Square-free class sizes in products of groups

We obtain some structural properties of a factorised group $G = AB$, given that the conjugacy class sizes of certain elements in $A\cup B$ are not divisible by $p^2$, for some prime $p$. The case when $G = AB$ is a mutually permutable product is especially considered

Smoothing tautologies, hidden dynamics, and sigmoid asymptotics for piecewise smooth systems

Switches in real systems take many forms, such as impacts, electronic relays, mitosis, and the implementation of decisions or control strategies. To understand what is lost, and what can be retained, when we model a switch as an instantaneous event, requires a consideration of so-called hidden terms. These are asymptotically vanishing outside the switch, but can be encoded in the form of nonlinear switching terms. A general expression for the switch can be developed in the form of a series of sigmoid functions. We review the key steps in extending the Filippov's method of sliding modes to such systems. We show how even slight nonlinear effects can hugely alter the behaviour of an electronic control circuit, and lead to `hidden' attractors inside the switching surface.Comment: 12 page

Electron beam induced electronic transport in alkyl amine-intercalated VOx nanotubes

The electron beam induced electronic transport in primary alkyl amine-intercalated V2O5 nanotubes is investigated where the organic amine molecules are employed as molecular conductive wires to an aminosilanized substrate surface and contacted to Au interdigitated electrode contacts. The results demonstrate that the high conductivity of the nanotubes is related to the non-resonant tunnelling through the amine molecules and a reduced polaron hopping conduction through the vanadium oxide itself. Both nanotube networks and individual nanotubes exhibit similarly high conductivities where the minority carrier transport is bias dependent and nanotube diameter invariant

Tensile strain mapping in flat germanium membranes

Under the terms of the Creative Commons Attribution (CC BY) license to their work.-- et al.Scanning X-ray micro-diffraction has been used as a non-destructive probe of the local crystalline quality of a thin suspended germanium (Ge) membrane. A series of reciprocal space maps were obtained with ~4 μm spatial resolution, from which detailed information on the strain distribution, thickness, and crystalline tilt of the membrane was obtained. We are able to detect a systematic strain variation across the membranes, but show that this is negligible in the context of using the membranes as platforms for further growth. In addition, we show evidence that the interface and surface quality is improved by suspending the Ge.This work was carried out under the RCUK Basic Technology Programme supported by research Grant Nos. EP/F040784/1, EP/J001074/1, EP/L007010/1, by the European Community's Seventh Framework Programme (FP7/2007-2013) under Grant Agreement NANOFUNCTION No. 257375, by TAPHOR (MAT2012–31392), and by FP7 project MERGING (Grant No. 309150). This research used equipment funded by AWM and ERDF through the Science City Energy Efficiency project.Peer Reviewe

Normas cefalometricas frontales en alumnos de primer ano de ensenanza media de colegios cientificos humanistas municipales en la comuna de Talca.

70 p.De un universo de 987 alumnos de primeros medios de colegios municipalizados científico humanistas de la comuna de Talca, se seleccionaron 50 que cumplia requisitos de simetría en el plano frontal al examen clínico. De estos, a 44 se les tomo una radiografía antero posterior de cráneo. La muestra comprendió 29 mujeres y 15 hombres, con una edad promedio total de 14.55 años Se comprobó la confiabilidad intraexaminador en la ubicación de puntos cefalometricos y la confiabilidad intraexaminador de la técnica radiográfica. Posteriormente se analizaron las 44 radiografías utilizando el análisis cefalométrico frontal de Grummons. La técnica radiográfica demostró ser segura y repetible en el tiempo por parte de un examinador. Los puntos cefalométricos Co, J y Ag derechos mostraron una diferencia significativa entre mediciones sucesivas. Las distancias Z-MSR, ZA-MSR, Co-MSR, CN-MSR, Co-Ag, Ag-Me y Co-Me derechos fueron mayores que el lado izquierdo. Se comprobó una menor longitud vertical del maxilar superior al comparar los radios obtenidos con los propuestos por Grummons. No se observó una diferencia por sexos en Ias medidas utilizadas ni tampoco una diferencia significativa en la diferencia vertical entre las estructuras bilaterales

Pressure induced anisotropy of electrical conductivity in polycrystalline molybdenum disulfide

Anisotropic specimens of MoS2 are obtained by pressing the microcrystalline powder into special die. This inelastic compression results in a rearrangement of the disulfide micro platelets observed by atomic force microscopy and reflected in the macroscopic anisotropy in electrical conductivity in these samples. The conductivity measured parallel and perpendicular to the direction of applied pressure exhibits an anisotropy factor of 10 at 1 GPa. This behaviour of the conductivity as a function of applied pressure is explained as the result of the simultaneous influence of a rearrangement of the micro platelets in the solid and the change of the inter-grain distances