Ratiometric pathlength calibration of integrating sphere-based absorption cells.

Chemical sensors based on optical absorption require accurate knowledge of the optical pathlength of the sample cell. Integrating spheres offer increased pathlengths compared to single pass cells combined with tolerance to misalignment, making them attractive for use in challenging environments subject to vibration. However, the equivalent optical pathlength can be degraded by dirt and / or condensation on the inner surface of the sphere. We present a new scheme for in-situ calibration that uses a ratiometric two-beam approach. Results are presented for an integrating sphere used in the measurement of methane by tunable diode laser spectroscopy (TDLS) at 1651nm. Reduced sphere reflectivity was simulated by applying small areas of black tape on the inner surface. At methane concentrations of 1500ppm and 3125 ppm, for areas of contamination up to 2.3% of the sphere wall, the technique reduced the error from over 50% to within ±4%. At a concentration of 6250 ppm and the most severe fouling corresponding to 2.9% wall coverage, the technique reduced the error from 55-65% to within ±11%.

Integrating cavity based gas cells: a multibeam compensation scheme for pathlength variation.

We present a four beam ratiometric setup for an integrating sphere based gas cell, which can correct for changes in pathlength due to sphere wall contamination. This allows for the gas absorption coefficient to be determined continuously without needing to recalibrate the setup. We demonstrate the technique experimentally, measuring methane gas at 1651nm. For example, contamination covering 1.2% of the sphere wall resulted in an uncompensated error in gas absorption coefficient of ≈41%. With the ratiometric scheme, this error was reduced to ≈2%. Potential limitations of the technique, due to subsequent deviations from mathematical assumptions are discussed, including severe sphere window contamination.

Lower limb complications of diabetes mellitus: a comprehensive review with clinicopathological insights from a dedicated high-risk diabetic foot multidisciplinary team.

Diabetic complications in the lower extremity are associated with significant morbidity and mortality, and impact heavily upon the public health system. Early and accurate recognition of these abnormalities is crucial, enabling the early initiation of treatments and thus avoiding or minimizing deformity, dysfunction and amputation. Following careful clinical assessment, radiological imaging is central to the diagnostic and follow-up process. We aim to provide a comprehensive review of diabetic lower limb complications designed to assist radiologists and to contribute to better outcomes for these patients.

Mapping functional groups on oxidised multi-walled carbon nanotubes at the nanometre scale.

Despite voluminous research on the acid oxidation of carbon nanotubes (CNTs), there is a distinct lack of experimental results showing distributions of functional groups at the nanometre length scale. Here, functional peaks have been mapped across individual multi-walled CNTs with low-dose, monochromated electron energy-loss spectroscopy (EELS) in the scanning transmission electron microscope (STEM). Density functional theory simulations show that the EELS features are consistent with oxygenated functional groups, most likely carboxyl moieties.

Increased incidence of invasive group A streptococcal disease in Ireland, 2012 to 2013.

Invasive group A streptococcal (iGAS) infections have been notifiable in Ireland since 2004. Incidence rates (2004-2011) have ranged from 0.8 to 1.65 per 100,000. In 2012, the iGAS rate rose to 2.66 per 100,000 and was associated with a high proportion of emm1 isolates. A further increase in January to June 2013 has been associated with increased prevalence of emm3. Public health departments and clinicians have been alerted to this increase.

Silver based wound dressings and topical agents for treating diabetic foot ulcers.

BACKGROUND: Foot ulceration affects 15-20% of people with diabetes. It is a major precursor to amputation in this patient group, and early and appropriate treatment provides the greatest opportunity for healing. The use of silver for its antimicrobial properties has re-emerged, and modern wound dressings that release a sustained amount of free silver ions, are now widely used in wound management. OBJECTIVES: To evaluate the effects of silver-containing dressings and topical agents on infection rates and healing of diabetes related foot ulcers. SEARCH STRATEGY: Searches were made of the Cochrane Wounds Group Specialised Register (August 2005), the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library Issue 3 2005) MEDLINE (1966 to October week 2 2004), EMBASE (1980 to October week 2 2004) and CINAHL (1982 to October week 2 2004). The Journal of Wound Care (Volume 12/13 Issues 1-10) was hand-searched. Manufacturers, researchers and local and international wound groups were contacted in order to identify unpublished trials. Web sites for wound groups and World Wide Wounds (www.worldwidewounds.com) were searched. SELECTION CRITERIA: Randomised controlled trials and non-randomised controlled clinical trials were considered for inclusion. Studies were included if they involved participants with Type 1 or Type 2 diabetes and related foot ulcers, met the requirements for randomisation, allocation and concealment where appropriate, and compared the intervention with a placebo or a sham dressing, an alternative non silver based dressing or no dressing, and reported outcomes that represent healing rate or infection. DATA COLLECTION AND ANALYSIS: Two authors independently evaluated the papers identified by the search strategy against the inclusion criteria but identified no trials eligible for inclusion in the review. It was not possible to perform planned subgroup and sensitivity analysis in the absence of data. In future, if eligible trials become available, a random effects model will be applied for meta-analysis in the presence of statistical heterogeneity (estimated using the I(2) statistic). Dichotomous outcomes will be reported as risk ratios with 95% confidence intervals (CI), and continuous outcomes as weighted mean differences (WMD) with 95% CI. Statistical significance will be set at P value < 0.05 for all outcomes and the magnitude of the effect will be estimated by calculating the number needed to treat (NNT) with 95% CI. MAIN RESULTS: No studies were identified that met with the inclusion criteria AUTHORS' CONCLUSIONS: Despite the widespread use of dressings and topical agents containing silver for the treatment of diabetic foot ulcers, no randomised trials or controlled clinical trials exist that evaluate their clinical effectiveness. Trials are needed to determine clinical and cost-effectiveness and long term outcomes including adverse events.

The importance of microbiological investigations, medications and artificial feeding in diarrhoea evaluation.

BACKGROUND: Diarrhoea in hospitalised patients is usually attributed to medications especially antibiotics, enteral tube feeding or enteropathogenic bacteria particularly Clostridium difficile. AIMS: The aim of this study was to evaluate the investigations performed on patients who developed diarrhoea during their stay in an acute general hospital. METHOD: Over 18 working days, an unselected group of adult inpatients who developed diarrhoea following their admission to hospital were reviewed. Symptoms, medications, nutritional support and any investigations performed were assessed. RESULTS: Eighty-one patients developed diarrhoea. Forty-nine (60%) were receiving antibiotics prior to the development of symptoms, 30 (37%) were being enterally tube fed, 14 (17%) had positive stool for Clostridium difficile A and B toxin and 3 (4%) had salmonella species positive stool. CONCLUSION: The majority of cases of diarrhoea were related to medications and enteral tube feeding. A small but significant number did develop bacterial infections. In contrast to some suggested guidelines, when investigating hospital acquired diarrhoea, it is considered worthwhile to perform microbiological stool examinations.

Women in contact with Sydney's gay and lesbian community: sexual identity, practice and HIV risks.

Total rates are low, but sex with a man remains the main risk for HIV transmission to women in Australia. In February 1998, 774 women in contact with gay, bisexual and lesbian communities completed a two-page questionnaire. Almost all respondents had some social contact with gay men. Two-thirds (503) thought of themselves as lesbian/dyke/homosexual/gay, 13% (100) as bisexual and 17% (133) as heterosexual/straight. In total, 212 women (27%) said they had ever had sex with a gay or bisexual man; 51 women (7%) had done so in the past six months. About 2% of the lesbians said they had recently had sex with a gay/bi man, as had 8% of the heterosexuals and 25% of the bisexuals; 25 women had recently had unprotected vaginal or anal intercourse with a male gay/bi partner. Forty-eight women (6%) had done sex work. Asked about drug use, 61 women (8%) said they had injected in the past six months. Twenty-three women had shared injecting equipment with someone, and five had shared with a gay/bi man. Compared with other women, these women have high rates of injecting drug use. If they have sex with men, these men are more likely to be gay or bisexual than are the male sexual partners of women moving in largely heterosexual milieux. For a case of so-called 'heterosexual' transmission of HIV to occur, neither person need be heterosexual.