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PubMed2002

A management information system to study space diets.

A management information system (MIS), including a database management system (DBMS) and a decision support system (DSS), was developed to dynamically analyze the variable nutritional content of foods grown and prepared in an Advanced Life Support System (ALSS) such as required for long-duration space missions. The DBMS was designed around the known nutritional content of a list of candidate crops and their prepared foods. The DSS was designed to determine the composition of the daily crew diet based on crop and nutritional information stored in the DBMS. Each of the selected food items was assumed to be harvested from a yet-to-be designed ALSS biomass production subsystem and further prepared in accompanying food preparation subsystems. The developed DBMS allows for the analysis of the nutrient composition of a sample 20-day diet for future Advanced Life Support missions and is able to determine the required quantities of food needed to satisfy the crew's daily consumption. In addition, based on published crop growth rates, the DBMS was able to calculate the required size of the biomass production area needed to satisfy the daily food requirements for the crew. Results from this study can be used to help design future ALSS for which the integration of various subsystems (e.g., biomass production, food preparation and consumption, and waste processing) is paramount for the success of the mission.

Biomass↗
PubMed2000

[Determination of chiral purity of synthetic amino acids by high performance liquid chromatography].

A series of synthetic beta-heterocyclic and beta-naphthyl alanine and aromatic substituted phenylalanine were separated by reversed-phase HPLC as diastereomeric derivatives obtained after derivatization with (1-fluoro-2,4-dinitrophenyl)-5-L-valinamide (FDNP-Val-NH2). The separation was performed with gradient elution. The mobile phase A was acetonitrile containing 0.1% trifluoroacetic acid and mobile phase B was 0.1% trifluoroacetic acid. According to the hydrophobicity of the side chain of the amino acids, 6 different linear gradient programs were selected and all gradients completed in 20 minutes. Good resolution was obtained for neutral amino acids. All L-L diastereomer of neutral amino acids (the first letter refers to the configuration of amino acid) were eluted faster than the D-L diastereomer with retention times less than 16 minutes. In the same gradient eluting system, the hydrophobic parameter (pi value) and the position of the substituent in benzene ring of phenylalanine also influence the retention time of diastereomers. Usually the retention time of the phenylalanine with a large pi value was longer than that with a small one. Among the three phenylalanines containing the same substituent, compounds with the substituent in 2-postion gave the shortest retention time. In the case of basic amino acids, the D-L diastereomers eluted prior to the L-L diastereomers and showed rather poor resolution. The chiral purity (ee) of the optical active amino acids (synthetic DL-amino acids after resolution by different enzymes) were calculated with the equation as follows: ee = [[A(L- or D-) - A(D- or L-)]/[A(L-) + A(D-)]] x 100% (L- or D-), A: peak area; L-, D-: amino acid diastereomer.

Amino Acids↗
PubMed1992

Ownership and organizational performance. A comparison of technical efficiency across hospital types.

Using a national data base of urban hospitals, the effect of ownership (government, nonprofit, and for-profit) on the technical efficiency of hospitals was examined. Efficiency scores were computed using a method called data envelopment analysis. Controlling for environmental and hospital characteristics, for-profit hospitals were found somewhat less frequently and government hospitals consistently more frequently in the efficient category. When examining highly inefficient hospitals as a percentage of those receiving inefficient scores, for-profit hospitals appeared to be highly inefficient relative to the other ownership forms. Government and nonprofit hospitals were somewhat indistinguishable from one another regarding their percentages of highly inefficient scores. For-profit hospitals also tended to use supply and capital asset (hospital size) inputs less efficiently, and service and labor inputs more efficiently than hospitals in the other ownership categories.

Efficiency↗
PubMed1992

[SCAN program for structural analysis of linear polysaccharides based on 13C-NMR spectral data using personal computers].

A programme SCAN was elaborated for the 13C NMR--based structural analysis of regular polysaccharides, which represents our earlier programme (Lipkind G.M. et al. Carbohydr. Res. 1988. V. 175. No 1. P. 59-75) modified for IBM-PC-compatible personal computers. SCAN was successfully applied for the structural elucidation of 24 polysaccharides of bacterial origin. Optimal combinations of the computer-assisted method with other approaches for analysis of carbohydrates and scopes of application of the programme are discussed.

Carbohydrate Conformation↗
PubMed1991

Metabolism of carbamazepine: evidence of autoinduction in Chinese.

To investigate the autoinduction of carbamazepine (CBZ) metabolism in Chinese, eleven healthy male volunteers joined in this study. There were two phases of drug administration with a wash-out interval of one month, 400 mg CBZ was taken orally in single-dose phase, and 200 mg three times per day were given for seven days in multiple-dose phase. Plasma samples were obtained in series of time after the last dose of drug in each phase. CBZ concentrations were determined by a high pressure liquid chromatography method. A non-linear regression program was applied in a personal computer to estimate the pharmacokinetic parameters. The average CBZ half-lives in single- and multiple-dose phases were 50.1 +/- 12.1 (mean +/- SD) hours and 26.1 +/- 4.2 hours and the clearances were 16.4 +/- 3.3 ml/kg/h and 45.3 +/- 23.4 ml/kg/h respectively, both with significant differences (p less than 0.005). There is evidence to support the presumption of autoinduction in Chinese.

Adult↗
PubMed1991

Open-loop feedback control of serum bentazepam concentrations and Bayesian estimation in multiple dosage regimens in patients.

The time course of serum levels of bentazepam was studied in 10 patients receiving anxiolytic agent orally at a dose of 25 mg on multiple dosage regimens with dosage intervals of 8 and 12 h. Using the methods of "open-loop feedback control", no linear regression programs and Bayesian estimation, it was possible to establish the best estimates of the pharmacokinetic parameters corresponding to the single-compartment model for each patient from all their data relating to the serum levels obtained after the first dose and after multiple dosing with different regimens. The application of the Kruskal Wallis test showed that there were only statistical differences for the absorption constant, determined with and without Bayesian estimation. However, no statistically significant differences were found on comparing the experimentally obtained serum levels with the corresponding theoretical values calculated independently for each patient from the parameters established with and without Bayesian estimation. As population pharmacokinetic parameters of bentazepam, the following were established: Ka = 2.330 +/- 0.665 l/h; Vd = 1.209 +/- 0.546 l/Kg and Ke = 0.160 +/- 0.118 l/h, corresponding to a mean value for the elimination half-life of 4.33 h.

Administration, Oral↗
PubMed1991

A heuristic approach to nurse scheduling in hospital units with non-stationary, urgent demand, and a fixed staff size.

We present a practical approach to personnel scheduling problems arising in hospital units with demand that is of an urgent nature, cannot be backlogged, and is highly dependent on the time of day. A simple rounding heuristic is combined with a simulated annealing algorithm to obtain near-optimal solutions to large linear integer programming models of these personnel scheduling problems in a reasonable amount of time on a personal computer. The models are designed to complement the current state-of-the-art of commercially available hospital staff scheduling systems.

Algorithms↗
PubMed1991

[Analysis of the circadian rhythm of pain].

An electronic pulp tester was used to study the stimulus threshold in human teeth of 28 healthy volunteers for 1,5-4 days and the duration of local anaesthesia in 55 patients with caries. Rhythm analysis was performed with a non-linear fitting program on an IBM computer (PHARMFIT); in 21 out of the 28 volunteers significant daily rhythms in stimulus threshold could be detected. In the patients the maximum duration of local anaesthesia was after drug application at 2 p.m.

Adolescent↗
PubMed1991

[Demographic and economic trends in medical schemes--a time series analysis].

A time series analysis was performed on medical scheme statistics with the aim of determining current and future demographic and economic trends. This would enable one to reach a better perspective on the current and future financial dilemma presently experienced by medical schemes. Data for the period 1978-1986 was analysed on a computer, using the Statgraphics program. The linear trend projection method, based on the regression analysis technique was used. Real values were determined by deflating nominal values against the consumer price index with 1980 as base year. There are at present 253 medical schemes in operation. Approximately 16 per cent of the economically active population are members of medical schemes. White members increased by only 3.8 per cent during the period 1978-1986, in comparison to the 87.1 per cent by black members. The beneficiaries represent 19 per cent of the total population; black beneficiaries increased by 422.1 per cent, while Whites increased only fractionally by 0.73 per cent. Membership fees increased by an average of R8.08/member/month or R1.72/member/month in real terms. Ninety five per cent of the income of medical schemes was derived from membership fees. The average real growth rate of income was 8.4 per cent, while net assets increased by only 3 per cent. An average deficit of R11.02 million/year is estimated for the recommended reserve funds in real terms. The greatest proportion of benefits paid was for professional services (47.4 per cent) followed by medicine (26.3 per cent) and hospital services (19.8 per cent). The real growth rate for benefits paid was 8.6 per cent per year.(ABSTRACT TRUNCATED AT 250 WORDS)

Economics↗
PubMedDate not supplied

Quantitative multiresidue analyses for volatile organics in water and milk, using a fused silica open-tubular wide-bore capillary column and automated headspace gas chromatography.

A modified multiresidue capillary gas chromatographic (GC) procedure has been developed using automated headspace sampling and a wide-bore fused silica open-tubular (FSOT) capillary column for the determination of volatiles in water and milk. Compounds are quantitated by the method of standard additions. An IBM System 9000 computer with the CAPMC3 chromatographic applications package and a BASIC linear regression program are used for data reduction. Data are presented for solutions prepared by fortifying water and milk with volatile solvents such as acetone, methyl ethyl ketone, benzene, methylene chloride, and chloroform, which are commonly used in the manufacture of packaging materials and adhesives. The wide-bore FSOT capillary columns showed dramatically improved detection for certain compounds, compared with normal-bore capillary GC columns. Data presented for various chemicals demonstrate the improved limits of detection from the use of automated headspace gas chromatography with wide-bore capillary columns and flame ionization detection.

Animals↗
PubMedDate not supplied

[A low-frequency magnetic field and regeneration of bony tissue of the jaw: optimization of exposure parameters (experimental research)].

The optimal parameters of exposure to low-frequency magnetic field were chosen in experiments with 132 rats, using a simplex method of the extreme exposure. These parameters are as follows: 22 mT induction, length of exposure 20 min, pulse regimen. Exposure in such conditions provides the most effective influence of magnetic field on the reparative osteogenesis and mineralization processes and on the subsequent organic restructuring of the bone at the site of the mandibular standard defect.

Animals↗