Dispersion corrections in graphenic systems: a simple and effective model of binding

We combine high-level theoretical and \emph{ab initio} understanding of graphite to develop a simple, parametrised force-field model of interlayer binding in graphite, including the difficult non-pairwise-additive coupled-fluctuation dispersion interactions. The model is given as a simple additive correction to standard density functional theory (DFT) calculations, of form $\Delta U(D)=f(D)[U^{vdW}(D)-U^{DFT}(D)]$ where $D$ is the interlayer distance. The functions are parametrised by matching contact properties, and long-range dispersion to known values, and the model is found to accurately match high-level \emph{ab initio} results for graphite across a wide range of $D$ values. We employ the correction on the difficult bigraphene binding and graphite exfoliation problems, as well as lithium intercalated graphite LiC$_6$. We predict the binding energy of bigraphene to be 0.27 J/m^2, and the exfoliation energy of graphite to be 0.31 J/m^2, respectively slightly less and slightly more than the bulk layer binding energy 0.295 J/m^2/layer. Material properties of LiC$_6$ are found to be essentially unchanged compared to the local density approximation. This is appropriate in view of the relative unimportance of dispersion interactions for LiC$_6$ layer binding

Disk M Dwarf Luminosity Function From HST Star Counts

We study a sample of 257 Galactic disk M dwarfs (8<M_V<18.5) found in images obtained using HST. These include 192 stars in 22 fields imaged with the repaired WFC2 with mean limiting mag I=23.7 and 65 stars in 162 fields imaged with the pre-repair Planetary Camera with mean limiting mag V=21.3. We find that the disk luminosity function (LF) drops sharply for M_V>12 (M<0.25 \ms), decreasing by a factor \gsim 3 by M_V~14 (M~0.14\ms). This decrease in the LF is in good agreement with the ground-based photometric study of nearby stars by Stobie et al. (1989), and in mild conflict with the most recent LF measurements based on local parallax stars by Reid et al. (1995). The local LF of the faint Galactic disk stars can be transformed into a local mass function using an empirical mass-M_V relation. The mass function can be represented analytically over the mass range 0.1\ms<M<1.6\ms by \log(\phi)=-1.35-1.34\log(M/\ms)-1.85 [\log(M/\ms)]^2 where \phi is the number density per logarithmic unit of mass. The total column density of M stars is only \Sigma_M=11.8\pm 1.8\ms\pc^{-2}, implying a total `observed' disk column density of \Sigma_\obs~=39\ms\pc^{-2}, lower than previously believed, and also lower than all estimates with which we are familiar of the dynamically inferred mass of the disk. The measured scale length for the M-star disk is 3.0\pm 0.4 kpc. The optical depth to microlensing toward the LMC by the observed stars in the Milky Way disk is \tau~1x10^{-8}, compared to the observed optical depth found in ongoing experiments \tau_\obs~ 10^{-7}. The M-stars show evidence for a population with characteristics intermediate between thin disk and spheroid populations. Approximating what may be a continuum of populations by two separate component, we find characteristic exponential scale heights of ~210 pc and ~740 pc.Comment: 30 pages, uuencoded postscript, includes 3 figures, 2 table

Enrollment in the 2003/2004 MILC Program: Does Timing Matter?

Agricultural and Food Policy, Marketing,

A review of Emma Wilby’s The Visions of Isobel Gowdie: Magic, Witchcraft and Dark Shamanism in Seventeenth-Century Scotland (Sussex University Press, 2010)

<div>This is an annotated data management plan (DMP) template for an Engineering and Physical Sciences Research Council (EPSRC) data management plan.<br></div><div><br></div><div>This document (available in .pdf and .docx formats) was created using the <a href="https://dmponline.dcc.ac.uk/">DMPonline tool</a>, which provides templates for structuring major research funders' DMPs. The document includes the guidance text provided in the tool, produced by the <a href="http://www.dcc.ac.uk/sites/default/files/documents/publications/DMP-themes.pdf">Digital Curation Centre (DCC)</a>, the <a href="https://www.epsrc.ac.uk/about/standards/researchdata/expectations/">EPSRC</a> and the <a href="https://www.sheffield.ac.uk/library/rdm/dmp">University of Sheffield Library</a>. </div><div><br></div><div>Although the EPSRC does not require that a DMP is submitted as part of a grant application, it still expects one to be in place. A DMP describes how you will collect, organise, manage, store, secure, backup, preserve, and where applicable, share your data. The EPSRC DMP template is organised into seven sections and the resulting DMP is expected to be two or three of pages of A4 in length. </div><div><br></div><div>For further guidance see the <a href="https://www.epsrc.ac.uk/about/standards/researchdata/expectations/">EPSRC expectations concerning management of research data</a> and the DCC webpages on <a href="http://www.dcc.ac.uk/resources/data-management-plans">Data management Plans</a> and <a href="http://www.dcc.ac.uk/resources/how-guides/develop-data-plan">How to Develop a Data Management and Sharing Plan</a>. </div