Optimized Schwarz waveform relaxation and discontinuous Galerkin time stepping for heterogeneous problems

We design and analyze a Schwarz waveform relaxation algorithm for domain decomposition of advection-diffusion-reaction problems with strong heterogeneities. The interfaces are curved, and we use optimized Robin or Ventcell transmission conditions. We analyze the semi-discretization in time with Discontinuous Galerkin as well. We also show two-dimensional numerical results using generalized mortar finite elements in space

Animal-Related Injuries in a Resource-Limited Setting: Experiences from a Tertiary Health Institution in Northwestern Tanzania.

Animal related injuries are a major but neglected emerging public health problem and contribute significantly to high morbidity and mortality worldwide. No prospective studies have been done on animal related injuries in our setting. This study was conducted to determine the management patterns and outcome of animal related injuries and their social impact on public health policy in the region. This was a descriptive prospective study of animal related injury patients that presented to Bugando Medical Centre between September 2007 and August 2011. Statistical data analysis was done using SPSS computer software version 17.0. A total of 452 (8.3%) animal-related injury patients were studied. The modal age group was 21-30 years. The male to female ratio was 2.1:1. Dog-bites (61.1%) were the most common injuries. Musculoskeletal (71.7%) region was the most frequent body region injured. Soft tissue injuries (92.5%) and fractures (49.1%) were the most common type of injuries sustained. Only 140 (31.0%) patients were hospitalized and most of them (97.1%) were treated surgically. Wound debridement was the most common procedure performed in 91.2% of patients. Postoperative complication rate was 15.9%, the commonest being surgical site infections (SSI) in 55.1% of patients. SSI was significantly associated with late presentation and open fractures (P < 0.001). The overall median duration of hospitalization was 16 days. Patients who had severe injuries, long bone fractures and those with hemiplegia stayed longer in the hospital (P < 0.001). Mortality rate was 10.2% and was significantly high in patients with severe injuries, severe head injury, tetanus and admission SBP < 90 mmHg (P < 0.001). The follow up of patients was poor. Animal related injuries constitute a major public health problem in our setting and commonly affect the young adult male in their economically productive age-group. Measures towards prevention and proper treatment and follow up are important in order to reduce morbidity and mortality resulting from this form of trauma

An efficient way to assemble finite element matrices in vector languages

Efficient Matlab codes in 2D and 3D have been proposed recently to assemble finite element matrices. In this paper we present simple, compact and efficient vectorized algorithms, which are variants of these codes, in arbitrary dimension, without the use of any lower level language. They can be easily implemented in many vector languages (e.g. Matlab, Octave, Python, Scilab, R, Julia, C++ with STL,...). The principle of these techniques is general, we present it for the assembly of several finite element matrices in arbitrary dimension, in the P1 finite element case. We also provide an extension of the algorithms to the case of a system of PDE's. Then we give an extension to piecewise polynomials of higher order. We compare numerically the performance of these algorithms in Matlab, Octave and Python, with that in FreeFEM++ and in a compiled language such as C. Examples show that, unlike what is commonly believed, the performance is not radically worse than that of C : in the best/worst cases, selected vector languages are respectively 2.3/3.5 and 2.9/4.1 times slower than C in the scalar and vector cases. We also present numerical results which illustrate the computational costs of these algorithms compared to standard algorithms and to other recent ones

Robin Schwarz algorithm for the NICEM Method: the Pq finite element case

In Gander et al. [2004] we proposed a new non-conforming domain decomposition paradigm, the New Interface Cement Equilibrated Mortar (NICEM) method, based on Schwarz type methods that allows for the use of Robin interface conditions on non-conforming grids. The error analysis was done for P1 finite elements, in 2D and 3D. In this paper, we provide new numerical analysis results that allow to extend this error analysis in 2D for piecewise polynomials of higher order and also prove the convergence of the iterative algorithm in all these cases.Comment: arXiv admin note: substantial text overlap with arXiv:0705.028

Space-time domain decomposition for advection-diffusion problems in mixed formulations

This paper is concerned with the numerical solution of porous-media flow and transport problems , i. e. heterogeneous, advection-diffusion problems. Its aim is to investigate numerical schemes for these problems in which different time steps can be used in different parts of the domain. Global-in-time, non-overlapping domain-decomposition methods are coupled with operator splitting making possible the different treatment of the advection and diffusion terms. Two domain-decomposition methods are considered: one uses the time-dependent Steklov--Poincar{\'e} operator and the other uses optimized Schwarz waveform relaxation (OSWR) based on Robin transmission conditions. For each method, a mixed formulation of an interface problem on the space-time interface is derived, and different time grids are employed to adapt to different time scales in the subdomains. A generalized Neumann-Neumann preconditioner is proposed for the first method. To illustrate the two methods numerical results for two-dimensional problems with strong heterogeneities are presented. These include both academic problems and more realistic prototypes for simulations for the underground storage of nuclear waste

A Simple and Efficient Tool for Trapping Gravid Anopheles at Breeding Sites.

No effective tool currently exists for trapping ovipositing malaria vectors. This creates a gap in our ability to investigate the behavior and ecology of gravid Anopheles.\ud Here we describe a simple trap that collects ovipositing Anopheline and Culicine mosquitoes. It consists of an acetate sheet coated in glue that floats on the water surface. Ten breeding sites were selected in rural Tanzania and 10 sticky traps set in each. These caught a total of 74 gravid Anopheles (54 An. arabiensis, 1 An. gambiae s.s. and 16 unamplified) and 1333 gravid Culicines, in just two trap nights. This simple sampling tool provides an opportunity to further our understanding of the behavior and ecology of gravid female Anophelines. It strongly implies that at least two of the major vectors of malaria in Africa land on the water surface during the oviposition process, and demonstrates that Anophelines and Culicines often share the same breeding sites. This simple and efficient trap has clear potential for the study of oviposition site choice and productivity, gravid dispersal, and vector control techniques which use oviposition behavior as a means of disseminating larvicides

Strategic Banking Operation for Customer Satisfaction:a Case Study of National Micro finance Bank

The major objective of this study was to find the strategic banking operation for customer satisfaction. More specifically daily operation, especially waiting time for the service on ATM, which will be provided to satisfy customers. Finding the time which customer perceive reasonable for them to spend while waiting banking service, and developing the model for matching the number of ATM to match various level of customer. for the tim

El papel del capital inmobiliario en la reconfiguración urbana y el estilo de vida

Ponència presentada a: Session 7: Participación en planeamiento / Participation in planning: enviromental and hermeneutic plannin

Social capital and the decline in HIV transmission - A case study in three villages in the Kagera region of Tanzania.

We present data from an exploratory case study characterising the social capital in three case villages situated in areas of varying HIV prevalence in the Kagera region of Tanzania. Focus group discussions and key informant interviews revealed a range of experiences by community members, leaders of organisations and social groups. We found that the formation of social groups during the early 1990s was partly a result of poverty and the many deaths caused by AIDS. They built on a tradition to support those in need and provided social and economic support to members by providing loans. Their strict rules of conduct helped to create new norms, values and trust, important for HIV prevention. Members of different networks ultimately became role models for healthy protective behaviour. Formal organisations also worked together with social groups to facilitate networking and to provide avenues for exchange of information. We conclude that social capital contributed in changing HIV related risk behaviour that supported a decline of HIV infection in the high prevalence zone and maintained a low prevalence in the other zones

Major Limb Amputations: A Tertiary Hospital Experience in Northwestern Tanzania.

Major limb amputation is reported to be a major but preventable public health problem that is associated with profound economic, social and psychological effects on the patient and family especially in developing countries where the prosthetic services are poor. The purpose of this study was to outline the patterns, indications and short term complications of major limb amputations and to compare our experience with that of other published data. This was a descriptive cross-sectional study that was conducted at Bugando Medical Centre between March 2008 and February 2010. All patients who underwent major limb amputation were, after informed consent for the study, enrolled into the study. Data were collected using a pre-tested, coded questionnaire and analyzed using SPSS version 11.5 computer software. A total of 162 patients were entered into the study. Their ages ranged between 2-78 years (mean 28.30 ± 13.72 days). Males outnumbered females by a ratio of 2:1. The majority of patients (76.5%) had primary or no formal education. One hundred and twelve (69.1%) patients were unemployed. The most common indication for major limb amputation was diabetic foot complications in 41.9%, followed by trauma in 38.4% and vascular disease in 8.6% respectively. Lower limbs were involved in 86.4% of cases and upper limbs in 13.6% of cases giving a lower limb to upper limb ratio of 6.4:1 Below knee amputation was the most common procedure performed in 46.3%. There was no bilateral limb amputation. The most common additional procedures performed were wound debridement, secondary suture and skin grafting in 42.3%, 34.5% and 23.2% respectively. Two-stage operation was required in 45.4% of patients. Revision amputation rate was 29.6%. Post-operative complication rate was 33.3% and surgical site infection was the most common complication accounting for 21.0%. The mean length of hospital stay was 22.4 days and mortality rate was 16.7%. Complications of diabetic foot ulcers and trauma resulting from road traffic crashes were the most common indications for major limb amputation in our environment. The majority of these amputations are preventable by provision of health education, early presentation and appropriate management of the common indications