59,477 research outputs found
Low-density series expansions for directed percolation III. Some two-dimensional lattices
We use very efficient algorithms to calculate low-density series for bond and
site percolation on the directed triangular, honeycomb, kagom\'e, and
lattices. Analysis of the series yields accurate estimates of the critical
point and various critical exponents. The exponent estimates differ only
in the digit, thus providing strong numerical evidence for the
expected universality of the critical exponents for directed percolation
problems. In addition we also study the non-physical singularities of the
series.Comment: 20 pages, 8 figure
Plasma Diagnostics by Antenna Impedance Measurements
The impedance of an electrically short antenna immersed in a plasma provides an excellent in situ diagnostic tool for electron density and other plasma parameters. By electrically short we mean that the wavelength of the free-space electromagnetic wave that would be excited at the driving frequency is much longer than the physical size of the antenna. Probes using this impedance technique have had a long history with sounding rockets and satellites, stretching back to the early 1960s. This active technique could provide information on composition and temperature of plasmas for comet or planetary missions. Advantages of the impedance probe technique are discussed and two classes of instruments built and flown by SDL-USU for determining electron density (the capacitance and plasma frequency probes) are described
Comment on: "Estimating the Hartree-Fock limit from finite basis set calculations" [Jensen F (2005) Theor Chem Acc 113:267]
We demonstrate that a minor modification of the extrapolation proposed by
Jensen [(2005): Theor Chem Acc 113:267] yields very reliable estimates of the
Hartree-Fock limit in conjunction with correlation consistent basis sets.
Specifically, a two-point extrapolation of the form
yields HF limits
with an RMS error of 0.1 millihartree using aug-cc-pVQZ and
aug-cc-pV5Z basis sets, and of 0.01 millihartree using aug-cc-pV5Z and
aug-cc-pV6Z basis sets.Comment: Theoretical Chemistry Accounts, in pres
How health systems in sub-Saharan Africa can benefit from tuberculosis and other infectious disease programmes.
Weak and dysfunctional health systems in low-income countries, particularly in sub-Saharan Africa, are recognised as major obstacles to attaining the health-related Millennium Development Goals by 2015. Some progress is being made towards achieving the targets of Millennium Development Goal 6 for tuberculosis (TB), HIV/AIDS and malaria, with the achievements largely resulting from clearly defined strategies and intervention delivery systems combined with large amounts of external funding. This article is divided into four main sections. The first highlights the crucial elements that are needed in low-income countries in sub-Saharan Africa to deliver good quality health care through general health systems. The second discusses the main characteristics of infectious disease and TB control programmes. The third illustrates how TB control and other infectious disease programmes can help to strengthen these components, particularly in human resources; infrastructure; procurement and distribution; monitoring, evaluation and supervision; leadership and stewardship. The fourth and final section looks at progress made to date at the international level in terms of policy and guidelines, with some specific suggestions about this might be moved forward at the national level. For TB and other infectious disease programmes to drive broad improvements in health care systems and patient care, the lessons that have been learnt must be consciously applied to the broader health system, and sufficient financial input and the engagement of all players are essential
Use of recurrence quantification analysis to examine associations between changes in text structure across an expressive writing intervention and reductions in distress symptoms in women wth breast cancer
The current study presents an exploratory analysis of using Recurrence Quantification Analysis (RQA) to analyze text data from an Expressive Writing Intervention (EWI) for Danish women treated for Breast Cancer. The analyses are based on the analysis of essays from a subsample with the average age 54.6 years (SD = 9.0), who completed questionnaires for cancer-related distress (IES) and depression symptoms (BDI-SF). The results show a significant association between an increase in recurrent patterns of text structure from first to last writing session and a decrease in cancer-related distress at 3 months post-intervention. Furthermore, the change in structure from first to last essay displayed a moderate, but significant correlation with change in cancer-related distress from baseline to 9 months post-intervention. The results suggest that changes in recurrence patterns of text structure might be an indicator of cognitive restructuring that leads to amelioration of cancer-specific distress
Complex coupled-cluster approach to an ab-initio description of open quantum systems
We develop ab-initio coupled-cluster theory to describe resonant and weakly
bound states along the neutron drip line. We compute the ground states of the
helium chain 3-10He within coupled-cluster theory in singles and doubles (CCSD)
approximation. We employ a spherical Gamow-Hartree-Fock basis generated from
the low-momentum N3LO nucleon-nucleon interaction. This basis treats bound,
resonant, and continuum states on equal footing, and is therefore optimal for
the description of properties of drip line nuclei where continuum features play
an essential role. Within this formalism, we present an ab-initio calculation
of energies and decay widths of unstable nuclei starting from realistic
interactions.Comment: 4 pages, revtex
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