Analytical solution of the Gross-Neveu model at finite density

Recent numerical calculations have shown that the ground state of the Gross-Neveu model at finite density is a crystal. Guided by these results, we can now present the analytical solution to this problem in terms of elliptic functions. The scalar potential is the superpotential of the non-relativistic Lame Hamiltonian. This model can also serve as analytically solvable toy model for a relativistic superconductor in the Larkin-Ovchinnikov-Fulde-Ferrell phase.Comment: 5 pages, no figures, revtex; vs2: appendix with analytical proof of self-consistency adde

Does agricultural structural change lead to a weakening of the sector’s social functions? – A case study from north-west Germany

The ongoing shift towards fewer and larger farms is perceived negatively and is often associated with adverse social impacts for rural communities throughout Europe. Empirical evidence on the social functions of agriculture and how these are fulfilled is fragmented. Implications of agricultural structural change for the social dimensions of agricultural multifunctionality have thus remained poorly understood. Addressing this research gap, this paper explores whether, and, if so, how, the declining number of farms affects the social dimensions of agricultural multifunctionality based on a qualitative case study approach. The case we explore is a rural region in North-West Germany. Our case study suggests several linkages between structural change and the social functions of agriculture: first, a declining number of farms is closely related to farming activities being increasingly practised according to industrial logics, which has weakened socio-economic and socio-ecological functions. Second, farm exits have led to fewer farmers being engaged in voluntary work, implying a weakening of socio-ecological and socio-cultural functions. Third, income-diversification activities have gained importance relative to farming activities, reinforcing several of agriculture's social functions. Our results hint at differences between capital- and labour-intensive income-diversification activities with regard to (i) social functions being fulfilled, (ii) a potential departure from the predominant growth paradigm and (iii) the relevance of extending contemporary conceptions of what is part of agriculture. Based on our results, we put forward three claims to inform both future research and debates on policies aiming at a better alignment of agricultural development and societal expectations.Peer Reviewe

Covariant boost and structure functions of baryons in Gross-Neveu models

Baryons in the large N limit of two-dimensional Gross-Neveu models are reconsidered. The time-dependent Dirac-Hartree-Fock approach is used to boost a baryon to any inertial frame and shown to yield the covariant energy-momentum relation. Momentum distributions are computed exactly in arbitrary frames and used to interpolate between the rest frame and the infinite momentum frame, where they are related to structure functions. Effects from the Dirac sea depend sensitively on the occupation fraction of the valence level and the bare fermion mass and do not vanish at infinite momentum. In the case of the kink baryon, they even lead to divergent quark and antiquark structure functions at x=0.Comment: 13 pages, 12 figures; v2: minor correction

Wave Conditions Inducing Extreme Mooring Loads on a Dynamically Responding Moored Structure

The aim of this paper is to determine which wave conditions are inducing extreme mooring loads on a highly dynamically responding moored structure. Currently, the design of a mooring system for a typical oil and gas offshore structure is based on the prediction of the extreme mooring loads for a limited number of wave conditions along the envelope of a wave scatter diagram. During the design process, an inappropriate choice of wave conditions could lead to an incorrect estimation of extreme mooring loads, which may result either in the loss of the mooring system or in a costly overdesign. This paper draws on mooring tensions and wave conditions that have been recorded at a mooring test facility using a multi-leg catenary mooring system. The mooring loads have been assessed to identify extreme mooring loads, which have been analysed in respect to the corresponding wave conditions. Further, joint probability distributions of wave conditions that results in extreme mooring loads have been determined. The most important finding is that extreme mooring loads were not necessarily identified to occur on the envelope of the wave climate parameter scatter diagram

A novel mooring tether for peak load mitigation: Initial performance and service simulation testing

Copyright © 2014 Elsevier. NOTICE: this is the author’s version of a work that was accepted for publication in International Journal of Marine Energy. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. The ‘In press‘ version is available at http://dx.doi.org/10.1016/j.ijome.2014.06.001One of the main engineering challenges for floating marine renewable energy devices is the design of reliable, yet cost-effective mooring solutions for the harsh and dynamic marine environment. The mooring system must be able to withstand the ultimate limit state during storm conditions as well as the fatigue limit state due to the highly cyclic wave motions. This paper presents the performance and service simulation testing of a novel mooring tether that combines the material properties of elastomeric and thermoplastic elements. This allows to 'tailor' the load-extension curve to exhibit a low stiffness response for the expected normal, operating, load conditions and a high stiffness response for the envisaged extreme, storm, conditions. The experimental results demonstrate the working principle of the mooring element and show good agreement between the theoretical load extension curve and the conducted performance tests with a distinct hysteresis effect caused by the thermoplastic element. The hysteresis is dependant on the applied pre-tension and load cycle amplitude of the element and to a lesser extent on the cycle frequency. The relaxation of the elastomeric element is quantified, giving insight into the expected longterm performance of the tether. The demonstrated working principle and the possibility to tailor the mooring response allows engineers to load- and cost-optimise the mooring system of floating marine energy converters.Engineering and Physical Sciences Research Council (EPSRC)Peninsula Research Institute for Marine Renewable Energy (PRIMaRE)European Regional Development Fund (ERDF)South West Regional Development Agency (SWRDA

Parathyroid localization

Twenty-nine consecutive patients with suspected primary hyperparathyroidism were examined preoperatively using ultrasound, sonographically guided fine needle aspiration, and aspirate immunostaining for PTH. In 25 patients, localization of enlarged parathyroid glands was successful. In 2 patients, the tumors were located retrosternally and, thus, could not be detected by ultrasound. One patient had a multinodular goiter which impeded localization. In 1 patient with renal osteodystrophy, 2 enlarged parathyroid glands in the neck were not visualized preoperatively. Cytology was not diagnostic, although some cytological features were suggestive of parathyroid cells. Immunostaining of the aspirated smears for PTH, however, correctly diagnosed all preoperatively localized lesions. Ultrasound should be the routine procedure of choice for preoperative localization of abnormal parathyroid glands in primary hyperparathyroidism. Fine needle aspiration and immunocytochemistry can supply confirmation, if necessary

Component reliability testing for wave energy converters: Rationale and implementation

Copyright © 2013 European Wave and Tidal Energy Conference10th European Wave and Tidal Energy Conference, Aalborg, Denmark, 2 – 5 September 2013The reliability of marine renewable energy (MRE) converters is a key issue that has to be addressed and included in a whole system approach, in order to make the energy extraction from these sources a viable option. At the current development stage of MRE converters, an increasing number of devices are being field tested at pre-commercial demonstration scale, yielding field experience and load data useful for refining, demonstrating and improving the reliability of devices. This paper gives a brief review of the most advanced technologies and common reliability aspects that provide the rationale for dedicated component testing. It describes a service simulation test approach and the development of a unique large-scale component test facility. The test rig is capable of replicating the forces and motions experienced by components for a range of floating marine applications. The replication of motion angles is demonstrated in this paper. The service simulation test of a marine power cable is presented as a case study on how component performance can be assessed and demonstrated prior to long-term field deployments in order to ensure the reliability of crucial sub-systems and components in the harsh marine environment.Engineering and Physical Sciences Research Council (EPSRC)PRIMaR

Biomechanics for inclusive urban design : effects of tactile paving on older adults’ gait when crossing the street

In light of our ageing population it is important that the urban environment is easily accessible and hence supports older adults’ independence. Tactile ‘blister’ paving was originally designed to provide guidance for visually impaired people at pedestrian crossings. However, as research links irregular surfaces to falls in older adults, such paving may have an adverse effect on older people. We investigated the effects of tactile paving on older adults’ gait in a scenario closely resembling “crossing the street”. Gait analysis of 32 healthy older adults showed that tactile, as compared to smooth, paving increases the variability in timing of foot placement by 20%, thereby indicating a disturbance of the rhythmic gait pattern. Moreover, toe-clearance during the swing phase increased by 7% on tactile paving, and the ability to stop upon cue from the traffic light was compromised. These results need to be viewed under consideration of the limitations associated with laboratory studies and real world analysis is needed to fully understand their implications for urban design

Wave conditions inducing extreme mooring loads on a dynamically responding moored structure

PublishedThe aim of this paper is to determine which wave conditions are inducing extreme mooring loads on a highly dynamically responding moored structure. Currently, the design of a mooring system for a typical oil and gas offshore structure is based on the prediction of the extreme mooring loads for a limited number of wave conditions along the envelope of a wave scatter diagram. During the design process, an inappropriate choice of wave conditions could lead to an incorrect estimation of extreme mooring loads, which may result either in the loss of the mooring system or in a costly overdesign. This paper draws on mooring tensions and wave conditions that have been recorded at a mooring test facility using a multi-leg catenary mooring system. The mooring loads have been assessed to identify extreme mooring loads, which have been analysed in respect to the corresponding wave conditions. Further, joint probability distributions of wave conditions that results in extreme mooring loads have been determined. The most important finding is that extreme mooring loads were not necessarily identified to occur on the envelope of the wave climate parameter scatter diagram.The work described in this publication has received funding from the European Commission under the 7th Framework Programme (FP7) through the MARINET initiative, grant agreement no 262552. It also received funding from the Technology Strategy Board. The authors would like to acknowledge the support of the South West Regional Development Agency for its support through the PRIMaRE institution.http://hdl.handle.net/10871/1430