Active lamp pulse driver circuit

A flashlamp drive circuit is described which uses an unsaturated transistor as a current mode switch to periodically subject a partially ionized gaseous laser excitation flashlamp to a stable, rectangular pulse of current from an incomplete discharge of an energy storage capacitor. A monostable multivibrator sets the pulse interval, initiating the pulse in response to a flash command by providing a reference voltage to a non-inverting terminal of a base drive amplifier; a tap on an emitter resistor provides a feedback signal sensitive to the current amplitude to an inverting terminal of amplifier, thereby controlling the pulse amplitude. The circuit drives the flashlamp to provide a squarewave current flashlamp discharge

Civil protective orders effective in stopping or reducing partner violence: challenges remain in rural areas with access and enforcement

Civil protective orders are a low cost, effective solution in either stopping or significantly reducing partner violence for women. While all women benefit from civil protective orders, this brief finds there are greater obstacles to enforcement in rural places, which result in less benefit for rural than urban women. The authors suggest that policies and services should be tailored to address community-specific barriers and differences such as hours of access, time it takes to obtain or serve an order, and access to information about the process

Two-channel Kondo physics in odd impurity chains

We study odd-membered chains of spin-(1/2) impurities, with each end connected to its own metallic lead. For antiferromagnetic exchange coupling, universal two-channel Kondo (2CK) physics is shown to arise at low energies. Two overscreening mechanisms are found to occur depending on coupling strength, with distinct signatures in physical properties. For strong inter-impurity coupling, a residual chain spin-(1/2) moment experiences a renormalized effective coupling to the leads; while in the weak-coupling regime, Kondo coupling is mediated via incipient single-channel Kondo singlet formation. We also investigate models where the leads are tunnel-coupled to the impurity chain, permitting variable dot filling under applied gate voltages. Effective low-energy models for each regime of filling are derived, and for even-fillings where the chain ground state is a spin singlet, an orbital 2CK effect is found to be operative. Provided mirror symmetry is preserved, 2CK physics is shown to be wholly robust to variable dot filling; in particular the single-particle spectrum at the Fermi level, and hence the low-temperature zero-bias conductance, is always pinned to half-unitarity. We derive a Friedel-Luttinger sum rule and from it show that, in contrast to a Fermi liquid, the Luttinger integral is non-zero and determined solely by the `excess' dot charge as controlled by gate voltage. The relevance of the work to real quantum dot devices, where inter-lead charge-transfer processes fatal to 2CK physics are present, is also discussed. Physical arguments and numerical renormalization group techniques are used to obtain a detailed understanding of these problems.Comment: 21 pages, 19 figure

Spectral scaling and quantum critical behaviour in the pseudogap Anderson model

The pseudogap Anderson impurity model provides a classic example of an essentially local quantum phase transition. Here we study its single-particle dynamics in the vicinity of the symmetric quantum critical point (QCP) separating generalized Fermi liquid and local moment phases, via the local moment approach. Both phases are shown to be characterized by a low-energy scale that vanishes at the QCP; and the universal scaling spectra, on all energy scales, are obtained analytically. The spectrum precisely at the QCP is also obtained; its form showing clearly the non-Fermi liquid, interacting nature of the fixed point.Comment: 7 pages, 2 figure

Fallen leaf: an Indian love song

https://digitalcommons.ithaca.edu/sheetmusic/1133/thumbnail.jp

Over the Hills

[Verse 1]O blissful memory! The soft shades of twilight o’er all the hill and valeThe pipes of the shepherd call his flock to the fold And sadly the voice of the nightingale is calling,While lonely I’m yearning for those days as of oldAgain thro’ this wildwood in mem’ry I’m roaming Far down by the brooklet where sweet violets grew,The faint chime of vespers I hear in the gloaming Once more as in childhood I ram again with you. N twilight’s soft purple the scene now fases before me As night draws her veil across the valley and hills, My heart it is longing For just one hour to be Back home with the lov’d ones there,Far over the hills

The Moonlight Waltz: Song

https://digitalcommons.library.umaine.edu/mmb-vp/2141/thumbnail.jp