3,245 research outputs found
Effects of adult aging on letter position coding in reading: evidence from eye movements
It is well-established that young adults encode letter position flexibly during natural reading. However, given the visual changes that occur with normal aging, it is important to establish whether letter position coding is equivalent across adulthood. In 2 experiments, young (18-25 years) and older (65 years) adults' were recorded while reading sentences with words containing transposed adjacent letters. Transpositions occurred at beginning (rpoblem), internal (porblem), or end (problme) locations in words. In Experiment 1, these transpositions were present throughout reading. By comparison, Experiment 2 used a gaze-contingent paradigm such that once the reader's gaze moved past a word containing a transposition, this word was shown correctly and did not subsequently change. Both age groups showed normal levels of comprehension for text including words with transposed letters. The pattern of letter transposition effects on eye movements was similar for the young and older adults, with greater increases in reading times when external relative to internal letters were transposed. In Experiment 1, however, effects of word beginning transpositions during rereading were larger for the older adults. In Experiment 2 there were no interactions, confirming that letter position coding is similar for both age groups at least during first-pass processing of words. These findings show that flexibility in letter position encoding during the initial processing of words is preserved across adulthood, although the interaction effect in rereading in Experiment 1 also suggests that older readers may use more stringent postlexical verification processes, for which the accuracy of word beginning letters is especially important
Eye movements during reading and topic scanning: effects of word frequency
The study examined the nature of eye movement control and word recognition during scanning for a specific topic, compared with reading for comprehension. Experimental trials included a manipulation of word frequency: the critical word was frequent (and orthographically familiar) or infrequent (2 conditions: orthographically familiar and orthographically unfamiliar). First-pass reading times showed effects of word frequency for both reading and scanning, with no interactions between word characteristics and task. Therefore, in contrast to the task of searching for a single specific word (Rayner and Fischer, 1996), there were immediate and localized influences of lexical processing when scanning for a specific topic, indicating that early word recognition processes are similar during reading and topic scanning. In contrast, there were interactions for later measures, with larger effects of word frequency during reading than scanning, indicating that reading goals can modulate later processes such as the integration of words into sentence context. Additional analyses of the distribution of first-pass single fixation durations indicated that first-pass fixations of all durations were shortened during scanning compared with reading, and reading for comprehension produced a larger subset of longer first-pass fixations compared with scanning. The implications for the nature of word recognition and eye movement control are discussed
Effects of aging, word frequency, and text stimulus quality on reading across the adult lifespan: evidence from eye movements
Reductions in stimulus quality may disrupt the reading performance of older adults more when compared with young adults because of sensory declines that begin early in middle age. However, few studies have investigated adult age differences in the effects of stimulus quality on reading, and none have examined how this affects lexical processing and eye movement control. Accordingly, we report two experiments that examine the effects of reduced stimulus quality on the eye movements of young (18-24 years), middle-aged (41-51 years), and older (65 years) adult readers. In Experiment 1, participants read sentences that contained a high-or low-frequency critical word and that were presented normally or with contrast reduced so that words appeared faint. Experiment 2 further investigated effects of reduced stimulus quality using a gaze-contingent technique to present upcoming text normally or with contrast reduced. Typical patterns of age-related reading difficulty (e.g., slower reading, more regressions) were observed in both experiments. In addition, eye movements were disrupted more for older than younger adults when all text (Experiment 1) or just upcoming text (Experiment 2) appeared faint. Moreover, there was an interaction between stimulus quality and word frequency (Experiment 1), such that readers fixated faint low-frequency words for disproportionately longer. Crucially, this effect was similar across all age groups. Thus, although older readers suffer more from reduced stimulus quality, this additional difficulty primarily affects their visual processing of text. These findings have important implications for understanding the role of stimulus quality on reading behavior across the lifespan
The test accuracy of antenatal ultrasound definitions of fetal macrosomia to predict birth injury: A systematic review.
OBJECTIVES: To determine which ultrasound measurement for predicted fetal macrosomia most accurately predicts adverse delivery and neonatal outcomes. STUDY DESIGN: Four biomedical databases searched for studies published after 1966. Randomised trials or observational studies of women with singleton pregnancies, resulting in a term birth who have undergone an index test of interest measured and recorded as predicted fetal macrosomia ≥28 weeks. Adverse outcomes of interest included shoulder dystocia, brachial plexus injury (BPI) and Caesarean section. RESULTS: Twenty-five observational studies (13,285 participants) were included. For BPI, the only significant positive association was found for Abdominal Circumference (AC) to Head Circumference (HC) difference > 50 mm (OR 7.2, 95 % CI 1.8-29). Shoulder dystocia was significantly associated with abdominal diameter (AD) minus biparietal diameter (BPD) ≥ 2.6 cm (OR 4.2, 95 % CI 2.3-7.5, PPV 11 %) and AC > 90th centile (OR 2.3, 95 % CI 1.3-4.0, PPV 8.6 %) and an estimated fetal weight (EFW) > 4000 g (OR 2.1 95 %CI 1.0-4.1, PPV 7.2 %). CONCLUSIONS: Estimated fetal weight is the most widely used ultrasound marker to predict fetal macrosomia in the UK. This study suggests other markers have a higher positive predictive value for adverse outcomes associated with fetal macrosomia
Use of continuous subcutaneous anesthetic infusion in cardiac surgical patients after median sternotomy
The use of opioid analgesics to control pain after median sternotomy in cardiac surgical patients is worldwide accepted and established. However, opioids have a wide range of possible side effects, concerning prolonged extubation time, gastrointestinal tract dyskinesia and urinary tract disorders mostly retention. All these may lead to a prolonged ICU stay or overall hospitalization time increase
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Are older adults more risky readers? Evidence from meta-analysis
According to an influential account of aging effects on reading, older adults (65+ years) employ a more “risky” reading strategy compared to young adults (18–30 years), in which they attempt to compensate for slower processing by using lexical and contextual knowledge to guess upcoming (i.e., parafoveal) words more often. Consequently, while older adults may read more slowly, they might also skip words more often (by moving their gaze past words without fixating them), especially when these are of higher lexical frequency or more predictable from context. However, this characterization of aging effects on reading has been challenged recently following several failures to replicate key aspects of the risky reading hypothesis, as well as evidence that key effects predicted by the hypothesis are not observed in Chinese reading. To resolve this controversy, we conducted a meta-analysis of 102 eye movement experiments comparing the reading performance of young and older adults. We focused on the reading of sentences displayed normally (i.e., without unusual formatting or structures, or use of gaze-contingent display change techniques), conducted using an alphabetic script or Chinese, and including experiments manipulating the frequency or predictability of a specific target word. Meta-analysis confirmed that slower reading by older compared to younger adults is accompanied by increased word-skipping, although only for alphabetic scripts. Meta-analysis additionally showed that word-skipping probabilities are unaffected by age differences in word frequency or predictability effects, casting doubt on a central component of the risky reading hypothesis. We consider implications for future research on aging effects on reading. (PsycInfo Database Record (c) 2022 APA, all rights reserved
A Review of One-Way and Two-Way Experiments to Test the Isotropy of the Speed of Light
As we approach the 125th anniversary of the Michelson-Morley experiment in
2012, we review experiments that test the isotropy of the speed of light.
Previous measurements are categorized into one-way (single-trip) and two-way
(round-trip averaged or over closed paths) approaches and the level of
experimental verification that these experiments provide is discussed. The
isotropy of the speed of light is one of the postulates of the Special Theory
of Relativity (STR) and, consequently, this phenomenon has been subject to
considerable experimental scrutiny. Here, we tabulate significant experiments
performed since 1881 and attempt to indicate a direction for future
investigation.Comment: Updated Fig. 7 and references; Revised sections 3.2 and 4. Accepted
in the Indian Journal of Physics on March 30, 201
How Does Blood-Retinal Barrier Breakdown Relate to Death and Disability in Pediatric Cerebral Malaria?
BACKGROUND: In cerebral malaria, the retina can be used to understand disease pathogenesis. The mechanisms linking sequestration, brain swelling and death remain poorly understood. We hypothesized that retinal vascular leakage would be associated with brain swelling. METHODS: We used retinal angiography to study blood-retinal barrier integrity. We analyzed retinal leakage, histopathology, brain MRI, and associations with death and neurological disability in prospective cohorts of Malawian children with cerebral malaria. RESULTS: Three types of retinal leakage were seen: Large focal leak (LFL), punctate leak (PL) and vessel leak. LFL and PL were associated with death (OR 13.20, 95%CI 5.21-33.78 and 8.58, 2.56-29.08 respectively), and brain swelling (p<0.05). Vessel leak and macular non-perfusion were associated with neurological disability (3.71, 1.26-11.02 and 9.06, 1.79-45.90). LFL was observed as an evolving retinal hemorrhage. A core of fibrinogen and monocytes was found in 39 (93%) white-centered hemorrhages. CONCLUSIONS: Blood-retina barrier breakdown occurs in three patterns in cerebral malaria. Associations between LFL, brain swelling, and death suggest that the rapid accumulation of cerebral hemorrhages, with accompanying fluid egress, may cause fatal brain swelling. Vessel leak from barrier dysfunction, and non-perfusion were not associated with severe brain swelling, but with neurological deficits, suggesting hypoxic injury in survivors
Unprecedented within-species chromosome number cline in the Wood White butterfly Leptidea sinapis and its significance for karyotype evolution and speciation
Background: Species generally have a fixed number of chromosomes in the cell nuclei while between-species differences are common and often pronounced. These differences could have evolved through multiple speciation events, each involving the fixation of a single chromosomal rearrangement. Alternatively, marked changes in the karyotype may be the consequence of within-species accumulation of multiple chromosomal fissions/fusions, resulting in highly polymorphic systems with the subsequent extinction of intermediate karyomorphs. Although this mechanism of chromosome number evolution is possible in theory, it has not been well documented. Results: We present the discovery of exceptional intraspecific variability in the karyotype of the widespread Eurasian butterfly Leptidea sinapis. We show that within this species the diploid chromosome number gradually decreases from 2n = 106 in Spain to 2n = 56 in eastern Kazakhstan, resulting in a 6000 km-wide cline that originated recently (8,500 to 31,000 years ago). Remarkably, intrapopulational chromosome number polymorphism exists, the chromosome number range overlaps between some populations separated by hundreds of kilometers, and chromosomal heterozygotes are abundant. We demonstrate that this karyotypic variability is intraspecific because in L. sinapis a broad geographical distribution is coupled with a homogenous morphological and genetic structure. Conclusions: The discovered system represents the first clearly documented case of explosive chromosome number evolution through intraspecific and intrapopulation accumulation of multiple chromosomal changes. Leptidea sinapis may be used as a model system for studying speciation by means of chromosomally-based suppressed recombination mechanisms, as well as clinal speciation, a process that is theoretically possible but difficult to document. The discovered cline seems to represent a narrow time-window of the very first steps of species formation linked to multiple chromosomal changes that have occurred explosively. This case offers a rare opportunity to study this process before drift, dispersal, selection, extinction and speciation erase the traces of microevolutionary events and just leave the final picture of a pronounced interspecific chromosomal difference
Transiently achieved very low low-density lipoprotein cholesterol levels by statin and alirocumab after acute coronary syndrome are associated with cardiovascular risk reduction: the ODYSSEY OUTCOMES trial
Aims Long-term, placebo-controlled cholesterol-lowering trials have demonstrated legacy effects (clinical benefits that persist or emerge after trial end). It is unknown whether legacy effects follow a short period of very low low-density lipoprotein cholesterol (LDL-C) levels achieved with statin plus proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitor. Methods and results In 18 924 patients with recent acute coronary syndrome, the ODYSSEY OUTCOMES trial compared the PCSK9 inhibitor alirocumab with placebo, each added to high-intensity or maximum-tolerated statin therapy. Patients with two consecutive LDL-C levels <0.39 mmol/L (15 mg/dL) on alirocumab had blinded placebo substitution for the remainder of the trial with continued statin treatment. In post hoc analyses, major adverse cardiovascular events (MACE) in these patients were compared to MACE in propensity score–matched patients from the placebo group with similar baseline characteristics and study medication adherence. In the alirocumab group, 730 patients had blinded placebo substitution at a median of 8.3 months from randomization, after a median of 6.0 months with LDL-C <0.39 mmol/L. They were matched to 1460 placebo patients. Both groups had lower baseline LDL-C and lipoprotein(a) and better study medication adherence than those of the overall cohort. Over a median follow-up of 2.8 years, MACE occurred in 47 (6.4%) alirocumab patients with limited-duration, very low achieved LDL-C vs. 122 (8.4%) matched placebo patients (treatment hazard ratio 0.72; 95% confidence interval 0.51, 0.997; P = 0.047). Conclusion A short period of LDL-C levels <0.39 mmol/L achieved with statin and alirocumab, followed by statin monotherapy, was associated with a lower risk of MACE than statin monotherapy throughout the observation period. Clinical benefit persisted for several years
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