Cross-language transfer of phonological and orthographic processing skills in Spanish-speaking children learning to read and spell in English

This dissertation included two studies designed to examine how young children acquire biliteracy skills. Specifically, I aimed to determine how reading and spelling acquisition in English second language (L2) is influenced by Spanish first language (L1). Study 1 investigated the contribution of Spanish phonological and orthographic processing skills to English reading and spelling in 89 Spanish-English bilingual children in grades 2 (n = 42) and 3 (n = 47). Comparable measures in English and Spanish tapping phonological and orthographic processing were administered to the bilingual children and to 53 monolingual English-speaking children in grades 2 (n = 32) and 3 (n = 21) as a comparison group. We found that cross language phonological and orthographic transfer occurs from Spanish to English for real word and pseudoword reading. However, Spanish orthographic processing only predicted reading, not spelling. Study 2 examined spelling errors committed on specific linguistic units - vowels that are spelled differently in the two languages (i.e., contrastive vowels) - to determine whether Spanish-speaking children spell these vowels using Spanish spelling rules. Participants for Study 2 were carefully recruited; these Spanish-speaking students had received about 2.2 years of literacy instruction in their native language, ensuring that they would have adequate orthographic knowledge to read and spell in Spanish. Error analyses indicated that the 27 native Spanish-speaking children who received prior literacy instruction in Spanish did indeed spell these contrastive vowels using Spanish orthography; therefore, these errors were influenced by their L1 orthographic knowledge. Taken together, these two studies highlight the importance of taking into consideration bilingual children's L1 phonological and orthographic knowledge in understanding L2 reading and spelling acquisition. The results of the two studies enhance the theoretical frameworks by providing empirical evidence to support the notion that bilingual children are indeed both positively and negatively affected by the differences in orthographic depths of the languages

Venous hemodynamics in neurological disorders: an analytical review with hydrodynamic analysis.

Venous abnormalities contribute to the pathophysiology of several neurological conditions. This paper reviews the literature regarding venous abnormalities in multiple sclerosis (MS), leukoaraiosis, and normal-pressure hydrocephalus (NPH). The review is supplemented with hydrodynamic analysis to assess the effects on cerebrospinal fluid (CSF) dynamics and cerebral blood flow (CBF) of venous hypertension in general, and chronic cerebrospinal venous insufficiency (CCSVI) in particular.CCSVI-like venous anomalies seem unlikely to account for reduced CBF in patients with MS, thus other mechanisms must be at work, which increase the hydraulic resistance of the cerebral vascular bed in MS. Similarly, hydrodynamic changes appear to be responsible for reduced CBF in leukoaraiosis. The hydrodynamic properties of the periventricular veins make these vessels particularly vulnerable to ischemia and plaque formation.Venous hypertension in the dural sinuses can alter intracranial compliance. Consequently, venous hypertension may change the CSF dynamics, affecting the intracranial windkessel mechanism. MS and NPH appear to share some similar characteristics, with both conditions exhibiting increased CSF pulsatility in the aqueduct of Sylvius.CCSVI appears to be a real phenomenon associated with MS, which causes venous hypertension in the dural sinuses. However, the role of CCSVI in the pathophysiology of MS remains unclear

MRI-based assessment of acute effect of head-down tilt position on intracranial hemodynamics and hydrodynamics

Purpose To quantify the acute effect of the head‐down tilt (HDT) posture on intracranial hemodynamics and hydrodynamics. Materials and Methods We evaluated the intracranial physiological parameters, blood flow‐related parameters, and brain morphology in the HDT (–6° and –12°) and the horizontal supine (HS) positions. Seven and 15 healthy subjects were scanned for each position using 3.0 T magnetic resonance imaging system. The peak‐to‐peak intracranial volume change, the peak‐to‐peak cerebrospinal fluid (CSF) pressure gradient (PGp‐p), and the intracranial compliance index were calculated from the blood and CSF flow determined using a cine phase‐contrast technique. The brain volumetry was conducted using SPM12. The measurements were compared using the Wilcoxon signed‐rank test or a paired t‐test. Results No measurements changed in the –6° HDT. The PGp‐p and venous outflow of the internal jugular veins (IJVs) in the –12° HDT were significantly increased compared to the HS (P < 0.001 and P = 0.025, respectively). The cross‐sectional areas of the IJVs were significantly larger (P < 0.001), and the maximum, minimum, and mean blood flow velocity of the IJVs were significantly decreased (P = 0.003, < 0.001, and = 0.001, respectively) in the –12° HDT. The mean blood flow velocities of the internal carotid arteries were decreased (P = 0.023). Neither position affected the brain volume. Conclusion Pressure gradient and venous outflow were increased in accordance with the elevation of the intracranial pressure as an acute effect of the HDT. However, the CSF was not constantly shifted from the spinal canal to the cranium. Level of Evidence: 2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;47:565–571

Numerical and Experimental Investigations on Supersonic Ejectors

Supersonic ejectors are widely used in a range of applications such as aerospace, propulsion and refrigeration. The primary interest of this study is to set up a reliable hydrodynamics model of a supersonic ejector, which may be extended to refrigeration applications. The first part of this work evaluated the performance of six well-known turbulence models for the study of supersonic ejectors. The validation concentrated on the shock location, shock strength and the average pressure recovery prediction. Axial pressure measurements with a capillary probe performed previously [Int. J. Turbo Jet Engines 19 (2002) 71; Conference Proc., 10th Int. Symp. Flow Visuzlization, Kyoto, Japan, 2002], were compared with numerical simulations while laser tomography pictures were used to evaluate the non-mixing length. The capillary probe has been included in the numerical model and the non-mixing length has been numerically evaluated by including an additional transport equation for a passive scalar, which acted as an ideal colorant in the flow. At this point, the results show that the k–omega–sst model agrees best with experiments. In the second part, the tested model was used to reproduce the different operation modes of a supersonic ejector, ranging from on-design point to off-design. In this respect, CFD turned out to be an efficient diagnosis tool of ejector analysis (mixing, flow separation), for design, and performance optimization (optimum entrainment and recompression ratios)

Impacts of cerebral small vessel disease on global and domain‐specific cognition

BackgroundThe 2021 Alzheimer’s Association International Conference press release forecasted global dementia cases to triple by 2050, due to the major contribution of increases in vascular risk factors. The Global Vascular Risk Score (GVRS) was developed to predict vascular events using a point‐based index for risk factor variables, though has demonstrated to be a significant predictor of global and domain‐specific cognitive performance in a multi‐ethnic cohort (Rundek, T. et al. Global Vascular Risk Score and CAIDE Dementia Risk Score Predict Cognitive Function in the Northern Manhattan Study. J Alzheimers Dis 73, 1221‐1231 (2020)). However, more than half of the variance in global and domain‐specific cognitive performance is still unexplained by GVRS variables. We sought to explain additional variance in cognitive performance by addition of MRI biomarkers of cerebral small vessel disease to the GVRS model.MethodWe included 1290 subjects from the multiethnic Northern Manhattan Study population (age 64+/‐8 years, 40% women, 66% Hispanic, 17% non‐Hispanic Black, 15% non‐Hispanic White, education 10+/‐5 years). Multivariate linear regression models were employed to assess the added value of the cerebral small vessel disease MRI measures (white matter hyperintensity volume, silent brain infarcts, cerebral microbleeds, and perivascular spaces) beyond GVRS variables in explaining more variance in global and domain‐specific (episodic memory, executive function, semantic memory, and processing speed) cognitive performance. The explained variance (R2) of the GVRS model was compared to the proposed model with added imaging markers to determine their predictive performance. Statistical significance was determined using F‐statistic difference test between the models.ResultThe explained variance (R2) and F‐statistic for models of global and domain‐specific cognition are in the table. Addition of MRI measures significantly improved the model for global cognition (F(4, 1108) = 2.68, p < 0.05) and domain‐specific cognitive performance models of episodic memory (F(4, 1096) = 3.34, p < 0.01) and processing speed (F(4, 1096) = 2.40, p < 0.05).ConclusionMRI measures of cerebral small vessel disease explain more variance in global cognition, episodic memory, and processing speed than GVRS factors alone. However, most of the variance in cognitive performance remains unexplained

Recovery from Proactive Semantic Interference in Mild Cognitive Impairment and Normal Aging: Relationship to Atrophy in Brain Regions Vulnerable to Alzheimer's Disease

There is growing evidence that proactive semantic interference (PSI) and failure to recover from PSI may represent early features of Alzheimer's disease (AD). This study investigated the association between PSI, recovery from PSI, and reduced MRI volumes in AD signature regions among cognitively impaired and unimpaired older adults. Performance on the LASSI-L (a novel test of PSI and recovery from PSI) and regional brain volumetric measures were compared between 38 cognitively normal (CN) elders and 29 older participants with amnestic mild cognitive impairment (MCI). The relationship between MRI measures and performance on the LASSI-L as well as traditional memory and non-memory cognitive measures was also evaluated in both diagnostic groups. Relative to traditional neuropsychological measures, MCI patients' failure to recover from PSI was associated with reduced volumes in the hippocampus (rs = 0.48), precuneus (rs = 0.50); rostral middle frontal lobules (rs = 0.54); inferior temporal lobules (rs = 0.49), superior parietal lobules (rs = 0.47), temporal pole (rs = 0.44), and increased dilatation of the inferior lateral ventricle (rs = -0.49). For CN elders, only increased inferior lateral ventricular size was associated with vulnerability to PSI (rs = -0.49), the failure to recover from PSI (rs = -0.57), and delayed recall on the Hopkins Verbal Learning Test-Revised (rs = -0.48). LASSI-L indices eliciting failure to recover from PSI were more highly associated with more MRI regional biomarkers of AD than other traditional cognitive measures. These results as well as recent amyloid imaging studies with otherwise cognitively normal subjects, suggest that recovery from PSI may be a sensitive marker of preclinical AD and deserves further investigation