Modern Theory of Nuclear Forces

Effective field theory allows for a systematic and model-independent derivation of the forces between nucleons in harmony with the symmetries of Quantum Chromodynamics. We review the foundations of this approach and discuss its application for light nuclei at various resolution scales. The extension of this approach to many-body systems is briefly sketched.Comment: Commissioned article for Reviews of Modern Physics, 52 pp, 40 fig

Renaturierung kleiner Lössbäche – ein Beitrag der Ökologischen Landwirtschaft zum Naturschutz

As a part of the interdisciplinary research project ”Integration of nature protection goals with organic farming: an the example from the Hessian ”state domain” [Staatsdomäne] area Frankenhausen”, different restoration measures have been carried out within this site, 15 km north of Kassel. Since 1998, intensive conventional agricultural practices have been substituted with organic farming here. One intention of the agricultural restructuring was to realise nature protection goals in cooperation with sustainable organic agricultural production. The hydrologic portion of the project addresses both the implementation of restoration measures in rivers and streams and their scientific monitoring. Starting in July 2007, several restoration measures were carried out in the hydrologic systems of the Jungfernbach and Esse streams within the Frankenhausen site. Both systems are formed by typical loess streams (catchment size about 9 km2) which had been heavily degraded for several hundred years by intensive agriculture. The most important restoration measures were removal of a piped section of a tributary of the Jungfernbach at Totenhof, restoration of biological passability by removal of weirs and substitution of narrow pipes under farm paths, relocation of a section of the Jungfernbach from the edge of the floodplain to its original location in the centre, widening of narrow sections and partial raising of the deepened stream bed by means of rough ramps (stone bars) and racks made of oak wood or iron. These physical restoration measures were accompanied by a scientific monitoring programme comprising morphological, hydrochemical and biological (aquatic macrophytes, aquatic macroinvertebrates, fish and amphibians) aspects. The aim of this study was to document the original ecological conditions, the restoration measures and the early ecological effects on the stream sections for the first six months following restoration as a basis for further ecological monitoring. The restoration measures effected clear morphological changes in cross-section and passability. The chemical condition of the streams showed slight changes in some aspects following the restoration, e. g. a reduction of phosphorus, magnesium and potassium concentration. Other than macrophytic algae in the newly shaped sections, aquatic macrophytes did not develop over the winter season before the end of the monitoring phase in April 2008. Within the newly shaped stream sections of a small tributary and of the Jungfernbach, up to 14 aquatic macroinvertebrate taxa started to colonise the new habitats 6 months after restoration. Fish fauna were very poorly represented in the streams and included only a few specimens of brown trout (Salmo trutta). This did not change markedly after restoration, possibly due to the isolation of the population caused by impassable weirs downstream of the investigation area.In einem interdisziplinären „Entwicklungs- und Erprobungs-Vorhaben“ der Universität Kassel „Die Integration von Naturschutzzielen in den Ökologischen Landbau am Beispiel der Hessischen Staatsdomäne Frankenhausen“ wurden unterschiedliche Naturschutz-Maßnahmen auf dem Domänengelände durchgeführt. Seit 1998 wird die Staatsdomäne Frankenhausen, die ca. 15 km nördlich von Kassel liegt, ökologisch bewirtschaftet. Ein Aspekt bei der Umstellung auf ökologische Landwirtschaft war die Umsetzung von naturschutz-orientierten Maßnahmen, die in Kooperation mit dem landwirtschaftlichen Betrieb umgesetzt wurden. Ein gewässerökologisches Teilprojekt umfasste unterschiedliche Entwicklungsmaßnahmen an und in Bächen des Jungfernbach- und Esse-Systems auf dem Gelände der Staatsdomäne ab Juli 2007. Beide Bachsysteme (Einzugsgebietsgröße jeweils ca. 9 km2) werden von typischen lössgeprägten Bördenbächen gebildet. Löss-Gebiete zählen zu den durch intensive Landwirtschaft am tiefgreifendsten veränderten Gebieten Deutschlands. Folgende wesentliche Renaturierungsmaßnahmen wurden auf dem Domänengelände umgesetzt: Entfernung der Verrohrung, Offenlegung und Neugestaltung eines Nebenbaches des Jungfernbaches am Totenhof, Rückverlegung eines Jungfernbach-Abschnitts vom Rand der Aue in seine ursprüngliche Lage im Zentrum der Aue nach historischen Angaben, Wiederherstellung der biologischen Durchgängigkeit durch die Entfernung von Wehren und den Ersatz von unpassierbaren Wege-Durchlässen durch voluminösere Durchlässe mit durchgängiger Sohle, partielle Aufweitung enger Querprofile und Anhebung der Gewässersohle durch Stein-Riegel und Sohlrechen aus Stahl oder Eichenholz. Die Maßnahmen wurden von einem wissenschaftlichen Monitoringvorhaben begleitet. Hauptaspekte der wissenschaftlichen Begleitung waren morphologische, hydrochemische und biologische Untersuchungen aquatischer Makrophyten, des Makrozoobenthos, der Fischfauna und der Amphibien. Sie dienten der Erfassung des ökologischen Status quo der Gewässer vor Durchführung der Maßnahmen und der Dokumentation der ökologischen Situation der Gewässer im Anschluss an die Maßnahmen als Basis für die Beobachtung der künftigen Gewässerentwicklung. Die Renaturierungsmaßnahmen induzierten markante Veränderungen der morphologischen Situation der ehemals zu engen und tiefen Querprofile und verbesserten die biologische Durchgängigkeit auf dem Domänengelände. An den Sohlrechen fand während der Folgemonate nach der Renaturierung wegen zu geringer Wasserführung nur ein geringer Totholztransport und damit noch keine erkennbare Sohlanhebung statt. Die chemischen Qualitätsparameter zeigten bei einigen Wasserinhaltsstoffen (z. B. bei Phosphor, Magnesium und Kalium) einen Rückgang der Konzentrationen, der seine Ursachen im Verzicht auf mineralische Düngung mit diesen Stoffen in der ökologischen Landwirtschaft haben könnte. Bei den Wasserpflanzen traten in den neu gestalteten Gewässerabschnitten unmittelbar nach den Renaturierungsmaßnahmen Pionierbestände makrophytischer Algen wie Spirogyra, Cladophora und Vaucheria auf. Über die Herbst- und Wintermonate nach Abschluss der Maßnahmen im Oktober 2009 bis zum Ende der Monitoring-Phase im April 2008 konnten sich noch keine Makrophytenbestände in den neu gestalteten Gewässerabschnitten entwickeln. Im Gegensatz hierzu fand in diesem Zeitraum eine rasche Ansiedlung von 14 Wirbellosen-Taxa im Jungfernbach und 13 Taxa im kleinen, offengelegten und neu gestalteten Bach am Totenhof statt. In diesem Nebengewässer siedelten sich zahlreiche für Lössbache charakteristische Makroinvertebraten bachaufwärts aus dem Jungfernbach heraus an. Die sehr spärliche Fischpopulation, die aus wenigen Bachforellen in einem einzigen Gewässerabschnitt bestand, veränderte sich infolge ihrer räumlichen Isolation durch unterhalb des Untersuchungsraums gelegene Wehre nicht nennenswert

Granular metal-carbon nanocomposites as piezoresistive sensor films-Part 2: Modeling longitudinal and transverse strain sensitivity

Granular and columnar nickel-carbon composites may exhibit large strain sensitivity, which makes them an interesting sensor material. Based on experimental results and morphological characterization of the material, we develop a model of the electron transport in the film and use it to explain its piezoresistive effect. First we describe a model for the electron transport from particle to particle. The model is then applied in Monte Carlo simulations of the resistance and strain properties of the disordered films that give a first explanation of film properties. The simulations give insights into the origin of the transverse sensitivity and show the influence of various parameters such as particle separation and geometric disorder. An important influence towards larger strain sensitivity is local strain enhancement due to different elastic moduli of metal particles and carbon matrix

High-precision determination of the electric and magnetic radius of the proton

Using dispersion theory with an improved description of the two-pion continuum based on the precise Roy-Steiner analysis of pion-nucleon scattering, we analyze recent data from electron-proton scattering. This allows for a high-precision determination of the electric and magnetic radius of the proton, $r_E = (0.838^{+0.005}_{-0.004}{}^{+0.004}_{-0.003})\,$fm and $r_M = (0.847\pm{0.004}\pm{0.004})\,$fm, where the first error refers to the fitting procedure using bootstrap and the data while the second one refers to the systematic uncertainty related to the underlying spectral functions.Comment: 8 pages, 2 figures, more discussions and references added, version accepted for publication in Physics Letters

Dispersion-theoretical analysis of the electromagnetic form factors of the nucleon: Past, present and future

We review the dispersion-theoretical analysis of the electromagnetic form factors of the nucleon. We emphasize in particular the role of unitarity and analyticity in the construction of the isoscalar and isovector spectral functions. We present new results on the extraction of the nucleon radii, the electric and magnetic form factors and the extraction of $\omega$-meson couplings. All this is supplemented by a detailed calculation of the theoretical uncertainties, using bootstrap and Bayesian methods to pin down the statistical errors, while systematic errors are determined from variations of the spectral functions. We also discuss the physics of the time-like form factors and point out further issues to be addressed in this framework.Comment: 31 pages, 33 pages, commissioned review article for EPJ

Granular metal-carbon nanocomposites as piezoresistive sensor films - Part 1: Experimental results and morphology

We have produced granular films based on carbon and different transition metals by means of plasma deposition processes. Some of the films possess an increased strain sensitivity compared to metallic films. They respond to strain almost linearly with gauge factors of up to 30 if strained longitudinally, while in the transverse direction about half of the effect is still measured. In addition, the film's thermal coefficient of resistance is adjustable by the metal concentration. The influence of metal concentration was investigated for the elements Ni, Pd, Fe, Pt, W, and Cr, while the elements Co, Au, Ag, Al, Ti, and Cu were studied briefly. Only Ni and Pd have a pronounced strain sensitivity at 55- €±- €5- €at.- €% (atomic percent) of metal, among which Ni–C is far more stable. Two phases are identified by transmission electron microscopy and X-ray diffraction: metal-containing nanocolumns densely packed in a surrounding carbon phase. We differentiate three groups of metals, due to their respective affinity to carbon. It turns out that only nickel has the capability to bond and form a stable and closed encapsulation of GLC around each nanoparticle. In this structure, the electron transport is in part accomplished by tunneling processes across the basal planes of the graphitic encapsulation. Hence, we hold these tunneling processes responsible for the increased gauge factors of Ni–C composites. The other elements are unable to form graphitic encapsulations and thus do not exhibit elevated gauge factors

Student Perceptions of Age and Ageing-An Evaluation of Swiss Dental Students Receiving Education in Gerodontology

Society is ageing and the higher number of senior citizens in the total population is a challenge for society and often perceived as a burden. Negative images of old age can lead to ageism and poorer healthcare for older people. The younger generation will have to master these demographic challenges. Therefore, their attitude towards and their perception of the older generation has to be monitored. The aim of this study is to present the images of ageing held by dental students who received education in gerodontology and to assess possible changes between different generations of students over time and separated by gender. An annual, anonymous questionnaire survey was conducted among dental students at the end of the 10th semester each year between 2008 and 2021. The questionnaire surveyed personal attitudes towards ageing, the assessment of seniors, and personal experience with seniors (images of ageing, "Aging Semantic Differential"). In addition to confirming Friedan's phenomenon regarding the assessment of age limits, the present study was able to demonstrate a positive image of ageing in dental students, which has remained almost constant over the years. An education in gerodontology might positively influence student perceptions of age and aging

Epidermal growth factor receptor subunit locations determined in hydrated cells with environmental scanning electron microscopy

Imaging single epidermal growth factor receptors (EGFR) in intact cells is presently limited by the available microscopy methods. Environmental scanning electron microscopy (ESEM) of whole cells in hydrated state in combination with specific labeling with gold nanoparticles was used to localize activated EGFRs in the plasma membranes of COS7 and A549 cells. The use of a scanning transmission electron microscopy (STEM) detector yielded a spatial resolution of 3 nm, sufficient to identify the locations of individual EGFR dimer subunits. The sizes and distribution of dimers and higher order clusters of EGFRs were determined. The distance between labels bound to dimers amounted to 19 nm, consistent with a molecular model. A fraction of the EGFRs was found in higher order clusters with sizes ranging from 32–56 nm. ESEM can be used for quantitative whole cell screening studies of membrane receptors, and for the study of nanoparticle-cell interactions in general

Multiscale spatial distribution of macrofauna response to fishery pressure

Trawling is one of the most damaging activities for fauna living at the ocean resulting in simultaneous pulse and chronic impacts on benthic communities on multiple spatio-temporal scales. Recently, high quality Vessel Monitoring by Satellite (VMS) data provides spatio-temporal information of swept area by fishery trawlers. Using this huge amount of information in combination with about 20 environmental descriptors, we aim to tease apart the effect of species endogenous features (i.e. dispersal capability) and exogenous factors (i.e. environmental conditions) on the fauna responses to fishery and its related spatial scales. We analyse data of 300 grab-samples taken in the German Bight (North Sea), encompassing 140 macrobenthic species collected on a regular grid over an area of about 8000 km2. We use Moran Eigenvector Maps to model patterns of potential connectivity between locations and shed light on which spatial scales fisheries, environmental characteristics, and macrobenthos are linked. Finally, we show maps of fauna response to fishery. We argue that despite the importance of proper quantification of fishing pressure and other human activities, shedding light on the effects and response to such activities is crucial for a sound understanding of the processes that shape ecosystems and diversity distribution