Combining Single and Packet-Ray Tracing for Arbitrary Ray Distributions on the Intel MIC Architecture.

Wide-SIMD hardware is power and area efficient, but it is challenging to efficiently map ray tracing algorithms to such hardware especially when the rays are incoherent. The two most commonly used schemes are either packet tracing, or relying on a separate traversal stack for each SIMD lane. Both work great for coherent rays, but suffer when rays are incoherent: The former experiences a dramatic loss of SIMD utilization once rays diverge; the latter requires a large local storage, and generates multiple incoherent streams of memory accesses that present challenges for the memory system. In this paper, we introduce a single-ray tracing scheme for incoherent rays that uses just one traversal stack on 16-wide SIMD hardware. It uses a bounding-volume hierarchy with a branching factor of four as the acceleration structure, exploits four-wide SIMD in each box and primitive intersection test, and uses 16-wide SIMD by always performing four such node or primitive tests in parallel. We then extend this scheme to a hybrid tracing scheme that automatically adapts to varying ray coherence by starting out with a 16-wide packet scheme and switching to the new single-ray scheme as soon as rays diverge. We show that on the Intel Many Integrated Core architecture this hybrid scheme consistently, and over a wide range of scenes and ray distributions, outperforms both packet and single-ray tracing.

In-frame triplet deletions in RHD alter the D antigen phenotype.

BACKGROUND: The deletion of three adjacent nucleotides in an exon may cause the lack of a single amino acid, while the protein sequence remains otherwise unchanged. Only one such in-frame deletion is known in the two RH genes, represented by the RHCE allele ceBP expressing a "very weak e antigen." STUDY DESIGN AND METHODS: Blood donor samples were recognized because of discrepant results of D phenotyping. Six samples came from Switzerland and one from Northern Germany. The molecular structures were determined by genomic DNA nucleotide sequencing of RHD. RESULTS: Two different variant D antigens were explained by RHD alleles harboring one in-frame triplet deletion each. Both single-amino-acid deletions led to partial D phenotypes with weak D antigen expression. Because of their D category V-like phenotypes, the RHD(Arg229del) allele was dubbed DVL-1 and the RHD(Lys235del) allele DVL-2. These in-frame triplet deletions are located in GAGAA or GAAGA repeats of the RHD exon 5. CONCLUSION: Partial D may be caused by a single-amino-acid deletion in RhD. The altered RhD protein segments in DVL types are adjacent to the extracellular loop 4, which constitutes one of the most immunogenic parts of the D antigen. These RhD protein segments are also altered in all DV, which may explain the similarity in phenotype. At the nucleotide level, the triplet deletions may have resulted from replication slippage. A total of nine amino acid positions in an Rhesus protein may be affected by this mechanism.

Development and laboratory evaluation of a new recombinant ELISA for the serodiagnosis of Lyme disease.

OBJECTIVE: The use of recombinant proteins for serologic testing represents a modern approach for the improved laboratory diagnosis of Lyme disease (LD). The aim of the present study was to develop and evaluate a new recombinant ELISA (RE) for the detection of specific IgG and IgM antibodies against Borrelia burgdorferi. MATERIALS AND METHODS: The RE (Biotest AG, Dreieich, Germany) uses mixtures of recombinant p100, OspC, p18 of Borrelia afzelii and a fusion protein of recombinant internal fragments of the flagellum protein (p41) of Borrelia garinii strain PBi and Borrelia afzelii strain PKo. Serologic testing was performed on a commercially available ELISA processor without pre-absorption of sera. The sensitivity of the RE was determined by testing 226 sera obtained from patients suffering from Lyme disease (stage I: n = 148, stage II: n = 35, stage III: n = 43). Specificity of the RE was evaluated in 1107 sera from healthy blood donors and 275 sera from patients with other infectious diseases or autoimmune illnesses (leptospirosis: n = 53, syphilis: n = 70, toxoplasmosis: n = 60, herpes simplex virus: n = 30, HIV: n = 30; rheumatoid-factor positive: n = 32). In addition, 394 routine samples were prospectively tested in comparison with a well established whole-cell lysate extract ELISA (ENZYGNOST Borreliosis, DadeBehring, Germany) for relative sensitivity and specificity. RESULTS: Overall specificity, determined in 1107 healthy blood donors and 275 sera from patients with other diseases, was 94% for IgG and 91% for IgM. The overall sensitivities in 226 sera obtained from patients suffering from different stages of LD were 67-95%. Moreover, as revealed by prospective testing of 394 routine samples, the relative sensitivity of the RE in comparison with an established whole-cell lysate extract ELISA in the detection of seropositive samples was 81.1% for IgG and 86.5% for IgM with a relative specificity of 98.5% and 93% respectively. The ELISAs showed an overall agreement of 97% for IgG and 92.4% for IgM test results. CONCLUSION: The RE proved to be a reliable and specific screening test in the routine serodiagnosis of LD. In addition, the RE is easy to perform and requires no pre-absorption.