Symmetric achromatic low-beta collider interaction region design concept

We present a new symmetry-based concept for an achromatic low-beta collider interaction region design. A specially-designed symmetric Chromaticity Compensation Block (CCB) induces an angle spread in the passing beam such that it cancels the chromatic kick of the final focusing quadrupoles. Two such CCBs placed symmetrically around an interaction point allow simultaneous compensation of the 1st-order chromaticities and chromatic beam smear at the IP without inducing significant 2nd-order aberrations to the particle trajectory. We first develop an analytic description of this approach and explicitly formulate 2nd-order aberration compensation conditions at the interaction point. The concept is next applied to develop an interaction region design for the ion collider ring of an electron-ion collider. We numerically evaluate performance of the design in terms of momentum acceptance and dynamic aperture. The advantages of the new concept are illustrated by comparing it to the conventional distributed-sextupole chromaticity compensation scheme.Comment: 12 pages, 17 figures, to be submitted to Phys. Rev. ST Accel. Beam

Loss compensation in Metamaterials through embedding of active transistor based negative differential resistance circuits

This paper presents an all-electronic approach for loss compensation in metamaterials. This is achieved by embedding active-transistors based negative differential resistance (NDR) circuits in each unit cell of the metamaterial lattice. NDR circuits provide tunable loss compensation over a broad frequency range limited only by the maximum operating frequency of transistors that is reaching terahertz values in newer semiconductor processes. Design, simulation and experimental results of metamaterials composed of split ring resonators (SRR) with and without loss compensation circuits are presented

Employment Stability Under Different Managerial Compensation Systems

Compensation design may influence the extent to which managerial decision-makers take a long-term perspective in managing important resources like employees. I hypothesize that organizations relying more heavily on long-term compensation incentives exhibit greater stability in employment, perhaps because of a greater concern among management with long-term effectiveness. I also hypothesize that employment stability is more feasible when employees are covered by variable pay plans, which permit labor cost reductions without cuts in employment. Using multiple years of employment, financial performance, and managerial compensation data on 156 organizations, support is found for both hypotheses

A Report from the Design Team for Compensation and Career Pathways

The Design Team for Compensation and Career Pathways is a group of teachers, and school and central office leaders selected by the Denver Public Schools (DPS) and the Denver Classroom Teachers Association (DCTA). They were charged with engaging in a learning process to determine if there were ways to strengthen the compensation, career pathways and related structures to support recruitment and retention of strong teachers and increase career satisfaction and success within DPS. They undertook this process in anticipation of the need to renew the agreement that governs the district's nationally renowned Professional Compensation System for Teachers (ProComp) as well as upcoming contract negotiations between DPS and DCTA.Over four months the Team met nine times. Its work involved reviewing research studies, examining compensation and career progression examples from other school districts and selected non-education industries, reviewing teacher and principal focus group and survey results, and engaging in deep discussion around design principles and possible frameworks that could be used to strengthen ProComp and career opportunities for teachers. This report is the product of their work

Error-compensation measurements on polarization qubits

Systematic errors are inevitable in most measurements performed in real life because of imperfect measurement devices. Reducing systematic errors is crucial to ensuring the accuracy and reliability of measurement results. To this end, delicate error-compensation design is often necessary in addition to device calibration to reduce the dependence of the systematic error on the imperfection of the devices. The art of error-compensation design is well appreciated in nuclear magnetic resonance system by using composite pulses. In contrast, there are few works on reducing systematic errors in quantum optical systems. Here we propose an error-compensation design to reduce the systematic error in projective measurements on a polarization qubit. It can reduce the systematic error to the second order of the phase errors of both the half-wave plate (HWP) and the quarter-wave plate (QWP) as well as the angle error of the HWP. This technique is then applied to experiments on quantum state tomography on polarization qubits, leading to a 20-fold reduction in the systematic error. Our study may find applications in high-precision tasks in polarization optics and quantum optics.Comment: 8 pages, 3 figure

A nonlinear disturbance observer for robotic manipulators

A new nonlinear disturbance observer (NDO) for robotic manipulators is derived in this paper. The global exponential stability of the proposed disturbance observer (DO) is guaranteed by selecting design parameters, which depend on the maximum velocity and physical parameters of robotic manipulators. This new observer overcomes the disadvantages of existing DOs, which are designed or analyzed by linear system techniques. It can be applied in robotic manipulators for various purposes such as friction compensation, independent joint control, sensorless torque control and fault diagnosis. The performance of the proposed observer is demonstrated by the friction estimation and compensation for a two-link robotic manipulator. Both simulation and experimental results show the NDO works well

Composite Dipolar Recoupling: Anisotropy Compensated Coherence Transfer in Solid-State NMR

The efficiency of dipole-dipole coupling driven coherence transfer experiments in solid-state NMR spectroscopy of powder samples is limited by dispersion of the orientation of the internuclear vectors relative to the external magnetic field. Here we introduce general design principles and resulting pulse sequences that approach full polarization transfer efficiency for all crystallite orientations in a powder in magic-angle-spinning experiments. The methods compensate for the defocusing of coherence due to orientation dependent dipolar coupling interactions and inhomogeneous radio-frequency fields. The compensation scheme is very simple to implement as a scaffold (comb) of compensating pulses in which the pulse sequence to be improved may be inserted. The degree of compensation can be adjusted and should be balanced as a compromise between efficiency and length of the overall pulse sequence. We show by numerical and experimental data that the presented compensation protocol significantly improves the efficiency of known dipolar recoupling solid-state NMR experiment

Is Short-Time Work a Good Method to Keep Unemployment Down?

Short-time work compensation aims at reducing lay-offs by allowing employers to temporarily reduce hours worked while compensating workers for the induced loss of income. These programs are now widespread in the OECD countries, notably following the 2008-2009 crisis. This paper discusses the efficiency of this type of policy and investigates its impact on unemployment and employment. There is some evidence that short-time compensation programs stabilize permanent employment and reduce unemployment during downturns. All in all, it seems that short-time work programs used in the recent downturn had significant beneficial effects. This suggests that countries which do not have short-time compensation programs could benefit from their introduction. But short-time compensation programs can also induce inefficient reductions in working hours and reduce the prospects of outsiders if used too intensively. Thus, the design of short-time compensation programs should include an experience-rating component.short-time work, unemployment, employment