle Entwicklung im Vorbereitungsdienst und im Berufseinstieg unterstützt. Die Grundhypothese des Projekts lautet: Bildungswissenschaftliche Inhalte und Zusammenhänge stellen einen begrifflichen Rahmen dar, den Lehrkräfte benötigen, um Unterrichts- und Schulereignisse angemessen zu interpretieren, zu reflektieren und so für die eigene Kompetenzentwicklung zu nutzen. Die in der Studie eingesetzten Instrumente sollen öffentlich für wissenschaftliche Zwecke zugänglich gemacht werden und sind vor allem als Hilfestellung für die Arbeit mit dem Längsschnittdatensatz anzusehen. Bereits veröffentlicht unter ISBN: 978-3-00-055380-6 finden Sie die Erhebungsinstrumente der Projektphasen des BilWiss-Forschungsprogramms von 2009-2016. Weiterführende Informationen zum theoretischen Ansatz der Studie und Ergebnissen der Studie können der Internetseite http://www.bilwiss.uni-frankfurt.de sowie den im Literaturverzeichnis aufgeführten Publikationen entnommen werden.
Der vorliegende Band dokumentiert die Erhebungsinstrumente der dritten Phase des BilWiss-Forschungsprogramms BilWiss-UV1 ("Ertrag und Entwicklung des universitären bildungswissenschaftlichen Wissens - Validierung eines Kompetenztests für Lehrkräfte"), zu wissenschaftlichen Zwecken. Das Projekt wird im Rahmen des BMBF-Förderprogramms "KoKoHS - Kompetenzmodelle und Instrumente der Kompetenzerfassung im Hochschulsektor-Validierung und methodische Innovationen" gefördert. Das Forschungsprogramm ist ein Verbundprojekt der Goethe-Universität Frankfurt (Prof. Dr. Mareike Kunter, Koordination), der Universität Duisburg-Essen (Prof. Dr. Detlev Leutner) sowie der Technischen Universität München (Prof. Dr. Tina Seidel). Das gesamte Programm zielt darauf ab, zu untersuchen, inwieweit angehende Lehrkräfte durch das Studium der Bildungswissenschaften unterstützt werden, mit den vielfältigen Herausforderungen ihres Berufs professionell umzugehen. Die zentrale Annahme dabei ist, dass konzeptuelles Wissen über bildungswissenschaftliche Inhalte die professionelle Entwicklung im Vorbereitungsdienst und im Berufseinstieg unterstützt. Die Grundhypothese des Projekts lautet: Bildungswissenschaftliche Inhalte und Zusammenhänge stellen einen begrifflichen Rahmen dar, den Lehrkräfte benötigen, um Unterrichts- und Schulereignisse angemessen zu interpretieren, zu reflektieren und so für die eigene Kompetenzentwicklung zu nutzen. Für die seit 2009 bestehende Längsschnittstichprobe der Vorgängerprojekte BilWiss und BilWiss-Beruf fand Mitte des Jahres 2017 der fünfte MZP statt. Alle Teilnehmer(innen), die sich zur Teilnahme an weiteren Befragungen bereit erklärt hatten, wurden per Email kontaktiert und zur Teilnahme an der Onlineumfrage eingeladen. Es konnten 136 Personen erneut befragt werden, davon sind 124 derzeit aktiv als Lehrkraft im Schuldienst tätig (120 Lehrkräfte in Vollzeit). Im Rahmen des fünften Messzeitpunktes wurde neben Fragebogenskalen zum professionellen Verhalten, auch die im Rahmen von Meilenstein 3 entwickelte Verhaltenscheckliste eingesetzt. Durch deren Einsatz konnte ermittelt werden, dass nahezu alle der befragten Lehrkräfte Sonderfunktionen im Schuldienst übernehmen. Um einige wenige Beispiele herauszugreifen: Es sind 7 befragte Lehrkräfte in der Stufenkoordination beschäftigt, 111 Lehrer(innen) sind Klassenleitung. Als Mentor(in) engagieren sich 34 Personen und ebenfalls 34 Lehrer(innen) kooperieren mit außerschulischen Partnern. Die Durchführung des Observers wurde vom Standort München administriert und betreut. Ende des Jahres 2018 fand schlieÿlich der sechste und letzte Messzeitpunkt als Onlineerhebung statt. Bei der Bearbeitung standen neben der aktuellen beruflichen Situation auch das Erleben und das professionelle Verhalten im Lehrerberuf im Fokus. Zur Erfassung der Professional Vision in Elternberatungssituationen wurde das in 2017 entwickelte Videotool eingesetzt. Ergänzend wurde der Szenariotest zur Elternberatungskompetenz in einer Kurzversion eingesetzt (Bruder, Keller, Klug & Schmitz, 2011). Zur Erfassung des proaktiven Engagements in der Schulentwicklung wurde auch bei diesem Messzeitpunkt die Verhaltenscheckliste eingesetzt. Zur Erfassung der diagnostischen Kompetenz wurde ein neu entwickelter Vignetten-Test eingesetzt. Insgesamt konnten im Online-Fragebogen (inkl. Videotool, Szenariotest, Verhaltenscheckliste und diagnostischen Fallvignetten) 68 Personen befragt werden, davon sind 56 derzeit aktiv als Lehrkraft im Schuldienst tätig (51 Lehrkräfte in Vollzeit). Die in der Studie eingesetzten Instrumente sollen öffentlich für wissenschaftliche Zwecke zugänglich gemacht werden und sind vor allem als Hilfestellung für die Arbeit mit dem Längsschnittdatensatz anzusehen. Bereits veröffentlicht unter ISBN: 978-3-00-055380-6 finden Sie die Erhebungsinstrumente der Projektphasen des BilWiss-Forschungsprogramms von 2009-2016. Weiterführende Informationen zum theoretischen Ansatz der Studie und Ergebnissen der Studie können der Internetseite http://www.bilwiss.uni-frankfurt.de sowie den im Literaturverzeichnis aufgeführten Publikationen entnommen werden.