23,151 research outputs found
The missing link between research and reality: The significance of the relationship between retail format and organic food consumption
The impact that the retail format has on the level of individual motivation tends to be overlooked in discussions of the determinants of organic consumption, this neglect due to the tendency to model individual and contextual factors separately. Hence, the dominant research paradigm has difficulty accounting for the differences in energy and motivation across consumers. Moreover, in spite of the expansions to the set of contextual factors, this paradigm is unable to increase the reality of descriptions of consumer behavior so long as such attempts are then filtered back through modeling frameworks initially developed to address different questions. To illustrate the dual importance of asking the right questions and using appropriate models, this paper utilizes a modeling exercise to explore the consequences of using two prevalent modeling approaches that utilize a limited form of the relationship between individual and retail format to explain the level of motivation. By illustrating the potential for omitted variable bias and misleading policy implications, it is argued that novel modeling approaches are necessary to integrate the broader range of relationships that exist, as well as the relevance of these relationships to the level of motivation
(M-theory-)Killing spinors on symmetric spaces
We show how the theory of invariant principal bundle connections for
reductive homogeneous spaces can be applied to determine the holonomy of
generalised Killing spinor covariant derivatives of the form in a purely algebraic and algorithmic way, where is a left-invariant homomorphism. Specialising this
to the case of symmetric M-theory backgrounds (i.e. with a
symmetric space and an invariant closed 4-form), we derive several criteria
for such a background to preserve some supersymmetry and consequently find all
supersymmetric symmetric M-theory backgrounds.Comment: Updated abstract for clarity. Added missing geometries to section 6.
Main result stand
Mass-produced food: the rise and fall of the promise of health and safety
The greater awareness of the negative environmental and health-related externalities of the large-scale food industry is directly responsible for the diminished confidence of the quality of its products. Using the multi-level perspective on socio-technical transitions (Geels, 2004; 2010), I argue that the initial impetus for the emergence of mass production was the presence of threats to health and safety in the broader societal context. Rather than simply serving economic considerations, the scale and scientific expertise of mass production functioned as a credible signal due to its relationship to these threats. The declining health and safety of the food industry represents, however, a consequence of the changing relationship of scale and quality due to the emergence of new threats to health and safety. Scale as a signal of credibility is no longer sufficient to guarantee these qualities, however. Absent the incentives to undertake costly investments in quality production, the criteria of productivity and efficiency become duly emphasized to the detriment of health and safety. Hence, the continued emphasis on scale now represents a limitation to improving health and safety. Instead, further quality innovation demands the development of a costly signal appropriate to the extant social context
Higgs Portals for Thermal Dark Matter - EFT Perspectives and the NMSSM -
We analyze a low energy effective model of Dark Matter in which the thermal
relic density is provided by a singlet Majorana fermion which interacts with
the Higgs fields via higher dimensional operators. Direct detection signatures
may be reduced if blind spot solutions exist, which naturally appear in models
with extended Higgs sectors. Explicit mass terms for the Majorana fermion can
be forbidden by a symmetry, which in addition leads to a reduction of the
number of higher dimensional operators. Moreover, a weak scale mass for the
Majorana fermion is naturally obtained from the vacuum expectation value of a
scalar singlet field. The proper relic density may be obtained by the
-channel interchange of Higgs and gauge bosons, with the longitudinal mode
of the boson (the neutral Goldstone mode) playing a relevant role in the
annihilation process. This model shares many properties with the
Next-to-Minimal Supersymmetric extension of the Standard Model (NMSSM) with
light singlinos and heavy scalar and gauge superpartners. In order to test the
validity of the low energy effective field theory, we compare its predictions
with those of the ultraviolet complete NMSSM. Extending our framework to
include neutral Majorana fermions, analogous to the bino in the NMSSM, we
find the appearance of a new bino-singlino well tempered Dark Matter region.Comment: 42 pages, 14 figures. v2: added references, published in JHE
Virtual image out-the-window display system study. Volume 2 - Appendix
Virtual image out-the-window display system imaging techniques and simulation devices - appendices containing background materia
Produktivitätsfortschritt, Wachstum und Lohnpolitik: Aktuelle Aspekte der Kontroverse zwischen Angebots- und Nachfragetheoretikern
Improving predictive power of physically based rainfall-induced shallow landslide models: a probabilistic approach
Distributed models to forecast the spatial and temporal occurrence of
rainfall-induced shallow landslides are based on deterministic laws. These
models extend spatially the static stability models adopted in geotechnical
engineering, and adopt an infinite-slope geometry to balance the resisting and
the driving forces acting on the sliding mass. An infiltration model is used to
determine how rainfall changes pore-water conditions, modulating the local
stability/instability conditions. A problem with the operation of the existing
models lays in the difficulty in obtaining accurate values for the several
variables that describe the material properties of the slopes. The problem is
particularly severe when the models are applied over large areas, for which
sufficient information on the geotechnical and hydrological conditions of the
slopes is not generally available. To help solve the problem, we propose a
probabilistic Monte Carlo approach to the distributed modeling of
rainfall-induced shallow landslides. For the purpose, we have modified the
Transient Rainfall Infiltration and Grid-Based Regional Slope-Stability
Analysis (TRIGRS) code. The new code (TRIGRS-P) adopts a probabilistic approach
to compute, on a cell-by-cell basis, transient pore-pressure changes and
related changes in the factor of safety due to rainfall infiltration.
Infiltration is modeled using analytical solutions of partial differential
equations describing one-dimensional vertical flow in isotropic, homogeneous
materials. Both saturated and unsaturated soil conditions can be considered.
TRIGRS-P copes with the natural variability inherent to the mechanical and
hydrological properties of the slope materials by allowing values of the TRIGRS
model input parameters to be sampled randomly from a given probability
distribution. [..]Comment: 25 pages, 14 figures, 9 tables. Revised version; accepted for
publication in Geoscientific Model Development on 13 February 201
The Mechanics of Malaria Parasite Invasion of the Human Erythrocyte - Towards a Reassessment of the Host Cell Contribution
Despite decades of research, we still know little about the mechanics of Plasmodium host cell invasion. Fundamentally, while the essential or non‐essential nature of different parasite proteins is becoming clearer, their actual function and how each comes together to govern invasion are poorly understood. Furthermore, in recent years an emerging world view is shifting focus away from the parasite actin–myosin motor being the sole force responsible for entry to an appreciation of host cell dynamics and forces and their contribution to the process. In this review, we discuss merozoite invasion of the erythrocyte, focusing on the complex set of pre‐invasion events and how these might prime the red cell to facilitate invasion. While traditionally parasite interactions at this stage have been viewed simplistically as mediating adhesion only, recent work makes it apparent that by interacting with a number of host receptors and signalling pathways, combined with secretion of parasite‐derived lipid material, that the merozoite may initiate cytoskeletal re‐arrangements and biophysical changes in the erythrocyte that greatly reduce energy barriers for entry. Seen in this light Plasmodium invasion may well turn out to be a balance between host and parasite forces, much like that of other pathogen infection mechanisms
Gonadal hormones, but not sex, affect the acquisition and maintenance of a Go/No-Go odor discrimination task in mice
In mice, olfaction is crucial for identifying social odors (pheromones) that signal the presence of suitable mates. We used a custom-built olfactometer and a thirst-motivated olfactory discrimination Go/No-Go (GNG) task to ask whether discrimination of volatile odors is sexually dimorphic and modulated in mice by adult sex hormones. Males and females gonadectomized prior to training failed to learn even the initial phase of the task, which involved nose poking at a port in one location obtaining water at an adjacent port. Gonadally intact males and females readily learned to seek water when male urine (S+) was present but not when female urine (S−) was present; they also learned the task when non-social odorants (amyl acetate, S+; peppermint, S−) were used. When mice were gonadectomized after training the ability of both sexes to discriminate urinary as well as non-social odors was reduced; however, after receiving testosterone propionate (castrated males) or estradiol benzoate (ovariectomized females), task performance was restored to pre-gonadectomy levels. There were no overall sex differences in performance across gonadal conditions in tests with either set of odors; however, ovariectomized females performed more poorly than castrated males in tests with non-social odors. Our results show that circulating sex hormones enable mice of both sexes to learn a GNG task and that gonadectomy reduces, while hormone replacement restores, their ability to discriminate between odors irrespective of the saliency of the odors used. Thus, gonadal hormones were essential for both learning and maintenance of task performance across sex and odor type.We thank David Giese for help in programming the apparatus used in GNG testing and Alberto Cruz-Martin for comments on an early version of the manuscript. This work was supported by NIDCD grant DC008962 to JAC. (DC008962 - NIDCD grant)Accepted manuscrip
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