Distribution of movement time in a target-aiming task

Various characteristics of the distribution of movement time were analyzed for a task involving serial and rotary arm movements aimed at a target. For experimental data generated from five Ss, (a) the distribution tended to be unimodal and more peaked than a normal distribution, (b) the skewness of the distribution was predominantly positive and (c) the standard deviation, in addition to the mean, of movement time was significantly affected by the complexity of the task as measured by Fitts' index of difficulty, while the skewness and the kurtosis were not. For the average results for the Ss, a first-order linear model with the standard deviation of movement time as the dependent variable and Fitts' index as the independent one explained 67% of the variation in standard deviation as compared to 98% of the variation in mean movement time accounted for by the Fitts' index.     

Correction to: Extreme Expansion and Reversible Hydrogen Solubility in h.c.p. Titanium Stabilized by Colossal Interstitial Alloying

Metallurgical and Materials Transactions A -     

Computer-based tests: the impact of test design and problem of equivalency

Nowadays, computerized forms of psychodiagnostic methods are often produced without providing appropriate psychometric characteristics, or without proving equivalency with conventional forms. Moreover, there exist tests with more than one computerized versions, which are mostly designed differently. Study I focused on the impact of test design. It was found that even simple change of color scheme (light stimuli on dark background vs. dark stimuli on light background) had a significant effect on subjects’ performance. Study II examined equivalency of a computerized speeded test, which is broadly used within psychological practitioners in the Czech Republic; this form was found non-equivalent with its conventional counterpart.     

Synthesis, magnetic and optical properties of core/shell Co1-xZnxFe2O4/SiO2 nanoparticles

The optical properties of multi-functionalized cobalt ferrite (CoFe₂O₄), cobalt zinc ferrite (Co_0.5Zn_0.5Fe₂O₄), and zinc ferrite (ZnFe₂O₄) nanoparticles have been enhanced by coating them with silica shell using a modified Stöber method. The ferrites nanoparticles were prepared by a modified citrate gel technique. These core/shell ferrites nanoparticles have been fired at temperatures: 400°C, 600°C and 800°C, respectively, for 2 h. The composition, phase, and morphology of the prepared core/shell ferrites nanoparticles were determined by X-ray diffraction and transmission electron microscopy, respectively. The diffuse reflectance and magnetic properties of the core/shell ferrites nanoparticles at room temperature were investigated using UV/VIS double-beam spectrophotometer and vibrating sample magnetometer, respectively. It was found that, by increasing the firing temperature from 400°C to 800°C, the average crystallite size of the core/shell ferrites nanoparticles increases. The cobalt ferrite nanoparticles fired at temperature 800°C; show the highest saturation magnetization while the zinc ferrite nanoparticles coated with silica shell shows the highest diffuse reflectance. On the other hand, core/shell zinc ferrite/silica nanoparticles fired at 400°C show a ferromagnetic behavior and high diffuse reflectance when compared with all the uncoated or coated ferrites nanoparticles. These characteristics of core/shell zinc ferrite/silica nanostructures make them promising candidates for magneto-optical nanodevice applications.     

Allogenic transplantation of hematopoietic stem cells in the treatment of children with high-risk acute leukemia

BACKGROUND: Most children with acute lymphoblastic leukemia (ALL) and increasing number of children with acute myelogenous leukemia (AML) are currently cured with conventional chemotherapy. Despite of this success there is a subset of patients with high-risk features at diagnosis who are predisposed to a very high risk of relapse. Relapse of AML and early bone marrow relapse of ALL can not be cured by conventional chemotherapy. Allogeneic hematopoietic stem cell transplantation (HSCT) is therapeutic option in these children with very high-risk acute leukemia. METHODS AND RESULTS: Between XI/1989-XII/1996 33 children with acute leukemia (ALL: 22, AML: 11) underwent an allogeneic HSCT from HLA identical related donors (HLA-identical sibling: 30, twin: 1, other HLA-identical relative: 2) at the 2nd Dept. of Pediatrics, University Hospital Motol. Median age of our group was 9 years (1.5-19 y.), boys (n = 23) clearly dominated over the girls (n = 10). The resource of stem cells was bone marrow in 31 children, bone marrow and peripheral blood progenitor cells (PBPC) and PBPC in one child respectively. Myeloablative conditioning regimen varied, consisting of total body irradiation and chemotherapy in 21 children and chemotherapy in 12 children. HSCT was performed in first complete remission of acute leukemia in 9 children (AML: 7, ALL: 2), in second remission in 14 children (AML: 2, ALL: 12), in third remission in 4 children (ALL: 4). Six children underwent HSCT in first partial remission (n = 1) and in second (n = 4) or third (n = 1) chemoresistant relapse. Seven (21%) children died due to post-transplant complications. Nine (28%) children suffered from clinically significant acute graft-versus-host reaction (GVH) and 15% (4/27) children who survived 100 days post-transplant suffered from chronic GVH disease. Relapse of leukemia was diagnosed in 39% (12/31) children. Fourteen (42%) children are alive and well in continuous remission with median follow-up 42 months. CONCLUSIONS: Allogeneic HSCT can cure children with very high-risk acute leukemia in the situations where conventional chemotherapy fails. Relapse of leukemia and GVH reaction are most important causes of post-transplant morbidity and mortality.     

Presence and activity of cytochrome P450 isoforms in minipig liver microsomes. Comparison with human liver samples

The average tritiated water concentration in the indoor air of the occupationally exposed worker's residence (55 Bq m(-3), range 53-59 Bq m(-3)) was higher than the indoor air of control residences (0.7 Bq m(-3), range 0.4-0.8 Bq m(-3)). The worker had an average concentration of tritium-in-urine of 30 kBq L(-1) from chronic intakes of occupational levels of tritiated water. Higher residential concentrations of tritiated water vapor were due to tritium transferred by the worker. Urine samples from an adult co-occupant were collected and had tritiated water concentrations between 89 and 345 Bq L(-1). These concentrations were higher than for individuals (range, 6-32 Bq L(-1)) living in other residences having similar outdoor and indoor concentrations of tritiated water in air. The range of measured tritiated water in urine was in agreement with the prediction of biokinetic models for tritium intakes as recommended by the International Commission on Radiological Protection Publication 56. The tritiated water vapor in the indoor air of the exposed worker's residence contributed about 96% of the daily tritium intakes. The annual average tritium dose to the family member (7 microSv) was well below the International Commission on Radiological Protection Publication 60 recommended annual dose limit (1 mSv) for members of the public. We conclude that, for a few members of the public living near a heavy-water research reactor facility, daily intakes of tritium will relate to tritiated water dispersed by the exposed worker, as well as to tritium transported by the atmosphere from the reactor site.     

The Influence of Vanadium Microalloying on Voids Occurence in Low-Alloyed Cr-Mo Steels After Continuous Casting

We discuss the correlation between segregation of carbide forming elements (vanadium) and void initiation and propagation in low-alloyed Cr-Mo steels. The internal defects are created during blooms straightening in radial type of casting machine due to strain deformation field in the temperature range characteristic for vanadium nitride, carbide or carbonitride precipitation. Based on the statistical analysis (1097 continuously cast blooms) of three low-alloyed Cr-Mo steel variants with different vanadium content, we conclude that the void occurence is strongly associated with the level of vanadium content. The experiments performed by means of microstructural, fractographic investigations and microchemical point analysis proved that preffered areas for void initiation are interdendritic segregations in the core of bloom. We observed vanadium carbide precipitates that are situated close to the cracks, whereas the content of vanadium was 7,5 times more then in an average smelt composition. The further development of defects is connected with fast heating up to the austenization temperature in soaking pit. Our results confirm that marked decrease of defects can be achieved by optimization of production process, i. e. optimized casting speed, steel overheat above the liquidus temperature and/or application of M-EMS.