Die Lehrerin / der Lehrer als Modell

Es gibt keine vernünftigere Erziehung, als Vorbild zu sein, wenn es nicht anders geht, ein abschreckendes. (Albert Einstein) So umstritten diese Aussage ist, sie berührt einen wichtigen Aspekt des Lehrberufs: die Vorbild- bzw. Modellfunktion von Lehrerinnen und Lehrern. Jedoch: Wie sieht diese Funktion genau aus? Unter welchen Voraussetzungen dienen Lehrpersonen als Vorbild, als Modell? Diese Fragen sind weniger einfach geklärt als sich intuitiv annehmen lässt. Der nachfolgende Text soll versuchen, einen Beitrag zur Klärung dieser Fragen zu leisten, indem die Funktion des Vorbilds mit Bezug auf Theorien aus der Sozial- und der Entwicklungspsychologie kritisch diskutiert wird.

Perceptual learning of motion discrimination by mental imagery.

Perceptual learning can occur when stimuli are only imagined, i.e., without proper stimulus presentation. For example, perceptual learning improved bisection discrimination when only the two outer lines of the bisection stimulus were presented and the central line had to be imagined. Performance improved also with other static stimuli. In non-learning imagery experiments, imagining static stimuli is different from imagining motion stimuli. We hypothesized that those differences also affect imagery perceptual learning. Here, we show that imagery training also improves motion direction discrimination. Learning occurs when no stimulus at all is presented during training, whereas no learning occurs when only noise is presented. The interference between noise and mental imagery possibly hinders learning. For static bisection stimuli, the pattern is just the opposite. Learning occurs when presented with the two outer lines of the bisection stimulus, i.e., with only a part of the visual stimulus, while no learning occurs when no stimulus at all is presented.

Dissection of floral pollination syndromes in petunia

Animal-mediated pollination is essential in the reproductive biology of many flowering plants and tends to be associated with pollination syndromes, sets of floral traits that are adapted to particular groups of pollinators. The complexity and functional convergence of various traits within pollination syndromes are outstanding examples of biological adaptation, raising questions about their mechanisms and origins. In the genus Petunia, complex pollination syndromes are found for nocturnal hawkmoths (P. axillaris) and diurnal bees (P. integrifolia), with characteristic differences in petal color, corolla shape, reproductive organ morphology, nectar quantity, nectar quality, and fragrance. We dissected the Petunia syndromes into their most important phenotypic and genetic components. They appear to include several distinct differences, such as cell-growth and cell-division patterns in the basal third of the petals, elongation of the ventral stamens, nectar secretion and nectar sugar metabolism, and enzymatic differentiation in the phenylpropanoid pathway. In backcross-inbred lines of species-derived chromosome segments in a transposon tagging strain of P. hybrida, one to five quantitative trait loci were identified for each syndrome component. Two loci for stamen elongation and nectar volume were confirmed in introgression lines and showed large allelic differences. The combined data provide a framework for a detailed understanding of floral syndromes from their developmental and molecular basis to their impact on animal behavior. With its molecular genetic tools, this Petunia system provides a novel venue for a pattern of adaptive radiation that is among the most characteristic of flowering plants.

The Social Imaginary of Culture/Civilization in the Arabic Literary Tradition

Charles Taylor’s contribution to social imaginaries offers an interpretive framework for better understanding modernity as secularity. One of its main aspects is conceiving of human society in linear, homogenous time (secular time). Looking into the Arabic intellectual tradition, I will argue in my paper that Taylor’s framework can help us understand major social and intellectual transformations. The Ottoman and Arabic modernization process during the 19th century has often been understood by focusing on certain core concepts. One of these is tamaddun, usually translated as “civilization.” I will be mostly talking about the works of two “pioneers” of Arab modernity (which is traditionally referred to as an-nahḍa, the so-called Arab Renaissance): the Syrian Fransīs Marrāsh and the Egyptian Rifāʿa aṭ-Ṭahṭāwī. First I will focus on Marrāsh’s didactic novel “The Forest of Truth” (1865), as it offers a complex view of tamaddun, which has sometimes been construed as merely a social and political reform program. The category of "social imaginary,” however, is useful in grasping the wider semantic scope of this concept, which is reading it as a signifier for human history conceived of in secular time, as Taylor defines it. This conceptualization of human history functioning within the immanent frame can also be observed in the introduction to “The Extraction of Pure Gold in the Description of Paris” (1834), a systematic account of a travel experience in France that was written by the other “pioneer,” aṭ-Ṭahṭāwī. Finally, in translating tamaddun as “the modern social imaginary of civilization/culture,” the talk aims to consider this imaginary as a major factor in the emergence of the “secular age.” Furthermore, it suggests the importance of studying (quasi-) literary texts, such as historiographical, geographical, and self-narratives in the Arabic literary tradition, in order to further elaborate continuities and ruptures in social imaginaries.

Successful pacing using a batteryless sunlight-powered pacemaker.

AIMS Today's cardiac pacemakers are powered by batteries with limited energy capacity. As the battery's lifetime ends, the pacemaker needs to be replaced. This surgical re-intervention is costly and bears the risk of complications. Thus, a pacemaker without primary batteries is desirable. The goal of this study was to test whether transcutaneous solar light could power a pacemaker. METHODS AND RESULTS We used a three-step approach to investigate the feasibility of sunlight-powered cardiac pacing. First, the harvestable power was estimated. Theoretically, a subcutaneously implanted 1 cm(2) solar module may harvest ∼2500 µW from sunlight (3 mm implantation depth). Secondly, ex vivo measurements were performed with solar cells placed under pig skin flaps exposed to a solar simulator and real sunlight. Ex vivo measurements under real sunlight resulted in a median output power of 4941 µW/cm(2) [interquartile range (IQR) 3767-5598 µW/cm(2), median skin flap thickness 3.0 mm (IQR 2.7-3.3 mm)]. The output power strongly depended on implantation depth (ρSpearman = -0.86, P < 0.001). Finally, a batteryless single-chamber pacemaker powered by a 3.24 cm(2) solar module was implanted in vivo in a pig to measure output power and to pace. In vivo measurements showed a median output power of >3500 µW/cm(2) (skin flap thickness 2.8-3.84 mm). Successful batteryless VVI pacing using a subcutaneously implanted solar module was performed. CONCLUSION Based on our results, we estimate that a few minutes of direct sunlight (irradiating an implanted solar module) allow powering a pacemaker for 24 h using a suitable energy storage. Thus, powering a pacemaker by sunlight is feasible and may be an alternative energy supply for tomorrow's pacemakers.

The effect of nontemporal stimulus size on perceived duration as assessed by the method of reproduction

Perceived duration is assumed to be positively related to nontemporal stimulus magnitude. Most recently, the finding that larger stimuli are perceived to last longer has been challenged to represent a mere decisional bias induced by the use of comparative duration judgments. Therefore, in the present study, the method of temporal reproduction was applied as a psychophysical procedure to quantify perceived duration. Another major goal was to investigate the influence of attention on the effect of visual stimulus size on perceived duration. For this purpose, an additional dual-task paradigm was employed. Our results not only converged with previous findings in demonstrating a functional positive relationship between nontemporal stimulus size and perceived duration, but also showed that the effect of stimulus size on perceived duration was not confined to comparative duration judgments. Furthermore, the effect of stimulus size proved to be independent of attentional resources allocated to stimulus size; nontemporal visual stimulus information does not need to be processed intentionally to influence perceived duration. Finally, the effect of nontemporal stimulus size on perceived duration was effectively modulated by the duration of the target intervals, suggesting a hitherto largely unrecognized role of temporal context for the effect of nontemporal stimulus size to become evident.

Acute onset incomitant image disparity modifies saccadic and vergence eye movements.

New-onset impairment of ocular motility will cause incomitant strabismus, i.e., a gaze-dependent ocular misalignment. This ocular misalignment will cause retinal disparity, that is, a deviation of the spatial position of an image on the retina of both eyes, which is a trigger for a vergence eye movement that results in ocular realignment. If the vergence movement fails, the eyes remain misaligned, resulting in double vision. Adaptive processes to such incomitant vergence stimuli are poorly understood. In this study, we have investigated the physiological oculomotor response of saccadic and vergence eye movements in healthy individuals after shifting gaze from a viewing position without image disparity into a field of view with increased image disparity, thus in conditions mimicking incomitance. Repetitive saccadic eye movements into a visual field with increased stimulus disparity lead to a rapid modification of the oculomotor response: (a) Saccades showed immediate disconjugacy (p < 0.001) resulting in decreased retinal image disparity at the end of a saccade. (b) Vergence kinetics improved over time (p < 0.001). This modified oculomotor response enables a more prompt restoration of ocular alignment in new-onset incomitance.

A Randomized, Controlled Trial of an Aerosolized Vaccine against Measles.

Background Aerosolized vaccine can be used as a needle-free method of immunization against measles, a disease that remains a major cause of illness and death. Data on the immunogenicity of aerosolized vaccine against measles in children are inconsistent. Methods We conducted an open-label noninferiority trial involving children 9.0 to 11.9 months of age in India who were eligible to receive a first dose of measles vaccine. Children were randomly assigned to receive a single dose of vaccine by means of either aerosol inhalation or a subcutaneous injection. The primary end points were seropositivity for antibodies against measles and adverse events 91 days after vaccination. The noninferiority margin was 5 percentage points. Results A total of 1001 children were assigned to receive aerosolized vaccine, and 1003 children were assigned to receive subcutaneous vaccine; 1956 of all the children (97.6%) were followed to day 91, but outcome data were missing for 331 children because of thawed specimens. In the per-protocol population, data on 1560 of 2004 children (77.8%) could be evaluated. At day 91, a total of 662 of 775 children (85.4%; 95% confidence interval [CI], 82.5 to 88.0) in the aerosol group, as compared with 743 of 785 children (94.6%; 95% CI, 92.7 to 96.1) in the subcutaneous group, were seropositive, a difference of -9.2 percentage points (95% CI, -12.2 to -6.3). Findings were similar in the full-analysis set (673 of 788 children in the aerosol group [85.4%] and 754 of 796 children in the subcutaneous group [94.7%] were seropositive at day 91, a difference of -9.3 percentage points [95% CI, -12.3 to -6.4]) and after multiple imputation of missing results. No serious adverse events were attributable to measles vaccination. Adverse-event profiles were similar in the two groups. Conclusions Aerosolized vaccine against measles was immunogenic, but, at the prespecified margin, the aerosolized vaccine was inferior to the subcutaneous vaccine with respect to the rate of seropositivity. (Funded by the Bill and Melinda Gates Foundation; Measles Aerosol Vaccine Project Clinical Trials Registry-India number, CTRI/2009/091/000673 .).

A review of antithrombotic therapy and the rationale and design of the randomized edoxaban in patients with peripheral artery disease (ePAD) trial adding edoxaban or clopidogrel to aspirin after femoropopliteal endovascular intervention.

Compared with the coronary setting, knowledge about antithrombotic therapies after endovascular treatment (EVT) is inadequate in patients with peripheral artery disease (PAD). Based on a review of trials and guidelines, which is summarized in this article, there is scant evidence that antithrombotic drugs improve outcome after peripheral EVT. To address this knowledge gap, the randomized, open-label, multinational edoxaban in patients with Peripheral Artery Disease (ePAD) study (ClinicalTrials.gov identifier NCT01802775) was designed to explore the safety and efficacy of a combined regimen of antiplatelet therapy with clopidogrel and anticoagulation with edoxaban, a selective and direct factor Xa inhibitor, both combined with aspirin. As of July 2014, 203 patients (144 men; mean age 67 years) from 7 countries have been enrolled. These patients have been allocated to once-daily edoxaban [60 mg for 3 months (or 30 mg in the presence of factors associated with increased exposure)] or clopidogrel (75 mg/d for 3 months). All patients received aspirin (100 mg/d) for the 6-month duration of the study. The primary safety endpoint is major or clinically relevant nonmajor bleeding; the primary efficacy endpoint is restenosis or reocclusion at the treated segment(s) measured at 1, 3, and 6 months using duplex ultrasound scanning. All outcomes will be assessed and adjudicated centrally in a masked fashion. The ePAD study is the first of its kind to investigate a combined regimen of antiplatelet therapy and anticoagulation through factor Xa inhibition with edoxaban.

Fast adaptive responses in the oral jaw of Lake Victoria cichlids

Rapid morphological changes in response to fluctuating natural environments are a common phenomenon in species that undergo adaptive radiation. The dramatic ecological changes in Lake Victoria provide a unique opportunity to study environmental effects on cichlid morphology. This study shows how four haplochromine cichlids adapted their premaxilla to a changed diet over the past 30 years. Directly after the diet change toward larger and faster prey in the late 1980s, the premaxilla (upper jaw) changed in a way that is in agreement with a more food manipulating feeding style. During the 2000s, two zooplanktivorous species showed a reversal of morphological changes after returning to their original diet, whereas two other species showed no reversal of diet and morphology. These rapid changes indicate a potential for extremely fast adaptive responses to environmental fluctuations, which are likely inflicted by competition release and increase, and might have a bearing on the ability of haplochromines to cope with environmental changes. These responses could be due to rapid genetic change or phenotypic plasticity, for which there is ample evidence in cichlid fish structures associated with food capture and processing. These versatile adaptive responses are likely to have contributed to the fast adaptive radiation of haplochromines.

Larger visual stimuli are perceived to last longer from time to time: The internal clock is not affected by nontemporal visual stimulus size

Performance on interval timing is often explained by the assumption of an internal clock based on neural counting. According to this account, a neural pacemaker generates pulses, and the number of pulses relating to a physical time interval is recorded by a counter. Thus, the number of accumulated pulses is the internal representation of this interval. Several studies demonstrated that large visual stimuli are perceived to last longer than smaller ones presented for the same duration. The present study was designed to investigate whether nontemporal visual stimulus size directly affects the internal clock. For this purpose, a temporal reproduction task was applied. Sixty participants were randomly assigned to one of two experimental conditions with stimulus size being experimentally varied within either the target or the reproduction interval. A direct effect of nontemporal stimulus size on the pacemaker-counter system should become evident irrespective of whether stimulus size was experimentally varied within the target or the reproduction interval. An effect of nontemporal stimulus size on reproduced duration only occurred when stimulus size was varied during the target interval. This finding clearly argues against the notion that nontemporal visual stimulus size directly affects the internal clock. Furthermore, our findings ruled out a decisional bias as a possible cause of the observed differential effect of stimulus size on reproduced duration. Rather the effect of stimulus size appeared to originate from the memory stage of temporal information processing at which the timing signal from the pacemaker-counter component is encoded in reference memory.

A duplication in the canine beta-galactosidase gene GLB1 causes exon skipping and GM1-gangliosidosis in Alaskan huskies

GM(1)-gangliosidosis is a lysosomal storage disease that is inherited as an autosomal recessive disorder, predominantly caused by structural defects in the beta-galactosidase gene (GLB1). The molecular cause of GM(1)-gangliosidosis in Alaskan huskies was investigated and a novel 19-bp duplication in exon 15 of the GLB1 gene was identified. The duplication comprised positions +1688-+1706 of the GLB1 cDNA. It partially disrupted a potential exon splicing enhancer (ESE), leading to exon skipping in a fraction of the transcripts. Thus, the mutation caused the expression of two different mRNAs from the mutant allele. One transcript contained the complete exon 15 with the 19-bp duplication, while the other transcript lacked exon 15. In the transcript containing exon 15 with the 19-bp duplication a premature termination codon (PTC) appeared, but due to its localization in the last exon of canine GLB1, nonsense-mediated RNA decay (NMD) did not occur. As a consequence of these molecular events two different truncated GLB1 proteins are predicted to be expressed from the mutant GLB1 allele. In heterozygous carrier animals the wild-type allele produces sufficient amounts of the active enzyme to prevent clinical signs of disease. In affected homozygous dogs no functional GLB1 is synthesized and G(M1)-gangliosidosis occurs.