902 research outputs found
Animal harms and food production: Informing ethical choices
Ethical food choices have become an important societal theme in post-industrial countries. Many consumers are particularly interested in the animal welfare implications of the various foods they may choose to consume. However, concepts in animal welfare are rapidly evolving towards consideration of all animals (including wildlife) in contemporary approaches such as âOne Welfareâ. This approach requires recognition that negative impacts (harms) may be intentional and obvious (e.g., slaughter of livestock) but also include the under-appreciated indirect or unintentional harms that often impact wildlife (e.g., land clearing). This is especially true in the Anthropocene, where impacts on non-human life are almost ubiquitous across all human activities. We applied the âharmsâ model of animal welfare assessment to several common food production systems and provide a framework for assessing the breadth (not intensity) of harms imposed. We considered all harms caused to wild as well as domestic animals, both direct effects and indirect effects. We described 21 forms of harm and considered how they applied to 16 forms of food production. Our analysis suggests that all food production systems harm animals to some degree and that the majority of these harms affect wildlife, not livestock. We conclude that the food production systems likely to impose the greatest overall breadth of harms to animals are intensive animal agriculture industries (e.g., dairy) that rely on a secondary food production system (e.g., cropping), while harvesting of locally available wild plants, mushrooms or seaweed is likely to impose the least harms. We present this conceptual analysis as a resource for those who want to begin considering the complex animal welfare trade-offs involved in their food choices
Resistivity of a Metal between the Boltzmann Transport Regime and the Anderson Transition
We study the transport properties of a finite three dimensional disordered
conductor, for both weak and strong scattering on impurities, employing the
real-space Green function technique and related Landauer-type formula. The
dirty metal is described by a nearest neighbor tight-binding Hamiltonian with a
single s-orbital per site and random on-site potential (Anderson model). We
compute exactly the zero-temperature conductance of a finite size sample placed
between two semi-infinite disorder-free leads. The resistivity is found from
the coefficient of linear scaling of the disorder averaged resistance with
sample length. This ``quantum'' resistivity is compared to the semiclassical
Boltzmann expression computed in both Born approximation and multiple
scattering approximation.Comment: 5 pages, 3 embedded EPS figure
Equivalent thermo-mechanical parameters for perfect crystals
Thermo-elastic behavior of perfect single crystal is considered. The crystal
is represented as a set of interacting particles (atoms). The approach for
determination of equivalent continuum values for the discrete system is
proposed. Averaging of equations of particles' motion and long wave
approximation are used in order to make link between the discrete system and
equivalent continuum. Basic balance equations for equivalent continuum are
derived from microscopic equations. Macroscopic values such as Piola and Cauchy
stress tensors and heat flux are represented via microscopic parameters.
Connection between the heat flux and temperature is discussed. Equation of
state in Mie-Gruneisen form connecting Cauchy stress tensor with deformation
gradient and thermal energy is obtained from microscopic considerations.Comment: To be published in proceedings of IUTAM Simposium on "Vibration
Analysis of Structures with Uncertainties", 2009; 14 pages
The generalized Robinson-Foulds metric
The Robinson-Foulds (RF) metric is arguably the most widely used measure of
phylogenetic tree similarity, despite its well-known shortcomings: For example,
moving a single taxon in a tree can result in a tree that has maximum distance
to the original one; but the two trees are identical if we remove the single
taxon. To this end, we propose a natural extension of the RF metric that does
not simply count identical clades but instead, also takes similar clades into
consideration. In contrast to previous approaches, our model requires the
matching between clades to respect the structure of the two trees, a property
that the classical RF metric exhibits, too. We show that computing this
generalized RF metric is, unfortunately, NP-hard. We then present a simple
Integer Linear Program for its computation, and evaluate it by an
all-against-all comparison of 100 trees from a benchmark data set. We find that
matchings that respect the tree structure differ significantly from those that
do not, underlining the importance of this natural condition.Comment: Peer-reviewed and presented as part of the 13th Workshop on
Algorithms in Bioinformatics (WABI2013
A First-Quantized Formalism for Cosmological Particle Production
We show that the amount of particle production in an arbitrary cosmological
background can be determined using only the late-time positive-frequency modes.
We don't refer to modes at early times, so there is no need for a Bogolubov
transformation. We also show that particle production can be extracted from the
Feynman propagator in an auxiliary spacetime. This provides a first-quantized
formalism for computing particle production which, unlike conventional
Bogolubov transformations, may be amenable to a string-theoretic
generalization.Comment: 18 pages, LaTeX; v2: significantly revised for clarity; conclusions
unchange
Temporally Variable Stream Width and Surface Area Distributions in a Headwater Catchment
Headwater stream networks expand and contract in response to event-driven and seasonal catchment wetness conditions. This dynamic behavior drives variability in the width, length, and surface area of streams, important parameters for constraining a range of ecological and biogeochemical processes, such as atmospheric gas exchange. While the longitudinal expansion and contraction of streams has been studied for some time, variability in stream widths remains poorly understood. Recent studies have found that stream widths at average baseflow conditions follow a log-normal frequency distribution across diverse physiographies. To examine how the distribution of widths varies with flow conditions, we surveyed stream widths 12 times across a 48.4-ha research watershed, located in the Duke Forest in central North Carolina, USA. Here, we show that as runoff increased from the 37th to 99th percentiles of flow, flowing streams widened across the network (âlateral expansionâ) and streamflow simultaneously extended upstream to reactivate dry channels (âlongitudinal expansionâ). In general, as runoff increased, the marginal increase in stream surface area was equally divided between longitudinal and lateral expansion. Even so, the median stream width widens on average with increasing runoff, suggesting that longitudinal and lateral expansion affect the distribution of stream width differently. We find that the form of the relationship between stream width and runoff is a power law, which can be used to refine models for surface area estimation
Phase Transition in Conformally Induced Gravity with Torsion
We have considered the quantum behavior of a conformally induced gravity in
the minimal Riemann-Cartan space. The regularized one-loop effective potential
considering the quantum fluctuations of the dilaton and the torsion fields in
the Coleman-Weinberg sector gives a sensible phase transition for an
inflationary phase in De Sitter space. For this effective potential, we have
analyzed the semi-classical equation of motion of the dilaton field in the
slow-rolling regime.Comment: 7pages, no figur
An MPEG-7 scheme for semantic content modelling and filtering of digital video
Abstract Part 5 of the MPEG-7 standard specifies Multimedia Description Schemes (MDS); that is, the format multimedia content models should conform to in order to ensure interoperability across multiple platforms and applications. However, the standard does not specify how the content or the associated model may be filtered. This paper proposes an MPEG-7 scheme which can be deployed for digital video content modelling and filtering. The proposed scheme, COSMOS-7, produces rich and multi-faceted semantic content models and supports a content-based filtering approach that only analyses content relating directly to the preferred content requirements of the user. We present details of the scheme, front-end systems used for content modelling and filtering and experiences with a number of users
Quantum-critical pairing with varying exponents
We analyse the onset temperature T_p for the pairing in cuprate
superconductors at small doping, when tendency towards antiferromagnetism is
strong. We consider the model of Moon and Sachdev (MS), which assumes that
electron and hole pockets survive in a paramagnetic phase. Within this model,
the pairing between fermions is mediated by a gauge boson, whose propagator
remains massless in a paramagnet. We relate the MS model to a generic
\gamma-model of quantum-critical pairing with the pairing kernel \lambda
(\Omega) \propto 1/\Omega^{\gamma}. We show that, over some range of
parameters, the MS model is equivalent to the \gamma-model with \gamma =1/3
(\lambda (\Omega) \propto \Omega^{-1/3}). We find, however, that the parameter
range where this analogy works is bounded on both ends. At larger deviations
from a magnetic phase, the MS model becomes equivalent to the \gamma-model with
varying \gamma >1/3, whose value depends on the distance to a magnetic
transition and approaches \gamma =1 deep in a paramagnetic phase. Very near the
transition, the MS model becomes equivalent to the \gamma-model with varying
\gamma <1/3. Right at the magnetic QCP, the MS model is equivalent to the
\gamma-model with \gamma =0+ (\lambda (\Omega) \propto \log \Omega), which is
the model for color superconductivity. Using this analogy, we verified the
formula for T_c derived for color superconductivity.Comment: 10 pages, 8 figures, submitted to JLTP for a focused issue on Quantum
Phase Transition
Citizen Science 2.0 : Data Management Principles to Harness the Power of the Crowd
Citizen science refers to voluntary participation by the general public in scientific endeavors. Although citizen science has a long tradition, the rise of online communities and user-generated web content has the potential to greatly expand its scope and contributions. Citizens spread across a large area will collect more information than an individual researcher can. Because citizen scientists tend to make observations about areas they know well, data are likely to be very detailed. Although the potential for engaging citizen scientists is extensive, there are challenges as well. In this paper we consider one such challenge â creating an environment in which non-experts in a scientific domain can provide appropriate and accurate data regarding their observations. We describe the problem in the context of a research project that includes the development of a website to collect citizen-generated data on the distribution of plants and animals in a geographic region. We propose an approach that can improve the quantity and quality of data collected in such projects by organizing data using instance-based data structures. Potential implications of this approach are discussed and plans for future research to validate the design are described
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