Stabilization study at the sub-nanometer level at the interaction point of the future Compact Linear Collider

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Alignment Dynamics of Slow Light Diffusion in Ultracold Atomic \u3csup\u3e85\u3c/sup\u3eRb

A combined experimental and theoretical investigation of time- and alignment-dependent propagation of light in an ultracold atomic gas of atomic 85Rb is reported. Coherences among the scattering amplitudes for light scattering off excited hyperfine levels produce strong variations of the light polarization in the vicinity of atomic resonance. Measurements are in excellent agreement with Monte Carlo simulations of the multiple scattering process

Sub-nanometer active seismic isolator control

Ambitious projects such as the design of the future Compact Linear Collider (CLIC) require challenging parameters and technologies. Stabilization of the CLIC particle beam is one of these challenges. Ground motion (GM) is the main source of beam misalignment. Beam dynamics controls are however efficient only at low frequency (<4Hz), due to the sampling of the beam at 50 Hz. Hence, ground motion mitigation techniques such as active stabilization are required. This paper shows a dedicated prototype able to manage vibration at a sub-nanometer scale. The use of cutting edge sensor technology is however very challenging for control applications as they are usually used for measurement purposes. Limiting factors such as sensor dynamics and noise lead to a performance optimization problem. The current state of the art in GM measurement and GM mitigation techniques is pointed out and shows limits of the technologies. The proposed active device is then described and a realistic model of the process has been established. A dedicated controller design combining feedforward and feedback techniques is presented and theoretical results in terms of Power Spectral Density (PSD) of displacement are compared to real time experimental results obtained with a rapid control prototyping tool

Interaction point feedback design and integrated simulations to stabilize the CLIC final focus

International audienceThe Compact Linear Collider (CLIC) accelerator has strong precision requirements on offset position between the beams. The beam which is sensitive to ground motion needs to be stabilized to unprecedented requirements. Different Beam Based Feedback (BBF) algorithms such as Orbit Feedback (OFB) and Beam-Beam Offset Feedback (BBOF) have been designed. This paper focuses on the BBOF control which could be added to the CLIC baseline. It has been tested for different ground motion models in the presence of noises or disturbances and uses digital linear control with or without an adaptive loop. The simulations demonstrate that it is possible to achieve the required performances and quantify the maximum allowed noise level. This amount of admitted noises and disturbances is given in terms of an equivalent disturbance on the position of the magnet that controls the beam offset. Due to the limited sampling frequency of the process, the control loop is in a very small bandwidth. The study shows that these disturbances have to be lowered by other means in the higher frequency range

Dynamic and volumetric variables reliably predict fluid responsiveness in a porcine model with pleural effusion

Background: The ability of stroke volume variation (SVV), pulse pressure variation (PPV) and global end-diastolic volume (GEDV) for prediction of fluid responsiveness in presence of pleural effusion is unknown. The aim of the present study was to challenge the ability of SVV, PPV and GEDV to predict fluid responsiveness in a porcine model with pleural effusions. Methods: Pigs were studied at baseline and after fluid loading with 8 ml kg−1 6% hydroxyethyl starch. After withdrawal of 8 ml kg−1 blood and induction of pleural effusion up to 50 ml kg−1 on either side, measurements at baseline and after fluid loading were repeated. Cardiac output, stroke volume, central venous pressure (CVP) and pulmonary occlusion pressure (PAOP) were obtained by pulmonary thermodilution, whereas GEDV was determined by transpulmonary thermodilution. SVV and PPV were monitored continuously by pulse contour analysis. Results: Pleural effusion was associated with significant changes in lung compliance, peak airway pressure and stroke volume in both responders and non-responders. At baseline, SVV, PPV and GEDV reliably predicted fluid responsiveness (area under the curve 0.85 (p<0.001), 0.88 (p<0.001), 0.77 (p = 0.007). After induction of pleural effusion the ability of SVV, PPV and GEDV to predict fluid responsiveness was well preserved and also PAOP was predictive. Threshold values for SVV and PPV increased in presence of pleural effusion. Conclusions: In this porcine model, bilateral pleural effusion did not affect the ability of SVV, PPV and GEDV to predict fluid responsiveness

RNA secondary structure prediction from multi-aligned sequences

It has been well accepted that the RNA secondary structures of most functional non-coding RNAs (ncRNAs) are closely related to their functions and are conserved during evolution. Hence, prediction of conserved secondary structures from evolutionarily related sequences is one important task in RNA bioinformatics; the methods are useful not only to further functional analyses of ncRNAs but also to improve the accuracy of secondary structure predictions and to find novel functional RNAs from the genome. In this review, I focus on common secondary structure prediction from a given aligned RNA sequence, in which one secondary structure whose length is equal to that of the input alignment is predicted. I systematically review and classify existing tools and algorithms for the problem, by utilizing the information employed in the tools and by adopting a unified viewpoint based on maximum expected gain (MEG) estimators. I believe that this classification will allow a deeper understanding of each tool and provide users with useful information for selecting tools for common secondary structure predictions.Comment: A preprint of an invited review manuscript that will be published in a chapter of the book `Methods in Molecular Biology'. Note that this version of the manuscript may differ from the published versio

Differences in designations of observation care in US freestanding children's hospitals: Are they virtual or real?

OBJECTIVE: To characterize practices related to observation care and to examine the current models of pediatric observation medicine in US children's hospitals. DESIGN: We utilized 2 web‐based surveys to examine observation care in the 42 hospitals participating in the Pediatric Health Information System database. We obtained information regarding the designation of observation status, including the criteria used to admit patients into observation. From hospitals reporting the use of observation status, we requested specific details relating to the structures of observation care and the processes of care for observation patients following emergency department treatment. RESULTS: A total of 37 hospitals responded to Survey 1, and 20 hospitals responded to Survey 2. Designated observation units were present in only 12 of 31 (39%) hospitals that report observation patient data to the Pediatric Health Information System. Observation status was variably defined in terms of duration of treatment and prespecified criteria. Observation periods were limited to <48 hours in 24 of 31 (77%) hospitals. Hospitals reported that various standards were used by different payers to determine observation status reimbursement. Observation care was delivered in a variety of settings. Most hospitals indicated that there were no differences in the clinical care delivered to virtual observation status patients when compared with other inpatients. CONCLUSIONS: Observation is a variably applied patient status, defined differently by individual hospitals. Consistency in the designation of patients under observation status among hospitals and payers may be necessary to compare quality outcomes and costs, as well as optimize models of pediatric observation care. Journal of Hospital Medicine 2012;. © 2011 Society of Hospital Medicine.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/91108/1/949_ftp.pd