Ringing the initial Universe: the response of overdensity and transformed-density power spectra to initial spikes

We present an experiment in which we 'ring' a set of cosmological N-body-simulation initial conditions, placing spikes in the initial power spectrum at different wavenumber bins. We then measure where these spikes end up in the final conditions. In the usual overdensity power spectrum, most sensitive to contracting and collapsing dense regions, initial power on slightly non-linear scales (k ~ 0.3 h/Mpc) smears to smaller scales, coming to dominate the initial power once there. Log-density and Gaussianized-density power spectra, sensitive to low-density (expanding) and high-density regions, respond differently: initial spikes spread symmetrically in scale, both upward and downward. In fact, in the power spectrum of 1/(1 + {\delta}), spikes migrate to larger scales, showing the magnifying effect of voids on small-scale modes. These power spectra show much greater sensitivity to small-scale initial features. We also test the difference between an approximation of the Ly-{\alpha} flux field, and its Gaussianized form, and give a toy model that qualitatively explains the symmetric power spreading in Gaussianized-density power spectra. Also, we discuss how to use this framework to estimate power-spectrum covariance matrices. This can be used to track the fate of information in the Universe, that takes the form of initial degrees of freedom, one random spike per initial mode.Comment: Accepted to MNRAS Letters. 6 pages, 5 figure

SMS text pre-notification and delivery of reminder e-mails to increase response rates to postal questionnaires in the SUSPEND trial : a factorial design, randomised controlled trial

Acknowledgements SUSPEND was funded by the National Institute for Health Research (NIHR) Health Technology Assessment (HTA) Programme (project 80/71/01) and will be published in full in Health Technology Assessment. The Health Services Research Unit of the University of Aberdeen is funded in part by the Chief Scientist Office of the Scottish Government Health and Social Care Directorates. The views and opinions expressed herein are those of the authors and do not necessarily reflect those of the Chief Scientist Office, HTA programme, NIHR, National Health Service, or Department of Health. The authors thank the SUSPEND staff and participants, without whom this study would not have been possible.Peer reviewedPublisher PD

PCORnet's Collaborative Research Groups.

The Patient-Centered Outcomes Research Institute (PCORI) launched a multi-institutional "network of networks" in 2013 - Patient-Centered Clinical Research Network (PCORnet) - that is designed to conduct clinical research that is faster, less expensive, and more responsive to the information needs of patients and clinicians. To enhance cross-network and cross-institutional collaboration and catalyze the use of PCORnet, PCORI has supported formation of 11 Collaborative Research Groups focusing on specific disease types (e.g., cardiovascular health and cancer) or particular patient populations (e.g., pediatrics and health disparities). PCORnet's Collaborative Research Groups are establishing research priorities within these focus areas, establishing relationships with potential funders, and supporting development of specific research projects that will use PCORnet resources. PCORnet remains a complex, multilevel, and heterogeneous network that is still maturing and building a diverse portfolio of observational and interventional people-centered research; engaging with PCORnet can be daunting, particularly for outside investigators. We believe the Collaborative Research Groups are stimulating interest and helping investigators navigate the complexity, but only time will tell if these efforts will bear fruit in terms of funded multicenter PCORnet projects

Concerto for the Young Adventurer.

Concerto for the Young Adventurer is a four-movement work written for cello, vibraphone and piano. Its themes are youthful adventure and exploration. Although the work is not programmatic in the strict sense, each movement is titled to guide the listener through a possible interpretation of the music\u27s meaning. Each instrument is featured in several places, and all three provide supporting material when not in the spotlight. As a whole, the work is symphonic in its structure. Each movement serves its purpose in the larger picture, while all can function independently from one another. Recurring ideas link the movements together thematically and unify the work

The sodium-potassium pump controls the intrinsic firing of the cerebellar Purkinje neuron

In vitro, cerebellar Purkinje cells can intrinsically fire action potentials in a repeating trimodal or bimodal pattern. The trimodal pattern consists of tonic spiking, bursting, and quiescence. The bimodal pattern consists of tonic spiking and quiescence. It is unclear how these firing patterns are generated and what determines which firing pattern is selected. We have constructed a realistic biophysical Purkinje cell model that can replicate these patterns. In this model, Na+/K+ pump activity sets the Purkinje cell's operating mode. From rat cerebellar slices we present Purkinje whole cell recordings in the presence of ouabain, which irreversibly blocks the Na+/K+ pump. The model can replicate these recordings. We propose that Na+/K+ pump activity controls the intrinsic firing mode of cerbellar Purkinje cells

Hard X‐ray polarimetry of solar flares with BATSE

We describe a technique for measuring the polarization of hard X‐rays from solar flares based on the angular distribution of that portion of the flux which is scattered off the top of the Earth’s atmosphere. The scattering cross section depends not only on the scatter angle itself, but on the orientation of the scatter angle with respect to the incident polarization vector. Consequently, the distribution of the observed albedo flux will depend on the direction and the polarization properties (i.e., the level of polarization and polarization angle) of the source. Since the albedo component can represent a relatively large fraction (up to 40%) of the direct source flux, there will generally be sufficient signal for making such a measurement. The sensitivity of this approach is therefore dictated by the effective area and the ability of a detector system to ‘image’ the albedo flux. The 4π coverage of the BATSE detectors on the Compton Gamma‐RayObservatory provides an opportunity to measure both the direct and the albedo flux from a given solar flare event. Although the BATSE design (with its large field‐of‐view for each detector) is not optimized for albedo polarimetry, we have nonetheless investigated the feasibility of this technique using BATSE data

The design of a gamma‐ray burst polarimeter

The study of the polarization properties of the gamma‐ray bursts is the one remaining unexplored avenue of research which may help to answer some of the fundamental problems regarding the nature of these mysterious objects. We have designed an instrument to measure linear polarization in cosmic gamma‐ray bursts at energies ≳50 keV. Here we describe the design of this instrument, which we call the Gamma‐ray Burst Polarimeter Experiment (GRAPE)

Using BATSE to measure gamma-ray burst polarization

We describe a technique for measuring the polarization of hard x-rays from γ-ray bursts based on the angular distribution of that portion of the flux which is scattered off the top of the Earth’s atmosphere. The scattering cross section depends not only on the scatter angle itself, but on the orientation of the scatter angle with respect to the incident polarization vector. Consequently, the distribution of the observed albedo flux will depend on the direction and the polarization properties (i.e., the level of polarization and polarization angle) of the source. Although the BATSE design (with its large field-of-view for each detector) is not optimized for albedo polarimetry, we have nonetheless investigated the feasibility of this technique using BATSE data