空间网络数据库中最近邻查询的设计与实现

随着无线通讯技术、位置定位技术以及数据库技术的发展,使得能为移动用户提供相关的位置服务.K近邻查询是位置服务的一个重要功能.本文主要研究了空间网络数据库中的K近邻查询.以提出的集成道路网络距离与欧式距离的道路网络框架为基础,提出了一种新的KNN查询算法,通过网络扩展方法计算最近邻(NN),避免了不必要的磁盘I0s,减少了昂贵的最短路径计算,从而有效地提高了算法效率.实验结果说明,在目标点分布比较密集的情况下,算法显著优于其它的算法.     

Single-chamber atrial pacing is better than single chamber ventricular pacing in patients with sick sinus syndrome. Results of long-term follow up in a prospective randomized study

In a study of 225 patients with sick sinus syndrome randomized to single chamber atrial pacing (n = 110) or ventricular pacing (n = 115), atrial pacing was associated with less atrial fibrillation and thromboembolism after 3.3 years follow-up. To determine whether this beneficial effect of atrial pacing is maintained at long-term, follow-up was extended. Follow-up visits were at 3 months, 12 months, and then once every year, and included physical examination, ECG, and pacemaker check-up. After 5.5 years follow-up, all-cause mortality, cardiovascular deaths, atrial fibrillation, thromboembolism, and heart failure were significantly less in the atrial group. AV block occurred in four patients in the atrial group. The beneficial effect of atrial pacing observed previously is enhanced substantially after extended follow-up. Patients with sick sinus syndrome should be treated with an atrial pacing system.     

The combined treatment of patients with digestive tract diseases by the action of the enterosorbent Enterosgel and of the intravascular laser irradiation of the blood

Rehabilitative, medical treatment involved a combined use of enterosorption (the drug Enterosgel) and intravascular laser irradiation of blood (ILIB). The results obtained showed the adopted combined mode of treatment (Enterosgel + ILIB) to have a positive effect on the patients' body. The above alternative while eliminating the remainder from the body promotes an increase in the content of large granule-containing lymphocytes, which events result in restoration of those morphology of those leucocytes having undergone degeneration, with crystallization of saliva getting back to normal. Considering the present health-hazard conditions, negative environmental effects on human organism, the above treatment option is indicated not only to patients having disorders of the alimentary canal but also to those presenting with other pathologies, as well as for preventive and health-promoting purposes.     

Measurement of the ferric diffusion coefficient in agarose and gelatine gels by utilization of the evolution of a radiation induced edge as reflected in relaxation rate images

A method has been developed to determine the diffusion coefficients of ferric ions in ferrous sulphate doped gels. A radiation induced edge was created in the gel, and two spin-echo sequences were used to acquire a pair of images of the gel at different points of time. For each of these image pairs, a longitudinal relaxation rate image was derived. From profiles through these images, the standard deviations of the Gaussian functions that characterize diffusion were determined. These data provided the basis for the determination of the ferric diffusion coefficients by two different methods. Simulations indicate that the use of single spin-echo images in this procedure may in some cases lead to a significant underestimation of the diffusion coefficient. The technique was applied to different agarose and gelatine gels that were prepared, irradiated and imaged simultaneously. The results indicate that the diffusion coefficient is lower in a gelatine gel than in an agarose gel. Addition of xylenol orange to a gelatine gel lowers the diffusion coefficient from 1.45 to 0.81 mm2 h-1, at the cost of significantly lower Rl sensitivity. The addition of benzoic acid to the latter gel did not increase the Rl sensitivity.     

Cystic fibrosis transmembrane conductance regulator (CFTR) anion binding as a probe of the pore

We compared the effects of mutations in transmembrane segments (TMs) TM1, TM5, and TM6 on the conduction and activation properties of the cystic fibrosis transmembrane conductance regulator (CFTR) to determine which functional property was most sensitive to mutations and, thereby, to develop a criterion for measuring the importance of a particular residue or TM for anion conduction or activation. Anion substitution studies provided strong evidence for the binding of permeant anions in the pore. Anion binding was highly sensitive to point mutations in TM5 and TM6. Permeability ratios, in contrast, were relatively unaffected by the same mutations, so that anion binding emerged as the conduction property most sensitive to structural changes in CFTR. The relative insensitivity of permeability ratios to CFTR mutations was in accord with the notion that anion-water interactions are important determinants of permeability selectivity. By the criterion of anion binding, TM5 and TM6 were judged to be likely to contribute to the structure of the anion-selective pore, whereas TM1 was judged to be less important. Mutations in TM5 and TM6 also dramatically reduced the sensitivity of CFTR to activation by 3-isobutyl 1-methyl xanthine (IBMX), as expected if these TMs are intimately involved in the physical process that opens and closes the channel.     

Comparison of the structures and the crystal contacts of trypanosomal triosephosphate isomerase in four different crystal forms

Triosephosphate isomerase (TIM) is a dimeric enzyme consisting of 2 identical subunits. Trypanosomal TIM can be crystallized in 4 different spacegroups: P2(1)2(1)2(1), C2(big cell), C2(small cell), and P1. The P1 crystal form only grows in the presence of 1.4 M DMSO; there are 2 DMSO binding sites per subunit. The structures have been refined at a resolution of 1.83 A, 2.10 A, 2.13 A, and 1.80 A, respectively. In the 4 different spacegroups the TIM subunit can be observed in the context of 7 different crystallographic environments. In the C2 cells, the dimer 2-fold axis coincides with a crystallographic 2-fold axis. The similarities and differences of the 7 subunits are discussed. In 6 subunits the flexible loop (loop 6) is open, whereas in the P2(1)2(1)2(1) cell, the flexible loop of subunit 2 is in an almost closed conformation. The crystal contacts in the 4 different crystal forms are predominantly generated by polar residues in loops. A statistical analysis of the residues involved in crystal contacts shows that, in particular, serines are frequently involved in these interactions; 19% of the exposed serines are involved in crystal contacts.     

Deuteriation of sugar protons simplify NMR assignments and structure determination of large oligonucleotide by the 1H-NMR window approach

The concept of the 1H-NMR window has been developed and examined through a comparative study of NOESY spectra of a self-complementary Dickerson's dodecamer (I) [5'd(5C6G7C8G9A10A11T12T13C-14G15C16G)2(3')], a self-complementary 20-mer (II) [(5'd(1C2G3C4G5C6G7C8G9A10A11T12T13C14G15C16G17C18G19C20G)2(3')] in which the core part consists of the same Dickerson's dodecamer sequence with the flanking CGCG residues at both 3' and 5'-ends, and the partly-deuteriated (shown by underlined CGCG residues at both 3' and 5'-ends) analogous duplex (III) [5'd(1C2G3C4G5C6G7C8G9A10A11T12T13C14G15C16G17C18G19C20G)2(3')] in which the core 5C to 16G part (i.e. 1H-NMR window) consists of the natural Dickerson's dodecamer sequence. A comparison of their NOESY spectra clearly demonstrates that the severe overlap of proton resonances in the larger DNA duplex (II) has been successfully reduced in the partly-deuterated duplex (III) as a result of specific incorporations of the sugar-deuteriated nucleotide residues in the latter [stereospecific > 97 atom % 2H enrichment at H2', H2' and H3' sites, approximately 85 atom % 2H enrichment at H4' and approximately 20 atom % 2H enrichment at H1' (see refs. 10 and 11) in the 20-mer duplex (III)]. These simplifications of the resonance overlap by the deuteriation approach have enabled unequivocal chemical shift assignments and extraction of the quantitative NOE data in the 1H-NMR window part of duplex (III). A comparison of the 12-nucleotide long 1H-NMR window in (III) with that of the 12-mer duplex (I) also shows the scope of studying the changes in conformation and dynamics of the core 12-mer region in (III) which result from the increase of molecular weight due to the DNA chain extension. It is noteworthy that such a study is clearly impossible for the natural 20-mer (II) because of the inherent problem of the overlap of resonances.     

Serum concentrations of neopterin, soluble interleukin 2 receptor, and soluble tumor necrosis factor receptor in Wegener's granulomatosis

OBJECTIVE: To investigate the possible relationship between serum levels of neopterin, soluble tumor necrosis factor-55 receptor (sTNF-55R), and soluble interleukin 2 receptor (sIL-2R) with disease activity in patients with Wegener's granulomatosis (WG). METHODS: Serum neopterin was measured by radioimmunoassay, sTNF-55R and sIL-2R were measured by ELISA in 26 patients with WG. RESULTS: Serum neopterin, sTNF-55R, and sIL-2R were significantly elevated in patients with generalized WG compared with healthy controls. Concentrations of the analytes correlated with disease activity indices in patients without infectious complications. The highest elevations of all 3 variables were observed in patients with intercurrent infections. CONCLUSION: The increased serum levels of neopterin, sTNF-55R, and sIL-2R suggest activation of cellular immunity in WG.     

Rotation fasciocutaneous flap for neglected club feet--a new technique

Skin necrosis and wound problems complicate surgical release of severe neglected clubfoot. This is primarily due to excessive tension on the skin edges and a poor understanding of abnormal vascular anatomy in clubfoot. We report a technique of primary skin closure using a local rotation fasciocutaneous flap using the conventional posteromedial skin incision (Turco). Primary uncomplicated wound healing was achieved within 2 weeks in all 16 rigid and neglected clubfeet (1-7 years) operated by this technique. This flap is scientifically logical, technically easy and ensures primary wound healing.