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61.
RE Droleskey PJ Holman KA Waldrup DE Corrier GG Wagner 《Canadian Metallurgical Quarterly》1993,79(3):424-434
Babesia odocoilei continuously cultured in white-tailed deer (Odocoileus virginianus) erythrocytes was examined by transmission and scanning electron microscopy. Merozoites, trophozoites, intermediate-stage forms, and dividing forms were observed. Merozoites possessed a single nucleus, inner membrane complex, rhoptries, free ribosomes, rough endoplasmic reticulum, and single membrane-bound vesicles. Trophozoites lacked an inner membrane complex and rhoptries. Intermediate stages were characterized by distinct segments of inner membrane complex. Dividing forms ranged from cells with an elongated nucleus to mature daughter cells joined by a ringlike structure. Babesia odocoilei was characterized by its close proximity to the erythrocyte membrane, membranous structures resembling feeding organelles, and reproduction via a method resembling budding sensu stricto. 相似文献
62.
The recent novel temperature-modulated differential scanning calorimetry (TA Instruments MDSCTM) technique has been applied
to the measurement of thermal properties of GexAsyS60 chalcogenide glasses in the glass transition region in bulk glasses
and in their thin films. The reversing and non-reversing heat flows through the glass transformation region during both heating
and cooling schedules were measured and the values of the parameters, Tg, ΔH, Cp and ΔCp, which characterize the thermal events
in the glass transition region, were determined. The structurally determined parameters, Tg, ΔH, Cp and ΔCp, reveal significant
changes with composition because in the GexAsyS60 glasses the average coordination number, 〈r〉, increases from 2.4 to 2.8
with increasing x from 0 to 40 at% Ge. A maximum in Tg, ΔH and Cp and a minimum in the heat capacity change, ΔCp, at Tg occur
near the composition for which x≈30 at% Ge. These extrema which appear in both films and bulk glasses are ascribed to a change
in the network function of Ge atoms replacing As atoms in a covalent network. Recent structural models for chalcogenide glasses
have been considered to explain the observed thermal properties.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
63.
D Knaack ME Goad M Aiolova C Rey A Tofighi P Chakravarthy DD Lee 《Canadian Metallurgical Quarterly》1998,43(4):399-409
Bacteroides fragilis strains isolated from different sources, i.e. 1 strain (AA1) from an aquatic environment, 1 strain from normal flora (118310) and the type strain (ATCC 25285) originally isolated from clinical material, were analysed for both cell envelope proteins composition and surviving under oxidative stress starvation. All strains examined showed a similar survival response when cultured in drinking water with a ten-fold decrease in viable counts per day during the 7 days of analysis. The outer membrane protein (OMP) profiles of all strains were quite similar during the stress period as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). However, the periplasmic proteins of the strain 118310 showed two protein bands at 48 and 58 kDa, respectively, that were absent in the strains AA1 and ATCC 25285 during the incubation period in potable water. Whole cells and periplasmic 35S-labelled proteins from bacteria cultured in drinking water showed a significant increase in proteins at 16, 18, 24, 26, 35, 48, and 58 kDa and 18, 22, 24, 48, 58, and 70 kDa, respectively, in all strains when compared to cells grown in BHI-PRAS media as detected by autoradiography following SDS-PAGE. These data suggest that B. fragilis may have a synthesis mechanism that allows them to adapt to adverse environments. 相似文献
64.
The computation of covariance and correlation matrices are critical to many data mining applications and processes. Unfortunately
the classical covariance and correlation matrices are very sensitive to outliers. Robust methods, such as Quadrant Correlation
(QC) and the Maronna method, have been proposed. However, existing algorithms for QC only give acceptable performance when
the dimensionality of the matrix is in the hundreds; and the Maronna method is rarely used in practice because of its high
computational cost. In this paper we develop parallel algorithms for both QC and the Maronna method. We evaluate these parallel
algorithms using a real data set of the gene expression of over 6000 genes, giving rise to a matrix of over 18 million entries.
In our experimental evaluation, we explore scalability in dimensionality and in the number of processors, and the trade-offs
between accuracy and computational efficiency. We also compare the parallel behaviours of the two methods. From a statistical
standpoint, the Maronna method is more robust than QC. From a computational standpoint, while QC requires less computation,
interestingly the Maronna method is much more parallelizable than QC. After a thorough experimentation, we conclude that for
many data mining applications, both QC and Maronna are viable options. Less robust, but faster, QC is the recommended choice
for small parallel platforms. On the other hand, the Maronna method is the recommended choice when a high degree of robustness
is required, or when the parallel platform features a large number of processors (e.g., 32). 相似文献
65.
This study investigated the impact of weblog use on individual learning in the context of university senior-level business education. As an emergent form of personal communication, weblogs enable people to publish their thoughts as webpages, and to share information and knowledge. Recognizing the potential impact of weblogs on knowledge expression and sharing, this research sought to empirically examine whether the continuous use of weblogs as online learning logs would affect student learning performance. The assumption was that effective use of weblogs promoted the constructivist models of learning by supporting both cognitive and social knowledge construction, and by reinforcing individual accountability in learning. Results from an Information Systems undergraduate course with 31 participants indicated that the performance of students' weblogs was a significant predictor of the learning outcome (while traditional coursework was not). Moreover, individuals' cognitive construction effort to build their own mental models and social construction effort to further enrich/expand knowledge resources appeared to be two key aspects of the constructivist learning with weblogs. Our results imply the potential benefit of using weblogs as a knowledge construction tool and a social learning medium 相似文献
66.
67.
RT Loder RN Hensinger PD Alburger DD Aronsson JH Beaty DR Roy RP Stanton R Turker 《Canadian Metallurgical Quarterly》1998,18(5):630-636
We reviewed 32 children with 41 radiation-therapy associated slipped capital femoral epiphyses (RTASCFE). Ten were from the authors' institutions and 22 from the literature. Gender distribution was equal. The age at diagnosis of the malignancy was 4.3 +/- 3.1 years; the amount of radiation was 4,240 +/- 1,445 rads. Children with RTASCFE presented younger (10.4 +/- 3.2 years) than a routine SCFE. The average symptom duration was 5 +/- 6 months. Children with RTASCFE are usually thin (median weight, 10th percentile) in contrast to children with typical SCFE, who are usually obese (<95th percentile). The majority (82%) of the slips were mild, compared to routine SCFEs (approximately 50%); 28% were bilateral. There was a positive linear relationship between the age at presentation of the SCFE and the age at diagnosis of the malignancy; there was a negative linear relationship between the age at presentation of the SCFE and the amount of radiation therapy. 相似文献
68.
DD De La Tour D Raccah MF Jannot T Coste C Rougerie P Vague 《Canadian Metallurgical Quarterly》1998,41(9):1080-1084
The purpose of this study is to clarify the volume effect of epidural saline injection 20 min after spinal anesthesia. Thirty patients undergoing combined spinal and epidural anesthesia for orthopedic surgery were randomly divided into two groups: a control group (n = 15) and a saline group (n = 15). In the control group, 2% lidocaine 3 ml with 0.4% tetracaine was injected into the subarachnoid space from L 4-5 interspace using Durasafe (Becton Dickinson, USA) and saline was not injected into the epidural space. In the saline group, saline 10 ml was injected through an epidural catheter 20 min after spinal anesthesia. The levels of analgesia 20 min after spinal anesthesia were not significantly different between the groups. However, the levels of analgesia 3, 5, 10, 40 and 100 min after epidural saline injection in the saline group were significantly higher than those in the control group (P < 0.05). The highest analgesic level was obtained 10 min after epidural saline injection and reached to T 4.3 +/- 1.1. In conclusion, epidural saline injection increases the analgesic level 20 min after spinal anesthesia because of the volume effect. 相似文献
69.
The mechanism of decline in viremia following acute infection with HIV is unknown. To characterize this process virologically, the expression of viral RNAs was analyzed in samples of peripheral blood mononuclear cells (PBMCs) from a patient who experienced a 100-fold decline in plasma viremia over a 13-day period prior to the initiation of antiretroviral therapy. Cell-associated viral RNA declined in association with the decline in plasma virus. During the initial 7 days of observation, plasma viremia declined more than 10-fold with no change in the ratio of unspliced to multiply spliced mRNAs. The efficiency of viral gene expression did not decline during the study period and varied from 380 to 2800 unspliced RNA copies per productively infected cell. Together, these data indicate no change in the relative proportion of cells in late- and early-stage gene expression during the initial decline and provide evidence against shortening of the viral replication cycle by immune surveillance. However, the prevalence of productively infected cells declined markedly during the 13 days of observation, from 1 in 250 to 1 in 25,000 PBMCs. These data are compatible with depletion of available target cells during the initial decline in viremia. As the level of plasma virus stabilized after 8 days of observation, the ratio of unspliced to multiply spliced mRNAs rose; this rise was due to a relatively greater decline in multiply spliced mRNA. These data suggest the possible onset of a blockade to new infection events (for example, by neutralizing antibody or chemokines), causing an increase in the relative proportion of cells in late-stage gene expression. They may also be explained, however, by the persistence of cell-associated virions together with the near disappearance of productively infected cells from the circulation. 相似文献
70.
PS Frenette S Subbarao IB Mazo UH von Andrian DD Wagner 《Canadian Metallurgical Quarterly》1998,95(24):14423-14428
The adhesive mechanisms allowing hematopoietic progenitor cells (HPC) homing to the bone marrow (BM) after BM transplantation are poorly understood. We investigated the role of endothelial selectins and vascular cell adhesion molecule-1 (VCAM-1) in this process. Lethally irradiated recipient mice deficient in both P-and E-selectins (P/E-/-), reconstituted with minimal numbers (=5 x 10(4)) of wild-type BM cells, poorly survived the procedure compared with wild-type recipients. Excess mortality in P/E-/- mice, after a lethal dose of irradiation, was likely caused by a defect of HPC homing. Indeed, we observed that the recruitment of HPC to the BM was reduced in P/E-/- animals, either splenectomized or spleen-intact. Homing into the BM of P/E-/- recipient mice was further compromised when a function-blocking VCAM-1 antibody was administered. Circulating HPC, 14 hr after transplantation, were greatly increased in P/E-/- mice treated with anti-VCAM-1 compared with P/E-/- mice treated with just IgG or wild-type mice treated with either anti-VCAM-1 or IgG. Our results indicate that endothelial selectins play an important role in HPC homing to the BM. Optimal recruitment of HPC after lethal doses of irradiation requires the combined action of both selectins and VCAM-1 expressed on endothelium of the BM. 相似文献