Measurement of a topological edge invariant in a microwave network

We report on the measurement of topological invariants in an electromagnetic topological insulator analog formed by a microwave network, consisting of the winding numbers of scattering matrix eigenvalues. The experiment can be regarded as a variant of a topological pump, with non-zero winding implying the existence of topological edge states. In microwave networks, unlike most other systems exhibiting topological insulator physics, the winding can be directly observed. The effects of loss on the experimental results, and on the topological edge states, is discussed.Comment: 10 pages, 10 figure

Reducing Aversive Interactions with Troubled Students

This paper is about the impact of staff in-service education on the quality of interactions between staff and students at an educational facility for at-risk youth operated by the Orange County Department of Education. Data on the use of punitive behavior management techniques was gathered before, during, and after staff training in the use of more positive approaches to responding to disruptive behavior. Staff members use of punitive techniques as physical restraint and suspensions was greatly reduced following the training

High power ultrashort pulse lasers

Small scale terawatt and soon even petawatt (1000 terawatt) class laser systems are made possible by application of the chirped-pulse amplification technique to solid-state lasers combined with the availability of broad bandwidth materials. These lasers make possible a new class of high gradient accelerators based on the large electric fields associated with intense laser-plasma interactions or from the intense laser field directly. Here, we concentrate on the laser technology to produce these intense pulses. Application of the smallest of these systems to the production of high brightness electron sources is also introduced

On the large-scale sweeping of small-scale eddies in turbulence -- A filtering approach

We present an analysis of the Navier-Stokes equations based on a spatial filtering technique to elucidate the multi-scale nature of fully developed turbulence. In particular, the advection of a band-pass-filtered small-scale contribution by larger scales is considered, and rigorous upper bounds are established for the various dynamically active scales. The analytical predictions are confirmed with direct numerical simulation data. The results are discussed with respect to the establishment of effective large-scale equations valid for turbulent flows.Comment: 14 pages, 6 figure

The effects of knee injury on skeletal muscle function, Na+, K+-ATPase content, and isoform abundance.

While training upregulates skeletal muscle Na+, K+‐ATPase (NKA), the effects of knee injury and associated disuse on muscle NKA remain unknown. This was therefore investigated in six healthy young adults with a torn anterior cruciate ligament, (KI; four females, two males; age 25.0 ± 4.9 years; injury duration 15 ± 17 weeks; mean ± SD) and seven age‐ and BMI‐matched asymptomatic controls (CON; five females, two males). Each participant underwent a vastus lateralis muscle biopsy, on both legs in KI and one leg in CON. Muscle was analyzed for muscle fiber type and cross‐sectional area (CSA), NKA content ([3H]ouabain binding), and α1–3 and β1–2 isoform abundance. Participants also completed physical activity and knee function questionnaires (KI only); and underwent quadriceps peak isometric strength, thigh CSA and postural sway assessments in both injured and noninjured legs. NKA content was 20.1% lower in the knee‐injured leg than the noninjured leg and 22.5% lower than CON. NKA α2 abundance was 63.0% lower in the knee‐injured leg than the noninjured leg, with no differences in other NKA isoforms. Isometric strength and thigh CSA were 21.7% and 7.1% lower in the injured leg than the noninjured leg, respectively. In KI, postural sway did not differ between legs, but for two‐legged standing was 43% higher than CON. Hence, muscle NKA content and α2 abundance were reduced in severe knee injury, which may contribute to impaired muscle function. Restoration of muscle NKA may be important in rehabilitation of muscle function after knee and other lower limb injury

Simulation-Based Design of Bicuspidization of the Aortic Valve

Objective: Severe congenital aortic valve pathology in the growing patient remains a challenging clinical scenario. Bicuspidization of the diseased aortic valve has proven to be a promising repair technique with acceptable durability. However, most understanding of the procedure is empirical and retrospective. This work seeks to design the optimal gross morphology associated with surgical bicuspidization with simulations, based on the hypothesis that modifications to the free edge length cause or relieve stenosis. Methods: Model bicuspid valves were constructed with varying free edge lengths and gross morphology. Fluid-structure interaction simulations were conducted in a single patient-specific model geometry. The models were evaluated for primary targets of stenosis and regurgitation. Secondary targets were assessed and included qualitative hemodynamics, geometric height, effective height, orifice area and prolapse. Results: Stenosis decreased with increasing free edge length and was pronounced with free edge length less than or equal to 1.3 times the annular diameter d. With free edge length 1.5d or greater, no stenosis occurred. All models were free of regurgitation. Substantial prolapse occurred with free edge length greater than or equal to 1.7d. Conclusions: Free edge length greater than or equal to 1.5d was required to avoid aortic stenosis in simulations. Cases with free edge length greater than or equal to 1.7d showed excessive prolapse and other changes in gross morphology. Cases with free edge length 1.5-1.6d have a total free edge length approximately equal to the annular circumference and appeared optimal. These effects should be studied in vitro and in animal studies

Confronting Standard Models of Proto--Planetary Disks With New Mid--Infrared Sizes from the Keck Interferometer

We present near and mid-infrared interferometric observations made with the Keck Interferometer Nuller and near-contemporaneous spectro-photometry from the IRTF of 11 well known young stellar objects, several observed for the first time in these spectral and spatial resolution regimes. With AU-level spatial resolution, we first establish characteristic sizes of the infrared emission using a simple geometrical model consisting of a hot inner rim and mid-infrared disk emission. We find a high degree of correlation between the stellar luminosity and the mid-infrared disk sizes after using near-infrared data to remove the contribution from the inner rim. We then use a semi-analytical physical model to also find that the very widely used "star + inner dust rim + flared disk" class of models strongly fails to reproduce the SED and spatially-resolved mid-infrared data simultaneously; specifically a more compact source of mid-infrared emission is required than results from the standard flared disk model. We explore the viability of a modification to the model whereby a second dust rim containing smaller dust grains is added, and find that the two-rim model leads to significantly improved fits in most cases. This complexity is largely missed when carrying out SED modelling alone, although detailed silicate feature fitting by McClure et al. 2013 recently came to a similar conclusion. As has been suggested recently by Menu et al. 2015, the difficulty in predicting mid-infrared sizes from the SED alone might hint at "transition disk"-like gaps in the inner AU; however, the relatively high correlation found in our mid-infrared disk size vs. stellar luminosity relation favors layered disk morphologies and points to missing disk model ingredients instead

Absorption Properties of a Porous Organic Crystalline Apohost Formed by a Self-Assembled Bis-Urea Macrocycle

We report herein the characterization and binding properties of a microporous crystalline host formed by the self assembly of a bis-urea macrocycle 1. Bis-urea macrocycle 1 has been designed to crystallize into stacked hollow columns. The self-assembly process is guided primarily by hydrogen bonding and aromatic stacking interactions that yield crystals of filled host 1âacetic acid (AcOH). The AcOH guests are bound in the cylindrical cavities of the crystal. The guest AcOH can be removed by heating to form a stable crystalline apohost 1. Apohost 1 displays a type I gas adsorption isotherm with CO2 that is consistent with an open framework microporous material. Apohost 1 binds a range of small molecule guests with specific stoichiometry. The formation of these inclusion complexes does not destroy the crystal framework and therefore apohost 1 can be reused, much like a zeolite. We investigated the structure of apohost 1 and its inclusion complexes by powder X-ray diffraction. The ability of guests to bind and their stoichiometry could be rationalized on the basis of the size, shape, and polarity of the guest molecules. Finally, the shape selectivity of these self-assembled porous materials was demonstrated in competition studies in which apohost 1 preferentially bound p-xylene from a mixture of xylene isomers