Gas exchange, blood acid-base balance and mechanical muscle efficiency during incremental levels of exertion in young healthy individuals

In this study we have evaluated the changes in gas exchange variables, blood acid-base balance and the mechanical efficiency of muscle in healthy young men during an incremental exercise test. Twenty-six healthy men: age 22.1 +/- 1.4 (mean +/- SD) years, body mass 73.6 +/- 7.4 kg, height 179 +/- 8 cm, were subjects in this study. The subjects performed an incremental exercise test on a cycloergometer at a pedalling rate of 70 rev.min-1. The exercise test started at a power output of 30 W, followed by an increase of power output by 30 W every 3 minutes. Gas exchange variables were measured continuously (breath by breath). Antecubital blood samples for acid-base balance variables and plasma lactate concentration [La]pl were taken at the end of each 3-minute step. The lactate threshold (LT) in this study was defined as the highest power output above which [La]pl showed a sustained increase of > 0.5 mmol.l-1.step-1. The power output at LT amounted to 127 +/- 28 W. It corresponded to 45% of the maximal power output (MPO) reached at maximal oxygen uptake (VO2 max). The oxygen uptake at the LT amounted to 1734 +/- 282 ml.min-1 and corresponded to 48% of VO2 max (3726 +/- 363 ml.min-1). The minute ventilation at the LT amounted to 47.8 +/- 7.5 l, and its increase to the level of 125.7 +/- 19.7 l reached at the MPO was obtained mainly by intensification of breathing frequency from 23.8 +/- 3.31.min-1 to 43 +/- 5.91.min-1, for LT and MPO respectively. Analysis of the changes in PETCO2 during the incremental exercise test showed significant differences between subjects. One could recognise a group of subjects (n = 8) with high values of PETCO2 (above 45 mmHg) and a group of subjects (n = 8) with lower values of PETCO2 (below 43 mmHg). However, no significant differences in exercise tolerance, expressed by the level of MPO and maximal oxygen uptake, were found between those groups of subjects. The mechanical efficiency calculated on the basis of power output/net oxygen uptake ratio during cycling at a power output of 60 W amounted to 24.1 +/- 3.8 percent, at the LT 25.8 +/- 2.1%, whereas at the maximal power output a significant (p < 0.01) drop in muscle efficiency occurred, to the value of 23.1 +/- 1.6%. This drop in muscle efficiency occurring at the MPO may be an important factor limiting exercise tolerance when performing high power output exercise. In conclusion: The above presented data illustrate the physiological responses to incremental exercise and the level of exercise tolerance, which may serve as a reference point for the population of healthy, young physically active Polish students.     

Error-dependency relationships for the na?ve Bayes classifier with binary features.

We derive a tight dependency-related bound on the difference between the Na?ve Bayes (NB) error and Bayes error for two binary features and two equiprobable classes. A measure of discrepancy of feature dependencies is proposed for multiple features. Its correlation with NB is shown using 23 real data sets.     

A system of automatic control of motion speed of a city transport system electric train

An adaptive system of automatic control of the electric train motion speed permitting one to take into account the specific requirements imposed by the control object is proposed. Such requirements include limitation of the level of the index of the movement smoothness during the transient movement modes characterizing the degree of comfort for the passengers, as well as the possibility of implementing accelerations (delays) differing from nominal ones. The methods of automatic control and simulation modeling theory are used while solving the problem. The required control quality is provided by the fact that the input drive signal for the speed control circuit is smoothed by means of an operator, which is based on integration with saturation. The speed control circuit parameters are determined as a result of solving the task of the parametrical synthesis. The result of the work is an operation algorithm of the automatic control system (ACS) of the electric train speed, application of which provides limitation of the level of the movement smoothness index within the transient movement modes. As a result of solving the task of the parametrical synthesis the analytical dependences are also obtained connecting the ACS control law parameters with the train weight, use of which provides independence of the control quality on the train weight.     

Analyzing the Economic Effect of Mobile Network Sharing in Korea

As mobile markets in most developed countries are rapidly coming close to saturation, it is increasingly challenging to cover the cost of providing the network, as revenues are not growing. This has driven mobile operators, thus far mostly involved in facility‐based competition, to turn their attention to network sharing. There exist various types of mobile network sharing (MNS), from passive to active sharing. In this paper, we propose a model, based on the supply‐demand model, for evaluating the economic effects of using six types of MNS. Our study measures the economic effects of employing these six types of MNS, using actual WiBro‐related data. Considering lower service price and expenditure reduction, the total economic effect from a year's worth of MNS use is estimated to be between 513 million and 689 million USD, which is equal to three to four percent of the annual revenue of Korean mobile operators. The results of this study will be used to support the establishment of a MNS policy in Korea. In addition, the results can be used as a basic model for developing various network sharing models.     

Kinetic and structural characterization of thermostabilized mutants of human carbonic anhydrase II

Carbonic anhydrases (CAs) are ubiquitous enzymes that catalyze the reversible hydration/dehydration of carbon dioxide/bicarbonate. As such, there is enormous industrial interest in using CA as a bio-catalyst for carbon sequestration and biofuel production. However, to ensure cost-effective use of the enzyme under harsh industrial conditions, studies were initiated to produce variants with enhanced thermostability while retaining high solubility and catalytic activity. Kinetic and structural studies were conducted to determine the structural and functional effects of these mutations. X-ray crystallography revealed that a gain in surface hydrogen bonding contributes to stability while retaining proper active site geometry and electrostatics to sustain catalytic efficiency. The kinetic profiles determined under a variety of conditions show that the surface mutations did not negatively impact the carbon dioxide hydration or proton transfer activity of the enzyme. Together these results show that it is possible to enhance the thermal stability of human carbonic anhydrase II by specific replacements of surface hydrophobic residues of the enzyme. In addition, combining these stabilizing mutations with strategic active site changes have resulted in thermostable mutants with desirable kinetic properties.     

End-to-end reliability of service oriented applications

As organizations move towards adopting a service oriented architecture that permits the coexistence of multiple technology environments, an increasing number of applications will be developed through the assembly of existing software components with standard web service interfaces. These components with web service interfaces may be available in-house, or may be supplied or hosted by external vendors. The use of multiple services, possibly utilizing different technologies, providers, locations, and sources, has implications for the end-to-end reliability of these applications to support a business process. Selecting the best service for individual tasks in a business process does not guarantee the most effective overall solution, particularly if criteria other than functional characteristics are employed. This paper examines reliability issues associated with applications developed within service oriented architecture. It develops a measure for deriving end-to-end application reliability, and develops a model to help select appropriate services for tasks in the business process which accommodate the redundant and overlapping functionality of available services and planned redundancy in task support to satisfy the reliability requirement of the resulting application. A genetic algorithm approach is adopted to select promising services to assemble the application using end-to-end reliability as the criterion of interest. An application to a real-world business process illustrates the effectiveness of the approach.