Ten simple rules for reporting voxel-based morphometry studies

Voxel-based morphometry [Ashburner, J. and Friston, K.J., 2000. Voxel-based morphometry—the methods. NeuroImage 11(6 Pt 1), 805–821] is a commonly used tool for studying patterns of brain change in development or disease and neuroanatomical correlates of subject characteristics. In performing a VBM study, many methodological options are available; if the study is to be easily interpretable and repeatable, the processing steps and decisions must be clearly described. Similarly, unusual methods and parameter choices should be justified in order to aid readers in judging the importance of such options or in comparing the work with other studies. This editorial suggests core principles that should be followed and information that should be included when reporting a VBM study in order to make it transparent, replicable and useful

A Generic Agent Organisation Framework For Autonomic Systems

Autonomic computing is being advocated as a tool for managing large, complex computing systems. Specifically, self-organisation provides a suitable approach for developing such autonomic systems by incorporating self-management and adaptation properties into large-scale distributed systems. To aid in this development, this paper details a generic problem-solving agent organisation framework that can act as a modelling and simulation platform for autonomic systems. Our framework describes a set of service-providing agents accomplishing tasks through social interactions in dynamically changing organisations. We particularly focus on the organisational structure as it can be used as the basis for the design, development and evaluation of generic algorithms for self-organisation and other approaches towards autonomic systems

Studies of RF Noise Induced Bunch Lengthening at the LHC

Radio Frequency noise induced bunch lengthening can strongly affect the Large Hadron Collider performance through luminosity reduction, particle loss, and other effects. Models and theoretical formalisms demonstrating the dependence of the LHC longitudinal bunch length on the RF station noise spectral content have been presented*,**. Initial measurements validated these studies and determined the performance limiting RF components. For the existing LHC LLRF implementation the bunch length increases with a rate of 1 mm/hr, which is higher than the intrabeam scattering diffusion and leads to a 27% bunch length increase over a 20 hour store. This work presents measurements from the LHC that better quantify the relationship between the RF noise and longitudinal emittance blowup. Noise was injected at specific frequency bands and with varying amplitudes at the LHC accelerating cavities. The experiments presented in this paper confirmed the predicted effects on the LHC bunch length due to both the noise around the synchrotron frequency resonance and the noise in other frequency bands aliased down to the synchrotron frequency by the periodic beam sampling of the accelerating voltage

Observation, control and modal analysis of longitudinal coupled-bunch instabilities in the ALS via a digital feedback system

The operation of a longitudinal multi-bunch damping system using digital signal processing techniques is shown via measurements from the LBL Advanced Light Source. The feedback system (developed for use by PEP-II, ALS and DA{Phi}NE) uses a parallel array of signal processors to implement a bunch by bunch feedback system for sampling rates up to 500 MHz. The programmable DSP system allows feedback control as well as accelerator diagnostics. A diagnostic technique is illustrated which uses the DSP system to excite and then damp the beam. The resulting 12 ms time domain transient is Fourier analyzed to provide the simultaneous measurement of growth rates and damping rates of all unstable coupled-bunch beam modes

Relative performance of four midge-resistant wheat varietal blends in western Canada

Non-Peer ReviewedOrange wheat blossom midge, Sitodiplosis mosellana (Géhin), causes significant yield losses to spring wheat in western Canada in severe infestations. To mitigate losses, midge-resistant wheat varietal blends, consisting of cultivars carrying the Sm1 midge resistance gene and 10% interspersed midge susceptible refuge, have been made available to farmers. To test their performance relative to conventional midge-susceptible cultivars, four varietal blends were grown during four consecutive years, at eight locations in the provinces of Manitoba Saskatchewan and Alberta, in comparison to four conventional, midge-susceptible cultivars. Midge damage was higher in 2007 and 2010 than in 2008 and 2009. In general, the varietal blends, as a group, yielded more grain than the susceptible cultivars, especially when grown in environments with high midge pressure (5.5 - 35% seed damage). In environments with low midge pressure (0 – 2.6% seed damage), the varietal blend average yield advantage was smaller but still significant, indicating that some of the varietal blends had additional superior attributes, in addition to midge resistance

The effect of incorporating the midge resistance (Sm1) gene in wheat

Non-Peer ReviewedOrange wheat blossom midge, Sitodiplosis mosellana (Géhin), was first detected in Manitoba in 1901, but now is present in all three prairie provinces of western Canada. In severe infestations, this insect may cause significant yield losses to spring wheat. To mitigate losses, midge-resistant wheat varietal blends, consisting of cultivars carrying the Sm1 midge resistance gene and 10% interspersed midge susceptible refuge, are now available to farmers. The refuge prevents this resistance to be overcome by the insect. To test the field performance of these varietal blends, relative to conventional midge-susceptible cultivars, four varietal blends were grown during four consecutive years, at eight locations in the provinces of Manitoba Saskatchewan and Alberta, in comparison to four conventional, midge-susceptible cultivars. Midge damage was higher in 2007 and 2010, than in 2008 and 2009. In general, the varietal blends, as a group, yielded more grain than the susceptible cultivars, especially when grown in environments with high midge pressure (5.5 - 35% seed damage). In environments with low midge pressure (0 – 2.6% seed damage), the varietal blend average yield advantage was smaller but still significant, indicating that some of the varietal blends had additional superior attributes, in addition to midge resistance. Significant differences in midge damage were observed within the resistant and the susceptible groups of the cultivars tested. Midge resistance did not protect wheat against loss of market grade

Mathematical Models of Feedback Systems for Control of Intra-Bunch Instabilities Driven by E-Clouds and TMCI

The feedback control of intra-bunch instabilities driven by electron-clouds or strong head-tail coupling (transverse mode coupled instabilities TMCI) requires bandwidth sufficient to sense the vertical position and apply correction fields to multiple sections of a nanosecond-scale bunch. These requirements impose challenges and limits in the design and implementation of the feedback control channel. This paper presents different models for the feedback subsystems: receiver, processing channel, amplifier and kicker, that take into account their frequency response and limits. These models are included in reduced mathematical models of the bunch dynamics and multi-particle simulation codes (WARP / C-MAD / HEADTAIL) to evaluate the impact of the subsystem limitations in the bunch stabilization and emittance improvement. With this realistic model of the hardware, it is possible to analyze and design the feedback system. This research is crucial to evaluate the boundary in the performance of the feedback control system due to technological limitations. Additionally, these models define the impact of parameter variations or mismatching and the effect of spurious perturbation and noise in the performance of the feedback system

LHC Beam Diffusion Dependence on RF Noise: Models and Measurements

Radio Frequency (RF) accelerating system noise and non-idealities can have detrimental impact on the LHC performance through longitudinal motion and longitudinal emittance growth. A theoretical formalism has been developed to relate the beam and RF loop dynamics with the bunch length growth [1]. Measurements were conducted at LHC to validate the formalism, determine the performance limiting RF components, and provide the foundation for beam diffusion estimates for higher energies and intensities. A brief summary of these results is presented in this work