Stark Ionization of Atoms and Molecules within Density Functional Resonance Theory

We show that the energetics and lifetimes of resonances of finite systems under an external electric field can be captured by Kohn--Sham density functional theory (DFT) within the formalism of uniform complex scaling. Properties of resonances are calculated self-consistently in terms of complex densities, potentials and wavefunctions using adapted versions of the known algorithms from DFT. We illustrate this new formalism by calculating ionization rates using the complex-scaled local density approximation and exact exchange. We consider a variety of atoms (H, He, Li and Be) as well as the hydrogen molecule. Extensions are briefly discussed.Comment: 5 pages, 5 figures. This document is the unedited Author's version of a Submitted Work that was subsequently accepted for publication in J.Phys.Chem.Lett., copyright (c) American Chemical Society after peer review. To access the final edited and published work see http://pubs.acs.org/doi/abs/10.1021/jz401110

Community-based care of stroke patients in a rural african setting

Background: In order to develop a community based-model of stroke care we assessed discharge planning of stroke patients, available resources, and continuity of care between hospital and community in a remote rural setting in South Africa. We sought to determine outcomes, family participation and support needs, as well as implementation of secondary prevention strategies. Methods: Thirty consecutive stroke patients from the local hospital were assessed clinically (including Barthel Index and modified Rankin scores) at time of discharge. Patients were re-assessed three months after discharge in their homes by a trained field worker using a structured questionnaire. Results: Two thirds of all families received no stroke education before discharge. At discharge 27 (90%) were either bed or chair-bound. All the patients were discharged into family care as there was no stroke rehabilitation facility available to the community. Of 30 patients recruited, 20 (66.7%) were alive at 3 months, 9 (30%) were deceased, and 1 was lost to follow-up. At 3 months, 55% of survivors were independently mobile as compared with 10% at discharge. A total of 13 (65%) patients in our cohort were visited by home-based carers. Only 45% reported taking aspirin at 3 months. Conclusions: The 3 month mortality rate was high. Most survivors improved functionally but were left with significant disability. Measures to improve family education and the level of home-based care can be introduced in a model of stroke care attempting to reduce carer strain and improve functional disability in rural stroke patients

Community-based care of stroke patients in a rural African setting

Background. To develop a community-based model of stroke care, we assessed discharge planning of stroke patients, available resources and continuity of care between hospital and community in a remote rural setting in South Africa. We sought to determine outcomes, family participation and support needs, and implementation of secondary prevention strategies.Methods. Thirty consecutive stroke patients from the local hospital were assessed clinically (including Barthel index and modified Rankin scores) at time of discharge and re-assessed 3 months after discharge in their homes by a trained field worker using a structured questionnaire.Results. Two-thirds of all families received no stroke educationbefore discharge. At discharge, 27 (90%) were either bed- or chair-bound. All patients were discharged into family care as there was no stroke rehabilitation facility available to the community. Of the 30 patients recruited, 20 (66.7%) were alive at 3 months, 9 (30%) had died, and 1 was lost to follow-up. At 3 months, 55% of the remaining cohort were independently mobile compared with 10% at discharge. Of the 20 surviving patients, 13 (65%) were visited by home-based carers. Only 45% reported taking aspirin at 3 months.Conclusions. The 3-month mortality rate was high. Most survivors improved functionally but were left with significant disability. Measures to improve family education and the level of home-based care can be introduced in a model of stroke care attempting to reduce carer strain and reduce the degree of functional disability in rural stroke patients

Is your EPL attractive? Classification of publications through download statistics

Here we consider the download statistics of EPL publications. We find that papers in the journal are characterised by fast accumulations of downloads during the first couple of months after publication, followed by slower rates thereafter, behaviour which can be represented by a model with predictive power. We also find that individual papers can be classified in various ways, allowing us to compare categories for open-access and non-open-access papers. For example, for the latter publications, which comprise the bulk of EPL papers, a small proportion (2%) display intense bursts of download activity, possibly following an extended period of less remarkable behaviour. About 18% have an especially high degree of attractiveness over and above what is typical for the journal. One can also classify the ageing of attractiveness by examining download half-lives. Approximately 18% have strong interest initially, waning in time. A further 20% exhibit "delayed recognition" with relatively late spurs in download activity. Although open-access papers enjoy more downloads on average, the proportions falling into each category are similar.Comment: 6 pages, 8 figures, accepted for publication in EP

Conservative management of breast cancer in the elderly in a developing country

<p>Abstract</p> <p>Background</p> <p>The cost effective treatment of cancer in developing countries remains challenging. In the elderly with possible limited life expectancy, the health expenditure associated with standard treatment regimes should be carefully considered. We present the results of conservative management of breast cancer in the aged in a resource-limited environment.</p> <p>Methods</p> <p>Patients aged 70 or older with early breast cancer were treated with tumour excision or simple mastectomy and adjuvant tamoxifen. The records of patients presenting to the Breast Unit between January 1990 and December 2004 were retrieved and demographic, clinical, pathological and oncological data were reviewed. Survival statistics were calculated using the life table method.</p> <p>Results</p> <p>A total of 483 patients above 70 years of age were identified. One hundred and eighty eight patients were managed according to the conservative protocol. Forty-one had a simple mastectomy and 147 tumour excision. Their mean age was 77.3 years. The mean follow-up is 62 months. Thirty-one patients (16.4%) were not compliant with tamoxifen use. TNM staging was 0 in 4 patients, I in 42 patients, II in 116 patients and III in 26 patients. There was no 30-day mortality. The cumulative incidence of local recurrence was 3.3% at 5 and 10 years. The cumulative incidence of regional recurrence was 3.3% at 5 years and 4.5% at 10 years. The cumulative incidence of distant recurrence was 6.2% at 5 years and 12.2% at 10 years. The cumulative overall, disease specific and disease free survival at 10 years was 59%, 88% and 81% respectively.</p> <p>Conclusion</p> <p>Limited surgery and tamoxifen provide excellent control of breast cancer in the elderly in a resource restricted environment. Radiotherapy and axillary dissection and can be safely omitted thereby reducing health care resource utilization.</p

Ab initio molecular dynamics simulations of Aluminum solvation

The solvation of Al and its hydrolyzed species in water clusters has been studied by means of ab initio molecular dynamics simulations. The hexa-hydrate aluminum ion formed a stable complex in the finite temperature cluster simulation of one aluminum ion and 16 waters. The average dipole moment of strongly polarized hydrated water molecules in the first solvation shell of the hexa-hydrate aluminum ion was found to be 5.02 Debye. The deprotonated hexa-hydrate complex evolves into a tetra-coordinated aluminate ion with two water molecules in the second solvation shell forming hydrogen bonds to the hydroxyl groups in agreement with the observed coordination.Comment: 12 pages in Elsevier LaTeX, 5 figures in Postscript, 2 last figures are in color, submitted to Chemical Physics Letter

Information dynamics algorithm for detecting communities in networks

The problem of community detection is relevant in many scientific disciplines, from social science to statistical physics. Given the impact of community detection in many areas, such as psychology and social sciences, we have addressed the issue of modifying existing well performing algorithms by incorporating elements of the domain application fields, i.e. domain-inspired. We have focused on a psychology and social network - inspired approach which may be useful for further strengthening the link between social network studies and mathematics of community detection. Here we introduce a community-detection algorithm derived from the van Dongen's Markov Cluster algorithm (MCL) method by considering networks' nodes as agents capable to take decisions. In this framework we have introduced a memory factor to mimic a typical human behavior such as the oblivion effect. The method is based on information diffusion and it includes a non-linear processing phase. We test our method on two classical community benchmark and on computer generated networks with known community structure. Our approach has three important features: the capacity of detecting overlapping communities, the capability of identifying communities from an individual point of view and the fine tuning the community detectability with respect to prior knowledge of the data. Finally we discuss how to use a Shannon entropy measure for parameter estimation in complex networks.Comment: Submitted to "Communication in Nonlinear Science and Numerical Simulation

Influence of a knot on the strength of a polymer strand

Many experiments have been done to determine the relative strength of different knots, and these show that the break in a knotted rope almost invariably occurs at a point just outside the `entrance' to the knot. The influence of knots on the properties of polymers has become of great interest, in part because of their effect on mechanical properties. Knot theory applied to the topology of macromolecules indicates that the simple trefoil or `overhand' knot is likely to be present with high probability in any long polymer strand. Fragments of DNA have been observed to contain such knots in experiments and computer simulations. Here we use {\it ab initio} computational methods to investigate the effect of a trefoil knot on the breaking strength of a polymer strand. We find that the knot weakens the strand significantly, and that, like a knotted rope, it breaks under tension at the entrance to the knot.Comment: 3 pages, 4 figure

Stark ionization of atoms and molecules within density functional resonance theory

We show that the energetics and lifetimes of resonances of finite systems under an external electric field can be captured by Kohn-Sham density functional theory (DFT) within the formalism of uniform complex scaling. Properties of resonances are calculated self-consistently in terms of complex densities, potentials, and wave functions using adapted versions of the known algorithms from DFT. We illustrate this new formalism by calculating ionization rates using the complex-scaled local density approximation and exact exchange. We consider a variety of atoms (H, He, Li, and Be) as well as the H2 molecule. Extensions are briefly discussed