Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Systems Analysis”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 523 records · Page 29Linked to original sources
PubMed2002

Computer systems analysis of the cardiovascular mechanisms of reentry orthostasis in astronauts.

Reentry orthostasis secondary to a prolonged exposure to microgravity is a common problem among astronauts. However, the physiologic mechanisms are poorly understood due to the many control systems involved. In this study an advanced computer model of cardiovascular functioning was employed in a systems analysis approach to clarify the relative importance of some of the adaptive physiologic processes engaged when humans return from space. After simulation of the conditions of zero gravity for one month, the model predicted that the change in capacitance of the lower extremity veins resulting from a loss of external fluid forces in the dehydrated extracellular compartment was the dominant mechanism associated with reentry orthostasis. This condition appears accentuated in women due to their inherent lower center of gravity and proportionately larger mass in the lower extremities.

Adaptation, Physiological↗
PubMed1998

An automatic image analysis system for RLGS films.

The RLGS (Restriction Landmark Genome Scanning) method was originally developed as a powerful method for enabling viewing of thousands of restriction landmarks. It offers a tool for obtaining information about genetic loci, with a single RLGS profile displaying approximately 2000 restriction landmarks as spots. One of the most useful applications is RLGS spot mapping, which allows the efficient, low-cost construction of the genetic map of any organism. However, analyses of the profiles depend mainly on human visual observation and are tedious and laborious. Although several commercially available image analyzing systems for profile comparison have been examined, they cannot be used for the RLGS spot mapping system owing to the background characteristics of the RLGS profiles, unsatisfactory rates of correspondence, and inefficient correction of informative genetic data. We therefore developed a novel automatic image analysis system for RLGS spot mapping, using an original algorithm based on the binary image transferred from the original RLGS profile. This system was employed for identifying non-polymorphic and parental strain-specific polymorphic spots of the F1 mouse profile and yielded efficient initial screening of RLGS profiles.

Animals↗
PubMed1999

Sources of variation in the morphological characteristics of sperm subpopulations assessed objectively by a novel automated sperm morphology analysis system.

There is evidence that the mammalian ejaculate contains distinct subpopulations of spermatozoa and that the variability among these subpopulations may have adaptive and functional significance. This study investigated the precision, reproducibility and operating characteristics of a novel automated sperm morphology analysis system, the Hobson Morphology package, establishing protocols to investigate boar sperm characteristics. Five ejaculates were collected from each of three boars from different genetic lines: Landrace-Meishan introgression, Sireline Large White and Damline Large White. Five semen smears per ejaculate were stained with haematoxylin and eosin. Two hundred spermatozoa per slide were analysed. No significant differences among slides within an ejaculate were detected for sperm tail length (P = 0.770), head width (P = 0.736) and head length (P = 0.615), indicating that both staining and morphology analysis were precise and reproducible. Among the boars, variability in tail length was detected (P = 0.001), but head width (P = 0.114) and length (P = 0.069) did not differ significantly. Multivariate pattern analysis (PATN computer package) highlighted three sub-populations of spermatozoa objectively on the basis of tail length (10.0-22.0 microns, 22.1-73.0 microns and 73.1-130.0 microns). The Landrace-Meishan introgression boar possessed more spermatozoa (P < 0.0001) with tails 73.1-130 microns long. Subsequent analysis of morphology parameters in a pure-bred Meishan boar showed similar measurements for tail length (mean +/- SD; 66.36 +/- 24.70 microns) to the Landrace-Meishan introgression boar (mean +/- SD; 67.09 +/- 21.80 microns). Sperm subpopulations originate during spermatogenesis, when heterogeneous genotypic effects determine the structural features of spermatozoa. The findings of this study confirm that tail length differs between boars and that subpopulations of spermatozoa can be detected within a single ejaculate.

Animals↗
PubMed2000

Amperometric biosensors/sequential injection analysis system for simultaneous determination of S- and R-captopril.

Two amperometric biosensors based on L- and D-amino acid oxidase, respectively, are proposed for the simultaneous detection of S- and R-captopril in a sequential injection analysis system (SIA). The linear concentration ranges are: 0.4-1.6 micromol/l (S-captopril) and 120-950 nmol/l (R-captopril) with detection limits of 0.2 and 15 nmol/l, respectively. The biosensors/SIA system can be used reliably on-line in synthesis process control, for the simultaneous assay of S- and R-captopril with a frequency of 34 samples/h.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2006

Integration of scanned document management with the anatomic pathology laboratory information system: analysis of benefits.

Electronic document management systems (EDMSs) have the potential to improve the efficiency of anatomic pathology laboratories. We implemented a novel but simple EDMS for scanned documents as part of our laboratory information system (AP-LIS) and collected cost-benefit data with the intention of discerning the value of such a system in general and whether integration with the AP-LIS is advantageous. We found that the direct financial benefits are modest but the indirect and intangible benefits are large. Benefits of time savings and access to data particularly accrued to pathologists and residents (3.8 h/d saved for 26 pathologists and residents). Integrating the scanned document management system (SDMS) into the AP-LIS has major advantages in terms of workflow and overall simplicity. This simple, integrated SDMS is an excellent value in a practice like ours, and many of the benefits likely apply in other practice settings.

Clinical Laboratory Information Systems↗
PubMed2001

Complex systems analysis: a tool for shock research.

For the past century, students of shock have focused research efforts to illuminate specific mechanisms that cause, or fail as a consequence of, circulatory collapse. Although clinical strategies aimed at supporting or restoring individual organ systems have proven effective, many patients succumb to more generalized multiple organ system failure. We suggest that general biological systems failure cannot be interpreted through reliance on reductionist science. We propose that complex systems analysis is an essential tool for shock research and we evaluate its application to genomic technologies.

Animals↗
PubMed1998

Laser speckle photography to measure surface displacements on cortical bone--verification of an automated analysis system.

A non-contact strain measurement method that could be used in a physiological environment was adapted to determine accurately the mechanical properties of bone. The technique of laser speckle photography was applied to record in-plane surface displacements. An automated image analysis system, based on a Fast Fourier Transform algorithm, was developed for data acquisition and its accuracy and precision verified. It was established that the technique could be used at magnifications of up to 60x , providing an ultimate resolution of approximately 1 microm. Displacement measurements on cortical bone submerged in water were demonstrated, which is of great value in determining the true physiological properties of bone.

Biomechanical Phenomena↗
PubMed2006

The feasibility of a video-based motion analysis system in measuring the segmental movements between upper and lower cervical spine.

The evaluation of the range of motion (ROM) and static posture in the cervical spine are important in physical examination. Despite offering dynamic assessment without radiation, the video-based motion analysis system has not yet been applied to measure the cervical segmental movements. The purposes of this study were to develop a neck model to differentiate the movements and posture between upper and lower cervical spine, and to examine the reliability of measuring cervical motion with surface markers and the aid of videofluoroscopy. Sixteen healthy adult subjects (eight males and eight females) participated in this study. Ten surface markers were used to estimate the discrepancies in cervical vertebral angles compared with corresponding bony landmarks throughout the ROM. The average intraclass correlation coefficients (ICCs) of the paired vertebral angles between surface markers and bony landmarks ranged from 0.844 to 0.975 and the mean absolute difference (MAD) averaged 2.96 degrees. Our results indicate high consistency between surface markers and bony landmarks throughout the cervical movements. The mean upper (C0-C2) and lower (C2-C7) cervical joint angles in the neutral position were 18.59+/-4.33 degrees and 23.98+/-6.15 degrees, respectively. Furthermore, the reliability of the digitizing procedure within raters (ICC=0.850-0.999; MAD=0.58-2.42 degrees) and between raters (ICC=0.759-0.988; MAD=0.59-2.66 degrees) suggests that the neck motion analysis model is a feasible method for investigating static neck posture or dynamic motion between upper and lower cervical spine.

Adult↗
PubMed2005

Systems analysis of a quorum sensing network: design constraints imposed by the functional requirements, network topology and kinetic constants.

Understanding the relationship between the structural organization of intracellular decision networks and the observable phenotypes they control is one of the exigent problems of modern systems biology. Here we perform a systems analysis of a prototypic quorum sensing network whose operation allows bacterial populations to activate certain patterns of gene expression cooperatively. We apply structural perturbations to the model and analyze the resulting changes in the network behavior with the aim to identify the contribution of individual network elements to the functional fitness of the whole network. Specifically, we demonstrate the importance of the dimerization of the transcription factor and the presence of the auxiliary positive feedback loop on the switch-like behavior of the network and the stability of its "on" and "off" states under the influence of molecular noise.

Bacterial Proteins↗
PubMed2004

Integrated systems analysis of persistent polar pollutants in the water cycle.

Persistent polar pollutants (P3) are difficult to degrade in standard waste water treatment plants. As a result, they end up in the effluent and are emitted to the surface water. In some areas, this problem is aggravated through "closed loop recycling", causing concentrations of P3 in surface water to build up over time. This could cause violation of (future) EU regulations. In the P-THREE project, various alternative waste water treatment techniques are investigated regarding their effectiveness in eliminating these substances, especially membrane bioreactor treatment and advanced oxidation processes, MBR and AOP. The integrated systems analysis which is the subject of this paper assesses these techniques in a broader systems context: (1) the life-cycle of the P3, (2) the life cycle of the WWTPs, and (3) the WWTP life cycle costs.

Bioreactors↗
PubMed1996

A dual-input nonlinear system analysis of autonomic modulation of heart rate.

Linear analyses of fluctuations in heart rate and other hemodynamic variables have been used to elucidate cardiovascular regulatory mechanisms. The role of nonlinear contributions to fluctuations in hemodynamic variables has not been fully explored. This paper presents a nonlinear system analysis of the effect of fluctuations in instantaneous lung volume (ILV) and arterial blood pressure (ABP) on heart rate (HR) fluctuations. To successfully employ a nonlinear analysis based on the Laguerre expansion technique (LET), we introduce an efficient procedure for broadening the spectral content of the ILV and ABP inputs to the model by adding white noise. Results from computer simulations demonstrate the effectiveness of broadening the spectral band of input signals to obtain consistent and stable kernel estimates with the use of the LET. Without broadening the band of the ILV and ABP inputs, the LET did not provide stable kernel estimates. Moreover, we extend the LET to the case of multiple inputs in order to accommodate the analysis of the combined effect of ILV and ABP effect on heart rate. Analyzes of data based on the second-order Volterra-Wiener model reveal an important contribution of the second-order kernels to the description of the effect of lung volume and arterial blood pressure on heart rate. Furthermore, physiological effects of the autonomic blocking agents propranolol and atropine on changes in the first- and second-order kernels are also discussed.

Adult↗
PubMed1991

A microcomputer-based interactive cough sound analysis system.

The occurrence and nature of cough sounds, especially those occurring in asthma in young children, is of considerable interest to workers in paediatrics and general practice. To facilitate our research into the characteristics of such sounds, we have developed a microcomputer-based analysis system, which we call COFF. In this paper we discuss the design and implementation of the system, emphasising its user-friendly, interactive features, and the manner in which it efficiently manages the large amounts of data that research into sounds incurs. We illustrate the operation of the system with examples of spectrograms computed from cough sounds recorded simultaneously at the mouth and through the chest wall.

Asthma↗
PubMed1993

On the efficacy of linear system analysis of renal autoregulation in rats.

In order to assess the linearity of the mechanisms subserving renal blood flow autoregulation, broad-band arterial pressure fluctuations at three different power levels were induced experimentally and the resulting renal blood flow responses were recorded. Linear system analysis methods were applied in both the time and frequency domain. In the frequency domain, spectral estimates employing FFT, autoregressive moving average (ARMA) and moving average (MA) methods were used; only the MA model showed two vascular control mechanisms active at 0.02-0.05 Hz and 0.1-0.18 Hz consistent with previous experimental findings [Holstein-Rathlou et al., Amer. J. Physiol., vol. 258, 1990.]. In the time domain, impulse response functions obtained from the MA model indicated likewise the presence of these two vascular control mechanisms, but the ARMA model failed to show any vascular control mechanism at 0.02-0.05 Hz. The residuals (i.e., model prediction errors) of the MA model were smaller than the ARMA model for all levels of arterial pressure forcings. The observed low coherence values and the significant model residuals in the 0.02-0.05 Hz frequency range suggest that the tubuloglomerular feedback (TGF) active in this frequency range is a nonlinear vascular control mechanism. In addition, experimental results suggest that the operation of the TGF mechanism is more evident at low/moderate pressure fluctuations and becomes overwhelmed when the arterial pressure forcing is too high.

Animals↗
PubMed2003

[Quantitative study on tongue color in primary liver cancer patients by analysis system for comprehensive information of tongue diagnosis].

OBJECTIVE: To explore the characteristics of tongue color in patients with primary liver cancer (PLC). METHODS: Tongue color and its RGB value were analyzed quantitatively for PLC patients in different clinical periods and other cancer patients by analysis system for comprehensive information of tongue diagnosis. RESULTS: The rate of blue and purple tongue was higher (P<0.05) and all the values of RGB were lower (P<0.01) in PLC patients compared with other cancer patients. In different clinical periods, the rate of blue and purple tongue in stage III was the highest (P<0.05). CONCLUSION: The blue and purple tongue is one of the most important tongue characteristics of PLC patients.

Adult↗
PubMed1976

Systems analysis in nutrition and health planning: approximate model relating birth weight and age to risk of deficient growth.

This paper summarizes the initial phase of an effort to develop semiquantitative methods for nutrition and health planning. The general approach is to utilize the methods of systems analysis and operations research where appropriate, but the emphasis is on developing a simplified, approximate analysis that government planning groups could conveniently apply in evaluating various potential programs for attaining specific nutrition and health objectives, while satisfying certain constraints (e.g., budget, facilities, personnel). An essential element of the analysis is a model that provides an approximate description of malnutrition (inadequate growth, as indicated by weight for age) and mortality in terms of those variables that can be affected by intervention programs. We have concentrated initially on using the results of two INCAP longitudinal studies to develop models relating the incidence of malnutrition (second and third degree on the Gomez scale) to age and previous growth, including birth weight. The two studies cover rural Guatemalan communities with considerable variability in ethnic, socioeconomic, and ecological conditions. Because they are tentative, the resulting models are discussed only qualitatively and not quantitatively. The models may serve as baselines to estimate the consequences of potential programs aimed at different target groups, such as pregnant women and children whose weights at birth or thereafter fall below prescribed levels. The possible benefits of using models of this nature in nutrition and health planning are discussed.

Age Factors↗
PubMed1995

Detection of degradation of magnetic resonance (MR) images: comparison of an automated MR image-quality analysis system with trained human observers.

RATIONALE AND OBJECTIVES: The perceived need for magnetic resonance (MR) imaging quality control (QC) is occasionally minimized on the assumption that significant errors will be detected by the users. To evaluate the validity of this assumption, we compared the sensitivity of a test object and automated image analysis system for MR imaging QC with the sensitivity of trained human observers by evaluating images that were intentionally degraded. METHODS: Parameters for imaging the test object and normal human volunteers were set to values that decreased the signal-to-noise ratio (SNR), caused distortion, and increased the slice thickness and separation. RESULTS: The human observers were able to detect a 6-13% reduction in the SNR and distortions of more than 15% in human images. They were unable to identify 40% increases in the slice thickness. Automated analysis of test object images was able to detect all image degradations at the minimum levels applied. CONCLUSION: The poor sensitivity of the human observers indicated that degradation, especially spatial measurements, could be significantly in error before being detected through visual analysis of clinical images. These errors would be detected by automated analysis of the test object used. Further investigation is needed to better define the accuracy with which quantitative image-quality analysis predicts the effects of degraded image quality on the ability of human observers to detect subtle abnormalities in clinical images.

Contrast Sensitivity↗