The Inverse Seesaw Mechanism in Noncommutative Geometry

In this publication we will implement the inverse Seesaw mechanism into the noncommutative framework on the basis of the AC-extension of the Standard Model. The main difference to the classical AC model is the chiral nature of the AC fermions with respect to a U(1) extension of the Standard Model gauge group. It is this extension which allows us to couple the right-handed neutrinos via a gauge invariant mass term to left-handed A-particles. The natural scale of these gauge invariant masses is of the order of 10^17 GeV while the Dirac masses of the neutrino and the AC-particles are generated dynamically and are therefore much smaller (ca. 1 GeV to 10^6 GeV). From this configuration a working inverse Seesaw mechanism for the neutrinos is obtained

On Spectral Triples in Quantum Gravity II

A semifinite spectral triple for an algebra canonically associated to canonical quantum gravity is constructed. The algebra is generated by based loops in a triangulation and its barycentric subdivisions. The underlying space can be seen as a gauge fixing of the unconstrained state space of Loop Quantum Gravity. This paper is the second of two papers on the subject.Comment: 43 pages, 1 figur

Transect width and missed observations in counting muskoxen (Ovibos moschatus) from fixed-wing aircraft

While conductioning muskox-censuses (Ovibos moschatus) in winter in Jameson Land, NE Greenland, from a fixed-wing aircraft, we examined the width of transects covered. We used a laser range-finder binocular for measuring the distance to observed groups. We found that 1000 m was a reasonable limit for observing a high proportion of the muskoxen present even though it was possible to observe muskoxen from 4000 m or even more. Using two observers on the right side of the aircraft each speaking into a tape recorder with an automatic time signal, we recorded observations and performed a double-observer experiment. By matching the group sizes and perpendicular distances with times of observation we could compare observations of the two observers. We found that both observers missed up to 25% of muskoxen within a 2000 m transect width. The main reasons for missing animals is difficulty in obtaining reference points in snow covered landscape and fatigue of the observers. Calibration of estimated distances using read-outs from the laser-range finder is an adequate method of obtaining distance data for line transect calculations. Our double-observer experiment demonstrated that even groups close to the transect are easily missed

Muskoxen in Angujaartorfiup Nunaa, West Greenland: Monitoring, Spatial Distribution, Population Growth, and Sustainable Harvest

In the 1960s, 27 muskoxen (Ovibos moschatus) were introduced to Angujaartorfiup Nunaa, which is located next to Kangerlussuaq Airport in West Greenland. Data from 12 aerial surveys of muskoxen from 1986 to 1996 show 1) that the population has stabilized at 3000 muskoxen since hunting was initiated in 1988, 2) that the population has maintained a high level of reproduction during the study period, and 3) that an annual kill of about 700 muskoxen will maintain the population at its current level if natural mortality and reproduction remain unchanged. Using a geographical information system to subdivide data by topography and altitude showed that muskoxen greatly favour valleys and lowland areas. Densities of muskoxen above 500 m above sea level were less than 51% of densities below 500 m above sea level.Dans les années 1960, 27 boeufs musqués (Ovibos moschatus) ont été relâchés à Angujaartorfiup Nunaa, qui est situé près de l'aéroport de Kangerlussuaq, dans le Groenland occidental. Des données provenant de 12 relevés aériens de boeufs musqués, effectués entre 1986 et 1996, montrent que: 1) la population s'est stabilisée à 3000 individus depuis l'instauration de la chasse en 1988; 2) la population a maintenu un niveau élevé de reproduction durant la période de l'étude; et 3) l'abattage annuel d'environ 700 individus devrait permettre de maintenir la population à son niveau actuel si la mortalité et la reproduction naturelles demeurent inchangées. L'utilisation d'un système d'information géographique pour subdiviser les données selon la topographie et l'altitude a montré que le boeuf musqué manifeste une préférence marquée pour les vallées et les zones de faible altitude. Les densités de boeufs musqués trouvées à plus de 500 m au-dessus du niveau de la mer étaient inférieures à 51 p. cent des densités trouvées à moins de 500 m d'altitude

Lignin biomarkers as tracers of mercury sources in lakes water column

This study presents the role of specific terrigenous organic compounds as important vectors of mercury (Hg) transported from watersheds to lakes of the Canadian boreal forest. In order to differentiate the autochthonous from the allochthonous organic matter (OM), lignin derived biomarker signatures [Lambda, S/V, C/V, P/(V ? S), 3,5-Bd/V and (Ad/Al)v] were used. Since lignin is exclusively produced by terrigenous plants, this approach can give a non equivocal picture of the watershed inputs to the lakes. Moreover, it allows a characterization of the source of OM and its state of degradation. The water column of six lakes from the Canadian Shield was sampled monthly between June and September 2005. Lake total dissolved Hg concentrations and Lambda were positively correlated, meaning that Hg and ligneous inputs are linked (dissolved OM r2 = 0.62, p\0.0001; particulate OM r2 = 0.76, p\0.0001). Ratios of P/(V ? S) and 3,5-Bd/V from both dissolved OM and particulate OM of the water column suggest an inverse relationship between the progressive state of pedogenesis and maturation of the OM in soil before entering the lake, and the Hg concentrations in the water column. No relation was found between Hg levels in the lakes and the watershed flora composition—angiosperm versus gymnosperm or woody versus non-woody compounds. This study has significant implications for watershed management of ecosystems since limiting fresh terrestrial OM inputs should reduce Hg inputs to the aquatic systems. This is particularly the case for largescale land-use impacts, such as deforestation, agriculture and urbanization, associated to large quantities of soil OM being transferred to aquatic systems

The role of biotic interactions in shaping distributions and realised assemblages of species: implications for species distribution modelling.

Predicting which species will occur together in the future, and where, remains one of the greatest challenges in ecology, and requires a sound understanding of how the abiotic and biotic environments interact with dispersal processes and history across scales. Biotic interactions and their dynamics influence species' relationships to climate, and this also has important implications for predicting future distributions of species. It is already well accepted that biotic interactions shape species' spatial distributions at local spatial extents, but the role of these interactions beyond local extents (e.g. 10 km(2) to global extents) are usually dismissed as unimportant. In this review we consolidate evidence for how biotic interactions shape species distributions beyond local extents and review methods for integrating biotic interactions into species distribution modelling tools. Drawing upon evidence from contemporary and palaeoecological studies of individual species ranges, functional groups, and species richness patterns, we show that biotic interactions have clearly left their mark on species distributions and realised assemblages of species across all spatial extents. We demonstrate this with examples from within and across trophic groups. A range of species distribution modelling tools is available to quantify species environmental relationships and predict species occurrence, such as: (i) integrating pairwise dependencies, (ii) using integrative predictors, and (iii) hybridising species distribution models (SDMs) with dynamic models. These methods have typically only been applied to interacting pairs of species at a single time, require a priori ecological knowledge about which species interact, and due to data paucity must assume that biotic interactions are constant in space and time. To better inform the future development of these models across spatial scales, we call for accelerated collection of spatially and temporally explicit species data. Ideally, these data should be sampled to reflect variation in the underlying environment across large spatial extents, and at fine spatial resolution. Simplified ecosystems where there are relatively few interacting species and sometimes a wealth of existing ecosystem monitoring data (e.g. arctic, alpine or island habitats) offer settings where the development of modelling tools that account for biotic interactions may be less difficult than elsewhere

Plant diversity dynamics over space and time in a warming Arctic

The Arctic is warming four times faster than the global average 1 and plant communities are responding through shifts in species abundance, composition and distribution 2–4 . However, the direction and magnitude of local changes in plant diversity in the Arctic have not been quantified. Using a compilation of 42,234 records of 490 vascular plant species from 2,174 plots across the Arctic, here we quantified temporal changes in species richness and composition through repeat surveys between 1981 and 2022. We also identified the geographical, climatic and biotic drivers behind these changes. We found greater species richness at lower latitudes and warmer sites, but no indication that, on average, species richness had changed directionally over time. However, species turnover was widespread, with 59% of plots gaining and/or losing species. Proportions of species gains and losses were greater where temperatures had increased the most. Shrub expansion, particularly of erect shrubs, was associated with greater species losses and decreasing species richness. Despite changes in plant composition, Arctic plant communities did not become more similar to each other, suggesting no biotic homogenization so far. Overall, Arctic plant communities changed in richness and composition in different directions, with temperature and plant–plant interactions emerging as the main drivers of change. Our findings demonstrate how climate and biotic drivers can act in concert to alter plant composition, which could precede future biodiversity changes that are likely to affect ecosystem function, wildlife habitats and the livelihoods of Arctic peoples 5,6