Detecting groundwater discharge dynamics from point-to-catchment scale in a lowland stream : Combining hydraulic and tracer methods

Acknowledgements. We would like to thank members of the Northern Rivers Institute, Aberdeen University, for helpful discussions of data. We also thank Lars Rasmussen, Jolanta Kazmierczak and Charlotte Ditlevsen for help in the field. This study is part of the Hydrology Observatory, HOBE (http://www.hobe.dk), funded by the Villum Foundation and was as well funded by the Aarhus University Research Foundation.Peer reviewedPublisher PD

Amplification of obliquity forcing through mean-annual and seasonal atmospheric feedbacks

International audiencePleistocene benthic ?18O records exhibit strong spectral power at ~41 kyr, indicating that global ice volume has been modulated by Earth's axial tilt. This feature, and weak spectral power in the precessional band, has been attributed to the influence of obliquity on mean-annual and seasonal insolation gradients at high latitudes. In this study, we use a coupled ocean-atmosphere general circulation model to quantify changes in continental snowfall associated with mean-annual and seasonal insolation forcing due to a change in obliquity. Our model results indicate that insolation changes associated with a decrease in obliquity amplify continental snowfall in two ways: (1) An increase in high-latitude winter insolation is enhanced through a low-cloud feedback, resulting in colder air temperatures and increased snow precipitation. (2) An increase in the summer insolation gradient enhances summer eddy activity, increasing vapor transport to high-latitude regions. In our experiments, a decrease in obliquity leads to an annual snowfall increase of 25.0 cm; just over one-half of this response (14.1 cm) is attributed to seasonal changes in insolation. Our results indicate that the role of insolation gradients is important in amplifying the relatively weak insolation forcing due to a change in obliquity. Nonetheless, the total snowfall response to obliquity is similar to that due to a shift in Earth's precession, suggesting that obliquity forcing alone can not account for the spectral characteristics of the ice-volume record

Palaeoclimate - A balmy Arctic

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62910/1/432814a.pd

An Evaluation of a Behaviour Assessment to Determine the Suitability of Shelter Dogs for Rehoming

We evaluated a scheme for assessing shelter dog behaviour, which used 28 tests and rated responses from 0 (positive response) to 5 (fear, tonic immobility, or escape attempts). The assessment was evaluated for 236 dogs, and was repeated by a different assessor for 39 dogs approximately 80 days after rehoming to determine relevance of individual test components. A new owner survey evaluated satisfaction with the dog. A total of 130 of 236 dogs passed (score ≤ 70), 24 scored 71–80 (referred for behavioural modification), and 82 (score > 80) failed. Scores were mainly unaffected by dog type and environmental variables, but decreased if dog faeces from a previous test was present in the arena during a test. Shelter tests only correlated with repeat tests if there was no direct contact with assessors. Adopters were satisfied with their dogs, despite reporting some behaviour problems. The shelter assessment was therefore robust against most outside influences but did not predict responses to people well

A quantum beam splitter for atoms

An interferometric method is proposed to controllably split an atomic condensate in two spatial components with strongly reduced population fluctuations. All steps in our proposal are in current use in cold atom laboratories, and we show with a theoretical calculation that our proposal is very robust against imperfections of the interferometer.Comment: 6 pages, 3 figures, revtex

Factors that inhibit snowball Earth simulation

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94616/1/palo1176.pd

Positive P simulations of spin squeezing in a two-component Bose condensate

The collisional interaction in a Bose condensate represents a non-linearity which in analogy with non-linear optics gives rise to unique quantum features. In this paper we apply a Monte Carlo method based on the positive P pseudo-probability distribution from quantum optics to analyze the efficiency of spin squeezing by collisions in a two-component condensate. The squeezing can be controlled by choosing appropiate collision parameters or by manipulating the motional states of the two components.Comment: 5 pages, 2 figures. Submitted to Phys. Rev.

Simulation of modern and middle Cretaceous marine δ 18 O with an ocean‐atmosphere general circulation model

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95522/1/palo1494.pd

Semi-Static Hedging Based on a Generalized Reflection Principle on a Multi Dimensional Brownian Motion

On a multi-assets Black-Scholes economy, we introduce a class of barrier options. In this model we apply a generalized reflection principle in a context of the finite reflection group acting on a Euclidean space to give a valuation formula and the semi-static hedge.Comment: Asia-Pacific Financial Markets, online firs