Simulating conical intersection dynamics in the condensed phase with hybrid quantum master equations

We present a framework for simulating relaxation dynamics through a conical intersection of an open quantum system that combines methods to approximate the motion of degrees of freedom with disparate time and energy scales. In the vicinity of a conical intersection, a few degrees of freedom render the nuclear dynamics nonadiabatic with respect to the electronic degrees of freedom. We treat these strongly coupled modes by evolving their wavepacket dynamics in the absence of additional coupling exactly. The remaining weakly coupled nuclear degrees of freedom are partitioned into modes that are fast relative to the nonadiabatic coupling and those that are slow. The fast degrees of freedom can be traced out and treated with second-order perturbation theory in the form of the time-convolutionless master equation. The slow degrees of freedom are assumed to be frozen over the ultrafast relaxation, and treated as sources of static disorder. In this way, we adopt the recently developed frozen-mode extension to second-order quantum master equations. We benchmark this approach to numerically exact results in models of pyrazine internal conversion and rhodopsin photoisomerization. We use this framework to study the dependence of the quantum yield on the reorganization energy and the characteristic timescale of the bath, in a two-mode model of photoisomerization. We find that the yield is monotonically increasing with reorganization energy for a Markovian bath, but monotonically decreasing with reorganization energy for a non-Markovian bath. This reflects the subtle interplay between dissipation and decoherence in conical intersection dynamics in the condensed phase

Atypical Work and Employment Continuity

Atypical employment arrangements such as agency temporary work and contracting have long been criticized as offering more precarious and unstable work than regular employment. Using data from two datasets – the CAEAS and the NLSY79 – we determine whether workers who take such jobs rather than regular employment, or the alternative of continued job search, subsequently experience greater or lesser employment continuity. Observed differences between the various working arrangements are starkest when we do not account for unobserved individual heterogeneity. Controlling for the latter, we report that the advantage of regular work over atypical work and atypical work over continued joblessness dissipates.employment continuity, open-ended work, atypical work, unemployment, inactivity

‘Atypical Work’ and Compensation

Atypical work, or alternative work arrangements in U.S. parlance, has long been criticized in popular debate as providing poorly-compensated employment. Although the early U.S. literature seemed to confirm this perception, more recent cet. par. analysis has offered a partial but somewhat more optimistic evaluation. The present paper builds on the latter body of research with a view to providing improved estimates of the effect of the full range alternative work arrangements on worker compensation. The improvements are basically two-fold. First, we account for the skewness in atypical worker earnings while retaining the Mincerian human capital earnings function. Second, we deploy additional waves of the main dataset on atypical workers (the CAEAS), while supplementing this cross-section analysis with longitudinal data from the NLSY. Our analysis covers earnings and (access to) health benefits. We report that although one group of atypical workers (contractors) seems to enjoy a wage premium, cross-section results from the CPS and NLSY for the better-known category of temporary workers point to a negative wage differential of some 6-15 percent. It emerges that much of the disparity stems from unobserved worker heterogeneity, accounting for which still supports a wage advantage for contracting work. As far as fringes are concerned, the appearance in cross section of a potentially large deficit in access to health benefits is again reduced after accounting for the permanent unobserved individual heterogeneity, although in this case the attenuation is much more modest.atypical/contingent work, alternative work arrangements, wage differentials, employer-related health insurance

Studying rare nonadiabatic dynamics with transition path sampling quantum jump trajectories

We present a method to study rare nonadiabatic dynamics in open quantum systems using transition path sampling and quantum jump trajectories. As with applications of transition path sampling to classical dynamics, the method does not rely on prior knowledge of transition states or reactive pathways, and thus can provide mechanistic insight into ultrafast relaxation processes in addition to their associated rates. In particular, we formulate a quantum path ensemble using the stochastic realizations of an unravelled quantum master equation, which results in trajectories that can be conditioned on starting and ending in particular quantum states. Because the dynamics rigorously obeys detailed balance, rate constants can be evaluated from reversible work calculations in this conditioned ensemble, allowing for branching ratios and yields to be computed in an unbiased manner. We illustrate the utility of this method with three examples: energy transfer in a donor-bridge-acceptor model, and models of photo-induced proton-coupled electron transfer and thermally activated electron transfer. These examples demonstrate the efficacy of path ensemble methods and pave the way for their use in studying of complex reactive quantum dynamics

Atypical Work and Employment Continuity

Atypical employment arrangements such as agency temporary work and contracting have long been criticized as offering more precarious and unstable work than regular employment. Using data from two datasets Ð the CAEAS and the NLSY79 Ð we determine whether workers who take such jobs rather than regular employment, or the alternative of continued job search, subsequently experience greater or lesser employment continuity. Observed differences between the various working arrangements are starkest when we do not account for unobserved individual heterogeneity. Controlling for the latter, we report that the advantage of regular work over atypical work and atypical work over continued joblessness dissipates.atypical work, open-ended work, employment continuity, unemployment, inactivity

?Atypical Work? and Compensation

Atypical work, or alternative work arrangements in U.S. parlance, has long been criticized for providing poorly-compensated employment. Although one group of atypical workers (contractors) seems to enjoy a wage premium, our cross-section results from the CPS and NLSY for the better-known category of temporary workers point to a negative wage differential of some 7-12 percent. It emerges that much of the latter disparity stems from unobserved worker heterogeneity (accounting for which supports a wage advantage for contracting work). Turning to fringes, the appearance in cross section of a potentially large deficit in atypical worker health benefits is again reduced after accounting for permanent unobserved individual heterogeneity. But on this occasion the reduction is very modest. Further, there is now some indication that the wage advantage of contract workers partly compensates for their reduced access to such benefits

Atypical Work: Who Gets It, and Where Does It Lead? Some U.S. Evidence Using the NLSY79

Atypical work arrangements have long been criticized as offering more precarious and lower paid work than regular open-ended employment. In an important paper published in this journal, Booth et al. (2002) were among the first to recognize that notwithstanding their potential deficiencies, such jobs also functioned as a stepping stone to permanent work. This conclusion proved prescient and has received increasing support in Europe. In the present note, we provide a parallel analysis to Booth et al. for the United States – somewhat of a missing link in the evolving empirical literature – and obtain not dissimilar similar findings for the category of temporary workers as do they for fixed-term contract workers.

Atypical Work: Who Gets It, and Where Does It Lead? Some U.S. Evidence Using the NLSY79

Atypical work arrangements have long been criticized as offering more precarious and lower paid work than regular open-ended employment. In an important paper, Booth et al. (2002) were among the first to recognize that notwithstanding their potential deficiencies, such jobs also functioned as a stepping stone to permanent work. This conclusion proved prescient and has received increasing support in Europe. In the present note, we provide a parallel analysis to Booth et al. for the United States – somewhat of a missing link in the evolving empirical literature – and obtain not dissimilar similar findings for the category of temporary workers as do they for fixed-term contract workers.atypical work, temporary jobs, contracting/consulting work, regular open-ended employment, earnings development

Does atypical work help the jobless? Evidence from a CAEAS/CPS cohort analysis

Atypical employment, such as temporary, on-call, and contract work, has been found disproportionately to attract the jobless. But there is no consensus in the literature as to the labour market consequences of such job choice by unemployed individuals. Using data from the Current Population Survey, we investigate the implications of the initial job-finding strategies pursued by the jobless for their short- and medium-term employment stability. At first sight, it appears that taking an offer of regular employment provides the greatest degree of employment continuity for the jobless. However, closer inspection indicates that the jobless who take up atypical employment are not only more likely to be employed one month and one year later than those who continue to search, but also to enjoy employment continuity that is no less favorable than that offered by regular, open-ended employment

Aid to conflict-affected countries : lessons for donors

The first section looks at the implications of conflict for aid effectiveness and selectivity. We argue that, while aid is generally effective in promoting growth and by implication reducing poverty, it is more effective in promoting growth in post-conflict countries. We then consider the implications of these findings for donor selectivity models and for assessment of donor performance in allocating development aid among recipient countries. We argue that, while further research on aid effectiveness in post-conflict scenarios is needed, existing selectivity models should be augmented with, inter alia, post-conflict variables, and donors should be evaluated on the basis, inter alia, of the share of their aid budgets allocated to countries experiencing post-conflict episodes. We also argue for aid delivered in the form of projects to countries with weak institutions in early post-conflict years. The second section focuses on policies for donors operating in conflict-affected countries. We set out five of the most important principles: (1) focus on broad-based recovery from war; (2) to achieve a broad-based recovery, get involved before the conflict ends; (3) focus on poverty, but avoid &lsquo;wish lists&rsquo;; (4) help to reduce insecurity so aid can contribute more effectively to growth and poverty reduction; and (5) in economic reform, focus on improving public expenditure management and revenue mobilisation. The third section concludes by emphasising the fact that there is no hard or fast dividing line between &lsquo;war&rsquo; and &lsquo;peace&rsquo; and that it may take many years for a society to become truly &lsquo;post&rsquo;-conflict&rsquo;. Donors, therefore, need to prepare for the long haul.<br /