PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Measuring algorithm”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 613 records · Page 34Linked to original sources

An alterative method for hospital partition determination using hierarchical cluster analysis.

The classification of short-term hospitals into homogeneous groups has become an integral part of many systems designed to abate continuing cost inflation in the hospital industry. This paper describes one approach which was developed to identify homogeneous groups of short-term hospitals. The approach, based on hierarchical cluster analysis, defines an objective measure (called expected distinctiveness) to evaluate any group of hospitals identified by a hierarchical grouping structure or dendrogram. Using this measure, an efficient algorithm is developed which finds the hospital partition from the identified groups which maximizes total expected distinctiveness. A numerical example illustrates the application and extensions.

Analysis of Variance↗

Practical issues in wave-front sensing by use of phase diversity.

We present the results of the phase-diversity algorithm applied to simulated and laboratory data. We show that the exact amount of defocus distance does not need to be known exactly for the phase-diversity algorithm on extended scene imaging. We determine, through computer simulation, the optimum diversity distance for various scene types. Using laboratory data, we compare the aberrations recovered with the phase-diversity algorithm and those measured with a Fizeau interferometer that uses a He-Ne laser. The two aberration sets agree with a Strehl ratio of over 0.9. The contrast of the recovered object is found to be ten times that of the raw image.

Journal Article↗

[Regional transcranial oximetry with near infrared spectroscopy (NIRS) in comparison with measuring oxygen saturation in the jugular bulb in infants and children for monitoring cerebral oxygenation].

Using a dual channel near infrared (NIR) in vivo optical spectroscopy (INVOS) system (INVOS 3100A, Somanetics Corp. Troy, MI, USA) we investigated the relationship between jugular venous oxygen saturation (SjvO2) and regional cerebral oxygen saturation (rSO2) in 30 infants and children (mean age 4.5 years) with congenital heart disease undergoing cardiac catheterisation. The NIRS-SomaSensor (emitter and dual receiver probe) was applied at a standardised right fronto-temporal location (over the right frontal cortex) on the infant's head and covered with an adhesive flexible bandage. Using NIR light (730 and 810 nm) and two source-detector spacings (3 and 4 cm from the transmitter), percentage values of rSO2 were calculated from detected haemoglobin saturations. Simultaneously, jugular venous oxygen saturation (SjvO2) monitoring was performed via a catheter placed in the right internal jugular vein with its tip positioned in the jugular bulb, as verified by fluoroscopy. To compare the reliability of NIRS measurement characteristics, jugular venous blood was analysed for SjvO2 as a reference measure of global cerebral oxygenation, by co-oximetry (OSM3-Hemoximeter, Radiometer Copenhagen, Denmark). Other measured variables included pulse oximetry, arterial blood pressure, and venous and arterial oxygen saturations. Over a jugular venous oxygen saturation range of 31-83%, a significant positive linear correlation was found between rSO2 (NIRS measurement) and SjvO2 (jugular bulb oximetry) (r = 0.93, p < 0.001). No significant correlation was observed between rSO2 values and arterial blood saturation or pulse oximetry. The quantitative correlation between rSO2 (haemoglobin oxygenation in a small hemi-elliptical area of the brain) and reference SjvO2 measurement (method for monitoring global cerebral oxygenation) suggests that NIRS measurement with subtraction algorithm should identify predominantly intracranial saturation in the pediatric age group, and will tend to reflect global oxygenation under physiological conditions. Transcranial oximetry using dual receiving channel NIRS offers a noninvasive, real-time, reliable and practicable means of monitoring cerebral haemoglobin oxygenation changes infants and children with cyanotic and noncyanotic congenital heart disease.

Adolescent↗

Laboratory quality control: using patient data to assess analytical performance.

Quality control plays a vital role helping to ensure the reliability of laboratory test results. The application of statistical quality control has been a component of laboratory medicine for approximately 50 years. Many of the control rules based on the early applications of statistical quality control have remained essentially unchanged since their initial introduction. Optimization of quality control rules can vary depending on the application for which a test is to be used. This review explores the various applications of laboratory quality control procedures and their role in identifying laboratory error. The ubiquitous use of computers in today's laboratories has enabled the development of more sophisticated means of assessing laboratory quality. The use of the Six Sigma technique and its adoption by the laboratory community is one example. Other examples include the use of patient-derived quality control procedures as a means of assessing laboratory performance. Early examples of these types of applications include use of Bull's algorithm, anion gap measurements, and delta checking. More recent applications include the correlation of laboratory test results, the average of normals procedure, and the Bhattacharya method.

Chemistry, Clinical↗

The effects of pubertal status and glycemic control on the growth hormone-IGF-I axis in boys with insulin-dependent diabetes mellitus.

Dysregulation of the growth hormone (GH)-insulin-like growth factor-I (IGF-I) axis in children and adolescents with insulin-dependent diabetes mellitus (IDDM) is well documented. Elevated levels of circulating GH, increased GH secretory amplitude, and decreased concentrations of IGF-I, IGFBP-3, and GHBP have been related to poor glycemic control. We proposed that pubertal maturation may be a more significant factor, potentially overriding the effects of metabolic control, especially during mid-puberty when the GH-IGF-I axis is maximally stimulated. We studied 24 male children and adolescents with IDDM over a 5 year period. Subjects were grouped both by pubertal stage (prepubertal vs mid-pubertal) and by level of glycemic control (hemoglobin A1 (<9%, 9-11.5%, and >11.5%). Twenty-four hour every 20 minute blood sampling for GH determination was analyzed using the Cluster algorithm, and static measures of IGF-I, IGFBP-3, and GHBP were obtained. When analyzed by pubertal status, we found no difference in the number of GH secretory peaks or the interval between concentration peaks. The sum of the peak heights and area under the curve were significantly greater in the mid-pubertal boys, as was the average GH nadir. Serum levels of IGF-I and IGFBP-3 were greater in the mid-pubertal boys, but levels of GHBP were higher in the prepubertal boys. When analyzed by level of glycemic control, we found no differences in the number of GH secretory peaks or interval between peaks among the 3 groups. However, the sum of the peak heights, area under the curve, and average GH nadir were all lower in the group with the intermediate level of glycemic control (HgbA1 9-11.5%); no differences were observed between the other 2 groups. This relationship persisted when the mid-pubertal subjects were analyzed separately. No differences were found among the 3 groups for levels of IGF-I, IGFBP-3, or GHBP. We conclude that normal increases in GH secretion and levels of IGF-I and IGFBP-3 occur during mid-puberty in boys with IDDM. A concomitant increase in average GH nadir may reflect an underlying effect of metabolic control. Greater GH secretion was observed in the groups with the lowest and highest levels of glycemic control. We speculate that this may be related to an increased incidence of severe hypoglycemic episodes in the group with the lowest levels of glycosylated hemoglobin, resulting in metabolic derangements similar to those with elevated glycosylated hemoglobin levels.

Blood Glucose↗

Computer-assisted measurement of peripheral blood flow.

An automated system for the measurement of peripheral blood flow using venous occlusion plethysmography based on the low-cost Apple II microcomputer, together with purpose-built compressor unit and data acquisition interface, has been developed. The computer performs the dual role of controlling the timing of inflation and deflation of the occluding cuffs and recording the resulting increase in limb circumference. Ten 8 s epochs of data are acquired and analysed per session. Flow rate is computed using a least squares fit between 0.5 and 4.0 s after cuff inflation, giving on-line indication of blood flow. Venous capacitance and digital systolic pressure may be measured using additional algorithms. The system has been used for the investigation of circulatory disorders and in the assessment of drugs acting on the peripheral circulation.

Blood Pressure↗

Effect of image compression on telepathology. A randomized clinical trial.

CONTEXT: For practitioners deploying store-and-forward telepathology systems, optimization methods such as image compression need to be studied. OBJECTIVE: To determine if Joint Photographic Expert Group (JPG or JPEG) compression, a glossy image compression algorithm, negatively affects the accuracy of diagnosis in telepathology. DESIGN: Double-blind, randomized, controlled trial. SETTING: University-based pathology departments. PARTICIPANTS: Resident and staff pathologists at the University of Illinois, Chicago, and University of Cincinnati, Cincinnati, Ohio. INTERVENTION: Compression of raw images using the JPEG algorithm. MAIN OUTCOME MEASURES: Image acceptability, accuracy of diagnosis, confidence level of pathologist, image quality. RESULTS: There was no statistically significant difference in the diagnostic accuracy between noncompressed (bit map) and compressed (JPG) images. There were also no differences in the acceptability, confidence level, and perception of image quality. Additionally, rater experience did not significantly correlate with degree of accuracy. CONCLUSIONS: For providers practicing telepathology, JPG image compression does not negatively affect the accuracy and confidence level of diagnosis. The acceptability and quality of images were also not affected.

Diagnosis, Computer-Assisted↗

[Establishing the personal identity of the victims in aviation catastrophes].

Algorithm of organization measures and expert investigations is proposed, based on experience gained in expert studies during liquidation of aircraft catastrophes. It permits effective classification, differentiation, and identification of victims and is based on traditional and high technological methods of investigation.

Accidents, Aviation↗

Surface EMG of the lumbar part of the erector trunci muscle in patients with fibromyalgia.

OBJECTIVE: To determine differences supposed in EMG parameters of the erector trunci region between patients with fibromyalgia and healthy subjects during defined investigation situations. METHODS: During sitting and standing in upright position surface EMG (SEMG) from 15 subjects with fibromyalgia and 10 healthy controls was performed using a 16-channel technique where the electrodes were applied in a well-defined grid pattern (gain 5000, 3 db points at 5 Hz and 700 Hz respectively). SEMG quantification was done by Fourier algorithm using 512 measurement points for calculation. RESULTS: An increased EMG amplitude could be recorded during rest in fibromyalgia patients compared with controls. Spatial amplitude differences (frequency range 100-500 Hz) in the low back region were significantly (p < 0.01) decreased in the patients' group during sitting. CONCLUSION: It is the first time that a decreased difference in EMG amplitude of different parts within a certain muscle could be proven in patients with fibromyalgia. As far as is known from the literature this result seems to be a uniquefinding in fibromyalgia patients.

Electromyography↗

[Improvement of the rehabilitation system of patients after aortocoronary bypass].

Using the significant representative sample the important conclusion was drawn about the necessity of patient early differentiation on the base of psychosomatic status evaluation. The algorithms of treatment measures were developed on the base of which two rehabilitation patterns were created. It is shown that the use of the patterns developed permits to decrease the treatment expenses (the important factor in modern conditions). For practical work the new integral indices are proposed that allow to improve the diagnosis quality and to work out the tactics of individual restorative treatment. The necessity to improve the medical rehabilitation system using the differential approach to determination of need of restorative treatment and place of its conduction is proved.

Adaptation, Psychological↗

[Postprandial hypotension and autonomic neuropathy in diabetic patients].

UNLABELLED: Postprandial hypotension is commonly defined as the decrease in systolic blood pressure of 20 mm Hg and more, observed within 2 hours after meal ingestion. This phenomenon was described in subjects with comprised function of autonomic nervous system. However, the data on its prevalence in diabetic patients are scarce. The aim of the study was to assess the concordance of postprandial hypotension and autonomic cardiovascular neuropathy in diabetes mellitus. The study included 67 patients (26 males, 41 females, mean age: 47.5 +/- 16.2 years) with diabetes type 1 or 2 (mean disease duration: 13.3 +/- 8.8 years), treated with diet and insulin injections. Postprandial hypotension was diagnosed based on results of automatic blood pressure recordings performed within 90 minutes after test meal ingestion. Tests of Ewing's battery were used to evaluate autonomic cardiovascular neuropathy. RESULTS: Mean postprandial decrease in systolic blood pressure of 17.7 +/- 11.7 mm Hg was noted at 48.0 +/- 13.7 min after meal ingestion. The study patients were divided into 2 groups based on results of systolic blood pressure recordings. In group A of 39 subjects (58.2%) the mean fall in systolic blood pressure of 8.9 +/- 4.4 mm Hg was observed. In group B of 28 (41.8%) subjects fulfilling the criteria of postprandial hypotension systolic blood pressure decreased after the meal of 30.0 +/- 6.2 mm Hg, the difference between groups was statistically significant (p < 0.001). Autonomic cardiovascular neuropathy was recognized in 41 (61.2%) of the study patients. The more advanced neuropathy was stated in group B (neuropathy scale score: group A--1.54 +/- 1.48 points, group B--5.11 +/- 1.93 points, p < 0.001). Statistically significant correlation between the magnitude of postprandial systolic blood pressure fall and cardiovascular neuropathy scale score was noted (Spearman's correlation co-efficient R: -0.612: p < 0.01). Postprandial blood pressure fall correlated significantly with orthostatic systolic blood pressure changes (correlation co-efficient R: 0.610; p < 0.001). CONCLUSIONS: Postprandial hypotension is an important symptom of diabetic cardiovascular neuropathy. It is recommended to include postprandial blood pressure measurements in diagnostic algorithm of autonomic nervous system dysfunction in diabetic patients.

Adult↗

Diabetes mellitus and exercise.

The study deals with the subject of exercise in diabetic patients, with particular emphasis on acute physical stress in type--I and type--II diabetics. The principal task was to define metabolic changes as they occur in the diabetic subjected to acute stress induced by exercise, in comparison with non-diabetics; metabolic changes during prolonged stress as well as during the period of rest; and finally, to propose, on the basis of authors' experimental results and detailed literature research, appropriate rules of procedure for prescriptive exercise for the individual patient. There were 120 subjects divided into 8 groups. Using primarily a bicycle ergometer, the members of the individual groups were subjected to physical stress of various intensity and duration. A detailed analysis of each subject's metabolic response was performed, involving an assessment of 35 physiological and biochemical parameters, with main focus on determining biochemical changes. The study results are presented in detail both with respect to the metabolic response to a given stress in individual groups and comparatively for individual parameters with regard to specific stress rates and groups. Significant differences were found in the metabolic responses concerning the following parameters: acid-base balance, potassium, triglycerols, glucose, cholesterol, FFA, free glycerol, lactate, uric acid. On the basis of the results of experimental measurements, the following algorithm has been designed for prescribing exercise to diabetics: appropriate motivation; determination of the type of exercise; determination of the intensity of exercise; determination of the duration of exercise; respecting related contraindications and complications. A conclusion has been made that provided all possible risks and contraindications as well as prescription guidelines are respected, exercise is to be considered one of the basic principles of diabetes management.

Acid-Base Equilibrium↗

Combined malignancy associated change and contextual analysis for computerized classification of cervical cell monolayers.

Previous efforts to automate cervical cell analysis have focused on algorithms that use measurements of high resolution images of individual cells for 'rare event' detection of abnormal cells, sometimes in combination with cluster analysis of low resolution images. A new methodology was developed in which intermediate cell markers (indicating malignancy associated change) and contextual analysis of slide architecture were performed on the same digital images at 0.33 mu pixel resolution. A total of one hundred and forty-six cases that were either negative or at least high grade squamous intraepithelial lesions (HGSIL) were prepared as monolayers, and about 20 fields per slide were analyzed. Features most important for intermediate cell marker analysis were those that measured the variation in nuclear texture measurements across the slide as well as densitometric features. The most discriminatory contextual features were those that measured the variation of the arrangement of cells within a cluster across the slide. Linear discriminants were calculated using the most important features from both types of analysis; they provided smear classification accuracies of 71-86%.

Carcinoma↗

Resistant hypertension: comparing hemodynamic management to specialist care.

Although resistant hypertension affects a minority of all hypertensives, this group continues to experience disproportionately high cardiovascular event rates despite newer antihypertensive agents. Hypertension represents an imbalance of hemodynamic forces within the circulation, usually characterized by elevated systemic vascular resistance. We studied the utility of serial hemodynamic parameters in the selection and titration of antihypertensive medication in resistant hypertensive patients using highly reproducible noninvasive measurements by thoracic bioimpedance. Resistant hypertension patients (n=104) were randomized to drug selection based either on serial hemodynamic (HD) measurements and a predefined algorithm or on drug selection directed by a hypertension specialist (SC) in a 3-month intensive treatment program. Blood pressure was lowered by intensified drug therapy in both treatment groups (169+/-3/87+/-2 to 139+/-2/72+/-1 mm Hg HD versus 173+/-3/91+/-2 to 147+/-2/79+/-1 mm Hg SC, P<0.01 for systolic and diastolic BP), using similar numbers and intensity of antihypertensive medications. Blood pressures were reduced further for those treated according to hemodynamic measurements, resulting in improved control rates (56% HD versus 33% SC controlled to </=140/90 mm Hg, P<0.05) and incremental reduction in systemic vascular resistance measurements. Although the number of patients taking diuretics did not differ between groups, final diuretic dosage was higher in the hemodynamic cohort. Our results demonstrate superior blood pressure control using a treatment algorithm and serial hemodynamic measurements compared with clinical judgment alone in a randomized prospective study. Our measurements of thoracic fluid volume support occult volume expansion as a mediator of antihypertensive drug resistance and use of impedance measurements to guide advancing diuretic dose and adjustment of multidrug antihypertensive treatment.

Adrenergic beta-Antagonists↗

Measuring costs of guideline-driven mental health care: the Texas Medication Algorithm Project.

BACKGROUND: Algorithms describe clinical choices to treat a specific disorder. To many, algorithms serve as important tools helping practitioners make informed choices about how best to treat patients, achieving better outcomes more quickly and at a lower cost. Appearing as flow charts and decision trees, algorithms are developed during consensus conferences by leading experts who explore the latest scientific evidence to describe optimal treatment for each disorder. Despite a focus on "optimal" care, there has been little discussion in the literature concerning how costs should be defined and measured in the context of algorithm-based practices. AIMS OF THE STUDY: This paper describes the strategy to measure costs for the Texas Medication Algorithm project, or TMAP. Launched by the Texas Department of Mental Health and Mental Retardation and the University of Texas Southwestern Medical Center at Dallas, this multi-site study investigates outcomes and costs of medication algorithms for bipolar disorder, schizophrenia and depression. METHODS: To balance costs with outcomes, we turned to cost-effectiveness analyses as a framework to define and measure costs. Alternative strategies (cost-benefit, cost-utility, cost-of-illness) were inappropriate since algorithms are not intended to guide resource allocation across different diseases or between health- and non-health-related commodities. "Costs" are operationalized consistent with the framework presented by the United States Public Health Service Panel on Cost Effectiveness in Medicine. Patient specific costs are calculated by multiplying patient units of use by a unit cost, and summing over all service categories. Outpatient services are counted by procedures. Inpatient services are counted by days classified into diagnosis groups. Utilization information is derived from patient self-reports, medical charts and administrative file sources. Unit costs are computed by payer source. Finally, hierarchical modeling is used to describe how costs and effectiveness differ between algorithm-based and treatment-as-usual practices. DISCUSSION: Cost estimates of algorithm-based practices should (i) measure opportunity costs, (ii) employ structured data collection methods, (iii) profile patient use of both mental health and general medical providers and (iv) reflect costs by payer status in different economic environments. IMPLICATION FOR HEALTH CARE PROVISION AND USE: Algorithms may help guide clinicians, their patients and third party payers to rely on the latest scientific evidence to make treatment choices that balance costs with outcomes. IMPLICATION FOR HEALTH POLICIES: Planners should consider consumer wants and economic costs when developing and testing new clinical algorithms. IMPLICATIONS FOR FURTHER RESEARCH: Future studies may wish to consider similar methods to estimate costs in evaluating algorithm-based practices.

Journal Article↗

Comparison of glaucomatous visual field defects using standard full threshold and Swedish interactive threshold algorithms.

OBJECTIVES: To compare the severity, size, and depth of glaucomatous visual field defects using standard full threshold (FT), Swedish interactive threshold algorithm (SITA) standard (SS), and SITA fast (SF) algorithms of the Humphrey perimeter. METHODS: A prospective observational case series of 77 patients with glaucoma performed FT, SS, and SF 30-2 white-on-white testing programs on the same day on 2 occasions for 1 month. The severity of defects was compared using the mean deviation, pattern standard deviation, Advanced Glaucoma Intervention Study, and Hodapp-Anderson-Parrish severity scores. The sizes of defects were compared using the total number of abnormal points on the pattern deviation plot that fit standard criteria for glaucomatous visual field defects. The depths of the defects were compared using the sum of the threshold values for points identified in the pattern deviation plot as fitting criteria for glaucomatous defects. RESULTS: The mean deviations were slightly better using the SS (-9.6 +/- 7.1 dB) or the SF (-9.1 +/- 6.7 dB) algorithm compared with the FT algorithm (-10.3 +/- 7.1 dB) (P<.005). There were no significant differences in pattern standard deviations between SS (8.6 +/- 4.0, P =.08) and SF (8.1 +/- 3.6, P =.19) compared with FT (8.3 +/- 3.3), although the pattern standard deviation was higher in SS fields compared with SF fields (P<.001). Advanced Glaucoma Intervention Study scores were slightly better when the SS (7.5 +/- 5.6) or SF (7.2 +/- 5.4) algorithm was used compared with the FT algorithm (8.6 +/- 5.4) (P<.001). The sizes of glaucomatous defects were slightly larger using the SS (20.9 +/- 10.7) algorithm compared with the FT algorithm (19.2 +/- 10.9) (P =.004) but not the SF algorithm (20.0 +/- 10.6) (P =.11). The depth of defects measured by the SS (220.4 +/- 108.0 dB) and SF (219.8 +/- 101.3 dB) algorithms was significantly shallower compared with that measured by the FT algorithm (152.3 +/- 79.1 dB) (P<.001). There were no significant differences in Hodapp-Anderson-Parrish severity scores among algorithms (P =.12). CONCLUSIONS: Glaucomatous defects are measured significantly shallower using the new SITA algorithms but are approximately the same size and severity compared with FT measurements. Care should be taken when using threshold values to compare glaucomatous defects in a patient when converting from FT to SITA algorithms.

Adult↗

No-reference quality assessment using natural scene statistics: JPEG2000.

Measurement of image or video quality is crucial for many image-processing algorithms, such as acquisition, compression, restoration, enhancement, and reproduction. Traditionally, image quality assessment (QA) algorithms interpret image quality as similarity with a "reference" or "perfect" image. The obvious limitation of this approach is that the reference image or video may not be available to the QA algorithm. The field of blind, or no-reference, QA, in which image quality is predicted without the reference image or video, has been largely unexplored, with algorithms focusing mostly on measuring the blocking artifacts. Emerging image and video compression technologies can avoid the dreaded blocking artifact by using various mechanisms, but they introduce other types of distortions, specifically blurring and ringing. In this paper, we propose to use natural scene statistics (NSS) to blindly measure the quality of images compressed by JPEG2000 (or any other wavelet based) image coder. We claim that natural scenes contain nonlinear dependencies that are disturbed by the compression process, and that this disturbance can be quantified and related to human perceptions of quality. We train and test our algorithm with data from human subjects, and show that reasonably comprehensive NSS models can help us in making blind, but accurate, predictions of quality. Our algorithm performs close to the limit imposed on useful prediction by the variability between human subjects.

Algorithms↗

Alveolar pressure monitoring: an evaluation in a lung model and in patients with acute lung injury.

OBJECTIVES: We evaluated an algorithm for continuous on-line monitoring of alveolar pressure over time in a lung model with lower and upper inflection points and variable resistance ratios and in patients with acute lung injury. The algorithm is based on "static" pressure/volume curves obtained from tracheal pressure measurements under dynamic conditions. DESIGN AND SETTING: Experimental and clinical evaluation of algorithm in a university hospital laboratory and intensive care unit. PATIENTS: Ten patients undergoing postoperative respiratory therapy (feasibility of tracheal measurement) and ten patients with acute lung injury undergoing ventilator treatment (evaluation of algorithm). MEASUREMENTS AND RESULTS: Direct tracheal pressure measurements with a catheter inserted through the endotracheal tube. Comparison of measured alveolar and the dynostatic alveolar pressure vs. time in a lung model with changes in five ventilatory parameters. Examples of clinical monitoring are reported. In the model there was excellent agreement between alveolar pressures obtained by the algorithm, the dynostatic alveolar pressure, and measured alveolar pressure at all ventilator settings. For inspiratory/expiratory resistance ratios between 1:2.1-2.1:1, the dynostatic alveolar pressure was within +/-1.5 cm H(2)O of measured alveolar pressure. In patients the technique for direct tracheal pressure measurement using a catheter inserted through the endotracheal tube functioned satisfactorily with intermittent air flushes for cleansing. CONCLUSIONS: Using a thin tracheal pressure catheter inserted through the endotracheal tube alveolar pressure allows continuous bedside monitoring with ease and precision using the dynostatic algorithm. The method is unaffected by tube and connector geometry or by secretions.

Adolescent↗