No effect of cropping system on the greenhouse gas N2O

Organic farming is comparable to conventional in terms of field emissions of the strong greenhouse gas nitrous oxide (N2O). Our study points to the need for increased yields in organic farming as measure to reduced emissions per unit of produce

Poly-essential and general Hyperelastic World (brane) models

This article provides a unified treatment of an extensive category of non-linear classical field models whereby the universe is represented (perhaps as a brane in a higher dimensional background) in terms of a structure of a mathematically convenient type describable as hyperelastic, for which a complete set of equations of motion is provided just by the energy-momentum conservation law. Particular cases include those of a perfect fluid in quintessential backgrounds of various kinds, as well as models of the elastic solid kind that has been proposed to account for cosmic acceleration. It is shown how an appropriately generalised Hadamard operator can be used to construct a symplectic structure that controles the evolution of small perturbations, and that provides a characteristic equation governing the propagation of weak discontinuities of diverse (extrinsic and extrinsic) kinds. The special case of a poly-essential model - the k-essential analogue of an ordinary polytropic fluid - is examined and shown to be well behaved (like the fluid) only if the pressure to density ratio $w$ is positive.Comment: 16 pages Latex, Contrib. to 10th Peyresq Pysics Meeting, June 2005: Micro and Macro Structures of Spacetim

Greenhouse gas emissions from cultivation of energy crops – is it important?

Replacing fossil fuel-derived energy with biomass-derived energy is commonly emphasized as a means to reduce CO2 emissions. However, our study highlights the risk of large greenhouse gas emissions when wastes from bioenergy production are recycled as fertilizer for energy crops. Crop management affects the magnitude of these emissions, which in some cases negate a considerable fraction of the global warming savings associated with biofuels

Techniques for studying gravity waves and turbulence: Horizontal, vertical and temporal resolution needed

One of the most important atmospheric measurements that is needed is a measure of the gravity-wave spectrum. The MST radar has been investigated as means to measure the temporal resolution required to determine gravity-wave oscillations. The required vertical and horizontal resolution is dependent on the particular part of the gravity wave spectrum that is analyzed. Horizontal spacing is also discussed

Twistable mold for helicopter blades

Design is described of mold for fabrication of blades composed of sets of aerodynamic shells having same airfoil section characteristics but different distributions. Mold consists of opposing stacks of thin templates held together by long bolts. When bolts are loosened, templates can be set at different positions with respect to each other and then locked in place

Ligula intestinalis (Cestoda: Pseudophyllidea): an ideal fish-metazoan parasite model?

Since its use as a model to study metazoan parasite culture and in vitro development, the plerocercoid of the tapeworm, Ligula intestinalis, has served as a useful scientific tool to study a range of biological factors, particularly within its fish intermediate host. From the extensive long-term ecological studies on the interactions between the parasite and cyprinid hosts, to the recent advances made using molecular technology on parasite diversity and speciation, studies on the parasite have, over the last 60 years, led to significant advances in knowledge on host-parasite interactions. The parasite has served as a useful model to study pollution, immunology and parasite ecology and genetics, as well has being the archetypal endocrine disruptor

On gait as a biometric: progress and prospects

There is increasing interest in automatic recognition by gait given its unique capability to recognize people at a distance when other biometrics are obscured. Application domains are those of any noninvasive biometric, but with particular advantage in surveillance scenarios. Its recognition capability is supported by studies in other domains such as medicine (biomechanics), mathematics and psychology which also suggest that gait is unique. Further, examples of recognition by gait can be found in literature, with early reference by Shakespeare concerning recognition by the way people walk. Many of the current approaches confirm the early results that suggested gait could be used for identification, and now on much larger databases. This has been especially influenced by DARPA’s Human ID at a Distance research program with its wide scenario of data and approaches. Gait has benefited from the developments in other biometrics and has led to new insight particularly in view of covariates. Equally, gait-recognition approaches concern extraction and description of moving articulated shapes and this has wider implications than just in biometrics

Why do people live apart together?

Interpretations of living apart together (LAT) have typically counter-posed 'new family form' versus 'continuist' perspectives. Recent surveys, however, construct LAT as a heterogeneous category that supports a 'qualified continuist' position – most people live apart as a response to practical circumstances or as a modern version of 'boy/girlfriend', although a minority represents something new in preferring to live apart more permanently. This article interrogates this conclusion by examining in depth why people live apart together, using a nationally representative survey from Britain and interview accounts from 2011. Our analysis shows that LAT as a category contains different sorts of relationship, with different needs and desires. While overall coupledom remains pivotal and cohabitation remains the goal for most, LAT allows people flexibility and room to manoeuvre in adapting couple intimacy to the demands of contemporary life. Hence, we suggest, LAT is both 'new' and a 'continuation'