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At least 433 records · Page 24Linked to original sources
PubMed2004

Degree of illiteracy and phonological and metaphonological skills in unschooled adults.

Phonological and metaphonological skills are explored in 97 Brazilian illiterate and semiliterate adults. A simple letter- and word-reading task was used to define the degree of illiteracy. Phonemic awareness was strongly dependent on the level of letter and word reading ability. Phonological memory was very low in illiterates and unrelated to letter knowledge. Rhyme identification was relatively preserved in illiterates and semiliterates, and unrelated to letter and word reading level. Phonetic discrimination (minimal pairs) was fairly good and marginally related to reading ability. These results suggest that phonological sensitivity, phonological memory, rhyme identification, and phonemic awareness are distinctive cognitive processes, and that only phonemic awareness is clearly and strongly dependent on the alphabetical acquisition.

Adult↗
PubMed2006

CreateTarget and Analyze This!: new software assisting imaging mass spectrometry on Bruker Reflex IV and Ultraflex II instruments.

Two new software programs are presented which enable matrix-assisted laser desorption/ionisation imaging mass spectrometry (MALDI-IMS) on Bruker Reflex and Ultraflex instruments. The first program, CreateTarget, creates a high density raster with the dimensions of the tissue section, and converts these parameters into a virtual target plate file that can be imported in the normal mass spectrometer control software. Following automated spectrum acquisition, the second program, Analyze This!, converts the array of spectra into an Analyze 7.5 image format that can be read by image analysis software. These two tools are sufficient to allow IMS, and offer a valid alternative to commercially available software. CreateTarget and Analyze This! are available free of charge.

Animals↗
PubMed2000

Theoretical considerations to the verification of dynamic multileaf collimated fields with a SLIC-type portal image detector.

The verification possibilities of dynamically collimated treatment beams with a scanning liquid ionization chamber electronic portal image device (SLIC-EPID) are investigated. The ion concentration in the liquid of a SLIC-EPID and therefore the read-out signal is determined by two parameters of a differential equation describing the creation and recombination of the ions. Due to the form of this equation, the portal image detector describes a nonlinear dynamic system with memory. In this work, the parameters of the differential equation were experimentally determined for the particular chamber in use and for an incident open 6 MV photon beam. The mathematical description of the ion concentration was then used to predict portal images of intensity-modulated photon beams produced by a dynamic delivery technique, the sliding window approach. Due to the nature of the differential equation, a mathematical condition for 'reliable leaf motion verification' in the sliding window technique can be formulated. It is shown that the time constants for both formation and decay of the equilibrium concentration in the chamber is in the order of seconds. In order to guarantee reliable leaf motion verification, these time constants impose a constraint on the rapidity of the image-read out for a given maximum leaf speed. For a leaf speed of 2 cm s(-1), a minimum image acquisition frequency of about 2 Hz is required. Current SLIC-EPID systems are usually too slow since they need about a second to acquire a portal image. However, if the condition is fulfilled, the memory property of the system can be used to reconstruct the leaf motion. It is shown that a simple edge detecting algorithm can be employed to determine the leaf positions. The method is also very robust against image noise.

Computer Simulation↗
PubMed2006

Simultaneous acquisition of multislice PET and MR images: initial results with a MR-compatible PET scanner.

UNLABELLED: PET and MRI are powerful imaging techniques that are largely complementary in the information they provide. We have designed and built a MR-compatible PET scanner based on avalanche photodiode technology that allows simultaneous acquisition of PET and MR images in small animals. METHODS: The PET scanner insert uses magnetic field-insensitive, position-sensitive avalanche photodiode (PSAPD) detectors coupled, via short lengths of optical fibers, to arrays of lutetium oxyorthosilicate (LSO) scintillator crystals. The optical fibers are used to minimize electromagnetic interference between the radiofrequency and gradient coils and the PET detector system. The PET detector module components and the complete PET insert assembly are described. PET data were acquired with and without MR sequences running, and detector flood histograms were compared with the ones generated from the data acquired outside the magnet. A uniform MR phantom was also imaged to assess the effect of the PET detector on the MR data acquisition. Simultaneous PET and MRI studies of a mouse were performed ex vivo. RESULTS: PSAPDs can be successfully used to read out large numbers of scintillator crystals coupled through optical fibers with acceptable performance in terms of energy and timing resolution and crystal identification. The PSAPD-LSO detector performs well in the 7-T magnet, and no visible artifacts are detected in the MR images using standard pulse sequences. CONCLUSION: The first images from the complete system have been successfully acquired and reconstructed, demonstrating that simultaneous PET and MRI studies are feasible and opening up interesting possibilities for dual-modality molecular imaging studies.

Anatomy, Cross-Sectional↗
PubMed1998

Verification of set-up deviations in patients with breast cancer using portal imaging in clinical practice.

AIM: The aim of this study was to determine set-up deviations during irradiation of patients with breast cancer using Electronic Portal Imaging (EPI). PATIENTS AND METHOD: In order to monitor the intrafractional set-up deviations multiple portal image readings were carried out on 5 patients with breast cancer. Moreover interfractional set-up deviations were determined by the acquisition of daily EPIs in a total of 20 patients. RESULTS: The results of intrafractional set-up deviation based on 130 EPIs revealed a maximum lateral and longitudinal (cranio-caudal) deviation of 2 mm (range:-10 mm to 8 mm) as well as 1 degree in rotation (range: -2 degree to 2 degrees). The interfractional set-up deviations in 20 breast cancer patients during a treatment series of 25 fractions showed mean standard deviations of 5 mm in lateral and longitudinal direction, respectively. Only in few cases deviations up to maximally 24 mm were observed. The mean standard deviation of the rotational error was 2 degrees and reached a maximum of 6.5 degrees. CONCLUSION: These results show that intrafractional set-up deviations in breast cancer patients are negligible in clinical practice. They can be attributed to random errors due to patient movement and breathing. The set-up deviations during a treatment series can be differentiated in systematic and random errors. Patient fixation and immobilization is crucial in minimizing random errors. Taking into account 10 mm safety margins as used in our department around the "clinical target volume" (CTV), set-up errors outside of this volume (PTV) were exceptional. The enlarged PTV definition of 15 mm for lateral and cranio-caudal field margins, respectively as used in this study covers 99% of the CTV in all patients.

Breast Neoplasms↗
PubMed2005

Transgenic expression of a novel M. truncatula phytase gene results in improved acquisition of organic phosphorus by Arabidopsis.

A full-length cDNA encoding an extracellular form of phytase was isolated from the model legume Medicago truncatula. The phytase cDNA (MtPHY1) has an open reading frame of 1,632 bp predicted to encode 543 amino acids including an N-terminal signal peptide of 27 amino acids. The MtPHY1 gene is 5,151 bp in length, containing 7 exons and 6 introns. MtPHY1 transcripts were detected in leaves and roots and levels elevated in roots during growth in low phosphate conditions. Transgenic Arabidopsis lines expressing MtPHY1 under the control of the root-specific MtPT1 promoter or the constitutive CaMV35S promoter were created. Phytase activities in root apoplast of the transgenic Arabidopsis were 12.3- to 16.2-fold higher than those of the control plants. The expressed phytase was secreted into the rhizosphere as demonstrated by enzyme activity staining and HPLC analysis of phytate degradation by root exudates. Transgenic expression of the MtPHY1 led to significant improvement in organic phosphorus utilization and plant growth. When phytate was supplied as the sole source of phosphorus, dry weight of the transgenic Arabidopsis lines were 3.1- to 4.0-fold higher than the control plants and total phosphorus contents were 4.1- to 5.5-fold higher than the control. Transgenic expression of phytase genes of plant origin has great potential for improving plant phosphorus acquisition and for phytoremediation.

6-Phytase↗
PubMedDate not supplied

Performance but not acquisition of skill learning is severely impaired in the elderly.

A battery of cognitive tests, specifically designed to assess verbal and skill learning, was administered to healthy volunteer subjects of different ages. Although there were age-related declines in initial and terminal performance in both a pursuit rotor and a mirror reading task, the increase in performance with practice on these tasks was little affected by age. Recall, but not recognition, of verbal material was also impaired in the elderly, as were some measures of frequency estimation. These findings are compatible with the contention that, although acquisition of declarative tasks, which requires conscious processing, is impaired in the elderly, acquisition of nondeclarative tasks, which can be learned without conscious awareness, is not affected by age. However, classical conditioning may be an exception to this generalization for reasons that are at the present time unknown.

Journal Article↗
PubMed1983

Reading, demographic, social and psychological factors related to pre-adolescent smoking and non-smoking behaviors and attitudes.

The purpose of this study was to examine reading, demographic, social and psychological factors related to pre-adolescent smoking and non-smoking behaviors and attitudes. The school-home humanistic education program was implemented in a large, urban public school system. It stressed responsible decision-making, increased self-esteem and the inter-relationships among the acquisition of knowledge of the consequences of smoking, personal feelings, family relationships and behavior. The results showed that family involvement was necessary to affect smoking attitudes and behaviors. Of all the variables studied, reading had a most pervasive relationship. Peer influence and self-esteem also were related to smoking knowledge, smoking attitude, future smoking intentions and the "purchase" of cigarettes. Two of several conclusions drawn from the results are: 1. Family involvement is necessary to affect attitudes and behaviors. 2. Health education research that does not investigate the relationship between program outcomes and reading achievement may be misleading.

Achievement↗
PubMed2000

The effect of Kana literacy acquisition on the speech segmentation unit used by Japanese young children.

Three experiments were undertaken to investigate whether young children's segmentation units would change as they learned to read kana letters, which represent morae (subsyllabic rhythmic units). The first 2 experiments used a vocal-motor segmentation task to examine whether 4- to 6-year-olds preferred to segment spoken words containing the special syllables CVN, CVQ, or CV: into syllables or into morae. The third experiment used a target monitoring task for CVN to examine whether children's detection of the target syllable in a series of words would vary depending on the moraic constitution of the target and the moraic-syllabic status of the word initial in which the target was embedded. Results indicated that the children's conscious segmentation of words, except for those having a geminate stop consonant (CVQ), developed from being a mixture of syllable- and mora-based to being predominantly mora-based as they learned to read kana letters. The tendency toward mora-based segmentation was also found in the target monitoring task, which required segmentation at a less conscious level.

Child, Preschool↗
PubMed1975

Children's acquisition of idioms in the English language.

Idiomatic comprehension was studied in four groups of 20 subjects each, ages six, nine, and 12 years, and adult. Each subject was read 10 sentences which could be interpreted literally or idiomatically. Following each sentence, the subject chose the two pictures that were closest in meaning to the sentence heard. This procedure generated 800 pairs of selections for analysis. The results indicated a (1) significant difference between literal and idiomatic choices regardless of the subject's age or the voice of the sentence, (2) significant difference between literal and idiomatic choices as a function of age regardless of the voice of the sentence, and (3) significant voice-by-choice interaction indicating that voice affected the choice of literal or idiomatic picture representations.

Adult↗
PubMedDate not supplied

Conductive hearing loss effects on children's language and scholastic skills. A review of the literature.

A review of available studies investigating the consequences of conductive hearing loss for language acquisition and scholastic performance was carried out. It uncovered no study that met the standards of rigor needed to provide a definitive answer to this question, although the burden of the evidence is that a persistent mild hearing loss, especially if present since infancy, probably has a measurably deleterious effect on the language of most but not all children. Diagnostic criteria documenting the severity, age of occurrence and duration of middle ear effusions were lacking. Measures of the detrimental effects of conductive losses on linguistic skills frequently were limited to the number of grades children were retained in school, their reading or vocabulary level on achievement tests, or a comparison of their scores on the verbal and performance scales of intelligence tests. Very few studies followed the acquisition of language in affected children or examined its structure. Very few considered the interaction between the socioeconomic and cultural environment of the child and the consequences of his hearing loss. The review underscored the need for prospective multidisciplinary studies in order to evaluate the actual impact of this common pediatric problem.

Achievement↗
PubMedDate not supplied

Phonological representations, reading development and dyslexia: towards a cross-linguistic theoretical framework.

This paper attempts to integrate recent research findings in phonological development, reading development and dyslexia into a coherent theoretical framework that can provide a developmental account of reading and reading difficulties across languages. It is proposed that the factors governing phonological development across languages are similar, but that important differences in the speed and level of phonological development are found following the acquisition of alphabetic literacy. The causal framework offered is at the level of a cognitive model, which may prove useful in organizing future cross-linguistic developmental work.

Adolescent↗
PubMed1999

FDG-PET in the Locoregional Lymph Node Staging of Non-small Cell Lung Cancer. A Comprehensive Review of the Leuven Lung Cancer Group Experience.

Exact staging of locoregional lymph node (LN) disease in non-small cell lung cancer (NSCLC) is of considerable clinical interest. Computed tomography (CT) is not very accurate for this purpose. In the past years, we performed several prospective studies examining the role of [18F]fluoro-2-deoxy-D-glucose-positron emission tomography (FDG-PET) in this setting. We compared the accuracy of CT, PET, and PET read with the anatomical aid of CT images in the distinction of early-stage operable cases (i.e., without metastatic LN or with only hilar metastatic LN) versus locally advanced cases (with metastatic mediastinal LN). LNs on PET were recorded as metastatic if the FDG-uptake was more intense than the mediastinal blood pool activity. In 105 patients (or an analysis of 980 LN stations), the accuracy of PET (85%) was significantly better than that of CT (64%; P = 0.0003). Visual correlation with CT images further improved the results to an accuracy of 90%. We also examined the value of different acquisition protocols and interpretation algorithms. The use of Standardized Uptake Values (SUVs) of LNs, or of anatometabolic PET-CT-fusion images, did not prove to be of additional value compared to visual PET-reading and correlation with the CT images. On the condition that positive-LN findings on PET are always confirmed by mediastinoscopy, a simple whole-body acquisition protocol is adequate. We conclude that FDG-PET plays an important role in LN-staging in NSCLC. The very high negative predictive value of mediastinal FDG-PET is able to reduce the need for invasive surgical staging substantially.

Journal Article↗
PubMed1997

Diltiazem slow-release and left-ventricular hypertrophy: a volumetric approach of left ventricular mass using magnetic resonance imaging.

AIMS: This study was designed to assess the changes in left ventricular mass (LVM) in hypertensive patients with left ventricular hypertrophy under drug therapy with once-daily slow-release diltiazem. Magnetic resonance imaging (MRI) was used for this purpose because of its higher reproducibility than M-mode or two-dimensional echocardiography. METHODS: Patients suffering from essential hypertension were included if their baseline LVM index (LVMI) was > or = 105 g/m2 in male or > or = 85 g/m2 in female patients, ie, equal or higher to the median values observed in hypertensive patients in our institution. MRI consisted in a true short-axis, electrocardiogram (ECG) gated spin-echo slice acquisition at baseline, after 3 and 6 months of therapy (M0, M3, and M6). Data were stored on magnetic tapes and read subsequently under blind conditions and the control of an external auditor. RESULTS: Thirty-five patients were included. Of these, 14 patients (40%) were not previously treated. Inter- and intra-observer variability for LVMI measurement were 5.6 +/- 4.3% and 2.1 +/- 3.0%, respectively. Mean baseline LVMI was 110 +/- 16 g/m2 in male and 96 +/- 16 g/m2 in female patients. It decreased by 3.6% at M3 (P = 0.05) and by 6.0% at M6 (P = 0.02). A trend towards a greater LVMI reduction was observed in previously untreated patients. CONCLUSION: This study confirms that MRI is a reproducible technique for the measurement of LVM. It demonstrates a significant reduction in LVMI as early as the 3rd month of therapy in hypertensive patients treated with once-daily sustained release (SR) diltiazem, although baseline LVMI in the majority of participating patients was only moderately increased.

Adult↗
PubMed2002

Determinants of picture naming times in Icelandic.

Numerous studies have found that word frequency has a significant effect on the time it takes to name an object or read a word. Recently, claims have been made that this frequency effect is perhaps more correctly interpreted as an age of acquisition effect. This paper reports an experiment in which naming times in Icelandic for 175 stimuli from the Snodgrass and Vanderwart picture set were determined. A multiple regression analysis of naming times against a number of independent factors showed that objective age of acquisition was the strongest predictor of naming time, with familiarity and name agreement also showing a significant effect. The effect of word frequency was, however, not significant. Possible reasons for this are discussed.

Adolescent↗
PubMed2000

Measurement of endometrial thickness at US in multicenter drug trials: value of central quality assurance reading.

PURPOSE: To assess the value of central quality assurance (QA) reading of transvaginal ultrasonographic (US) images obtained to measure endometrial thickness and to assess image quality. MATERIALS AND METHODS: Results of 2,000 US examinations performed in 1,000 subjects during one of two multicenter drug trials were evaluated. Endometrial thickness was measured at the study site; images were then sent to the QA center, where an experienced sonologist evaluated endometrial thickness and image quality. RESULTS: In 360 (18%) of the 2,000 examinations, image quality was insufficient for central QA reading. Repeat examinations were requested, and suggestions for improvement in technique were provided. In 349 (97%) of the 360 examinations, repeat US images were of acceptable quality. In 99 (5%) of the 1,989 examinations in which endometrial thickness was measured, central measurement of thickness differed by more than 2 mm from that of the site. In a group (n = 300) that was followed up for 1 year, requests for repeat US examinations decreased from 24% at baseline to 11% at 1 year. CONCLUSION: Central QA reading provides a consistent evaluation of endometrial thickness on US images obtained in multicenter drug trials and helps to ensure the acquisition of high-quality transvaginal US images. It further leads to demonstrable improvement in site performance.

Endometrium↗
PubMed2004

Accurate, simplified and rapid three-dimensional echocardiographic volume quantifications: Comparison of different algorithms in symmetric and asymmetric left ventricular geometry.

OBJECTIVE: A comparative investigation of dynamic three-dimensional freehand echocardiography (D3DFE) and magnetic resonance imaging (MRI) was conducted to determine the accuracy and rapidity of the average rotation method (ARM) and the disk summation method (DSM) for volumetric analysis. METHODS: In 15 patients with an asymmetric left ventricle and 12 normal subjects, end-diastolic and end-systolic left ventricular volumes were assessed by D3DFE and by MRI. Both DSM and ARM were used for volume determination. All echocardiographic readings were performed by two examiners blinded to each other and to the MRI results. The times needed for echocardiographic data acquisition and volumetric analysis with either algorithm were determined. RESULTS: Correlation between ARM and MRI measurements was tighter than between DSM and MRI measurements (end-diastolic volume: r=0.95, P<0.0001 versus r=0.94, P<0.0001 in asymmetric ventricles; and r=0.97, P<0.0001 versus r=0.96, P<0.0001 in symmetric ventricles; end-systolic volume: r=0.94, P<0.0001 versus r=0.93, P<0.0001 in asymmetric ventricles and r=0.96, P<0.0001 versus r=0.94, P<0.0001 in symmetric ventricles). In addition, ARM analysis was less time-consuming than DSM (6.4+/-0.4 min versus 7.6+/-0.3 min, P<0.05). CONCLUSIONS: For D3DFE, ARM is the most accurate and rapid approach to left ventricular volume determination. ARM benefits from advanced two-dimensional imaging and can be easily added to any standard transthoracic echocardiographic examination.

Adult↗