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Université de Neuchâtel

High-throughput sequencing of litter and moss eDNA reveals a positive correlation between the diversity of Apicomplexa and their invertebrate hosts across alpine habitats

Singer, David ; Duckert, Clément ; Heděnec, Petr ; Lara, Enrique ; Hiltbrunner, Erika ; Mitchell, Edward A.D

In: Soil Biology & Biochemistry, 2020, vol. 147, no. art. 107837, p. 1-4

A high diversity of Apicomplexa was recently found in tropical soils presumably reflecting the diversity of their invertebrate hosts, but such patterns have not been explored in colder regions. We analysed the diversity of Apicomplexa and their potential metazoan hosts in litter and mosses collected in 11 different alpine habitats using an eDNA metabarcoding approach. The abundance and diversity...

Université de Neuchâtel

Carrier-Envelope Offset Frequency Stabilization of a Thin-Disk Laser Oscillator via Depletion Modulation

Andrade, José R. C ; Modsching, Norbert ; Tajalli, Ayhan ; Dietrich, Christian M ; Kleinert, Sven ; Placzek, Fabian ; Kreipe, Bernhard ; Schilt, Stéphane ; Wittwer, Valentin J ; Südmeyer, Thomas ; Morgner, Uwe

In: IEEE Photonics Journal, 2020, vol. 12, no. 2, p. 1-9

We present a novel concept for the stabilization of the carrier-envelope offset (CEO) frequency of femtosecond pulse trains from thin-disk laser oscillators by exploiting gain depletion modulation in the active gain region. We shine a small fraction of the laser output power back onto the thin disk allowing the population inversion in the gain medium to be controlled. We employ this technique in...

Université de Neuchâtel

Frequency noise correlation between the offset frequency and the mode spacing in a mid-infrared quantum cascade laser frequency comb

Shehzad, Atif ; Brochard, Pierre ; Matthey, Renaud ; Kapsalidis, Filippos ; Shahmohammadi, Mehran ; Beck, Mattias ; Hugi, Andreas ; Jouy, Pierre ; Faist, Jérôme ; Südmeyer, Thomas ; Schilt, Stéphane

In: Optics Express, 2020, vol. 28, no. 6, p. 8200-8210

The generation of frequency combs in the mid-infrared (MIR) spectral range by quantum cascade lasers (QCLs) has the potential for revolutionizing dual-comb multi-heterodyne spectroscopy in the molecular fingerprint region. However, in contrast to frequency combs based on passively mode-locked ultrafast lasers, their operation relies on a completely different mechanism resulting from a four-wave...

Université de Neuchâtel

Towards compact ultralow phase noise lasers and microwave signals based on new approaches

Brochard, Pierre ; Südmeyer, Thomas (Dir.)

Thèse de doctorat : Université de Neuchâtel, 2019.

Today, the lowest phase noise microwave signals are generated optically by frequency division of an ultra-stable optical reference using a femtosecond frequency comb. In the commonly used approach, the ultra-stable optical reference is obtained by frequency-stabilizing a laser to a high-finesse ultra-low expansion optical cavity, and the frequency division is performed by optically locking a...

Université de Neuchâtel

Les tourbières du Vieux Continent se meurent

Pop, Georges

In: Sécurité Environnement, 2020, vol. 1, p. 14-15

Le constat est alarmant : au cours de ces 300 dernières années, depuis le début de l’ère industrielle, les tourbières européennes ont subi un assèchement généralisé dû essentiellement aux activités humaines. Or, ces biotopes contribuent fortement à l’équilibre écologique de la planète en absorbant bien plus de CO2 qu’elles n’en rejettent. La fonction de puits de...

Université de Neuchâtel

The foraging ecology of two neighbouring chimpanzee communities from Budongo Forest

Villioth, Jakob ; Newton-Fisher, Nicholas E. (Dir.) ; Zuberbühler, Klaus (Codir.)

Thèse de doctorat : Université de Neuchâtel, 2019.

Chimpanzees (Pan troglodytes) often serve as a model species to test socio-ecological theories of foraging behaviour. Due to a high degree of fission-fusion dynamics, essential foraging variables, such as group size, patch size and travel distance, are expected to be more closely linked in chimpanzees than in animals that forage in cohesive groups. While it has been clearly established...

Université de Neuchâtel

Modeling heat and fluid flow in discrete fracture networks : application to fluid-driven seismicity and engineered geothermal systems

Jansen, Gunnar ; Miller, Stephen A. (Dir.) ; Valley, Benoît (Codir.)

Thèse de doctorat : Université de Neuchâtel, 2018.

Understanding the dynamics of naturally fractured systems and fractured reservoirs in terms of flow, heat transport and fracture stability (e.g. earthquakes) is important for a range of applications including geothermal systems, waste water injection and natural fluid-driven seismicity. Many numerical codes exist that can simulate aspects of these dynamics, but in general require either expensive...

Université de Neuchâtel

Conditioning groundwater flow parameters with iterative ensemble smoothers : analysis and approaches in the continuous and the discrete cases

Lam, Dan-Thuy ; Renard, Philippe (Dir.) ; Kerrou, Jaouher (Codir.)

Thèse de doctorat : Université de Neuchâtel, 2019.

Data assimilation (DA) consists in combining observations and predictions of a numerical model to produce an optimal estimate of the evolving state of a system. Over the last decade, DA methods based on the Ensemble Kalman Filter (EnKF) have been particularly explored in various geoscience fields for inverse modelling. Although this type of ensemble methods can handle high-dimensional systems,...

Université de Neuchâtel

The role of insecticides and malaria infection on the mosquito’s behaviour and the consequences for malaria transmission

Thiévent, Kevin ; Koella, Jacob (Dir.)

Thèse de doctorat : Université de Neuchâtel, 2018.

Insecticide treated bed nets (ITNs) are one of the most cost-effective techniques used for malaria control. While the repellent and irritant actions of ITNs offer personal protection, their insecticidal action contributes to community protection by lowering the number of infectious mosquitoes in the population. Despite this, the efficacy of ITNs to provide both personal and community protection...

Université de Neuchâtel

Impacts of urban gardening on soil quality, soil fauna and soil multifunctionality

Tresch, Simon ; Le Bayon, Claire (Dir.) ; Fliessbach, Andreas (Codir.) ; Moretti, Marco (Codir.)

Thèse de doctorat : Université de Neuchâtel, 2019.

Urban gardens are important and at the same time popular greenspaces. As urban areas are expanding globally, urban gardens play an increasingly important role in contributing to essential ecosystem services, well-being of citizens, and biodiversity in a city. Gardening activities determine above- and belowground diversity of plants and insects. However, the effect of gardening activities on soil...