Computer science

We present a parallel algorithm for k-nearest neighbor graph construction that uses Morton ordering. Experiments show that our approach has the following advantages over existing methods: (1) Faster construction of k-nearest neighbor graphs in practice on multi-core machines.

Synthesis and blending of partially sulfonated polymers polyaniline and PVdF-co-HFP. PEM prepared from blend having 40 wt% sufonated polyaniline produced best results. A methanol permeability of 1.16 Â 10 À8 cm 2 s À1 was obtained. A membrane selectivity ratio of 5.85 Â 10 5 Ss cm À3 was obtained. These results were superior compared to pure sulfonated PVdFco-HFP and Nafion.

Polyglutamyl derivatives of methotrexate (MIX) and 10-deazaaminopterin (10-DAM) containing a total of one through six glutamate residues (Glu residues) were tested as inhibitors of dihydrofolate reductase (DHFR) derived from sheep, chicken, and beef Over. The ability of dihydropteroylpentaglutamate to antagonize the inhibitory activity of these analogues was also studied. The most striking effects were seen with sheep liver DHFR, where polyglutamylation of MIX causes stepwise decreases in the concentration required for 50% inhibition (IQo) with each additional Glu residue until MIX with a total of six Glu residues has an 1C* value '/>that of MIX With 10-DAM the pattern is more complex. The 1C»values increase with addition of Glu residues until a maximum is reached with 10-DAM having a total of three Glu residues which has a value twice that of 10-DAM. 10-DAM with a total of four Glu residues and 10-DAM with a total of five Giùresidues have progressively lower IQo values, the latter being equipment with 10-DAM. With dihydropteroylpentaglutamate as substrate instead of dihy drofolate, the ICjo values are increased 2-to 5-fold for both MIX and 10-DAM derivatives. The results obtained with chicken liver and beef liver DHFR are generally similar to those described for the sheep liver enzyme, but the effects of polyglutamylation are less pronounced. The addition of 0.2 M KC1 to the assay system reduces the differences in inhibitory potency of the polyglutamyl derivatives with all three enzymes tested. We conclude that polyglutamylation can alter the interaction of folate analogues and dihydrofolate with DHFR.

1 Introduction We consider the problem of curve reconstruction that takes a set of sample points on a smooth closed curve C, and requires to produce a geometric graph G having exactly those edges that connect sample points adjacent in C. Obviously, given only the samples, it is ...

We study the minimum enclosing ball (MEB) problem for sets of points or balls in high dimensions. Using techniques of second-order cone programming and "coresets", we have developed (1 + )-approximation algorithms that perform well in practice, especially for very high dimensions, in addition to having provable guarantees. We prove the existence of core-sets of size O(1/ ), improving the previous bound of O(1/ 2 ), and we study empirically how the core-set size grows with dimension. We show that our algorithm, which is simple to implement, results in fast computation of nearly optimal solutions for point sets in much higher dimension than previously computable using exact techniques.

18 F-labeling of the nitroimidazole nucleoside analogue 1-(5-fluoro-5-deoxy-a-D-arabinofuranosyl)-2-nitroimidazole (FAZA) was developed to use this tracer in PET for detection of hypoxia. Parameters for labeling and hydrolysis were optimized with regard to amount of precursor, temperature and time. Labeling yields reached a maximum of 6274% at 100 1C within 5 min using 5 mg of precursor. Hydrolysis was best performed with 1 mL of 0.1 N NaOH at 20 1C for 2 min. Transfer of these conditions to an automated synthesizer resulted in an overall radiochemical yield of 20.773.5%. Absolute yields at EOS were 9.872.3 GBq of [ 18 F]FAZA ready for injection (n ¼ 21; 50 min after EOB; irradiation parameters: 35 mA, 60 min). Thus, a convenient approach suitable for large-scale production of [ 18 F]FAZA was developed by an automated process. r

An 8-month-old female infant presented with vesicular lesions on the right lower extremity for 2 days. There were grouped vesicles on an erythematous base over right leg, dorsum of right foot and sole, distributed in the L5 and S1 dermatomes . The baby was irritable, but afebrile. The baby was born at term and by normal vaginal delivery and her birth weight was 2.5 kg. Postnatal period was uneventful. Her developmental milestones were within normal range. There was history of maternal varicella infection during 3rd months of pregnancy. Tzanck smear from the lesions showed mononuclear and multinucleated acantholytic cells with ground glass nuclei, consistent with Tzanck cells. Based on history and clinical findings, diagnosis of Herpes zoster was made. The infant was treated symptomatically with topical calamine lotion and oral antipyretic. The lesions crusted in 1 week and resolved completely in 2 weeks, without any sequelae.

Stereospecific synthesis of 1-a-D D-(2-deuteroribofuranosyl)-2-nitroimidazole (2 0 -[ 2 H]-a-AZR) is reported. This, deuteration was independent of the configuration of C-2 0 -OH group (arabinose or ribose) in sugar moiety of starting molecules. Slightly better yield (>37%) of the deuterated product, 6, from arabinosyl precursor in comparison to corresponding ribose precursor (29%) was obtained which may reflect better stereochemical availability of C-2 0 -OH in arabinose during oxidation.

The present work describes the synthesis of the b b-isomer of 1-a a-D-(5-deoxy-5-iodoarabinofuranosyl)-2-nitroimidazole (IAZA). Radioiodinated IAZA ( 123 I-IAZA) has been extensively studied as a radiopharmaceutical for the diagnosis of regional and/or focal tissue hypoxia in a variety of clinical pathologies. The b b-anomer of IAZA, 1-b b-D-(5-deoxy-5-iodoarabinofuranosyl)-2-nitroimidazole (b b-IAZA, 1), was synthesized via an unconventional route starting from 1-b b-D-(ribofuranosyl)-2-nitroimidazole (AZR), with a change of configuration at the C-2-position to afford 1-b b-D-(arabinofuranosyl)-2-nitroimidazole (b b . Nucleophilic iodination of the 5-Otoluenesulfonyl-2,3-di-O-acetyl precursor of b b-AZA, 9, followed by deprotection, afforded 1 in satisfactory yield. b b-IAZA (1) was also synthesized from 7 using molecular iodine and triphenylphosphine.