2,123 research outputs found
Abrupt climate change and extinction events
There is a growing body of theoretical and empirical support for the concept of instabilities in the climate system, and indications that abrupt climate change may in some cases contribute to abrupt extinctions. Theoretical indications of instabilities can be found in a broad spectrum of climate models (energy balance models, a thermohaline model of deep-water circulation, atmospheric general circulation models, and coupled ocean-atmosphere models). Abrupt transitions can be of several types and affect the environment in different ways. There is increasing evidence for abrupt climate change in the geologic record and involves both interglacial-glacial scale transitions and the longer-term evolution of climate over the last 100 million years. Records from the Cenozoic clearly show that the long-term trend is characterized by numerous abrupt steps where the system appears to be rapidly moving to a new equilibrium state. The long-term trend probably is due to changes associated with plate tectonic processes, but the abrupt steps most likely reflect instabilities in the climate system as the slowly changing boundary conditions caused the climate to reach some threshold critical point. A more detailed analysis of abrupt steps comes from high-resolution studies of glacial-interglacial fluctuations in the Pleistocene. Comparison of climate transitions with the extinction record indicates that many climate and biotic transitions coincide. The Cretaceous-Tertiary extinction is not a candidate for an extinction event due to instabilities in the climate system. It is quite possible that more detailed comparisons and analysis will indicate some flaws in the climate instability-extinction hypothesis, but at present it appears to be a viable candidate as an alternate mechanism for causing abrupt environmental changes and extinctions
Legume Pick ‘n’ Mix
In Spring 2009, ORC set up a legume trial on an organic farm, Barrington Park in Gloucestershire, as part of a large research project called Legume LINK. One of its aims is to compare the performance of several legume and grass species for use in fertility building leys. ORC researchers Thomas Döring and Oliver Crowley report that the trial shows the advantage of mixing species grows over time
Harmonic spinors and metrics of positive curvature via the Gromoll filtration and Toda brackets
We construct non-trivial elements of order 2 in the homotopy groups
, for * congruent 1 or 2 modulo 8, which are
detected by the "assembling homomorphism" (giving rise to the Gromoll
filtration), followed by the alpha-invariant in . These elements are
constructed by means of Morlet's homotopy equivalence between
and , and Toda brackets in .
We also construct non-trivial elements of order 2 in for every m
greater or equal to 6 and * congruent to 1 or 2 modulo 8, which are detected by
the alpha-invariant.
As consequences, we (a) obtain non-trivial elements of order 2 in for m greater or equal to 6, and * + m congruent 0 or 1
modulo 8; (b) these elements remain non-trivial in where M is a
closed spin manifold of the same dimension m and * > 0; (c) they act
non-trivially on the corresponding homotopy group of the space of metrics of
positive scalar curvature of such an M; in particular these homotopy groups are
all non-trivial. The same applies to all other diffeomorphism invariant metrics
of positive curvature, like the space of metrics of positive sectional
curvature, or the space of metrics of positive Ricci curvature, provided they
are non-empty.
Further consequences are: (d) any closed spin manifold of dimension m greater
or equal to 6 admits a metric with harmonic spinors; (e) there is no analogue
of the odd-primary splitting of for the prime 2; (f) for any
-sphere (where j > 0) of order which divides 4, the corresponding
element in lifts to , i.e., lies correspondingly deep down in the Gromoll
filtration.Comment: Final version, to appear in Journal of Topology. 26 page
Saving fuel with non-inversion tillage
The mouldboard plough is the traditional and proven method of preparing a seedbed for drilling and controlling arable weeds. However there is a downside; trials have shown deterioration in structural stability, losses of soil organic matter, poor moisture retention and infiltration rates (Riley et al 2008). Farmers have long been aware of these adverse impacts of mouldboard ploughing, but concerns over the greenhouse gas emissions associated with tractor usage have prompted a fresh look at cultivations. ORC researchers, Oliver Crowley, Jemima Showering and Thomas F. Döring consider the case for non-inversion tillage
Using minimum tillage to improve the efficiency of ecosystem service delivery on organic farms
Organic farming practices aim to maximise the delivery of ecosystem services in the agricultural landscape. However, in order to maintain optimal crop productivity the mouldboard plough is often used to control weeds and this can have negative effects on a range of soil parameters, thereby jeopardizing delivery of these services. Reduced tillage (RT) can be beneficial to soils and could improve both the efficiency of production and the delivery of ecosystem services on organic farms. However, abandoning the plough on organic farms is challenging due to impaired weed control. Here we report on a two year trial where an RT system with the Ecodyn, with duck feet shares operating at a depth of 7.6 cm in combination with seed drilling, was compared with mouldboard ploughing. Spring oat and spring barley establishment was improved under RT. Weed cover and biomass was greater under RT, but there was no difference in cereal grain yields in either year. The RT system used 71% less fuel and tillage operations took 72% less time that the plough system
Against the grain
An Organic Research Centre project is examining how diversity-based tools can assist in the on-farm improvement of organic wheat.
Successful organic crop production requires varieties that are resistant to diseases, competitive against weeds, and effective at scavenging nutrients. Yet conventional plant breeding has largely neglected organic systems by breeding varieties exclusively for high input conditions. As a consequence, organic producers currently do not have enough choice of plant varieties for organic conditions.
One way to expand the choice is to create plant diversity anew and subject it to natural selection on organic farms.
After several generations the dominating plants would be better suited to organic systems. This idea is being tested in the Organic Research Centre’s Wheat Breeding LINK project
Community Policing: The Foundation of Trust between Police and Society
Police officers wear many hats such as protecting people, preventing crimes, and responding to other calls for help. Policing is under a microscope in the current climate of the country with debates about police brutality, body-worn cameras, and the overall trust between police and the public. The most universally accepted way to improve trust between the police and public is through community policing. Studies show the community policing policies have improved community-police relations in the United States. I plan to use this knowledge in my career as a police officer by making sure that every interaction I have with the public is from the foundation of integrity and honesty
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To Change Is to Be: The Kalasha of Pakistan’s Afghan Frontier and the Age of Heritage
This thesis examines the relationship between heritage and borders. It argues that the study of heritage has a tendency to overlook important aspects of the borders of heritage discourses. The dissonance and conflict which occurs at the meeting points of different heritages is well worn academic territory. What is less comprehensively understood are the other products which issue from these meeting points.
Taking as its case study the Kalasha, a non-Muslim community of only 4000 members positioned on the Pakistani side of the Afghan border, I demonstrate how in certain settings different heritages can come together in creative combinations. The theoretical underpinnings of my argument are drawn from borderland studies, a discourse which has much to offer the critical discussion of heritage, but which has thus far been underutilised. I also make use of the ecological principal of the ecotone, a methodology which allows me to abstract what I learnt from my case study into a format which is applicable to the wider study of heritage.
The thesis makes several novel contributions to the academic discourse. The first is to draw attention to the potential of indeterminate borderlands for advancing critical heritage studies in productive new directions. The second is to produce a methodology for studying the meeting points of different heritages which offers the conceptual space to explore both dissonant and creative outcomes. The final contribution is to argue for a theorisation of heritage narratives as malleable and capable of being combined and in so doing nuance the prevalent understanding of heritage narratives as immutable and immiscible
Multimodal Observation and Interpretation of Subjects Engaged in Problem Solving
In this paper we present the first results of a pilot experiment in the
capture and interpretation of multimodal signals of human experts engaged in
solving challenging chess problems. Our goal is to investigate the extent to
which observations of eye-gaze, posture, emotion and other physiological
signals can be used to model the cognitive state of subjects, and to explore
the integration of multiple sensor modalities to improve the reliability of
detection of human displays of awareness and emotion. We observed chess players
engaged in problems of increasing difficulty while recording their behavior.
Such recordings can be used to estimate a participant's awareness of the
current situation and to predict ability to respond effectively to challenging
situations. Results show that a multimodal approach is more accurate than a
unimodal one. By combining body posture, visual attention and emotion, the
multimodal approach can reach up to 93% of accuracy when determining player's
chess expertise while unimodal approach reaches 86%. Finally this experiment
validates the use of our equipment as a general and reproducible tool for the
study of participants engaged in screen-based interaction and/or problem
solving
Deep learning investigation for chess player attention prediction using eye-tracking and game data
This article reports on an investigation of the use of convolutional neural
networks to predict the visual attention of chess players. The visual attention
model described in this article has been created to generate saliency maps that
capture hierarchical and spatial features of chessboard, in order to predict
the probability fixation for individual pixels Using a skip-layer architecture
of an autoencoder, with a unified decoder, we are able to use multiscale
features to predict saliency of part of the board at different scales, showing
multiple relations between pieces. We have used scan path and fixation data
from players engaged in solving chess problems, to compute 6600 saliency maps
associated to the corresponding chess piece configurations. This corpus is
completed with synthetically generated data from actual games gathered from an
online chess platform. Experiments realized using both scan-paths from chess
players and the CAT2000 saliency dataset of natural images, highlights several
results. Deep features, pretrained on natural images, were found to be helpful
in training visual attention prediction for chess. The proposed neural network
architecture is able to generate meaningful saliency maps on unseen chess
configurations with good scores on standard metrics. This work provides a
baseline for future work on visual attention prediction in similar contexts
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