Electron-impact excitation of FeII - Collision strengths and effective collision strengths for low-lying fine-structure forbidden transitions

Context. Absorption or emission lines of Fe II are observed in many astrophysical spectra and accurate atomic data are required to interpret these lines. The calculation of electron-impact excitation rates for transitions among even the lowest lying levels of Fe II is a formidable task for theoreticians.

Aims. In this paper, we present collision strengths and effective collision strengths for electron-impact excitation of Fe II for low-lying forbidden transitions among the lowest 16 fine-structure levels arising from the four LS states 3d(6)4s D-6(e), 3d(7) F-4(e), 3d(6)4s D-4(e), and 3d(7) P-4(e). The effective collision strengths are calculated for a wide range of electron temperatures of astrophysical importance from 30-100 000 K.

Methods. The parallel suite of Breit-Pauli codes are utilised to compute the collision cross sections for electron-impact excitation of Fe II and relativistic terms are included explicitly in both the target and the scattering approximation. 100 LS or 262-jj levels formed from the basis configurations 3d(6)4s, 3d(7), and 3d(6)4p were included in the wavefunction representation of the target, including all doublet, quartet, and sextet terms. Collision strengths for a total of 34191 individual transitions were computed.

Results. A detailed comparison is made with previous theoretical works and significant differences were found to occur in the effective collision strengths, particularly at low temperatures.

Medically unexplained symptoms: The need for effective communication and an integrated care strategy

Much is already known about medically unexplained symptoms (MUS) in terms of incidence, presentation and current treatment. What needs to be urgently addressed is a strategy for dealing with patients and their conditions, particularly when they do not fall neatly into medical frameworks or pathologies where the syndrome can be easily explained. This article will consider the provision of health and social care support for patients with MUS within an interprofessional education context. The author will contend that a sensitive and valued service for this large client group is dependent upon services without professional boundaries and practitioners with a clinical interest that can work together and agree an appropriate way forward in terms of care, support and strategic service provision. The article will support the idea that clear guidelines through the National Institute for Health and Care Excellence can offer clear clinical direction for practitioners working in primary and secondary care settings to work together interprofessionally to ensure a seamless and sensitive service for people with this condition.

Urethral atrophy after artificial urinary sphincter placement:Is cuff downsizing effective?

Purpose: We reviewed the outcome of cuff downsizing with an artificial urinary sphincter for treating recurrent incontinence due to urethral atrophy.

Materials and Methods: We analyzed the records of 17 patients in a 7-year period in whom clinical, radiological and urodynamic evidence of urethral atrophy was treated with cuff downsizing. Cuff downsizing was accomplished by removing the existing cuff and replacing it with a 4 cm. cuff within the established false capsule. Incontinence and satisfaction parameters before and after the procedure were assessed by a validated questionnaire.

Results: Mean patient age was 70 years (range 62 to 79). Average time to urethral atrophy was 31 months (range 5 to 96) after primary sphincter implantation. Mean followup after downsizing was 22 months (range 1 to 64). Cuff downsizing caused a mean decrease of 3.9 to 0.5 pads daily. The number of severe leakage episodes decreased from a mean of 5.4 to 2.1 The mean SEAPI (stress leakage, emptying, anatomy, protection, inhibition) score decreased from 8.2 to 2.4. Patient satisfaction increased from 15% to 80% after cuff downsizing. In 1 patient an infected cuff required complete removal of the device.

Conclusions: Patient satisfaction and continence parameters improved after cuff downsizing. We believe that this technique is a simple and effective method of restoring continence after urethral atrophy.

Non-invasive antidromic neurostimulation:A simple effective method for improving bladder storage

Patients with intractably diminished bladder storage function are encountered frequently by neurourologists, occasionally requiring reconstructive surgery for appropriate resolution. Although sacral neuromodulation is a recognized effective therapeutic modality, present techniques are technically demanding, invasive, and expensive. This study investigated the effect of non-invasive third sacral nerve (S3) stimulation on bladder activity during filling cystometry. One hundred forty-six patients underwent standard urodynamic filling cystometry that was then immediately repeated. Patients in the study group (n = 74) received antidromic transcutaneous sacral neurostimulation during the second fill and the control group (n = 72) underwent a second fill without neurostimulation. A statistically significant increase in bladder storage capacity without a corresponding rise in detrusor pressure was observed in the neurostimulated patients. This improvement in functional capacity is an encouraging finding that further supports the use of this non-invasive treatment modality in clinical practice. Neurourol. Urodynam. 20:73-84. 2001. (C) 2001 Wiley-Liss, Inc.

Effective grain size distribution analysis for interpretation of tidal-deltaic facies: West Bengal Sundarbans

Research over the past two decades on the Holocene sediments from the tide dominated west side of the lower Ganges delta has focussed on constraining the sedimentary environment through grain size distributions (GSD). GSD has traditionally been assessed through the use of probability density function (PDF) methods (e.g. log-normal, log skew-Laplace functions), but these approaches do not acknowledge the compositional nature of the data, which may compromise outcomes in lithofacies interpretations. The use of PDF approaches in GSD analysis poses a series of challenges for the development of lithofacies models, such as equifinal distribution coefficients and obscuring the empirical data variability. In this study a methodological framework for characterising GSD is presented through compositional data analysis (CODA) plus a multivariate statistical framework. This provides a statistically robust analysis of the fine tidal estuary sediments from the West Bengal Sundarbans, relative to alternative PDF approaches.

Removal of microorganisms and their chemical metabolites from water using semiconductor photocatalysis

Semiconductor photocatalysis has been applied to the remediation of an extensive range of chemical pollutants in water over the past 30 years. The application of this versatile technology for removal of micro-organisms and cyanotoxins has recently become an area that has also been the subject of extensive research particularly over the past decade. This paper considers recent research in the application of semiconductor photocatalysis for the treatment of water contaminated with pathogenic micro-organisms and cyanotoxins. The basic processes involved in photocatalysis are described and examples of recent research into the use of photocatalysis for the removal of a range of microorganisms are detailed. The paper concludes with a review of the key research on the application of this process for the removal of chemical metabolites generated from cyanobacteria.

A comparison of the effectiveness of TiO2 photocatalysis and UVA photolysis for the destruction of three pathogenic micro-organisms

TiO₂ photocatalysis has demonstrated efficacy as a treatment process for water contaminated with chemical pollutants. When exposed to UVA light TiO₂ also demonstrates an effective bactericidal activity. The mechanism of this process has been reported to involve attack by valence band generated hydroxyl radicals. In this study when three common bacterial pathogens, Escherichia coli, Salmonella enterica serovar Enteritidis and Pseudomonas aeruginosa, were exposed to TiO₂ and UVA light a substantial decrease in bacterial numbers was observed. Control experiments in which all three pathogens were exposed to UVA light only resulted in a similar reduction in bacterial numbers. Moreover, exposure to UVA light alone resulted in the production of a smaller than average colony phenotype among the surviving bacteria, for all three pathogens examined, a finding which was not observed following treatment with UVA and TiO₂. Small slow growing colonies have been described for several pathogenic bacteria and are referred to as small colony variants. Several studies have demonstrated an association between small colony variants and persistent, recurrent and antibiotic resistant infections. We propose that the production of small colony variants of pathogenic bacteria following UVA treatment of drinking water may represent a health hazard. As these small colony variants were not observed with the UVA/TiO₂ system this potential hazard is not a risk when using this technology. It would also appear that the bactericidal mechanism is different with the UVA/TiO₂ process compared to when UVA light is used alone.