Analytic solutions for a three-level system in a time-dependent field

This paper generalizes some known solitary solutions of a time-dependent Hamiltonian in two ways: The time-dependent field can be an elliptic function, and the time evolution is obtained for a complete set of basis vectors. The latter makes it feasible to consider arbitrary initial conditions. The former makes it possible to observe a beating caused by the non-linearity of the driving field.Comment: 8 pages, 4 figure

Beiträge zur Heterozyklensynthese basierend auf Ringtransformationsreaktionen der Δ 2 -1,2-Diazetine

Ein 2002 in der Arbeitsgruppe gefundener, synthetischer Zugang zu der Verbindungsklasse der Δ2-1,2-Diazetine bildet die Grundlage für diese Arbeit. In ihr werden optimierte Synthesen sowie grundlegende Reaktionswege dieser viergliedrigen Heterozyklen aufgezeigt. Anhand zahlreicher Beispiele wird demonstriert, dass sich die Δ2-1,2-Diazetine aufgrund von Ringspannung und Sollbruchstellen regioselektiv zu einem breiten Spektrum hochsubstituierter Heterozyklen mit eigenständiger Folgechemie transformieren lassen. Es werden Synthesen und Eigenschaften von 1,3,4-Oxadiazinen, 1,3,4-Thiadiazinen, 1,3,4-Selenadiazinen, 1,3,4-Thiadiazolen, 1,3,4-Selenadiazolen und 1,4-Dihydropyridazinen beschrieben. Gemeinsam mit Quantenchemikern, Physikochemikern und Pharmazeuten konnten mechanistische Details der Ringtransformations-Kaskaden aufgeklärt, strukturelle Besonderheiten herausgearbeitet und mögliche Applikationsfelder erschlossen werden. Basierend auf der Struktur eines Abbauproduktes von Δ2-1,2-Diazetinen wurden zwei Retrosynthesen für Fluorubinderivate konzipiert und demgemäß linear ringanellierte Hexaaza-pentacensysteme erfolgreich dargestellt

Photoplethysmography upon cold stress — impact of measurement site and acquisition mode

Photoplethysmography (PPG) allows various statements about the physiological state. It supports multiple recording setups, i.e., application to various body sites and different acquisition modes, rendering the technique a versatile tool for various situations. Owing to anatomical, physiological and metrological factors, PPG signals differ with the actual setup. Research on such differences can deepen the understanding of prevailing physiological mechanisms and path the way towards improved or novel methods for PPG analysis. The presented work systematically investigates the impact of the cold pressor test (CPT), i.e., a painful stimulus, on the morphology of PPG signals considering different recording setups. Our investigation compares contact PPG recorded at the finger, contact PPG recorded at the earlobe and imaging PPG (iPPG), i.e., non-contact PPG, recorded at the face. The study bases on own experimental data from 39 healthy volunteers. We derived for each recording setup four common morphological PPG features from three intervals around CPT. For the same intervals, we derived blood pressure and heart rate as reference. To assess differences between the intervals, we used repeated measures ANOVA together with paired t-tests for each feature and we calculated Hedges’ g to quantify effect sizes. Our analyses show a distinct impact of CPT. As expected, blood pressure shows a highly significant and persistent increase. Independently of the recording setup, all PPG features show significant changes upon CPT as well. However, there are marked differences between recording setups. Effect sizes generally differ with the finger PPG showing the strongest response. Moreover, one feature (pulse width at half amplitude) shows an inverse behavior in finger PPG and head PPG (earlobe PPG and iPPG). In addition, iPPG features behave partially different from contact PPG features as they tend to return to baseline values while contact PPG features remain altered. Our findings underline the importance of recording setup and physiological as well as metrological differences that relate to the setups. The actual setup must be considered in order to properly interpret features and use PPG. The existence of differences between recording setups and a deepened knowledge on such differences might open up novel diagnostic methods in the future

Was bedeutet Meinungsfreiheit?: am 8. Oktober 2020

Ein Streitgespräch zwischen Jan Fleischhauer (FOCUS) und Dr. Heinrich Wefing (DIE ZEIT) zum Thema »Was bedeutet Meinungsfreiheit?« Danach folgt die Podiumsdiskussion

Porphyrin dyes for nonlinear optical imaging of live cells

Second harmonic generation (SHG)-based probes are useful for nonlinear optical imaging of biological structures, such as the plasma membrane. Several amphiphilic porphyrin-based dyes with high SHG coefficients have been synthesized with different hydrophilic head groups, and their cellular targeting has been studied. The probes with cationic head groups localize better at the plasma membrane than the neutral probes with zwitterionic or non-charged ethylene glycol-based head groups. Porphyrin dyes with only dications as hydrophilic head groups localize inside HEK293T cells to give SHG, whereas tricationic dyes localize robustly at the plasma membrane of cells, including neurons, in vitro and ex vivo. The copper(II) complex of the tricationic dye with negligible fluorescence quantum yield works as an SHG-only dye. The free-base tricationic dye has been demonstrated for two-photon fluorescence and SHG-based multimodal imaging. This study demonstrates the importance of a balance between the hydrophobicity and hydrophilicity of amphiphilic dyes for effective plasma membrane localization

Process-based analysis of students\u27 argumentation: approach, proceeding, results, and implications

Die Identifikation und Analyse von Schülerargumentationen nimmt in den letzten Jahren in zunehmendem Maße in den Naturwissenschaftsdidaktiken einen zentralen Stellenwert in Forschungsprojekten ein. Die in den Projekten genutzten Kriterien zur Identifikation einer Argumentation unterscheiden sich dabei ebenso deutlich wie die Kriterien, die zur Qualitätsbeschreibung von Argumentationen genutzt werden. Was wird unter einer Argumentation verstanden, was unter einem Argument? Wie kann eine Argumentation von anderen Diskursformen wie z.B. einer Erklärung abgegrenzt werden? Und was unterscheidet eine hochwertige von einer qualitativ weniger anspruchsvollen Argumentation? Im Beitrag wird die heterogene Forschungslandschaft im Bereich Argumentation zunächst vorgestellt, bevor der theoretische Rahmen und das methodische Vorgehen einer explorativen Studie zur Analyse von Argumentationsprozessen aufgezeigt werden. Die Ergebnisse dieser Untersuchung werden genutzt, um Konsequenzen für Forschungsprojekte im Bereich Argumentation abzuleiten. (DIPF/Orig.)During the last couple of years, an increasing number of science education research projects have addressed student argumentation. Criteria with which argumentation is identified and its quality is assessed differ largely within these projects. Which kind of discussions can be identified as argumentation? What is the difference between argumentation and argument? How can an argumentation be distinguished from, for instance, an explanation? What criteria can be used to assess the quality of students\u27 argumentation? In the paper, current research frameworks on argumentation are reviewed as well as how the quality of argumentation is typically assessed. Further on, the design of our own exploratory study on student argumentation is reported. The results are then used to infer possible implications on further research on argumentation as well as on the teaching of argumentation at school or university. (DIPF/Orig.

Integrating biological HLA-DPB1 mismatch models to predict survival after unrelated hematopoietic cell transplantation

Non peer reviewe

Donor KIR genotype based outcome prediction after allogeneic stem cell transplantation:no land in sight

Optimizing natural killer (NK) cell alloreactivity could further improve outcome after allogeneic hematopoietic cell transplantation (alloHCT). The donor’s Killer-cell Immunoglobulin-like Receptor (KIR) genotype may provide important information in this regard. In the past decade, different models have been proposed aiming at maximizing NK cell activation by activating KIR-ligand interactions or minimizing inhibitory KIR-ligand interactions. Alternative classifications intended predicting outcome after alloHCT by donor KIR-haplotypes. In the present study, we aimed at validating proposed models and exploring more classification approaches. To this end, we analyzed samples stored at the Collaborative Biobank from HLA-compatible unrelated stem cell donors who had donated for patients with acute myeloid leukemia (AML) or myelodysplastic neoplasm (MDS) and whose outcome data had been reported to EBMT or CIBMTR. The donor KIR genotype was determined by high resolution amplicon-based next generation sequencing. We analyzed data from 5,017 transplants. The median patient age at alloHCT was 56 years. Patients were transplanted for AML between 2013 and 2018. Donor-recipient pairs were matched for HLA-A, -B, -C, -DRB1, and -DQB1 (79%) or had single HLA mismatches. Myeloablative conditioning was given to 56% of patients. Fifty-two percent of patients received anti-thymocyte-globulin-based graft-versus-host disease prophylaxis, 32% calcineurin-inhibitor-based prophylaxis, and 7% post-transplant cyclophosphamide-based prophylaxis. We tested several previously reported classifications in multivariable regression analyses but could not confirm outcome associations. Exploratory analyses in 1,939 patients (39%) who were transplanted from donors with homozygous centromeric (cen) or telomeric (tel) A or B motifs, showed that the donor cen B/B-tel A/A diplotype was associated with a trend to better event-free survival (HR 0.84, p=.08) and reduced risk of non-relapse mortality (NRM) (HR 0.65, p=.01). When we further dissected the contribution of B subtypes, we found that only the cen B01/B01-telA/A diplotype was associated with a reduced risk of relapse (HR 0.40, p=.04) while all subtype combinations contributed to a reduced risk of NRM. This exploratory finding has to be validated in an independent data set. In summary, the existing body of evidence is not (yet) consistent enough to recommend use of donor KIR genotype information for donor selection in routine clinical practice.</p