Intensifying pastoralism may not reduce greenhouse gas emissions : wildlife-dominated landscape scenarios as a baseline in life cycle analysis

The general public is increasingly critical of extensive, ruminant-dominated systems for their attributed high greenhouse gas emissions. However, advocates of low input, grass-fed systems present them as paradigmatic sustainable production systems because of their biodiversity, land use, rural development and animal welfare benefits. We reconcile both analyses by proposing to assess baseline emissions in grazed ecosystems. We show that policies aiming at transitioning grass-fed systems towards fodder-based (concentrate- or grain-based) systems can be ineffective at reducing emissions because wild ruminants or termites fill livestock's ecological niche. Climate change policies targeting livestock should carefully evaluate derived emissions scenarios.Peer reviewe

Considering Natural Baselines When Calculating Livestock Impacts Point to a Negligible Role of Grass-Fed Livestock Systems in Climate Change

ISBN: 978-9966-30-094-2The use of baselines is common in a variety of academic disciplines, including environmental science, but they are subjected to relativity depending on the geographical or historical reference considered. Such considerations are illustrated by how invasive species are evaluated or what reference baselines are considered in biodiversity assessments. The measurement of livestock effects on climate change has, however, disregarded the use of baselines. Current methodology is based exclusively on greenhouse gas emissions by individual animals, without putting them in their ecological context. As a consequence, current analyses of livestock impacts put grass-fed ruminant systems in the spotlight, because of their high methane emissions. Conversion into intensive, grain-fed chicken and pork systems is recommended to cope with increased meat demand, an approach that is being echoed by media. In this study we reviewed existing literature on baseline greenhouse gas emissions by wild ruminants, with models available for North America and northern Russia. We also considered the potential of termites in filling herbivore niches in an ungulate-free scenario and reviewed the literature for possible consequences of ensuing wildfires. We found consistent evidence for natural baseline scenarios to be of the same order of magnitude as current livestock scenarios. This implies that the current policy recommendations for tackling climate change through the livestock sector are likely to be much less effective than currently thought. Other studies on livestock environmental impacts, such as for water or biodiversity, have also not taken into account natural baseline levels from wild herbivores, hence depicting an exaggerated negative image on grass-fed livestock. Policy recommendations should take baseline levels into account, concentrate on reducing intensive use of fossil fuel and focus on double-win strategies for methane emission reduction, such as the use of manure-fed biogas cooking stoves. This paper uses concepts originally developed at Manzano & White (2019).Peer reviewe

Quantum data compression, quantum information generation, and the density-matrix renormalization group method

We have studied quantum data compression for finite quantum systems where the site density matrices are not independent, i.e., the density matrix cannot be given as direct product of site density matrices and the von Neumann entropy is not equal to the sum of site entropies. Using the density-matrix renormalization group (DMRG) method for the 1-d Hubbard model, we have shown that a simple relationship exists between the entropy of the left or right block and dimension of the Hilbert space of that block as well as of the superblock for any fixed accuracy. The information loss during the RG procedure has been investigated and a more rigorous control of the relative error has been proposed based on Kholevo's theory. Our results are also supported by the quantum chemistry version of DMRG applied to various molecules with system lengths up to 60 lattice sites. A sum rule which relates site entropies and the total information generated by the renormalization procedure has also been given which serves as an alternative test of convergence of the DMRG method.Comment: 8 pages, 7 figure

Using the average spectrum method to extract dynamics from quantum Monte Carlo simulations

We apply the Average Spectrum Method to the problem of getting the excitation spectrum from imaginary-time quantum Monte Carlo simulations. We show that with high quality QMC data this method reproduces the dominant spectral features very well. It is also capable of giving information on the spectrum in regions dominated by the many-particle continuum of excitations.Comment: v2: Major revision. Title and abstract as well as the focus of the paper have been changed. Added a figure about the dynamics of 1D Heisenberg chai

Strategies for method comparison when changes in the immunogenicity method are needed within a clinical program.

Aim: To present the reader with different approaches used to compare immunogenicity methods when changes are needed during a clinical program. Results: Five case studies are presented, in the first two case studies, the approach utilized a small sample size for the comparison. In the third case, all samples from a study were analyzed by both methods. In the fourth case, the intended use of noncomparable assays in an integrated summary drove design of experiments to establish the expected limits of pooling data. In the fifth case, a selectivity approach was used as an alternate to use of incurred samples. Conclusion: When data pooling across methods is needed, it is important to define the limits of comparability

Orthogonality catastrophe in a one-dimensional system of correlated electrons

We present a detailed numerical study of the orthogonality catastrophe exponent for a one-dimensional lattice model of spinless fermions with nearest neighbor interaction using the density matrix remormalization group algorithm. Keeping up to 1200 states per block we achieve a very great accuracy for the overlap which is needed to extract the orthogonality exponent reliably. We discuss the behavior of the exponent for three different kinds of a localized impurity. For comparison we also discuss the non-interacting case. In the weak impurity limit our results for the overlap confirm scaling behavior expected from perturbation theory and renormalization group calculations. In particular we find that a weak backward scattering component of the orthogonality exponent scales to zero for attractive interaction. In the strong impurity limit and for repulsive interaction we demonstrate that the orthogonality exponent cannot be extracted from the overlap for systems with up to 100 sites, due to finite size effects. This is in contradiction to an earlier interpretation given by Qin et al. based on numerical data for much smaller system sizes. Neverthless we find indirect evidence that the backward scattering contribution to the exponent scales to 1/16 based on predictions of boundary conformal field theory.Comment: 16 pages, Latex, 8 eps figures, submitted to Phys. Rev.

Magnetic Phase Diagram of Spin-1/2 Two-Leg Ladder with Four-Spin Ring Exchange

We study the spin-1/2 two-leg Heisenberg ladder with four-spin ring exchanges under a magnetic field. We introduce an exact duality transformation which is an extension of the spin-chirality duality developed previously and yields a new self-dual surface in the parameter space. We then determine the magnetic phase diagram using the numerical approaches of the density-matrix renormalization-group and exact diagonalization methods. We demonstrate the appearance of a magnetization plateau and the Tomonaga-Luttinger liquid with dominant vector-chirality quasi-long-range order for a wide parameter regime of strong ring exchange. A "nematic" phase, in which magnons form bound pairs and the magnon-pairing correlation functions dominate, is also identified.Comment: 18pages, 7 figure

Estimating Grizzly Bear Use of Large Ungulate Carcasses With GPS Telemetry Data

Ungulate meat is among the most calorie-rich food sources available to grizzly bears  (Ursus arctos) in the greater Yellowstone ecosystem (GYE). However, the ephemeral and unpredictable nature of carcasses makes them difficult to study and their influence on grizzly bear foraging and spatial ecology is poorly understood. We developed a spatial-clustering technique specifically for detecting grizzly bear use of large ungulate carcasses using Global Positioning System (GPS) telemetry locations (n = 54 bear years). We used the DBScan algorithm to identify GPS clusters of individual bears (n = 2,038) and intersected these clusters with an independent dataset of site  visits to recent bear movement paths based from randomly selected days (n = 732 site visits; 2004–2011) resulting in 174 clusters associated with field measured bear behavior. Using a suite of predictor variables derived from GPS telemetry locations, e.g., duration of cluster, area used, activity sensor values, re-visitation rate, we used multinomial logistic regression to predict the probability of belonging to  each of the five response classes (resting, multiple-use, low-biomass carcass, high-biomass carcass, old carcass). Focusing on the high-biomass carcass category, for which our top model correctly classified 88 percent of the carcasses correctly, we applied our approach to a larger dataset of GPS data to examine trends in large-ungulate carcass using of grizzly bears in the GYE from 2002-2011. We found quantitative support for a positive effect of year and mortality adjusted white bark pine cone counts on the carcass-use index during the fall months (Sep and Oct) from 2002-2011

Spin-Charge Separation, Anomalous Scaling and the Coherence of Hopping in exactly solved Two Chain Models

The coherence of transport between two one-dimensional interacting Fermi liquids, coupled by single particle hopping and interchain interaction, is examined in the context of two exactly soluble models. It is found that the coherence of the inter-chain hopping depends on the interplay between inter-chain hopping and inter-chain interaction terms, and not simply on the ground state spectral properties of an isolated chain. Specifically, the splitting of levels in associated with interchain hopping in a $g_4$ soluble model is found to be enhanced by the introduction of interchain interaction. It is also shown that, for an exactly solvable model with both $g_2$ and $g_4$ interactions, coherent interchain hopping coexists with anomalous scaling and non-Fermi liquid behavior in the chain direction.Comment: Two postscript figure