25,062 research outputs found
Where’s the Remote? Face Time, Remote Work, and Implications for Performance Management
[Excerpt] Yahoo CEO Marissa Mayer’s ban on telecommuting and the subsequent uproar over that decision highlights the need for a deeper understanding of the impact of remote work. Although it would prove comforting to assert that the peer-reviewed findings of the social and managerial sciences are in accord as to the benefits of telework in the face of the discord among organizational leaders, the reality is that little such agreement exists. Consequently, the proponents of remote work in management and HR are given little support in defense of such potentially large-scale initiatives or interventions. To that end, what follows is a discussion of the relative merits of remote work, as compared to the traditional conception of work, and an exploration of the practical implications for HR practitioners in performance management and employee evaluation
Theoretical study of finite temperature spectroscopy in van der Waals clusters. II Time-dependent absorption spectra
Using approximate partition functions and a master equation approach, we
investigate the statistical relaxation toward equilibrium in selected CaAr
clusters. The Gaussian theory of absorption (previous article) is employed to
calculate the average photoabsorption intensity associated with the 4s^2->
4s^14p^1 transition of calcium as a function of time during relaxation. In
CaAr_6 and CaAr_10 simple relaxation is observed with a single time scale.
CaAr_13 exhibits much slower dynamics and the relaxation occurs over two
distinct time scales. CaAr_37 shows much slower relaxation with multiple
transients, reminiscent of glassy behavior due to competition between different
low-energy structures. We interpret these results in terms of the underlying
potential energy surfaces for these clusters.Comment: 10 pages, 9 figure
Theoretical study of the finite temperature spectroscopy in van der Waals clusters. III Solvated Chromophore as an effective diatomics
The absorption spectroscopy of calcium-doped argon clusters is described in
terms of an effective diatomics molecule Ca-(Ar_n), in the framework of
semiclassical vertical transitions. We show how, upon choosing a suitable
reaction coordinate, the effective finite-temperature equilibrium properties
can be obtained for the ground- and excited-surfaces from the potential of mean
force (PMF). An extension of the recent multiple range random-walk method is
used to calculate the PMF over continuous intervals of distances. The
absorption spectra calculated using this single-coordinate description are
found to be in good agreement with the spectra obtained from high-statistics
Monte Carlo data, in various situations. For CaAr, we compare the
performances of two different choices of the reaction coordinate. For CaAr_37,
the method is seen to be accurate enough to distinguish between different
low-energy structures. Finally, the idea of casting the initial many-body
problem into a single degree of freedom problem is tested on the spectroscopy
of calcium in bulk solid argon.Comment: 8 pages, 9 figure
Exploring structure based charge transport relationships in phenyl diketopyrrolopyrrole single crystals using a 2D π–π dimer model system
This document is the Accepted Manuscript version of the following article: Jesus Calvo-Castro, and Callum J. McHugh, ‘Exploring structure based charge transport relationships in phenyl diketopyrrolopyrrole single crystals using a 2D π–π dimer model system’, Journal of Materials Chemistry C, Issue 16, 2017, first published 28 March 2017. The version of record is available online at DOI: http://dx.doi.org/10.1039/C7TC00434F © Royal Society of Chemistry 2017Crystalline phenyl diketopyrrolopyrroles are often overlooked as charge transfer mediating materials in optoelectronic applications. We report an experimentally ratified two dimensional π–π model dimer system dispelling previous misconceptions regarding the potential of these materials as organic semiconductors and that will enable researchers to screen and predict charge transport potential solely on the basis of their single crystal derived π-stacking architectures. In testing our model system versus the available database of phenyl diketopyrrolopyrrole single crystal structures we reveal that these materials are characterised by intrinsically large thermal integrities and in many cases large charge transfer integrals, not solely restricted to dimeric interactions exhibiting close intermonomer arrangements and bearing low torsion of the core phenyl rings. This study will be of significant interest to the increasingly large community engaged in the quest to engineer π-conjugated organic based semiconducting devices and particularly those employing crystalline diketopyrrolopyrroles.Peer reviewe
Effects of constraints in general branched molecules: A quantitative ab initio study in HCO-L-Ala-NH2
A general approach to the design of accurate classical potentials for protein
folding is described. It includes the introduction of a meaningful statistical
measure of the differences between approximations of the same potential energy,
the definition of a set of Systematic and Approximately Separable and Modular
Internal Coordinates (SASMIC), much convenient for the simulation of general
branched molecules, and the imposition of constraints on the most rapidly
oscillating degrees of freedom. All these tools are used to study the effects
of constraints in the Conformational Equilibrium Distribution (CED) of the
model dipeptide HCO-L-Ala-NH2. We use ab initio Quantum Mechanics calculations
including electron correlation at the MP2 level to describe the system, and we
measure the conformational dependence of the correcting terms to the naive CED
based in the Potential Energy Surface (PES) without any simplifying assumption.
These terms are related to mass-metric tensors determinants and also occur in
the Fixman's compensating potential. We show that some of the corrections are
non-negligible if one is interested in the whole Ramachandran space. On the
other hand, if only the energetically lower region, containing the principal
secondary structure elements, is assumed to be relevant, then, all correcting
terms may be neglected up to peptides of considerable length. This is the first
time, as far as we know, that the analysis of the conformational dependence of
these correcting terms is performed in a relevant biomolecule with a realistic
potential energy function.Comment: 8 pages, 1 figure, LaTeX, aipproc style (included
Flow damping in stellarators close to quasisymmetry
Quasisymmetric stellarators are a type of optimized stellarators for which
flows are undamped to lowest order in an expansion in the normalized Larmor
radius. However, perfect quasisymmetry is impossible. Since large flows may be
desirable as a means to reduce turbulent transport, it is important to know
when a stellarator can be considered to be sufficiently close to quasisymmetry.
The answer to this question depends strongly on the size of the spatial
gradients of the deviation from quasisymmetry and on the collisionality regime.
Recently, formal criteria for closeness to quasisymmetry have been derived in a
variety of situations. In particular, the case of deviations with large
gradients was solved in the regime. Denoting by a parameter
that gives the size of the deviation from quasisymmetry, it was proven that
particle fluxes do not scale with , as typically claimed, but
with . It was also shown that ripple wells are not necessarily the main
cause of transport. This paper reviews those works and presents a new result in
another collisionality regime, in which particles trapped in ripple wells are
collisional and the rest are collisionless.Comment: 14 pages, 2 figures. To appear in Plasma Physics and Controlled
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