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LatticeQCD using OpenCL
(2011)
Background: Anemia is a common condition in the elderly and a significant risk factor for increased morbidity and mortality, reducing not only functional capacity and mobility but also quality of life. Currently, few data are available regarding anemia in hospitalized geriatric patients. Our retrospective study investigated epidemiology and causes of anemia in 405 hospitalized geriatric patients.
Methods: Data analysis was performed using laboratory parameters determined during routine hospital admission procedures (hemoglobin, ferritin, transferrin saturation, C-reactive protein, vitamin B12, folic acid, and creatinine) in addition to medical history and demographics.
Results: Anemia affected approximately two-thirds of subjects. Of 386 patients with recorded hemoglobin values, 66.3% were anemic according to WHO criteria, mostly (85.1%) in a mild form. Anemia was primarily due to iron deficiency (65%), frequently due to underlying chronic infection (62.1%), or of mixed etiology involving a combination of chronic disease and iron deficiency, with absolute iron deficiency playing a comparatively minor role.
Conclusion: Greater awareness of anemia in the elderly is warranted due to its high prevalence and negative effect on outcomes, hospitalization duration, and mortality. Geriatric patients should be routinely screened for anemia and etiological causes of anemia individually assessed to allow timely initiation of appropriate therapy.
Quarks and gluons are the building blocks of all hadronic matter, like protons and neutrons. Their interaction is described by Quantum Chromodynamics (QCD), a theory under test by large scale experiments like the Large Hadron Collider (LHC) at CERN and in the future at the Facility for Antiproton and Ion Research (FAIR) at GSI. However, perturbative methods can only be applied to QCD for high energies. Studies from first principles are possible via a discretization onto an Euclidean space-time grid. This discretization of QCD is called Lattice QCD (LQCD) and is the only ab-initio option outside of the high-energy regime. LQCD is extremely compute and memory intensive. In particular, it is by definition always bandwidth limited. Thus—despite the complexity of LQCD applications—it led to the development of several specialized compute platforms and influenced the development of others. However, in recent years General-Purpose computation on Graphics Processing Units (GPGPU) came up as a new means for parallel computing. Contrary to machines traditionally used for LQCD, graphics processing units (GPUs) are a massmarket product. This promises advantages in both the pace at which higher-performing hardware becomes available and its price. CL2QCD is an OpenCL based implementation of LQCD using Wilson fermions that was developed within this thesis. It operates on GPUs by all major vendors as well as on central processing units (CPUs). On the AMD Radeon HD 7970 it provides the fastest double-precision D= kernel for a single GPU, achieving 120GFLOPS. D=—the most compute intensive kernel in LQCD simulations—is commonly used to compare LQCD platforms. This performance is enabled by an in-depth analysis of optimization techniques for bandwidth-limited codes on GPUs. Further, analysis of the communication between GPU and CPU, as well as between multiple GPUs, enables high-performance Krylov space solvers and linear scaling to multiple GPUs within a single system. LQCD calculations require a sampling of the phase space. The hybrid Monte Carlo (HMC) algorithm performs this. For this task, a single AMD Radeon HD 7970 GPU provides four times the performance of two AMD Opteron 6220 running an optimized reference code. The same advantage is achieved in terms of energy-efficiency. In terms of normalized total cost of acquisition (TCA), GPU-based clusters match conventional large-scale LQCD systems. Contrary to those, however, they can be scaled up from a single node. Examples of large GPU-based systems are LOEWE-CSC and SANAM. On both, CL2QCD has already been used in production for LQCD studies.