504 research outputs found
Innovations in air sampling to detect plant pathogens
Many innovations in the development and use of air sampling devices have occurred in plant pathology since the first description of the Hirst spore trap. These include improvements in capture efficiency at relatively high air-volume collection rates, methods to enhance the ease of sample processing with downstream diagnostic methods and even full automation of sampling, diagnosis and wireless reporting of results. Other innovations have been to mount air samplers on mobile platforms such as UAVs and ground vehicles to allow sampling at different altitudes and locations in a short space of time to identify potential sources and population structure. Geographical Information Systems and the application to a network of samplers can allow a greater prediction of airborne inoculum and dispersal dynamics. This field of technology is now developing quickly as novel diagnostic methods allow increasingly rapid and accurate quantifications of airborne species and genetic traits. Sampling and interpretation of results, particularly action-thresholds, is improved by understanding components of air dispersal and dilution processes and can add greater precision in the application of crop protection products as part of integrated pest and disease management decisions. The applications of air samplers are likely to increase, with much greater adoption by growers or industry support workers to aid in crop protection decisions. The same devices are likely to improve information available for detection of allergens causing hay fever and asthma or provide valuable metadata for regional plant disease dynamics
A review of diagnostic and functional imaging in headache
The neuroimaging of
headache patients has revolutionised
our understanding of the pathophysiology
of primary headaches and provided
unique insights into these syndromes.
Modern imaging studies
point, together with the clinical picture,
towards a central triggering
cause. The early functional imaging
work using positron emission
tomography shed light on the genesis
of some syndromes, and has
recently been refined, implying that
the observed activation in migraine
(brainstem) and in several trigeminal-autonomic headaches (hypothalamic
grey) is involved in the pain
process in either a permissive or
triggering manner rather than simply
as a response to first-division nociception
per se. Using the advanced
method of voxel-based morphometry,
it has been suggested that there
is a correlation between the brain
area activated specifically in acute
cluster headache — the posterior
hypothalamic grey matter — and an
increase in grey matter in the same
region. No structural changes have
been found for migraine and medication
overuse headache, whereas
patients with chronic tension-type
headache demonstrated a significant
grey matter decrease in regions
known to be involved in pain processing.
Modern neuroimaging thus
clearly suggests that most primary
headache syndromes are predominantly
driven from the brain, activating
the trigeminovascular reflex and
needing therapeutics that act on both
sides: centrally and peripherally
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Points in Mental Space: an Interdisciplinary Study of Imagery in Movement Creation
As part of a programme of research that is developing tools to enhance choreographic practice, an interdisciplinary team of cognitive scientists, neuroscientists and dance professionals collaborated on two studies examining the mental representations used to support movement creation. We studied choreographer Wayne McGregor’s approach to movement creation through tasking, in which he asks dancers to create movement in response to task instructions that require a great deal of mental imagery and decision making.
In our first experiment, we used experience sampling methods (self-report scales and reports about the current focus of thought) with the full company of Wayne McGregor | Random Dance to describe what the dancers report thinking about while creating movement, and to establish how their experiences change as a function of different task conditions. In particular, we contrasted a conventional ‘active’ condition (where dancers are free to move around) with a ‘static’ condition (where they have to create movement mentally, without moving), because all neuroimaging studies of dance require participants to lie motionless within a scanner. We adapted the static mode from Experiment 1 for the neuroimaging session in Experiment 2. Here we recorded the brain activity of an experienced dancer from Wayne McGregor | Random Dance while she mentally undertook movement creation tasks similar to those used in our experience sampling experiment. Both studies involved imagery tasks of a primarily spatial-praxic nature (involving an imagined object or volume that could be approached and manipulated) and imagery that focused on content invoking emotional narratives.
In the first study, the dancers’ awareness was focused more than they had anticipated upon conceptual rather than physical or bodily aspects. The very act of reflecting on, and categorising, their experiences provided the dancers with insights about their mental habits during innovative movement creation. Such insights provide conditions under which habits can be recognised and then altered to adopt alternative points in mental space from which to create movement material. Providing the dancers and McGregor with a means to communicate more productively about the properties of the task-based instructions has been acknowledged by the company to be of clear benefit and a useful addition to their working
process.
In the second study we assessed the feasibility of using fMRI to study the neural underpinnings of choreographing movement tasks. The experiment enabled us to compare brain activity in imagery and movement creation. The data raise some key questions Points in Mental Space 3 concerning the mental context in which such thinking occurs and, given the clear limitations of the current fMRI and experience sampling work, how future research might usefully be directed.
Taken together, these two exploratory studies indicate that the experiential and neural attributes of imagery during movement creation are open to systematic investigation: innovative movement creation can start from alternative points in mental, as well as physical, space. This enables us to look forward to establishing with greater precision how tasks that challenge dancers in different ways may affect mental and neural processes and how variation in imagery use across dancers might contribute to the variety of movement creation that they produce. Notably, the act of reflecting on the experience of movement creation also offers some practical leverage to help dancers develop a wider range of strategies for innovation. These findings are being used to contribute to further work informing the development of personal, notebook-like, Choreographic Thinking Tools
Red Queen Coevolution on Fitness Landscapes
Species do not merely evolve, they also coevolve with other organisms.
Coevolution is a major force driving interacting species to continuously evolve
ex- ploring their fitness landscapes. Coevolution involves the coupling of
species fit- ness landscapes, linking species genetic changes with their
inter-specific ecological interactions. Here we first introduce the Red Queen
hypothesis of evolution com- menting on some theoretical aspects and empirical
evidences. As an introduction to the fitness landscape concept, we review key
issues on evolution on simple and rugged fitness landscapes. Then we present
key modeling examples of coevolution on different fitness landscapes at
different scales, from RNA viruses to complex ecosystems and macroevolution.Comment: 40 pages, 12 figures. To appear in "Recent Advances in the Theory and
Application of Fitness Landscapes" (H. Richter and A. Engelbrecht, eds.).
Springer Series in Emergence, Complexity, and Computation, 201
Evidence of Color Coherence Effects in W+jets Events from ppbar Collisions at sqrt(s) = 1.8 TeV
We report the results of a study of color coherence effects in ppbar
collisions based on data collected by the D0 detector during the 1994-1995 run
of the Fermilab Tevatron Collider, at a center of mass energy sqrt(s) = 1.8
TeV. Initial-to-final state color interference effects are studied by examining
particle distribution patterns in events with a W boson and at least one jet.
The data are compared to Monte Carlo simulations with different color coherence
implementations and to an analytic modified-leading-logarithm perturbative
calculation based on the local parton-hadron duality hypothesis.Comment: 13 pages, 6 figures. Submitted to Physics Letters
Formation of dense partonic matter in relativistic nucleus-nucleus collisions at RHIC: Experimental evaluation by the PHENIX collaboration
Extensive experimental data from high-energy nucleus-nucleus collisions were
recorded using the PHENIX detector at the Relativistic Heavy Ion Collider
(RHIC). The comprehensive set of measurements from the first three years of
RHIC operation includes charged particle multiplicities, transverse energy,
yield ratios and spectra of identified hadrons in a wide range of transverse
momenta (p_T), elliptic flow, two-particle correlations, non-statistical
fluctuations, and suppression of particle production at high p_T. The results
are examined with an emphasis on implications for the formation of a new state
of dense matter. We find that the state of matter created at RHIC cannot be
described in terms of ordinary color neutral hadrons.Comment: 510 authors, 127 pages text, 56 figures, 1 tables, LaTeX. Submitted
to Nuclear Physics A as a regular article; v3 has minor changes in response
to referee comments. Plain text data tables for the points plotted in figures
for this and previous PHENIX publications are (or will be) publicly available
at http://www.phenix.bnl.gov/papers.htm
Observation of a new chi_b state in radiative transitions to Upsilon(1S) and Upsilon(2S) at ATLAS
The chi_b(nP) quarkonium states are produced in proton-proton collisions at
the Large Hadron Collider (LHC) at sqrt(s) = 7 TeV and recorded by the ATLAS
detector. Using a data sample corresponding to an integrated luminosity of 4.4
fb^-1, these states are reconstructed through their radiative decays to
Upsilon(1S,2S) with Upsilon->mu+mu-. In addition to the mass peaks
corresponding to the decay modes chi_b(1P,2P)->Upsilon(1S)gamma, a new
structure centered at a mass of 10.530+/-0.005 (stat.)+/-0.009 (syst.) GeV is
also observed, in both the Upsilon(1S)gamma and Upsilon(2S)gamma decay modes.
This is interpreted as the chi_b(3P) system.Comment: 5 pages plus author list (18 pages total), 2 figures, 1 table,
corrected author list, matches final version in Physical Review Letter
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