Lattice-dynamics of a Disordered solid-solid Interface

Generic properties of elastic phonon transport at a disordered interface are studied. The results show that phonon transmittance is a strong function of frequency and the disorder correlation length. At frequencies lower than the van Hove singularity the transmittance at a given frequency increases as the correlation length decreases. At low frequencies, this is reflected by different power-laws for phonon conductance across correlated and uncorrelated disordered interfaces which are in approximate agreement with perturbation theory of an elastic continuum. These results can be understood in terms of simple mosaic and two-colour models of the interface.Comment: 17 pages, 5 figures, submitted to PR

The use and benefits of computer mediated learning in teaching biology

Of increasing concern among higher education institutions is the problem of maintaining the quality of education in the face of increased student numbers and continuing funding cuts. These concerns, coupled with the advent of readily accessible and relatively cost effective computer technology, has seen a marked increase in the use of computer-based education delivery systems in universities. Much debate now centres on how effective and beneficial computer-based learning (CBL) is, particularly with respect to learning and cognitive processes (Brown et al. 1989; Rowe 1993), student performance (Mevarech et al. 1991; Stewell and Delpierre 1992; Blackmore and Britt 1993; Mevarech 1993; Chambers et al. 1995), gender and age related performance (Massoud 1991; Lee 1993; Colley et al. 1994; Dyck and Smither 1994) and software design and mode of delivery (Ahern 1993; Jackson et al. 1993; Rowe 1993; Chambers et al. 1995). Addressing these questions is difficult due to a lack of published data and because comparisons of student performance are difficult given the highly diverse ways in which CBL is approached, implemented and evaluated. One area to which CBL readily lends itself is the use of computer simulations in practical or laboratory teaching. Laboratory classes aim to teach students principles of experimental design, data collection, data processing as well as the correct usage of commonly used laboratory equipment. The application of computer simulations can be beneficial if (i) the costs of running a particular experiment are prohibitive (ii) time constraints apply e.g., growth or breeding experiments (iii) ethical or humane considerations are involved e.g., experiments involving euthanasia of large numbers of animals (iv) it is difficult to observe or manipulate the phenomenon under consideration e.g., nutrient cycling in a plant community (v) it is important that students are familiar with a piece of equipment or procedure prior to undertaking an experiment e.g., familiarity with the use of a spectrophotometer (vi) rapid and efficient feedback on a students understanding of the subject material is desirable (vii) the experiments are technically demanding (ix) require the use of dangerous or radioactive compounds. This talk will be primarily on the use of computer simulations in biology but I will talk about laboratory marking programs and tutorial assessment programs

Assessment of available evidence in the management of gallbladder and bile duct stones:a systematic review of international guidelines

BACKGROUND: Gallstone disease is a frequent disorder in the Western world with a prevalence of 10-20%. Recommendations for the assessment and management of gallstones vary internationally. The aim of this systematic review was to assess quality of guideline recommendations for treatment of gallstones. METHODS: PubMed, EMBASE and websites of relevant associations were systematically searched. Guidelines without a critical appraisal of literature were excluded. Quality of guidelines was determined using the AGREE II instrument. Recommendations without consensus or with low level of evidence were considered to define problem areas and clinical research gaps. RESULTS: Fourteen guidelines were included. Overall quality of guidelines was low, with a mean score of 57/100 (standard deviation 19). Five of 14 guidelines were considered suitable for use in clinical practice without modifications. Ten recommendations from all included guidelines were based on low level of evidence and subject to controversy. These included major topics, such as definition of symptomatic gallstones, indications for cholecystectomy and intraoperative cholangiography. CONCLUSION: Only five guidelines on gallstones are evidence-based and of a high quality, but even in these controversy exists on important topics. High quality evidence is needed in specific areas before an international guideline can be developed and endorsed worldwide

Prospective Volumetric Assessment of the Liver on a Personal Computer by Nonradiologists Prior to Partial Hepatectomy

Ó The Author(s) 2010. This article is published with open access at Springerlink.com Background A small remnant liver volume is an important risk factor for posthepatectomy liver failure. ImageJ and OsiriX Ò are both free, open-source image processing software packages. The aim of the present study was to compare ImageJ and OsiriX Ò in performing prospective computed tomography (CT) volumetric analysis of the liver on a personal computer (PC) in patients undergoing major liver resection. Methods Patients scheduled for a right hemihepatectomy were eligible for inclusion. Two surgeons and one surgical trainee measured volumes of total liver, tumor, and future resection specimen prospectively with ImageJ and OsiriX Ò. A radiologist also measured these volumes with CT scanner-linked Aquarius iNtuition Ò software. Resection volumes were compared with the actual weights of the live

Liver Volumetry Plug and Play: Do It Yourself with ImageJ

AB - BACKGROUND: A small remnant liver volume is an important risk factor for posthepatectomy liver failure and can be predicted accurately by computed tomography (CT) volumetry using radiologic image analysis software. Unfortunately, this software is expensive and usually requires support by a radiologist. ImageJ is a freely downloadable image analysis software package developed by the National Institute of Health (NIH) and brings liver volumetry to the surgeon's desktop. We aimed to assess the accuracy of ImageJ for hepatic CT volumetry. METHODS: ImageJ was downloaded from http://www.rsb.info.nih.gov/ij/ . Preoperative CT scans of 15 patients who underwent liver resection for colorectal cancer liver metastases were retrospectively analyzed. Scans were opened in ImageJ; and the liver, all metastases, and the intended parenchymal transection line were manually outlined on each slice. The area of each selected region, metastasis, resection specimen, and remnant liver was multiplied by the slice thickness to calculate volume. Volumes of virtual liver resection specimens measured with ImageJ were compared with specimen weights and calculated volumes obtained during pathology examination after resection. RESULTS: There was an excellent correlation between the volumes calculated with ImageJ and the actual measured weights of the resection specimens (r(2) = 0.98, p < 0.0001). The weight/volume ratio amounted to 0.88 +/- 0.04 (standard error) and was in agreement with our earlier findings using CT-linked radiologic software. CONCLUSION: ImageJ can be used for accurate hepatic CT volumetry on a personal computer. This application brings CT volumetry to the surgeon's desktop at no expense and is particularly useful in cases of tertiary referred patients, who already have a proper CT scan on CD-ROM from the referring institution. Most likely the discrepancy between volume and weight results from exsanguination of the liver after resectio

The SM and NLO multileg working group: Summary report

This report summarizes the activities of the SM and NLO Multileg Working Group of the Workshop "Physics at TeV Colliders", Les Houches, France 8-26 June, 2009.Comment: 169 pages, Report of the SM and NLO Multileg Working Group for the Workshop "Physics at TeV Colliders", Les Houches, France 8-26 June, 200

The influence of systemic inflammation, dietary intake and stage of disease on rate of weight loss in patients with gastro-oesophageal cancer

Although weight loss is often a dominant symptom in patients with upper gastrointestinal malignancy, there is a lack of objective evidence describing changes in nutritional status and potential associations between weight loss, food intake, markers of systemic inflammation and stage of disease in such patients. Two hundred and twenty patients diagnosed with gastric/oesophageal cancer were studied. Patients underwent nutritional assessment consisting of calculation of body mass index, measurement of weight loss, dysphagia scoring and estimation of dietary intake. Serum acute-phase protein concentrations were determined by enzyme-linked immunosorbent assay. In all, 182 (83%) patients had lost weight at diagnosis (median loss, 7% body weight). Weight loss was associated with poor performance status, advanced disease stage, dysphagia, reduced dietary intake and elevated serum C-reactive protein (CRP) concentrations. Multiple regression identified dietary intake (estimate of effect, 38%), serum CRP concentrations (estimate of effect, 34%) and stage of disease (estimate of effect, 28%) as independent variables in determining degree of weight loss. Mechanisms other than reduced dietary intake or mechanical obstruction by the tumour appear to be involved in the nutritional decline in patients with gastro-oesophageal malignancy. Recognition that systemic inflammation plays a role in nutritional depletion may inform the development of appropriate therapeutic strategies to ameliorate weight loss, making patients more tolerant of cancer-modifying treatments such as chemotherapy