Improved dynamic geomagnetic rigidity cutoff modeling: testing predictive accuracy

. In the polar atmosphere, significant chemical and ionization changes occur during solar proton events (SPE). The access of solar protons to this region is limited by the dynamically changing geomagnetic field. In this study we have used riometer absorption observations to investigate the accuracy of a model to predict Kp-dependent geomagnetic rigidity cutoffs, and hence the changing proton fluxes. The imaging riometer at Halley, Antarctica is ideally situated for such a study, as the rigidity cutoff sweeps back and forth across the instrument's field of view, providing a severe test of the rigidity cutoff model. Using observations from this riometer during five solar proton events, we have confirmed the basic accuracy of this rigidity model. However, we find that the model can be improved by setting a lower Kp limit (i.e., Kp=5 instead of 6) at which the rigidity modeling saturates. We also find that for L>4.5 the apparent L-shell of the beam moves equatorwards. In addition, the Sodankyla Ion and Neutral Chemistry model is used to determine an empirical relationship between integral proton precipitation fluxes and nighttime ionosphere riometer absorption, in order to allow consideration of winter time SPEs. We find that during the nighttime the proton flux energy threshold is lowered to include protons with energies of >5 MeV in comparison with >10 MeV for the daytime empirical relationships. In addition, we provide an indication of the southern and northern geographic regions inside which SPEs play a role in modifying the neutral chemistry of the stratosphere and mesosphere

The Classical Limit of the Quantum Baker\u27s Map

This work concerns the finding of the semi-classical form of the coherent state representation for the class of quantum baker’s maps defined by Schack and Caves. It begins by introducing the finite-dimensional Hilbert space on which the quantum baker’s map is defined. Its pertinent features including the all important symmetry operators are introduced and given a full explanation. We also introduce the finite-dimensional phase space which will give the semi-classical limit a geometrical interpretation. For a D dimensional Hilbert space, the finite-dimensional phase space is found to be a grid with D2 points. Each point corresponds to a particular pair of position and momentum displacement operator eigenphases. We then detail the derivation of the finite-dimension version of the Wigner function, a quasi-distribution for the finite-dimensional phase space. We show that its most “irregular” feature, mainly its property of having more values than was thought necessary, can be explained by its correct behavior under the symmetry operations, a feature lacking in other Wigner candidates. However, even this special choice for the Wigner function proves unusable in the semi-classical limit as it is found to have a non-convergent limit. We then turn to another possible phase space function: the Q-function. It being necessary to find a suitable coherent state for the finite-dimensional Hilbert space, we begin by studying the properties of the periodically continued Gaussian states. These are the typical Weyl coherent states made periodic in both position and momentum such as to make them legitimate finite-dimensional states. Developing certain mathematical techniques allows us to show that they have compatible position and momentum representations, that a subset of them are complete and can be used to define a Q-function, and that this function obeys all of the symmetry properties. Finally, we use these coherent states to find a representation for the propagator of the quantum baker’s map. In the semi-classical limit, i.e. the large dimension limit, this representation is found, for most of the maps, to take a form of the exponentiation of the classical map’s generating function. This form was predicted long ago by Van Vleck as indicator of an operator’s classical limit. Therefore, we assert that these maps limit to the classically chaotic baker’s map. In certain limiting schemes, however, the Schack-Caves maps do not reach this form and must be given a different interpretation

Concentration of norms and eigenvalues of random matrices

We prove concentration results for $\ell_p^n$ operator norms of rectangular random matrices and eigenvalues of self-adjoint random matrices. The random matrices we consider have bounded entries which are independent, up to a possible self-adjointness constraint. Our results are based on an isoperimetric inequality for product spaces due to Talagrand.Comment: 15 pages; AMS-LaTeX; updated one referenc

Consistent Scenarios for Cosmic-Ray Excesses from Sommerfeld-Enhanced Dark Matter Annihilation

Anomalies in direct and indirect detection have motivated models of dark matter consisting of a multiplet of nearly-degenerate states, coupled by a new GeV-scale interaction. We perform a careful analysis of the thermal freezeout of dark matter annihilation in such a scenario. We compute the range of "boost factors" arising from Sommerfeld enhancement in the local halo for models which produce the correct relic density, and show the effect of including constraints on the saturated enhancement from the cosmic microwave background (CMB). We find that boost factors from Sommerfeld enhancement of up to ~800 are possible in the local halo. When the CMB bounds on the saturated enhancement are applied, the maximal boost factor is reduced to ~400 for 1-2 TeV dark matter and sub-GeV force carriers, but remains large enough to explain the observed Fermi and PAMELA electronic signals. We describe regions in the DM mass-boost factor plane where the cosmic ray data is well fit for a range of final states, and show that Sommerfeld enhancement alone is enough to provide the large annihilation cross sections required to fit the data, although for light mediator masses (less than ~200 MeV) there is tension with the CMB constraints in the absence of astrophysical boost factors from substructure. Additionally, we consider the circumstances under which WIMPonium formation is relevant and find for heavy WIMPs (greater than ~2 TeV) and soft-spectrum annihilation channels it can be an important consideration; we find regions with dark matter mass greater than 2.8 TeV that are consistent with the CMB bounds and have ~600-700 present-day boost factors.Comment: Related web application at http://astrometry.fas.harvard.edu/mvogelsb/sommerfeld . v2: added brief clarification regarding propagation parameters, plots now show effect of relaxing CMB bounds. 35 pages in JCAP format, 4 figures. Accepted for publication in JCA

The ISCIP Analyst, Volume III, Issue 4

This repository item contains a single issue of The ISCIP Analyst, an analytical review journal published from 1996 to 2010 by the Boston University Institute for the Study of Conflict, Ideology, and Policy

Study of an Aviation Design Supportability Course for Engineering and Technology

The following reports on a study examining a typical aeronautical/aviation engineering senior design course, and examines how an aviation technology based course applying the elements of logistics support analysis might be taught concurrently. The study examines the content of a typical senior engineering design course, the required content for a technology based logistics support analysis course, and analyzes the overlaps. Over the course of the study the methods and limitations of engineering design were observed by the technology researchers and were used to formulate the content of an aviation logistics course

Romance for Oboe and Piano

The breadth of contemporary music includes an expansion of harmonies, genres, instrumentation, and techniques. With all these options available today, many composers still feel it is important to connect with the audience on a personal and expressive level. The submitted piece Romance for Oboe and Piano attempts to do just that. Romance features post-tonal materials of modern compositional writing. Some of the compositional techniques included in Romance are octatonicism, more complex chord structures, pandiatonicism, modal, pentatonic, and whole tone scales. At the beginning of Romance, the piano and oboe are treated as two separate entities but as the work progresses, they gradually merge together into a warm, fervent, and unbreakable relationship. To take it a step further, and on a more personal note, this piece is a declaration of my love for my wife (and oboist) Tracy. Many composers of the 19th–century (the “Romantic” period) sought to create strong emotional bonds with their audience. The desired end result of Romance is one in which materials of modern composition coalesce into a unique, cogent musical work exhibiting the same emotive and impassioned feelings frequently found in music of the “Romantic” era

Comparative clinical evaluation of rub vs. no rub lens care regimens for a silicone hydrogel soft contact lens

Purpose. Although no-rub cleaning regimens have proven effective with traditional HEMA based lenses, there has been little reported on the impact of deleting the rubbing step for silicone hydrogel lenses. This study investigated the impact of a rub vs. no-rub cleaning regimen on the comfort of a silicone hydrogel contact lens. Methods. Sixteen subjects wore 0 20ptix silicone hydrogel contact lenses (CIBA Vision, Duluth, GA) on a daily wear schedule for two consecutive two week periods. The study was a subject-blind cross-over study in which the subjects were told they would be comparing the comfort of two different silicone hydrogel lenses. They were instructed to rub and rinse the lenses for 2 weeks and rinse without rubbing the lenses for the other 2 weeks using OPTI-FREE! RepleniSH™ (Alcon, Fort Worth, Texas) cleaning solution. Subjective comfort and symptoms were assessed after 2 weeks with each cleaning regimen. Results: Mean comfortable wearing time for the rubbed lenses (R) was 10 hours (95% CI 7.9, 12.0) compared to the non-rubbed (NR) at 8.35 hours (95% Cl6.1, 10.6). P = 0.1064. Comfort as recorded on a visual analogue scale had a mean of75.1 for the Rand 66.4 for the NR. P = 0.3708. The R group scored higher for overall comfort, end of day comfort and dryness. Forced choice results indicated that subjects preferred the R regimen over the NR. P = 0.0847. There were no differences in slit lamp examination findings. Conclusions: A cleaning regimen consisting of a 10 second rub showed a trend towards improved comfort and wear time in a pilot study of silicone hydrogel lens wearers. Practitioners may wish to consider this when prescribing lens care for these patients, however, further research with a larger sample size would be warranted to confirm the results of this study

New BERA SIG: Nature, Outdoor Learning and Play

The strategic priority of the Nature, Outdoor Learning and Play (NOLAP) special interest group (SIG) is to encourage educational research into nature, outdoor learning and play across the lifespan, by engaging in critical dialogue about the health, wellbeing and educational benefits available through a broad range of activities, contexts and locations. Extensive outdoor learning research is taking place in the UK that is of special interest to researchers and educational professionals alike – and through the activities of this SIG we aim to bring this together in a cohesive way

Implementation, context and complexity

Background - Context is a problem in research on health behaviour change, knowledge translation, practice implementation and health improvement. This is because many intervention and evaluation designs seek to eliminate contextual confounders, when these represent the normal conditions into which interventions must be integrated if they are to be workable in practice. Discussion - We present an ecological model of the ways that participants in implementation and health improvement processes interact with contexts. The paper addresses the problem of context as it affects processes of implementation, scaling up and diffusion of interventions. We extend our earlier work to develop Normalisation Process Theory and show how these processes involve interactions between mechanisms of resource mobilisation, collective action and negotiations with context. These mechanisms are adaptive. They contribute to self-organisation in complex adaptive systems. Conclusion - Implementation includes the translational efforts that take healthcare interventions beyond the closed systems of evaluation studies into the open systems of ‘real world’ contexts. The outcome of these processes depends on interactions and negotiations between their participants and contexts. In these negotiations, the plasticity of intervention components, the degree of participants’ discretion over resource mobilisation and actors’ contributions, and the elasticity of contexts, all play important parts. Understanding these processes in terms of feedback loops, adaptive mechanisms and the practical compromises that stem from them enables us to see the mechanisms specified by NPT as core elements of self-organisation in complex systems