Optimization Approach to the Treatment of Open Boundary-Conditions

A solution to an optimization problem is developed that deals with minimizing a measure of difference between the values of observed and predicted variables at an open ocean boundary. Minimization is based on the change of the flux of energy through the open boundary. It is shown that many of the longwave radiation conditions that are commonly used in ocean modeling can be derived using this optimization criteria. However, the minimization process is seen to produce a modification of these radiation conditions in that they are multiplied by a coefficient, which allows the conditions to adapt to a change in the flux of energy penetrating the boundary. An example of the numerical implementation is presented for the Reid and Bodine boundary formulation. For a standing wave problem with an analytical solution, use of the modified Reid and Bodine formulation is seen to eliminate almost entirely errors in the predicted amplitudes and phases. Overall, this approach is seen to allow a modeler to generate different types of boundary conditions based on observations as well as the inclinations of the modeler

Local Data Assimilation in the Estimation of Barotropic and Baroclinic Open Boundary Conditions

The problem of data assimilation in the specification of open boundary conditions for limited area models is addressed in this paper. Optimization approaches are detailed, which are based on combining available data on an open boundary with the physics of the hydrodynamical model. In our case the physics is in terms of the flux of energy through the open boundary. These optimized boundary conditions, for both barotropic and baroclinic situations, interpreted physically as special Linearizations of the Bernoulli equation for each normal mode. Because of the complexity of decomposing variables into normal modes for open boundaries with varying bathymetry, we present two alter native approaches. The first is a simplification of the optimized baroclinic boundary condition based on normal modes. The second makes use of empirical orthogonal functions instead of normal modes. The results of testing and comparisons of these approaches are presented for coupling coarse- and fine-resolution models. In this case our approach is in assimilating values and variables from a large-scale model. (along the open boundaries of a limited area model). In the proposed coupling schemes the energy fluxes are estimated either from coarse or from fine-grid model results. With the progress of oceanographic observing systems we would like to explore ways of combining model outputs with the oceanographic measurements in order to estimate energy fluxes used in optimized open boundary conditions

Optimized Boundary Conditions and Data Assimilation with Application to the M-2 Tide in the Yellow Sea

An optimization approach is derived for assimilating tidal height information along the open boundaries of a numerical model. The approach is then extended so that similar data along transects inside a model domain can also be optimally assimilated. To test the application of such an optimized methodology, M-2 tidal simulations were conducted with a numerical ocean model of the Yellow Sea, an area with a strong tidal influence. The use of the optimized open boundary conditions and internal data assimilation leads to a significant improvement of the predictive skill of the model. Average errors can be reduced by up to 75% when compared to nonoptimized boundary conditions

Biopsy case mix and diagnostic yield at a Malawian central hospital

Cancer is a major disease burden worldwide resulting in high morbidity and mortality. It is the leading cause of mortality in developed countries and is one of the three leading causes of death for adults in developing countries. Pathological examination of tissue biopsies with histological confirmation of a correct cancer diagnosis is central to cancer care. Without an accurate and specific pathologic diagnosis, effective treatment cannot be planned or delivered. In addition, there are marked geographical variations in incidence of cancer overall, and of the specific cancers seen. Much of the published literature on cancer incidence in developing countries reflects gross estimates and may not reflect reality. Performing baseline studies to understand these distributions lays the groundwork for further research in this area of cancer epidemiology. Our current study surveys and ranks cancer diagnoses by individual anatomical site at Queen Elizabeth Central Hospital (QECH) which is the largest teaching and referral hospital in Malawi. A retrospective study was conducted reviewing available pathology reports over a period of one full year from January 2010 to December 2010 for biopsies from patients suspected clinically of having cancer. There were 544 biopsies of suspected cancer, taken from 96 anatomical sites. The oesophagus was the most common biopsied site followed by breast, bladder, bone, prostate, bowel, and cervical lymph node. Malignancies were found in biopsies of the oesophagus biopsies (squamous cell carcinoma, 65.1%; adenocarcinoma, 11.6%), breast (57.5%), bladder (squamous cell carcinoma, 53.1%) and stomach (37.6%). Our study demonstrates that the yield of biopsy for clinically suspected malignancy was greater than 50% for the 11 most common sites and provides a current survey of cancer types by site present in the population reporting to our hospital

Multiple Myeloma

The results of the use of melphalan in 52 patients with multiple myeloma have been analysed.  The median survival of the whole group of patients was 30 months, and of those with renal insufficiency only 12,5 months. Bence-lones proteinuria was also a poor prognostic finding,. but only because of its association with renal failure. Patients with Bence-Jones proteinuria and normal renal function had a median survival of 41 months. Responsiveness to therapy by criteria based on those of the Chronic Leukemial Multiple Myeloma Task Force could be assessed in 25 patients. Dramatic symptomatic relief occurred in all but one of the responsive patients, but in only one-fifth of those who did not respond to therapy.S. Afr. Med. J., 48, 1026 (1974)

Multiple Myeloma

The clinical, biochemical and immunochemical features of 52 patients suffering from multiple myelomatosis are reported. Three major criteria were used to establish the diagnosis: serum and urine protein chemistry, bone marrow morphology and the radiological appearances of bone. The fact that abnormalities of gamma globulin synthesis were present in 49 of the 52 patients indicates the importance of adequate examination of urine by electrophores's and immunochemical techniques in the early diagnosis of multiple myeloma. Bradshaw's test, which is a simple screening test for fence-Jones proteinuria, was positive in 63% of patients.S. Afr. Med. J., 48, 1023 (1974)

Multiple Myeloma

The results of the use of melphalan in 52 patients with multiple myeloma have been analysed. The median survival of the whole group of patients was 30 months, and of those w:th renal insufficiency only 12,5 months. Bence-lones proteinuria was also a poor prognostic finding,. but only because of its association with renal failure. Patients with Bence-Jones protcinur;a and normal renal function had a median survival of 41 months. Responsiveness to therapy by criteria based on those of the Chronic Leukemial Multip!e Myeloma Task Force could be assessed in 25 patients. Dramatic symptomatic relief occurred in all but one of the responsive patients, but in only one-fifth of those who did not respond to therapy.S. Afr. Med. J., 48, 1026 (1974

Candida albicans biofilm heterogeneity does not influence denture stomatitis but strongly influences denture cleansing capacity

Approximately 20  % of the UK population wear some form of denture prosthesis, resulting in denture stomatitis in half of these individuals. Candida albicans is primarily attributed as the causative agent, due to its biofilm -forming ability. Recently, there has been increasing evidence of C. albicans biofilm heterogeneity and the negative impact it can have clinically; however, this phenomenon has yet to be studied in relation to denture isolates. The aims of this study were to evaluate C. albicans biofilm formation of clinical denture isolates in a denture environment and to assess antimicrobial activity of common denture cleansers against these tenacious communities. C. albicans isolated from dentures of healthy and diseased individuals was quantified using real-time PCR and biofilm biomass assessed using crystal violet. Biofilm development on the denture substratum poly(methyl methacrylate), Molloplast B and Ufi-gel was determined. Biofilm formation was assessed using metabolic and biomass stains, following treatment with denture hygiene products. Although C. albicans was detected in greater quantities in diseased individuals, it was not associated with increased biofilm biomass. Denture substrata were shown to influence biofilm biomass, with poly(methyl methacrylate) providing the most suitable environment for C. albicans to reside. Of all denture hygiene products tested, Milton had the most effective antimicrobial activity, reducing biofilm biomass and viability the greatest. Overall, our results highlight the complex nature of denture- related disease, and disease development cannot always be attributed to a sole cause. It is the distinct combination of various factors that ultimately determines the pathogenic outcome