SEARCH · PubMed Health

Results for “Read depth”

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 181 records · Page 10Linked to original sources

PubMed1982

Finely graded binocular disparities from random-dot stereograms.

Rotation of a stereogram around an axis through its centre provides a method of presenting finely graded binocular disparities. Such displays are useful for clinical testing of stereopsis. A comparison between projected- and real-depth thresholds indicated that most of the differences could be accounted for in terms of the change in stereoscopic sensitivity associated with differing errors in the equidistance judgements. The method of disparity display described allows for the direct observation of those attributes of random-dot stereopsis known as global stereopsis and local stereopsis and requires caution in comparison of stereopsis thresholds using these different perceptual criteria.

Adult↗

PubMed2000

Reversed stereo depth and motion direction with anti-correlated stimuli.

We used anti-correlated stimuli to compare the correspondence problem in stereo and motion. Subjects performed a two-interval forced-choice disparity/motion direction discrimination task for different displacements. For anti-correlated 1d band-pass noise, we found weak reversed depth and motion. With 2d anti-correlated stimuli, stereo performance was impaired, but the perception of reversed motion was enhanced. We can explain the main features of our data in terms of channels tuned to different spatial frequencies and orientation. We suggest that a key difference between the solution of the correspondence problem by the motion and stereo systems concerns the integration of information at different orientations.

Depth Perception↗

PubMed2000

The predictability of corneal flap thickness and tissue laser ablation in laser in situ keratomileusis.

OBJECTIVE: To evaluate the relationship between predicted flap thickness and actual flap thickness and between predicted tissue ablation and actual tissue ablation. DESIGN: Prospective, nonrandomized comparative (self-controlled) trial. PARTICIPANTS: A total of 60 patients (102 eyes) who underwent laser in situ keratomileusis (LASIK). MAIN OUTCOME MEASURES: Subtraction pachymetry was used to determine actual corneal flap thickness and corneal tissue ablation depth. Other measurements included flap diameter and keratometry readings. RESULTS: Actual flap thickness was significantly different (P < 0.0001) from predicted flap thickness. Fifteen eyes had a predicted flap thickness of 160 micrometer and a mean actual flap of 105 micrometer (standard deviation [SD], +/-24. 3 micrometer range, 48-141 micrometer). Sixty-four had a predicted flap of 180 micrometer with an actual flap mean of 125 micrometer (SD, +/-18.5 micrometer range, 82-155 micrometer). Seventeen eyes had a predicted flap of 200 micrometer, with an actual flap mean of 144 micrometer (SD, +/-19.3 micrometer range, 108-187 micrometer). In addition, we found that significantly more tissue (P < 0.0001) was ablated than predicted. Linear regression of the observed ablation on predicted ablation yielded the following relationship: actual ablation = 14.5 + 1.5 (predicted ablation). Neither flap diameter nor flap thickness were found to increase with respect to steeper corneal curvatures. CONCLUSIONS: Actual corneal flap thickness was consistently less than predicted regardless of the depth plate used; actual tissue ablation was consistently greater than predicted tissue ablation for the laser used in this study.

Cornea↗

PubMed2006

Clinical implementation of MOSFET detectors for dosimetry in electron beams.

BACKGROUND AND PURPOSE: To determine the factors converting the reading of a MOSFET detector placed on the patient's skin without additional build-up to the dose at the depth of dose maximum (D(max)) and investigate their feasibility for in vivo dose measurements in electron beams. MATERIALS AND METHODS: Factors were determined to relate the reading of a MOSFET detector to D(max) for 4 - 15 MeV electron beams in reference conditions. The influence of variation in field size, SSD, angle and field shape on the MOSFET reading, obtained without additional build-up, was evaluated using 4, 8 and 15 MeV beams and compared to ionisation chamber data at the depth of dose maximum (z(max)). Patient entrance in vivo measurements included 40 patients, mostly treated for breast tumours. The MOSFET reading, converted to D(max), was compared to the dose prescribed at this depth. RESULTS: The factors to convert MOSFET reading to D(max) vary between 1.33 and 1.20 for the 4 and 15 MeV beams, respectively. The SSD correction factor is approximately 8% for a change in SSD from 95 to 100 cm, and 2% for each 5-cm increment above 100 cm SSD. A correction for fields having sides smaller than 6 cm and for irregular field shape is also recommended. For fields up to 20 x 20 cm(2) and for oblique incidence up to 45 degrees, a correction is not necessary. Patient measurements demonstrated deviations from the prescribed dose with a mean difference of -0.7% and a standard deviation of 2.9%. CONCLUSION: Performing dose measurements with MOSFET detectors placed on the patient's skin without additional build-up is a well suited technique for routine dose verification in electron beams, when applying the appropriate conversion and correction factors.

Breast Neoplasms↗

PubMed1984

A detailed study of sequential saccadic eye movements for normal- and poor-reading children.

This paper presents the results of an in-depth study of parameters characterizing sequenced saccadic eye movements for a group of dyslexic children and a comparative normal control group with ages in the range greater than 8.0 yr. and less than 13.0 yr. No parameters were statistically different for the two groups, which supports the findings of Brown, et al. and contradicts the findings of Pavlidis. Our results indicate that sequenced saccadic eye movements are not diagnostically useful for early detection of dyslexia.

Child↗

PubMed2026

Long-read low-pass sequencing enhances variant detection in a peanut MAGIC population.

Accurate genotyping accelerates crop improvement, yet long-read sequencing remains underused in breeding due to cost. We present a scalable long-read low-pass (LRLP) sequencing framework for high-throughput variant discovery and trait mapping. Using PacBio HiFi reads in an allotetraploid peanut (Arachis hypogaea; AABB, 2n = 4x = 40) MAGIC population, we generated both LRLP and short-read low-pass (SRLP) data. At comparable depths, LRLP achieved substantially greater whole-genome and gene-space coverage than SRLP. Data were analyzed using both a single-reference genome and an 18-parent pangenome graph constructed with KhufuPan, a new tool for graph-based genotyping. Across analytical approaches, LRLP consistently identified more SNPs, indels (2-1,000 bp), and structural variants (>1 kb) than SRLP, improving genotype resolution and selection accuracy, particularly for large structural variants. By reducing cost barriers and increasing variant discovery in complex genomes, LRLP provides a practical path for deploying advanced genomics in under-resourced and orphan crops critical to global food security.

Arachis↗

PubMed1987

Dosimetry considerations for a Lipowitz metal tissue compensator system.

The present report describes the fabrication technique and the dosimetry aspects of a new compensator system that uses the low melting point allow Lipowitz metal. Compensating ratios (CR, mm of tissue compensated per mm of cerrobend) were determined for various field sizes and depths for 60Co, and X ray energies of 4, 6, 18, and 25 MV. Typical CR for 10 cm X 10 cm field and 10 cm depth were: 60Co, 4 MV, and 6 MV, 1:15; 18 and 25 MV, 1:20. Verification of these CR were performed at 6 MV using polystyrene phantoms. Ionization measurements were made for various field sizes and depths and normalized to central axis full-phantom readings for both compensated and non-compensated fields. Without compensation, percent differences ranged as high as 40% for a tissue deficit of 10 cm. With the compensating filters (CF) in place, this difference was reduced to 2-4%. Overall, the CF system was capable of producing dose uniformity to within +/- 10% for a wide range of depths and field sizes.

Metals↗

PubMed2005

Digital slot-scan charge-coupled device radiography versus AMBER and Bucky screen-film radiography: comparison of image quality in a phantom study.

PURPOSE: To evaluate the image quality and performance of a chest digital radiography system and to compare this with the image quality and performance of advanced multiple-beam equalization radiography (AMBER) and Bucky screen-film radiography systems. MATERIALS AND METHODS: The chest digital radiography system is a digital charge-coupled device (CCD) chest imaging unit that uses slot-scan technology. A contrast-detail test object was used in combination with a phantom that simulates the primary and scatter transmission for the lungs and mediastinum. Twelve phantom images were obtained with each modality (ie, CCD digital radiography and AMBER and Bucky screen-film radiography) and were judged by six observers. CCD digital radiography soft-copy reading was compared with AMBER hard-copy reading. To measure image quality, contrast-detail curves were constructed from the observer data. The Wilcoxon signed rank test was used for statistical analysis. RESULTS: For the lung configuration, contrast-detail curves showed lower threshold depth for hard-copy images obtained with CCD digital radiography than for those obtained with Bucky screen-film radiography. For hard-copy images, the difference between contrast-detail curves for CCD digital radiography and those for Bucky screen-film radiography was statistically significant (P < .006). No significant difference was found between CCD digital radiography and AMBER for hard-copy images obtained in either the lung or mediastinum configuration. For the lung configuration, a lower threshold depth was observed for CCD digital radiography soft-copy reading than for AMBER hard-copy reading, with significantly different contrast-detail curves for CCD digital radiography soft copy and AMBER hard copy (P < .006). No significant difference was found between either system for the mediastinum configuration. CONCLUSION: Contrast-detail curves indicate that image quality for the CCD chest system provides a digital alternative to AMBER and Bucky screen-film radiography.

Phantoms, Imaging↗

PubMed1985

Determining intraocular lens power within the eye.

A method is described for determining the power of an intraocular lens (IOL) within the eye by measuring the horizontal dimension of the corneal reflected image (Purkinje-Sanson I) and the anterior IOL reflected image (Purkinje-Sanson III) as seen through a standard slitlamp with a target positioned 68 mm anterior to the focal plane of the biomicroscope. The horizontal K-reading (at 180 degrees) and the anterior chamber depth are the two other parameters necessary to calculate the exact power of the IOL. Seven tables that use these four measurements have been provided, eliminating the need for complex calculations. To determine the accuracy of this technique, ten implanted IOLs ranging from 9 diopters (D) to 27 D were chosen and their powers calculated; these calculated values were then compared to the actual IOL powers. The largest error was 0.5 D and the average error was 0.17 D.

Anterior Chamber↗

PubMed2026

Genome-targeted enrichment and sequencing of human-infecting Cryptosporidium spp.

Cryptosporidium spp. are parasites that cause severe illness in vulnerable human populations. Obtaining pure and sufficient Cryptosporidium DNA from clinical and environmental samples is a challenging task. Oocysts shed in available fecal samples can be limited in quantity, require purification (biased towards dominant strains), and yield limited DNA ( < 40 fg/oocyst). Here, we use updated genomic sequences from a broad diversity of Cryptosporidium species that have been found to infect humans (C. cuniculus, C. hominis, C. meleagridis, C. parvum, C. tyzzeri, and C. viatorum) to develop and validate a set of 100,000 RNA baits (CryptoCap_100k) with the aim of enriching Cryptosporidium DNA from varied samples. Compared to unenriched libraries, CryptoCap_100k increases the percentage of reads mapping to target genome sequences, increases the depth and breadth of genome coverage, and facilitates analyses of genetic variants in many samples, while decreasing overall costs.

Cryptosporidium↗

PubMed1986

Nonius horopter in projected viewing.

Nonius horopter measurements were made on three normal subjects using both physically displaced (real viewing) and stereogrammetrically displaced (projected viewing) test objects. Three subjects with ocular anomalies were tested using the projected viewing arrangement with and without 5% overall magnifier before the right eye, and seven complete measurements of the projected viewing horopter were made on a fourth subject with an ocular anomaly over the period of 1 month. These latter individual plots showed large irregularities that changed location from day to day. Plotting the mean and standard error of the means of these seven sets of data produced a smoothing out of the horopter locus. Plotting each individual horopter setting in the sequence of measurement and monitoring eye position indicated that all of the irregularities and regional horopter changes found are most likely introduced by changes in fixation disparity (vergence eye movements).

Depth Perception↗

PubMed2025

GENOME TARGETED ENRICHMENT AND SEQUENCING OF HUMAN-INFECTING CRYPTOSPORIDIUM spp.

Cryptosporidium spp. are parasites that cause severe illness in vulnerable human populations. Obtaining pure and sufficient Cryptosporidium DNA from clinical and environmental samples is a challenging task. Oocysts shed in available fecal samples can be limited in quantity, require purification (biased towards dominant strains), and yield limited DNA (<40 fg/oocyst). Here, we use updated genomic sequences from a broad diversity of human-infecting Cryptosporidium species ( C. cuniculus , C. hominis , C. meleagridis , C. parvum , C. tyzzeri , and C. viatorum ) to develop and validate a set of 100,000 RNA baits (CryptoCap_100k) with the aim of enriching Cryptosporidium spp. DNA from varied samples. Compared to unenriched libraries, CryptoCap_100k increases the percentage of reads mapping to target genome sequences, increases the depth and breadth of genome coverage and the reliability of detecting species and mixed infections within a sample, and allows assessment of genetic variation via SNP calling, while decreasing costs.

Journal Article↗

PubMed1990

A retrospective analysis of the perio-prosthetic aspect of teeth re-prepared during periodontal surgery.

This paper describes a retrospective study in which the gingival and periodontal status was assessed at crowned and natural teeth. 510 crowned teeth and 510 natural teeth in 109 subjects were examined. The time elapsed between active therapy and the clinical examination was: (i) 1 to 3 years for 270 teeth; (ii) 3 to 5 years for 168 teeth; (iii) 6 to 9 years for 72 teeth. 90% of the patients were on a recall schedule that required prophylaxis once every 3 months; 8% returned every 6 months and 2% once a month. Plaque index and gingival index were assessed at 4 sites per tooth and pocket depth at 6 sites per tooth, the highest reading per tooth being used for the statistical analysis. The results indicated that there was no difference in plaque and gingival indices between crowned and natural teeth. In addition, the gingival status of the crowned teeth was good, irrespective of the position of the crown margin (subgingival, at the gingival margin or supragingival).

Adult↗

PubMed2003

Correlation between inflammatory periodontal diseases and cardiovascular diseases.

AIMS: Since cardiovascular diseases can exhibit a possible connection with chronic periodontal diseases, the aim of the present study was to examine the presence of periodontal impairment in patients with coronary heart diseases (CHD). METHODS: For this purpose periodontal charts were raised for 101 patients (78 male, 23 female, mean age 61.8 +/- 10.5 years) with cardiovascular diseases; comparison was drawn between theses charts and those for a control group of 101 healthy patients (59 male, 42 female, mean age 56.6 +/- 9.9 years). Over and above the dental diagnosis (probing depth [mm], vitality, tooth mobility, plaque index (PI), inclination towards sulcus bleeding) each related to 6 characteristic teeth, various habitual aspects (diet, smoke and drink patterns, stress, body weight) were recorded. RESULTS: Within the CHD-group the periodontal chart revealed for all teeth examined a mean probing depth of 3.4 +/- 1.1mm, with the corresponding reading for the control group being 2.8 +/- 0.9 mm. The mean bleeding index (Van-der-Weiden) read 1.1 +/- 0.7 for the CHD-group and 0.7 +/- 0.6 for the control group. The mean plaque index reading was 1.4 +/- 0.9 for the group suffering from heart diseases and 0.7 +/- 0.8 for the control group. Comparison of these periodontal charts showed statistically significant differences (p<= 0.01), whereas mean degrees of tooth mobility did not differ in a statistically significant way. In summary, the results described hint at a correlation between an existent coronary heart disease and the presence of a periodontitis. CONCLUSION: However, also for consideration below are further influential factors, such as diet, individual life conduct, smoking habits, Body-Mass-Index or microbiological aspects.

Adult↗

PubMed1980

The threshold of stereopsis in the presence of differences in magnification of the ocular images.

A comparison between 100 percent correct response thresholds of stereopsis for nine subjects measured with and without viewing using a 33 percent difference in ocular image magnification is presented. Two subjects performed threshold settings, using the method of adjustments, with 1, 5, 10, 15, and 33 percent magnification differences. The extent of the increase explains reports of stereopsis in corrected unilateral aphakia.

Adult↗

PubMed1993

Defining the major nursing administration issue: doing more with less.

"What is the major nursing administrative issue today?" The question was posed to a community of scholars in the masters program in nursing administration at the University of California, San Francisco. Using a modified nominal group approach, multiple issues were identified, explored, and prioritized. There was consensus that "doing more with less" is the most important issue and greatest of challenges. To explore this issue in depth, books relating to the topic were identified, read, and applied to nursing administrative practice. Before discussion, administrative briefings were written and distributed among the group. Previous readings and experience also contributed to the synthesis of ideas over the academic year, and the subsequent development of the following position paper.

California↗

PubMedDate not supplied

Determination of electron beam mean incident energy from d50 (ionization) values.

Depth-ionization measurements have been obtained with an air-filled Nordic Association of Clinical Physicists (NACP) design parallel-plate ionization chamber in a water phantom for ten foil-scattered electron beams from two different machines with nominal energies between 6 and 20 MeV and field sizes from 6 X 6 to 25 X 25 cm2. Depths of 50% ionization and practical range have been determined from least-squares fits to both the raw data and values corrected to parallel-beam geometry using measured virtual source distances. Depths of 50% dose have also been obtained from fits to divergence-corrected depth-dose measurements performed under identical conditions using, a p-type silicon diode detector. Utilizing accepted conversion factors between mean incident energy (E0) and depth of 50% dose for parallel incident beams, and taking advantage of the fact that p-type silicon diode detector readings are nearly directly indicative of relative dose, conversion factors between E0 and depth of 50% ionization for divergence-corrected and raw, uncorrected finite source-surface distance depth-ionization data are empirically determined. Those values, obtained using the results of both ETRAN and EGS4 dose calculations as base lines, are compared to values currently recommended for use in clinical dosimetry.

Electrons↗

PubMed2006

Temperature measurement and stratification in facultative waste stabilisation ponds in the UK climate.

Temperature measurements were taken at three pilot-scale facultative ponds located at Esholt wastewater treatment works in West Yorkshire, UK over two one-year periods. The measurements were taken at different depths using a technology called Thermochron iButton. The iButton readings were compared with temperature measurements taken by a YSI sonde probe and maximum/minimum thermometers: they were found to be within 1 .C. In the temperature range 3.18 .C the mean weekly and monthly air temperatures were found to be good predictors for the mean weekly and monthly pond water-column temperatures. The level of stratification in the ponds under UK climatic conditions was assessed; the data revealed that the ponds remained thermally stratified for significant periods during the year despite their shallow depth.

Climate↗