1,397 research outputs found
Measurement and reporting of climate-smart agriculture: technical guidance for a countrycentric process
Given the extent of climate-smart agriculture (CSA) initiatives at project, national, regional and global levels, there is increasing interest in tracking progress in implementing CSA at national level. CSA is also expected to contribute to higher-level goals (e.g., the Paris Agreement, Africa Unionās Vision 25x25, and the Sustainable Development Goals [SDGs], etc.). Measurement and reporting of climate-smart agriculture (MR of CSA) provides intelligence on necessary the status, effectiveness, efficiency and impacts of interventions, which is critical for meeting stakeholdersā diverse management and reporting needs. In this paper, we build the case for a stakeholder-driven, country-centric framework for MR of CSA, which aims to increase coordination and coherence across stakeholdersā MR activities, while also aligning national reporting with reporting on international commitments. We present practical guidance on how to develop an integrated MR framework, drawing on findings from a multi-country assessment of needs, opportunities and capacities for national MR of CSA. The content of a unified MR framework is determined by stakeholdersā activities (how they promote CSA), needs (why MR is useful to them) and current capacities to conduct periodic monitoring, evaluation and reporting (how ready are institutions, staff and finances). Our analysis found that explicit demand for integration of data systems and active engagement of stakeholders throughout the entire process are key ingredients for building a MR system that is relevant, useful and acted upon. Based on these lessons, we identify a seven-step framework for stakeholders to develop a comprehensive information system for MR of progress in implementing CSA
Strong Amplifiers of Natural Selection: Proofs
We consider the modified Moran process on graphs to study the spread of
genetic and cultural mutations on structured populations. An initial mutant
arises either spontaneously (aka \emph{uniform initialization}), or during
reproduction (aka \emph{temperature initialization}) in a population of
individuals, and has a fixed fitness advantage over the residents of the
population. The fixation probability is the probability that the mutant takes
over the entire population. Graphs that ensure fixation probability of~1 in the
limit of infinite populations are called \emph{strong amplifiers}. Previously,
only a few examples of strong amplifiers were known for uniform initialization,
whereas no strong amplifiers were known for temperature initialization.
In this work, we study necessary and sufficient conditions for strong
amplification, and prove negative and positive results. We show that for
temperature initialization, graphs that are unweighted and/or self-loop-free
have fixation probability upper-bounded by , where is a
function linear in . Similarly, we show that for uniform initialization,
bounded-degree graphs that are unweighted and/or self-loop-free have fixation
probability upper-bounded by , where is the degree bound and
a function linear in . Our main positive result complements these
negative results, and is as follows: every family of undirected graphs with
(i)~self loops and (ii)~diameter bounded by , for some fixed
, can be assigned weights that makes it a strong amplifier, both
for uniform and temperature initialization
Stuart Hall and the Self-Renewal of Social Critique
The slogan āback to Marxā always appears during every crisis cycle of Marxism. However, the idea of a return to Marx is problematic because each generation that embraces a critical approach is faced with new conditions and questions that have changed. Employing the work of Stuart Hall is a particularly fruitful means of updating Marx because it provides us with suitable guidelines with which to re-employ Marx. Hall calls for a Marxism without guarantees that renounces historical-philosophical ultimate justification. He calls for a form of Marxism that engages in theoretical, social and political conflicts and that takes Marx seriously, not just in his strengths, but also in his weaknesses. Consequently, he sets out an approach that could truly provide a foundation with which to undertake the self-renewal of social critique. In this essay we want to find out how to revitalise a fruitful engagement with Marx by utilising Hallās writings
Magnetic field control of the spin Seebeck effect
The origin of the suppression of the longitudinal spin Seebeck effect by
applied magnetic fields is studied. We perform numerical simulations of the
stochastic Landau-Lifshitz-Gilbert equation of motion for an atomistic spin
model and calculate the magnon accumulation in linear temperature gradients for
different strengths of applied magnetic fields and different length scales of
the temperature gradient. We observe a decrease of the magnon accumulation with
increasing magnetic field and we reveal that the origin of this effect is a
field dependent change of the frequency distribution of the propagating
magnons. With increasing field the magnonic spin currents are reduced due to a
suppression of parts of the frequency spectrum. By comparison with measurements
of the magnetic field dependent longitudinal spin Seebeck effect in YIG thin
films with various thicknesses, we find that our model describes the
experimental data very well, demonstrating the importance of this effect for
experimental systems
Quantitative analysis of pedestrian counterflow in a cellular automaton model
Pedestrian dynamics exhibits various collective phenomena. Here we study
bidirectional pedestrian flow in a floor field cellular automaton model. Under
certain conditions, lane formation is observed. Although it has often been
studied qualitatively, e.g., as a test for the realism of a model, there are
almost no quantitative results, neither empirically nor theoretically. As basis
for a quantitative analysis we introduce an order parameter which is adopted
from the analysis of colloidal suspensions. This allows to determine a phase
diagram for the system where four different states (free flow, disorder, lanes,
gridlock) can be distinguished. Although the number of lanes formed is
fluctuating, lanes are characterized by a typical density. It is found that the
basic floor field model overestimates the tendency towards a gridlock compared
to experimental bounds. Therefore an anticipation mechanism is introduced which
reduces the jamming probability.Comment: 11 pages, 12 figures, accepted for publication in Phys. Rev.
Nonmelanoma Skin Cancer with Skull Infiltration and Cranial Involvement
BACKGROUND: Skin cancer is an uncommon cause of skull invasion, dural infiltration and brain parenchyma involvement.
CASE REPORT: We report on a series of three elderly patients who presented with squamous cell carcinoma of the scalp with skull bone and cerebral invasion and discuss the diagnostic and therapeutic challenges.
CONCLUSION: A major factor of delayed diagnosis of this potentially life-threatening skin cancer feature is patientsĆ¢ā¬ā¢ neglecting
CFD Analysis of Flow Characteristics in a Jet Laryngoscope and the Different Application Forms of Superimposed Jet Ventilation
IST Austria Technical Report
The fixation probability is the probability that a new mutant introduced in a homogeneous population eventually takes over the entire population.
The fixation probability is a fundamental quantity of natural selection, and known to depend on the population structure.
Amplifiers of natural selection are population structures which increase the fixation probability of advantageous mutants, as compared to the baseline case of well-mixed populations. In this work we focus on symmetric population structures represented as undirected graphs. In the regime of undirected graphs, the strongest amplifier known has been the Star graph, and the existence of undirected graphs with stronger amplification properties has remained open for over a decade.
In this work we present the Comet and Comet-swarm families of undirected graphs. We show that for a range of fitness values of the mutants, the Comet and Comet-swarm graphs have fixation probability strictly larger than the fixation probability of the Star graph, for fixed population size and at the limit of large populations, respectively
- ā¦