Peri-urban farmland conservation and development of alternative food networks: Insights from a case-study area in metropolitan Barcelona (Catalonia, Spain)

There has been a growing literature on alternative food networks (AFNs); structures that reconfigure the systems of production, distribution and consumption of food. Part of this literature emphasises the local scale and the idea of proximity. In a world that is increasingly urban, AFNs at a local scale can be more easily developed by linking peri-urban farmlands and cities. However, agriculture in the rural–urban fringe struggles to survive in the face of urban pressures and sprawl; a process which undermines viable agricultural production in the city's countryside. A widely used strategy to address these pressures has been farmland protection, undertaken in different ways depending on the legal framework of particular countries. This paper considers farmland conservation and AFNs development issues through a case-study of the Baix Llobregat Agricultural Park (BLAP) in metropolitan Barcelona. It concludes that AFNs in peri-urban areas are only possible if farmland preservation is guaranteed, and that the former does not come as a direct consequence of the latter. The specific conditions in which both can occur will be of interest for scholars as well as policy-makers and planners

Antiferromagnetic Spin Fluctuations in the Metallic Phase of Quasi-Two-Dimensional Organic Superconductors

We give a quantitative analysis of the previously published nuclear magnetic resonance (NMR) experiments in the k-(ET)2X family of organic charge transfer salts by using the phenomenological spin fluctuation model of Moriya, and Millis, Monien and Pines (M-MMP). For temperatures above T_nmr ~ 50 K, the model gives a good quantitative description of the data in the metallic phases of several k-(ET)2X materials. These materials display antiferromagnetic correlation lengths which increase with decreasing temperature and grow to several lattice constants by T_nmr. It is shown that the fact that the dimensionless Korringa ratio is much larger than unity is inconsistent with a broad class of theoretical models (such as dynamical mean-field theory) which neglects spatial correlations and/or vertex corrections. For materials close to the Mott insulating phase the nuclear spin relaxation rate, the Knight shift and the Korringa ratio all decrease significantly with decreasing temperature below T_nmr. This cannot be described by the M-MMP model and the most natural explanation is that a pseudogap, similar to that observed in the underdoped cuprate superconductors, opens up in the density of states below T_nmr. Such a pseudogap has recently been predicted to occur in the dimerised organic charge transfer salts materials by the resonating valence bond (RVB) theory. We propose specific new experiments on organic superconductors to elucidate these issues. For example, measurements to see if high magnetic fields or high pressures can be used to close the pseudogap would be extremely valuable.Comment: 11 pages, 2 figures. Accepted for publication in Phys. Rev.

Sensitivity of the interlayer magnetoresistance of layered metals to intralayer anisotropies

Many of the most interesting and technologically important electronic materials discovered in the past two decades have two common features: a layered crystal structure and strong interactions between electrons. Two of the most fundamental questions about such layered metals concern the origin of intralayer anisotropies and the coherence of interlayer charge transport. We show that angle dependent magnetoresistance oscillations (AMRO) are sensitive to anisotropies around an intralayer Fermi surface. Hence, AMRO can be a probe of intralayer anisotropies that is complementary to angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy (STM). However, AMRO are not very sensitive to the coherence of the interlayer transport. We illustrate this with comparisons to recent AMRO experiments on an overdoped cuprate.Comment: 7 pages, 3 figure

Economic evaluation of the treatment of grade II haemorrhoids : a comparison of stapled haemorrhoidopexy and rubber band ligation.

The definitive version is available at www3.interscience.wiley.comPeer reviewedPostprin

Mott Transition, Compressibility Divergence and P-T Phase Diagram of Layered Organic Superconductors: An Ultrasonic Investigation

The phase diagram of the organic superconductor $\kappa$-(BEDT-TTF)$_2$Cu[N(CN)$_2$Cl has been investigated by ultrasonic velocity measurements under helium gas pressure. Different phase transitions were identified trough several elastic anomalies characterized from isobaric and isothermal sweeps. Our data reveal two crossover lines that end on the critical point terminating the first-order Mott transition line. When the critical point is approached along these lines, we observe a dramatic softening of the velocity which is consistent with a diverging compressibility of the electronic degrees of freedom.Comment: 4 pages, 5 figure

Modeling Bell's Non-resonant Cosmic Ray Instability

We have studied the non-resonant streaming instability of charged energetic particles moving through a background plasma, discovered by Bell (2004). We confirm his numerical results regarding a significant magnetic field amplification in the system. A detailed physical picture of the instability development and of the magnetic field evolution is given.Comment: 12 pages, 4 figures, accepted to Ap

Diffusive Shock Acceleration with Magnetic Amplification by Non-resonant Streaming Instability in SNRs

We investigate the diffusive shock acceleration in the presence of the non-resonant streaming instability introduced by Bell (2004). The numerical MHD simulations of the magnetic field amplification combined with the analytical treatment of cosmic ray acceleration permit us to calculate the maximum energy of particles accelerated by high-velocity supernova shocks. The estimates for Cas A, Kepler, SN1006, and Tycho historical supernova remnants are given. We also found that the amplified magnetic field is preferentially oriented perpendicular to the shock front downstream of the fast shock. This explains the origin of the radial magnetic fields observed in young supernova remnants.Comment: 18 pages, 9 figures, accepted to Ap

Progress of the National Bobwhite Conservation Initiative

Northern bobwhites (Colinus virginianus) have declined precipitously over 5 decades because of a decline in habitat, largely a result of agricultural intensification and inadequate management of natural plant succession. In response, quail biologists developed strategic and operational plans, and formed a national partnership of state and federal agencies, bobwhite institutions, non-government organizations, universities and private citizens. The early history of these efforts was reviewed in 2006 at the Sixth National Quail Symposium. Over the past 10 years, exponential growth occurred, including establishment of a home for national bobwhite conservation at the University of Tennessee, and funding from the National Fish and Wildlife Foundation, the United States Fish Wildlife Service Pitmann-Robertson (Federal Aid in Wildlife Restoration Program), individual state agencies and citizens. The result in 2016 is the National Bobwhite Conservation Initiative (NBCI), a 25-state consortium of state wildlife agencies and partners, led by the National Bobwhite Technical Committee and NBCI Management Board. In 2011, NBCI published an updated strategic restoration plan, and spatially-explicit planning tool, NBCI 2.0, followed in 2014 by an implementation plan, the NBCI Coordinated Implementation Program (CIP). We update the history of the NBCI, including changes in funding mechanisms, leadership, administration, and technical programs, and we assess current opportunities and the future of bobwhite conservation