Creep motion of a model frictional system

We report on the dynamics of a model frictional system submitted to minute external perturbations. The system consists of a chain of sliders connected through elastic springs that rest on an incline. By introducing cyclic expansions and contractions of the springs we observe a reptation of the chain. We account for the average reptation velocity theoretically. The velocity of small systems exhibits a series of plateaus as a function of the incline angle. Due to elastic e ects, there exists a critical amplitude below which the reptation is expected to cease. However, rather than a full stop of the creep, we observe in numerical simulations a transition between a continuous-creep and an irregular-creep regime when the critical amplitude is approached. The latter transition is reminiscent of the transition between the continuous and the irregular compaction of granular matter submitted to periodic temperature changes

Effects of NHC-Backbone Substitution on Efficiency in Ruthenium-Based Olefin Metathesis

series of ruthenium olefin metathesis catalysts bearing N-heterocyclic carbene (NHC) ligands with varying degrees of backbone and N-aryl substitution have been prepared. These complexes show greater resistance to decomposition through C−H activation of the N-aryl group, resulting in increased catalyst lifetimes. This work has utilized robotic technology to examine the activity and stability of each catalyst in metathesis, providing insights into the relationship between ligand architecture and enhanced efficiency. The development of this robotic methodology has also shown that, under optimized conditions, catalyst loadings as low as 25 ppm can lead to 100% conversion in the ring-closing metathesis of diethyl diallylmalonate

On Integral Class field theory for varieties over pp-adic fields

Let $K$ be a finite extension of the $p$-adic numbers $\mathbb Q_p$ with ring of integers $\mathcal O_K$, $\mathcal X$ a regular scheme, proper, flat, and geometrically irreducible over $\mathcal O_K$ of dimension $d$, and $\mathcal X_K$ its generic fiber. We show, under some assumptions on $\mathcal X_K$, that there is a reciprocity isomorphism of locally compact groups $H_{ar}^{2d-1}(\mathcal X_K, \mathbb Z(d)) \simeq \pi_1^{ab}(\mathcal X_K)_{W}$ from a new cohomology theory to an integral model $\pi_1^{ab}(\mathcal X_K)_{W}$ of the abelianized geometric fundamental groups $\pi_1^{ab}(\mathcal X_K)^{geo}$. After removing the contribution from the base field, the map becomes an isomorphism of finitely generated abelian groups

Realizing students’ every day realities: Community analysis as a model for social justice

This article examines the implications and effect of the Community Analysis (CA) Project assignment that we utilize in the Multicultural Education (MCE) course1 at New Mexico State University, located in Las Cruces, New Mexico. The CA enables pre-service teachers to critically examine, through a social justice lens, the manifestations and intersectionalities of race, class, gender, sexual orientation, language, ability, and religion in PreK-12 students’ communities, which may be rejected and ignored, or embraced, serving to connect students’ lives to learning contexts and opportunities in their schools. The CA compels pre-service teachers to analyze systemic inequities and inequalities in communities which impact the everyday lives of students. They discover organic knowledge possessed by students and families to bridge students’ knowledge and the knowledge promoted within the school curriculum. Pre-service teachers also contemplate how their privileged or disadvantaged identity statuses intersect with their future students’ privileged or disadvantaged statuses, or impact how they read communities

Gemini Planet Imager Observational Calibrations III: Empirical Measurement Methods and Applications of High-Resolution Microlens PSFs

The newly commissioned Gemini Planet Imager (GPI) combines extreme adaptive optics, an advanced coronagraph, precision wavefront control and a lenslet-based integral field spectrograph (IFS) to measure the spectra of young extrasolar giant planets between 0.9-2.5 um. Each GPI detector image, when in spectral model, consists of ~37,000 microspectra which are under or critically sampled in the spatial direction. This paper demonstrates how to obtain high-resolution microlens PSFs and discusses their use in enhancing the wavelength calibration, flexure compensation and spectral extraction. This method is generally applicable to any lenslet-based integral field spectrograph including proposed future instrument concepts for space missions.Comment: 10 pages, 6 figures. Proceedings of the SPIE, 9147-282 v2: reference adde

Fluctuations of the Casimir-like force between two membrane inclusions

Although Casimir forces are inseparable from their fluctuations, little is known about these fluctuations in soft matter systems. We use the membrane stress tensor to study the fluctuations of the membrane-mediated Casimir-like force. This method enables us to recover the Casimir force between two inclusions and to calculate its variance. We show that the Casimir force is dominated by its fluctuations. Furthermore, when the distance d between the inclusions is decreased from infinity, the variance of the Casimir force decreases as -1/d^2. This distance dependence shares a common physical origin with the Casimir force itself.Comment: 5 pages, 3 figure