Uniform asymptotics of area-weighted Dyck paths

Using the generalized method of steepest descents for the case of two coalescing saddle points, we derive an asymptotic expression for the bivariate generating function of Dyck paths, weighted according to their length and their area in the limit of the area generating variable tending towards 1. The result is valid uniformly for a range of the length generating variable, including the tricritical point of the model.Comment: 14 pages, 5 figure

In situ magnetoresistance measurements of ferromagnetic nanocontacts in the Lorentz transmission electron microscope

We report on in situ magnetoresistance measurements of a 30-nm-wide ferromagnetic nanocontact with simultaneous magnetic imaging in the Lorentz transmission electron microscope. The magnetoresistive measurements are correlated with the micromagnetic configuration of the sample. This allows us to assign characteristic features in the magnetoresistance curves to different magnetic configurations of the sample. From our experiments we can conclude that the micromagnetic configuration of the whole sample—not only the nanocontact region—has to be taken into account for the interpretation of magnetoresistive effects or hysteresis loops. Micromagnetic simulations were performed which confirm the experimental results

Inelastic scattering and local heating in atomic gold wires

We present a method for including inelastic scattering in a first-principles density-functional computational scheme for molecular electronics. As an application, we study two geometries of four-atom gold wires corresponding to two different values of strain, and present results for nonlinear differential conductance vs. device bias. Our theory is in quantitative agreement with experimental results, and explains the experimentally observed mode selectivity. We also identify the signatures of phonon heating.Comment: 4 pages, 3 figures; minor changes, updated figures, final version published in Phys. Rev. Let

Optical properties of graphene antidot lattices

Undoped graphene is semi-metallic and thus not suitable for many electronic and optoelectronic applications requiring gapped semiconductor materials. However, a periodic array of holes (antidot lattice) renders graphene semiconducting with a controllable band gap. Using atomistic modelling, we demonstrate that this artificial nanomaterial is a dipole-allowed direct gap semiconductor with a very pronounced optical absorption edge. Hence, optical infrared spectroscopy should be an ideal probe of the electronic structure. To address realistic experimental situations, we include effects due to disorder and the presence of a substrate in the analysis.Comment: 11 pages, 9 figures, accepted for publication in Phys. Rev.

The Diversity of Aphidlion-like Larvae over the Last 130 Million Years

Aphidlions are larvae of certain lacewings (Neuroptera), and more precisely larvae of the groups Chrysopidae, green lacewings, and Hemerobiidae, brown lacewings. The name ‘aphidlion’ originates from their ecological function as specialised predators of aphids. Accordingly, they also play an economic role as biological pest control. Aphidlions have, mostly, elongated spindle-shaped bodies, and similarly to most lacewing larvae they are equipped with a pair of venom-injecting stylets. Fossils interpreted as aphidlions are known to be preserved in amber from the Cretaceous (130 and 100 million years ago), the Eocene (about 35 million years ago) and the Miocene (about 15 million years ago) ages. In this study, new aphidlion-like larvae are reported from Cretaceous amber from Myanmar (about 100 million years old) and Eocene Baltic amber. The shapes of head and stylets were compared between the different time slices. With the newly described fossils and specimens from the literature, a total of 361 specimens could be included in the analysis: 70 specimens from the Cretaceous, 5 from the Eocene, 3 from the Miocene, 188 extant larvae of Chrysopidae, and 95 extant larvae of Hemerobiidae. The results indicate that the diversity of head shapes remains largely unchanged over time, yet there is a certain increase in the diversity of head shapes in the larvae of Hemerobiidae. In certain other groups of Neuroptera, a distinct decrease in the diversity of head shapes in larval stages was observed

«Har du hatt det vanskelig på skolen noen gang kanskje?» En undersøkelse om foreldres opplevelse av overgang barnehage-skole for barn med nedsatt hørsel.

Tema for denne oppgaven er overgangen fra barnehage til skole for barn med nedsatt hørsel. Det er et behov for mer kunnskap og kompetanse om barn med spesialpedagogiske behovs overgang mellom de pedagogiske institusjonene. Med denne oppgaven ønsker jeg å bidra med økt kompetanse på overgangen for barn med nedsatt hørsel. Problemstillingen er derfor følgende: «Hvordan opplever foreldre til barn med nedsatt hørsel at overgangen fra barnehage til skole er for barnet deres?». De aktuelle lovverkene og styringsdokumentene som Rammeplanen for barnehage, Læreplanverket og Veilederen «Fra eldst til yngst» poengterer hvor viktig samarbeidet mellom barnehage og skolen er for overgangen fra barnehage til skole. Ansvaret for overgangen ligger både hos skoleeier og barnehageeier. Veilederen «Fra eldst til yngst» påpeker at arbeidet med overgangen skal foregå i nært samarbeid med hjemmet. Bronfenbrenners utviklingsøkologiske modell betegner dette samarbeidet i mesosystemet. Samarbeidet og interaksjonen i barnets mesosystem påvirker barns videre utvikling. Studien undersøker overgangen fra barnehage til skole fra foreldrenes perspektiv. Dette gjøres gjennom kvalitative forskningsintervjuer av tre foreldre til barn med nedsatt hørsel som i nyere tid har gjennomgått overgangen fra barnehage til skole. Intervjuene er blitt analysert og tolket gjennom en hermeneutisk tilnærming som har ført til ulike funn. Barna til foreldrene i denne studie har ikke opplevd et tilfredsstillende tilbud i ordinære barnehager. Likevel har foreldrene ansett det å dele informasjon mellom ulike instanser som viktig. Resultatene viser at foreldrene i samarbeid med skole ønsker å bli hørt og tatt på alvor. Dersom en ikke blir møtt på denne måten kan samarbeidet bli vanskelig og opplevelsen være frustrerende. To av foreldrene i dette utvalget flyttet fra distriktet til en større by for at barnet deres skulle få bedre opplæringsvilkår. Det kan tyde på at tilbudet i distriktene ikke blir ansett som gode nok av brukerne selv

Urban Stress and Bicycle Infrastructure in the City of Osnabrück – Analysing Well-Being and Infrastructure Relationships in Streetscapes through a Triangulation Approach

Active mobility is a key factor in the mobility revolution and is thus elementary in combating the climate crisis. At the same time, however, much research is still needed to improve the situation of active mobility, especially regarding inhibiting factors in the choice of active modes of transport. Essential here is road users\u27 positive and negative emotional experiences in different infrastructure settings. Due to high volumes and speeds of motorised traffic, high noise and pollution levels and a lack of greenery urban space, today is often associated with increased stress and an excess of stress-related diseases such as cardiovascular diseases, depression, or schizophrenia (Adli, 2017). Providing data and objectifying much-discussed issues such as perceived safety in transport infrastructure is essential for decision-making at the community level (Sørensen, 2009). Such data can provide evidence to refine traffic planning guidelines and improve public space for pedestrians and cyclists. It is therefore necessary to get a differentiated picture of social and ecological considerations in the mobility sector. The BMDV project “Emotion Sensing for (E-)Bicycle Safety and Mobility Comfort ESSEM” investigates the subjective perception of cyclists’ safety in urban traffic. With the help of iterative environmental and body-related data collection, stress points in the municipal cycling network are identified and analysed in the two model cities of Ludwigsburg and Osnabrück . The framework given in this study applies a triangulating approach that allows statements on individual “stress” utilising biological markers (skin conductivity, skin temperature) via a sensor wristband and through standardised questionnaires. In this way, vulnerable groups can be identified, which can be better taken into account in project development and planning. This study focuses on three “stress hotspots” in Osnabrück, considering different forms of bicycle infrastructure

Towards a Swiss National Research Infrastructure

In this position paper we describe the current status and plans for a Swiss National Research Infrastructure. Swiss academic and research institutions are very autonomous. While being loosely coupled, they do not rely on any centralized management entities. Therefore, a coordinated national research infrastructure can only be established by federating the various resources available locally at the individual institutions. The Swiss Multi-Science Computing Grid and the Swiss Academic Compute Cloud projects serve already a large number of diverse user communities. These projects also allow us to test the operational setup of such a heterogeneous federated infrastructure

Inelastic quantum transport: the self-consistent Born approximation and correlated electron-ion dynamics

A dynamical method for inelastic transport simulations in nanostructures is compared with a steady-state method based on non-equilibrium Green's functions. A simplified form of the dynamical method produces, in the steady state in the weak-coupling limit, effective self-energies analogous to those in the Born Approximation due to electron-phonon coupling. The two methods are then compared numerically on a resonant system consisting of a linear trimer weakly embedded between metal electrodes. This system exhibits enhanced heating at high biases and long phonon equilibration times. Despite the differences in their formulation, the static and dynamical methods capture local current-induced heating and inelastic corrections to the current with good agreement over a wide range of conditions, except in the limit of very high vibrational excitations, where differences begin to emerge.Comment: 12 pages, 7 figure