2,618 research outputs found
Seeking Sustainability: COSA preliminary analysis of sustainability initiatives in the coffee sector
The growing economic value and consumer popularity of sustainability standards inevitably raise questions about the extent to which their structure and dynamics actually address many environmental, economic and public welfare issues. The Committee on Sustainable Assessment (COSA) was formed, in part, to develop a scientifically credible framework capable of assessing the impacts associated with the adoption of sustainability initiatives. This paper examines the pilot phase of vetting and testing the COSA method, an innovative management tool used to gather and analyze data using economic, environmental and social metrics.sustainability initiatives, standards, organic, fair trade, Rainforest, social, environmental, economic certification
Potts-Percolation-Gauss Model of a Solid
We study a statistical mechanics model of a solid. Neighboring atoms are
connected by Hookian springs. If the energy is larger than a threshold the
"spring" is more likely to fail, while if the energy is lower than the
threshold the spring is more likely to be alive. The phase diagram and
thermodynamic quantities, such as free energy, numbers of bonds and clusters,
and their fluctuations, are determined using renormalization-group and
Monte-Carlo techniques.Comment: 10 pages, 12 figure
An Evaluation Service for Digital Public Health Interventions: User-Centered Design Approach
BACKGROUND:
Digital health interventions (DHIs) have the potential to improve public health by combining effective interventions and population reach. However, what biomedical researchers and digital developers consider an effective intervention differs, thereby creating an ongoing challenge to integrating their respective approaches when evaluating DHIs.
OBJECTIVE:
This study aims to report on the Public Health England (PHE) initiative set out to operationalize an evaluation framework that combines biomedical and digital approaches and demonstrates the impact, cost-effectiveness, and benefit of DHIs on public health.
METHODS:
We comprised a multidisciplinary project team including service designers, academics, and public health professionals and used user-centered design methods, such as qualitative research, engagement with end users and stakeholders, and iterative learning. The iterative approach enabled the team to sequentially define the problem, understand user needs, identify opportunity areas, develop concepts, test prototypes, and plan service implementation. Stakeholders, senior leaders from PHE, and a working group critiqued the outputs.
RESULTS:
We identified 26 themes and 82 user needs from semistructured interviews (N=15), expressed as 46 Jobs To Be Done, which were then validated across the journey of evaluation design for a DHI. We identified seven essential concepts for evaluating DHIs: evaluation thinking, evaluation canvas, contract assistant, testing toolkit, development history, data hub, and publish health outcomes. Of these, three concepts were prioritized for further testing and development, and subsequently refined into the proposed PHE Evaluation Service for public health DHIs. Testing with PHE’s Couch-to-5K app digital team confirmed the viability, desirability, and feasibility of both the evaluation approach and the Evaluation Service.
CONCLUSIONS:
An iterative, user-centered design approach enabled PHE to combine the strengths of academic and biomedical disciplines with the expertise of nonacademic and digital developers for evaluating DHIs. Design-led methodologies can add value to public health settings. The subsequent service, now known as Evaluating Digital Health Products, is currently in use by health bodies in the United Kingdom and is available to others for tackling the problem of evaluating DHIs pragmatically and responsively
The Cooperative Participatory Evaluation of Renewable Technologies on Ecosystem Services (CORPORATES)
Publisher PD
A non trivial extension of the two-dimensional Ising model: the d-dimensional "molecular" model
A recently proposed molecular model is discussed as a non-trivial extension
of the Ising model. For d=2 the two models are shown to be equivalent, while
for d>2 the molecular model describes a peculiar second order transition from
an isotropic high temperature phase to a low-dimensional anisotropic low
temperature state. The general mean field analysis is compared with the results
achieved by a variational Migdal-Kadanoff real space renormalization group
method and by standard Monte Carlo sampling for d=3. By finite size scaling the
critical exponent has been found to be 0.44\pm 0.02 thus establishing that the
molecular model does not belong to the universality class of the Ising model
for d>2.Comment: 25 pages, 5 figure
2D Potts Model Correlation Lengths: Numerical Evidence for at
We have studied spin-spin correlation functions in the ordered phase of the
two-dimensional -state Potts model with , 15, and 20 at the
first-order transition point . Through extensive Monte Carlo
simulations we obtain strong numerical evidence that the correlation length in
the ordered phase agrees with the exactly known and recently numerically
confirmed correlation length in the disordered phase: . As a byproduct we find the energy moments in the ordered phase
at in very good agreement with a recent large -expansion.Comment: 11 pages, PostScript. To appear in Europhys. Lett. (September 1995).
See also http://www.cond-mat.physik.uni-mainz.de/~janke/doc/home_janke.htm
Universal aspects of vacancy-mediated disordering dynamics: the effect of external fields
We investigate the disordering of an initially phase-segregated binary alloy,
due to a highly mobile defect which couples to an electric or gravitational
field. Using both mean-field and Monte Carlo methods, we show that the late
stages of this process exhibit dynamic scaling, characterized by a set of
exponents and scaling functions. A new scaling variable emerges, associated
with the field. While the scaling functions carry information about the field
and the boundary conditions, the exponents are universal. They can be computed
analytically, in excellent agreement with simulation results.Comment: 15 pages, 6 figure
A Q-Ising model application for linear-time image segmentation
A computational method is presented which efficiently segments digital
grayscale images by directly applying the Q-state Ising (or Potts) model. Since
the Potts model was first proposed in 1952, physicists have studied lattice
models to gain deep insights into magnetism and other disordered systems. For
some time, researchers have realized that digital images may be modeled in much
the same way as these physical systems (i.e., as a square lattice of numerical
values). A major drawback in using Potts model methods for image segmentation
is that, with conventional methods, it processes in exponential time. Advances
have been made via certain approximations to reduce the segmentation process to
power-law time. However, in many applications (such as for sonar imagery),
real-time processing requires much greater efficiency. This article contains a
description of an energy minimization technique that applies four Potts
(Q-Ising) models directly to the image and processes in linear time. The result
is analogous to partitioning the system into regions of four classes of
magnetism. This direct Potts segmentation technique is demonstrated on
photographic, medical, and acoustic images.Comment: 7 pages, 8 figures, revtex, uses subfigure.sty. Central European
Journal of Physics, in press (2010
Decoding Polo-like kinase 1 signaling along the kinetochore–centromere axis
Protein kinase signaling along the kinetochore-centromere axis is crucial to assure mitotic fidelity, yet its spatial coordination is obscure. Here, we examined how pools of human Polo-like kinase 1 (Plk1) within this axis control signaling events to elicit mitotic functions. To do this, we restricted active Plk1 to discrete subcompartments within the kinetochore-centromere axis using chemical genetics and decoded functional and phosphoproteomic signatures of each. We observe distinct phosphoproteomic and functional roles, suggesting that Plk1 exists and functions in discrete pools along this axis. Deep within the centromere, Plk1 operates to assure proper chromosome alignment and segregation. Thus, Plk1 at the kinetochore is a conglomerate of an observable bulk pool coupled with additional functional pools below the threshold of microscopic detection/resolution. Although complex, this multiplicity of locales provides an opportunity to decouple functional and phosphoproteomic signatures for a comprehensive understanding of Plk1’s kinetochore functions
Interaction-Induced Magnetization of the Two-Dimensional Electron Gas
We consider the contribution of electron-electron interactions to the orbital
magnetization of a two-dimensional electron gas, focusing on the ballistic
limit in the regime of negligible Landau-level spacing. This regime can be
described by combining diagrammatic perturbation theory with semiclassical
techniques. At sufficiently low temperatures, the interaction-induced
magnetization overwhelms the Landau and Pauli contributions. Curiously, the
interaction-induced magnetization is third-order in the (renormalized) Coulomb
interaction. We give a simple interpretation of this effect in terms of
classical paths using a renormalization argument: a polygon must have at least
three sides in order to enclose area. To leading order in the renormalized
interaction, the renormalization argument gives exactly the same result as the
full treatment.Comment: 11 pages including 4 ps figures; uses revtex and epsf.st
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