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Results for “data reproducibility”

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At least 289 records · Page 16Linked to original sources
PubMed2006

Characteristics of inhalable particulate matter concentration and size distribution from power plants in China.

In this investigation, the collection efficiency of particulate emission control devices (PECDs), particulate matter (PM) emissions, and PM size distribution were determined experimentally at the inlet and outlet of PECDs at five coal-fired power plants. Different boilers, coals, and PECDs are used in these power plants. Measurement in situ was performed by an electrical low-pressure impactor with a sampling system, which consisted of an isokinetic sampler probe, precut cyclone, and two-stage dilution system with a sample line to the instruments. The size distribution was measured over a range from 0.03 to 10 microm. Before and after all of the PECDs, the particle number size distributions display a bimodal distribution. The PM2.5 fraction emitted to atmosphere includes a significant amount of the mass from the coarse particle mode. The controlled and uncontrolled emission factors of total PM, inhalable PM (PM10), and fine PM P(M2.5) were obtained. Electrostatic precipitator (ESP) and baghouse total collection efficiencies are 96.38-99.89% and 99.94%, respectively. The minimum collection efficiency of the ESP and the baghouse both appear in the particle size range of 0.1-1 microm. In this size range, ESP and baghouse collection efficiencies are 85.79-98.6% and 99.54%. Real-time measurement shows that the mass and number concentration of PM10 will be greatly affected by the operating conditions of the PECDs. The number of emitted particles increases with increasing boiler load level because of higher combustion temperature. During test run periods, the data reproducibility is satisfactory.

Air Pollutants↗
PubMed1977

Tension generation by threads of contractile proteins.

Threads of contractile proteins were formed via extrusion and their isometric tensions and isotonic contraction velocities were measured. We obtained reproducible data by using a new and sensitive tensiometer. The force-velocity curves of actomyosin threads were similar to those of muscle, with isometric tensions of the order of 10g/cm2 and maximum contraction velocites of the order of 10(-2) lengths/s. The data could be fitted by Hill's equation. Addition of tropomyosin and troponin to the threads increased isometric tension and maximum contraction velocity. Threads which contained troponin and tropomyosin required Ca++ for contraction and the dependence of their isometric tension on the level of free Ca++ was like that of muscle. The dependence of tension or of contraction velocity upon temperature or upon ionic strength is similar for actomyosin threads and muscle fibers. In contrast, the dependence of most parameters which are characteristic of the actomyosin interaction in solution (or suspension) upon these variables is not similar to the dependence of the muscle fiber parameters. The conclusion we have drawn from these results is that the mechanism of tension generation in the threads is similar to the mechanism that exists in muscle. Because the protein composition of the thread system can be manipulated readily and because the tensions and velocities of the threads can be related directly to the physiological parameters of muscle fibers, the threads provide a powerful method for studying contractile proteins.

Actins↗
PubMed1995

Errors in prolonged electrical impedance measurements due to electrode repositioning and postural changes.

Long-term electrical impedance measurements are affected by specific errors. Electrode failure, changes in its impedance due to aging, and postural changes are among the most important. We analyse errors due to electrode replacement and body postural changes. Electrode replacement errors can cause impedance changes up to 5% of basal value. This is one of the most important factors in data reproducibility. Body postural changes also contribute to impedance variations. We have proposed the use of a reference position to carry out impedance measurements as the one that shows the smallest impedance sensitivity to postural changes. In general, we observed that this is achieved with arms and legs slightly separated from the body. We propose the use of a ratio of impedance at two different frequencies to discern the origin of impedance changes, whether from physiological phenomena or postural errors.

Adult↗
PubMed1996

The intra- and interobserver variability of impedance cardiography in patients at rest and during exercise.

We studied the intra- and interobserver variability in the calculation of stroke volume by the impedance technique, using the recently proposed refinements in the electrode configuration and signal processing. Three groups of patients were included in this study: ten stable cardiac patients who underwent a diagnostic heart catheterization, ten patients 24-26 h after coronary artery bypass surgery and ten patients with severe chronic obstructive pulmonary disease (COPD). The first two groups were studied at rest and the COPD group during submaximal exercise. The intra-observer variability was 4.2%, 3.9-4.0% and 6.0-6.9% for the catheterized, surgical and COPD groups, respectively. The interobserver variability was 4.3%, 2.6% and 2.4%, respectively. It is concluded that highly reproducible data can be obtained with the newly proposed impedance technique in patients at rest and exercise which may be comparable or superior to other techniques used in clinical settings.

Cardiac Catheterization↗
PubMed1996

Experience in autologous and allogeneic cord blood banking.

Transplantation and gene therapy offer the hope of treating thousands of individuals with various malignancies and genetic disorders. However, if this approach is to become a reality, there must be readily available sources of suitable HLA-A typed stem cells. Cord blood has been demonstrated to be a suitable source of hematopoietic stem cells that can be used in place of bone marrow stem cells for transplant. However, to implement the widespread clinical use of cord blood, it is necessary to establish both autologous and allogeneic cord blood banks from which stem cell specimens can be obtained. These cord blood banks must be large in size, reflect the ethnic diversity of the patient populations in need, and be financially and logistically feasible. At the Cord Blood Stem Cell Bank at the University of Arizona, we have addressed many of these issues and have taken the necessary steps to create both autologous and allogeneic cord blood banks. We have developed simple, efficient, and reproducible methods for cord blood collection that can be used by any physician without need for previous training. Further, we have developed methodologies to process the cord blood specimen so that samples can be stored in cryovials. This approach to cord blood banking allows for the storage of more than 10,000 independent cord blood specimens in a single liquid nitrogen freezer, reducing the costs and physical space requirements for such a facility. We also have developed the use of electronic integration of laboratory worksheets and controlled rate freezers that permit high laboratory throughput with reduced problems of reproducibility, data entry, and management errors. In terms of allogeneic cord blood banking, we have based our bank on several important assumptions regarding HLA haplotype frequency, ethnic diversity, and the need for less than perfect HLA matching between donor and recipient. These assumptions have allowed us to begin to create an allogeneic cord blood bank that can rapidly attain the size needed for clinical utility without exorbitant costs or time involved. Results of our efforts in autologous and allogeneic cord blood banking are presented (including factors that positively and negatively affect cord blood collection and banking).

Blood Banks↗
PubMed2002

Miniaturization: an overview of biotechnologies for monitoring the physiology and pathophysiology of rodent animal models.

Recent advances in bioengineering technologies have made it possible to collect high-quality reproducible data quantitatively in a wide range of laboratory animal species, including rodents. Several of these technologies are incorporated into a plan called Miniaturization, which aims to design, develop, and maintain rodent animal models to study the pathophysiology and therapy of human diseases. Laser Doppler flowmetry, digital sonomicrometry, bioelectrical impedance, and microdialysis are some of the most widely used methods under the plan because they cause minimal pain and distress, reduce the number of animals used in biomedical research, and allow chronic, nonterminal assessment of physiological parameters in rodents. An overview of each of these technologies and their major applications in rodents used for biomedical research is provided.

Animals↗
PubMed1992

Identification of kinetochore-containing (CREST+) micronuclei in mouse bone marrow erythrocytes.

A methodology for the characterization of kinetochore-containing (CREST+) micronuclei (MN), based on the use of antikinetochore antibodies (derived from CREST patients) and indirect immunofluorescence, was applied to mouse bone marrow erythrocytes. The proposed protocol allows us to obtain fluorescent signals of good quality and highly reproducible data. The clastogenic agent mitomycin C (MMC; 1 mg/kg body wt) and the two aneugenic compounds chloral hydrate (CH; 200 mg/kg body wt) and colchicine (COL; 1 mg/kg body wt) were used to verify the sensitivity of this approach to chemicals with different mechanisms of action. These compounds were tested at a 20 h time interval from treatment and all of them were able to significantly increase (P less than 0.001) the frequency of MN in polychromatic erythrocytes. Of the MN observed in preparations from control animals, 45% were CREST+ and this percentage increased significantly (P less than 0.001) after treatment with CH or COL. On the contrary, only 22% CREST+ MN were found after treatment with MMC (statistical comparison with the control value: P less than 0.001). The CREST characterization of MN induced in vivo in mouse bone marrow allows us to infer the origin of MN formation, thus contributing to the identification of aneugenic agents.

Animals↗
PubMed2006

Commercial optical fibre as TLD material.

This work presents a study of commercial SiO2 optical fibre thermoluminescence (TL) properties as part of the efforts within the Dosimetric Application Project at the Physics Institute of the University of Mexico to develop new radiation detection materials and technologies. The SiO2 commercial optical fibre studied demonstrates useful TL properties and is an excellent candidate for use in TL dosimetry of ionising radiation. The optical fibre's glow curve was observed between 30 and 400 degrees C after exposure to 60Co gamma radiation. One very well-defined glow peak has a maximum at 230 degrees C. The TL response between 100 and 350 degrees C increases monotonically over a wide dose range, from 0.1 Gy to several kGy. It is linear in the range 0.1-3 Gy, which is important for clinical high dose or accident dosimetry. The optical fibre demonstrated high data reproducibility, low residual signal and almost no fading in our study. Moreover, the optical fibre can be re-used several times, after thermal annealing, without any detriment in the dose-response. All these TL characteristics, plus the small size of the 150 microm diameter SiO2 optical fibre, the high flexibility, easy handling and low cost compared with other TL materials, make the commercial optical fibre a very promising TL material for use in research, medicine, industry, reactors, and a variety of other applications.

Dose-Response Relationship, Radiation↗
PubMed1988

Practical instrumentation and common sources of error.

A thorough comprehension of electrodiagnostic equipment is essential to consistently obtain accurate and reproducible data. Unreliable waveform latencies or morphologies may result from inappropriate filter settings, sensitivity comparisons, sweep speeds, interelectrode separation, cathode/anode reversals and stimulus artifact. A low frequency filter with too high a frequency limit may decrease amplitude, shorten peak latency, decrease the negative spike duration, add a phase and increase total waveform duration. A high frequency filter with too low a cut-off may decrease amplitude and prolong onset and peak latencies. Increasing the amplifier's sensitivity may shorten the onset latency of a response. Sweep speeds that are too slow may omit phases, turns or entire potentials when using digital equipment. If the interelectrode separation is inadequate, waveform morphology and amplitude can be altered. Reversing cathode and anode placement affects latency and velocity determinations. Stimulus artifact may obscure a response and its reduction must be understood. Comparing latencies and amplitudes at different instrument settings is never appropriate and can lead to serious errors and misdiagnoses. A naive approach to instrumentation, therefore, is indefensible.

Electrodiagnosis↗
PubMedDate not supplied

Cholecystographic agents and drug binding to plasma albumin.

These studies have identified two separate sites for drug binding to human serum albumin (HSA). They began in an attempt to explain the persistence in plasma of iophenoxic acid, a now abandoned oral cholecystographic agent. This is identical to iopanoic acid save for -OH instead of -NH2 in the 3 position. Iophenoxate has a half-life in man of about three years, compared to several weeks for iopanoate. Both drugs are reversibly bound to HSA with high affinity. Attempts to determine the exact extent of binding were complicated by drug-radiolysis of 125I-labeled contrast agent. Once this was overcome, reproducible data were obtained, which yielded KD at the site of highest affinity of 0.15 microM for iopanoate and 0.013 microM for iophenoxic acid, thus making the latter the most tightly bound of known drugs. We then studied competitive binding, measuring free and bound drug and competitor. From analysis by computerized programs, iophenoxate binds most firmly at site I, iopanoate most firmly at the site II, both showing competition with each other. The findings are in agreement with Sudlow, Birkett, and Wade, who identified separate binding sites with completely different techniques. They have identified a large number of commonly used drugs that bind specifically to one site or the other. It is clear that drug binding to HSA will in the future be considered in reference to specific sites. It is not known at present to what extent the cholecystographic agents may participate in drug-drug interactions related to binding to HSA. The available data will be reviewed.

Binding Sites↗
PubMed2006

Optimization of 3-dimensional imaging of the breast region with 3-dimensional laser scanners.

The anatomic conditions of the female breast require imaging the breast region 3-dimensionally in a normal standing position for quality assurance and for surgery planning or surgery simulation. The goal of this work was to optimize the imaging technology for the mammary region with a 3-dimensional (3D) laser scanner, to evaluate the precision and accuracy of the method, and to allow optimum data reproducibility. Avoiding the influence of biotic factors, such as mobility, we tested the most favorable imaging technology on dummy models for scanner-related factors such as the scanner position in comparison with the torso and the number of scanners and single shots. The influence of different factors of the breast region, such as different breast shapes or premarking of anatomic landmarks, was also first investigated on dummies. The findings from the dummy models were then compared with investigations on test persons, and the accuracy of measurements on the virtual models was compared with a coincidence analysis of the manually measured values. The best precision and accuracy of breast region measurements were achieved when landmarks were marked before taking the shots and when shots at 30 degrees left and 30 degrees right, relative to the sagittal line, were taken with 2 connected scanners mounted with a +10-degree upward angle. However, the precision of the measurements on test persons was significantly lower than those measured on dummies. Our findings show that the correct settings for 3D imaging of the breast region with a laser scanner can achieve an acceptable degree of accuracy and reproducibility.

Breast↗
PubMed1993

The application of flow cytometry to the study of bacterial responses to antibiotics.

Experiments were performed to determine whether a modern flow cytometer could be used to study bacterial populations in suspension, with particular reference to their morphological characteristics and their responses to antibiotics. The FACScan, a commercial benchtop flow cytometer fitted with an air-cooled laser, designed primarily for the study of eukaryotic peripheral blood mononuclear cells, yielded reproducible data relating to bacterial shape and internal architecture. It was sensitive enough to detect changes in bacterial morphology on entry into the growth cycle and after exposure to antibiotics. Antibiotic-induced morphological changes affecting subpopulations of bacteria were sufficiently specific to allow differentiation between antibiotics with different cell-wall enzyme targets. Simultaneously, the effect of such antibiotics on the integrity of the outer cell membrane of Escherichia coli was assessed by measurement of the association of the nucleic acid-binding dye propidium iodide with the bacteria. These experiments demonstrated complex patterns of probable cell-wall leakage, related to the modes of action of the antibiotics. The FACScan is a useful and sensitive tool for the study of the morphology and physiology of bacterial populations in suspension, and is especially applicable to the study of antibiotic action.

Amdinocillin↗
PubMed2006

Accurate and reliable high-throughput detection of copy number variation in the human genome.

This study describes a new tool for accurate and reliable high-throughput detection of copy number variation in the human genome. We have constructed a large-insert clone DNA microarray covering the entire human genome in tiling path resolution that we have used to identify copy number variation in human populations. Crucial to this study has been the development of a robust array platform and analytic process for the automated identification of copy number variants (CNVs). The array consists of 26,574 clones covering 93.7% of euchromatic regions. Clones were selected primarily from the published "Golden Path," and mapping was confirmed by fingerprinting and BAC-end sequencing. Array performance was extensively tested by a series of validation assays. These included determining the hybridization characteristics of each individual clone on the array by chromosome-specific add-in experiments. Estimation of data reproducibility and false-positive/negative rates was carried out using self-self hybridizations, replicate experiments, and independent validations of CNVs. Based on these studies, we developed a variance-based automatic copy number detection analysis process (CNVfinder) and have demonstrated its robustness by comparison with the SW-ARRAY method.

Algorithms↗
PubMed2003

Collective ionic dynamics in the liquid Na-Cs alloy: an ab initio molecular dynamics study.

We present results for several structural and dynamical properties of the liquid Na-Cs alloy. The study has been carried out by means of the orbital-free ab initio molecular dynamics method, combined with local ionic pseudopotentials constructed within the same framework. The results show good agreement with the available experimental data, reproducing the homocoordinating tendency exhibited by this alloy.

Journal Article↗
PubMed2004

Microscopic dynamics in the liquid Li-Na alloy: an ab initio molecular dynamics study.

We present results for several structural and dynamical properties of the liquid Li(1-x)Na(x) alloy. The study has been carried out by means of the orbital-free ab initio molecular dynamics method, combined with local ionic pseudopotentials constructed within the same framework. We obtain good agreement with the available experimental data, reproducing accurately, the strong homocoordinating tendencies exhibited by this alloy. The calculated partial dynamic structure factors exhibit clear side peaks whose frequencies, for q<or=0.25 A(-1), correspond to the hydrodynamic sound dispersion of the binary alloy, whereas for larger q values fast and slow sound modes are identified. The mass ratio in this system, m(Na)/m(Li) approximately 3, is the smallest one so far for which the fast mode is observed.

Journal Article↗
PubMed2004

Pole dynamics for the flierl-petviashvili equation and zonal flow.

Using the method of positions of the complex singularities, we identify a class of new, exact solutions of the Flierl-Petviashvili equation. The solutions are periodic and have the geometry of the zonal flow. We examine the physical properties and find that the solution can reproduce data from experimental observations and numerical simulations.

Journal Article↗
PubMed2006

Clarification of pathway-specific inhibition by Fourier transform ion cyclotron resonance/mass spectrometry-based metabolic phenotyping studies.

We have developed a metabolic profiling scheme based on direct-infusion Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR/MS). The scheme consists of: (1) reproducible data collection under optimized FT-ICR/MS analytical conditions; (2) automatic mass-error correction and multivariate analyses for metabolome characterization using a newly developed metabolomics tool (DMASS software); (3) identification of marker metabolite candidates by searching a species-metabolite relationship database, KNApSAcK; and (4) structural analyses by an MS/MS method. The scheme was applied to metabolic phenotyping of Arabidopsis (Arabidopsis thaliana) seedlings treated with different herbicidal chemical classes for pathway-specific inhibitions. Arabidopsis extracts were directly infused into an electrospray ionization source on an FT-ICR/MS system. Acquired metabolomics data were comprised of mass-to-charge ratio values with ion intensity information subjected to principal component analysis, and metabolic phenotypes from the herbicide treatments were clearly differentiated from those of the herbicide-free treatment. From each herbicide treatment, candidate metabolites representing such metabolic phenotypes were found through the KNApSAcK database search. The database search and MS/MS analyses suggested dose-dependent accumulation patterns of specific metabolites including several flavonoid glycosides. The metabolic phenotyping scheme on the basis of FT-ICR/MS coupled with the DMASS program is discussed as a general tool for high throughput metabolic phenotyping studies.

Arabidopsis↗
PubMed1979

Histometric analysis of human skin in organ culture.

A histometric method is used for the study of human skin kept in organ culture in a defined medium for up to 10 days. The method provides quantitative, reproducible data on tissue survival, cell migration, and cellular differentiation (keratinization). With this method, the behavior of epidermal skin tissue can be effectively monitored during organ culture. As quantitative data are obtained, even subtle changes can be accurately demonstrated, and accumulated data may be subjected to statistical analysis. The various applications of this method are pointed out.

Adult↗