Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 230
Filtrar
Más filtros

Banco de datos
Tipo del documento
Intervalo de año de publicación
1.
Sex Transm Dis ; 2024 Apr 30.
Artículo en Inglés | MEDLINE | ID: mdl-38687341

RESUMEN

BACKGROUND: The United States (US) has seen a > 40% increase in syphilis cases since 2017. Early disease identification and treatment are crucial. This review sought to identify emergency department (ED) patients at risk for syphilis. METHODS: A 30-day retrospective review was conducted of visits to a single ED. Patient visits were assessed for pre-determined syphilis 'flags' to include history of sexually transmitted infection (STI), current chief complaint (CC) or reason for visit (RFV) keyword(s) suggestive of potential STI, or positive pregnancy test. Flagged charts were assessed for STI testing results within six-months of ED visit. Data was analyzed using chi-square. RESULTS: There were 5537 total patient encounters, resulting in 455 flagged visits from 408 (8.4%) unique individuals, majority female (282, 69.1%; p < .001)), Black (251, 61.5%; p < .001), aged 15-44 (308, 75.5%; p < .001). Chief complaint was the most frequent flag (65.3%) followed by RFV (37.4%), prior STI (31.0%), and pregnancy (12.3%). Syphilis testing data was available for 120 flagged patents; 29 (24.2%) screened positive, including 11 (2.7% of total flagged cohort) with evidence for active infection. Among those, majority were Black (90.9%), male (72.7%), aged 25 to 34 (63.6%); nine (81.8%) had concomitant HIV; in active infection, prior STI flag was most common (72.7%), followed by CC (54.5%) and RFV (45.5%). CONCLUSION: This review demonstrates the performance of an EMR-based 'syphilis risk flag' screener applied to ED patients. Sex- and race-based discrepancies exist in flag rates, which may be reflective of sex- and race-based epidemiologic discrepancies in STI incidence.

2.
J Am Chem Soc ; 145(36): 19533-19541, 2023 Sep 13.
Artículo en Inglés | MEDLINE | ID: mdl-37642307

RESUMEN

The environment around a host-guest complex is defined by intermolecular interactions between the complex, solvent molecules, and counterions. These interactions govern both the solubility of these complexes and the rates of reactions occurring within the host molecules and can be critical to catalytic and separation applications of host-guest systems. However, these interactions are challenging to detect using standard analytical chemistry techniques. Here, we quantify the hydration and ion pairing of a FeII4L4 coordination cage with a set of guest molecules having widely varying physicochemical properties. The impact of guest properties on host ion pairing and hydration was determined through microwave microfluidic measurements paired with principal component analysis (PCA). This analysis showed that introducing guest molecules into solution displaced counterions that were bound to the cage, and that the solvent solubility of the guest has the greatest impact on the solvent and ion-pairing dynamics surrounding the host. Specifically, we found that when we performed PCA of the measured equivalent circuit parameters and the solubility and dipole moment, we observed a high (>90%) explained variance for the first two principal components for each circuit parameter. We also observed that cage-counterion pairing is well-described by a single ion-pairing type, with a one-step reaction model independent of the type of cargo, and that the ion-pairing association constant is reduced for cargo with higher water solubility. Quantifying hydration and cage-counterion interactions is a critical step to building the next generation of design criteria for host-guest chemistries.

3.
Hum Brain Mapp ; 44(13): 4812-4829, 2023 09.
Artículo en Inglés | MEDLINE | ID: mdl-37483170

RESUMEN

Over the course of literacy development, children learn to recognize word sounds and meanings in print. Yet, they do so differently across alphabetic and character-based orthographies such as English and Chinese. To uncover cross-linguistic influences on children's literacy, we asked young Chinese-English simultaneous bilinguals and English monolinguals (N = 119, ages 5-10) to complete phonological and morphological awareness (MA) literacy tasks. Children completed the tasks in the auditory modality in each of their languages during functional near-infrared spectroscopy neuroimaging. Cross-linguistically, comparisons between bilinguals' two languages revealed that the task that was more central to reading in a given orthography, such as phonological awareness (PA) in English and MA in Chinese, elicited less activation in the left inferior frontal and parietal regions. Group comparisons between bilinguals and monolinguals in English, their shared language of academic instruction, revealed that the left inferior frontal was less active during phonology but more active during morphology in bilinguals relative to monolinguals. MA skills are generally considered to have greater language specificity than PA skills. Bilingual literacy training in a skill that is maximally similar across languages, such as PA, may therefore yield greater automaticity for this skill, as reflected in the lower activation in bilinguals relative to monolinguals. This interpretation is supported by negative correlations between proficiency and brain activation. Together, these findings suggest that both the structural characteristics and literacy experiences with a given language can exert specific influences on bilingual and monolingual children's emerging brain networks for learning to read.


Asunto(s)
Alfabetización , Multilingüismo , Niño , Humanos , Lingüística , Neuroimagen
4.
Genet Med ; 25(4): 100006, 2023 04.
Artículo en Inglés | MEDLINE | ID: mdl-36621880

RESUMEN

PURPOSE: Assessing the risk of common, complex diseases requires consideration of clinical risk factors as well as monogenic and polygenic risks, which in turn may be reflected in family history. Returning risks to individuals and providers may influence preventive care or use of prophylactic therapies for those individuals at high genetic risk. METHODS: To enable integrated genetic risk assessment, the eMERGE (electronic MEdical Records and GEnomics) network is enrolling 25,000 diverse individuals in a prospective cohort study across 10 sites. The network developed methods to return cross-ancestry polygenic risk scores, monogenic risks, family history, and clinical risk assessments via a genome-informed risk assessment (GIRA) report and will assess uptake of care recommendations after return of results. RESULTS: GIRAs include summary care recommendations for 11 conditions, education pages, and clinical laboratory reports. The return of high-risk GIRA to individuals and providers includes guidelines for care and lifestyle recommendations. Assembling the GIRA required infrastructure and workflows for ingesting and presenting content from multiple sources. Recruitment began in February 2022. CONCLUSION: Return of a novel report for communicating monogenic, polygenic, and family history-based risk factors will inform the benefits of integrated genetic risk assessment for routine health care.


Asunto(s)
Genoma , Genómica , Humanos , Estudios Prospectivos , Genómica/métodos , Factores de Riesgo , Medición de Riesgo
5.
Br J Anaesth ; 130(2): e361-e369, 2023 02.
Artículo en Inglés | MEDLINE | ID: mdl-36437124

RESUMEN

BACKGROUND: Ischaemic brain infarction can occur without acute neurological symptoms (covert strokes) or with symptoms (overt strokes), both associated with poor health outcomes. We conducted a pilot study of the incidence of preoperative and postoperative (intraoperative or postoperative) covert strokes, and explored the relationship of postoperative ischaemic brain injury to blood levels of neurofilament light, a biomarker of neuronal damage. METHODS: We analysed 101 preoperative (within 2 weeks of surgery) and 58 postoperative research MRIs on postoperative days 2-9 from two prospective cohorts collected at the University of Wisconsin (NCT01980511 and NCT03124303). Participants were aged >65 yr and undergoing non-intracranial, non-carotid surgery. RESULTS: Preoperative covert stroke was identified in 2/101 participants (2%; Bayesian 95% confidence interval [CI], 0.2-5.4). This rate was statistically different from the postoperative ischaemic brain injury rate of 7/58 (12%, 4.9-21.3%; P=0.01) based on postoperative imaging. However, in a smaller group of participants with paired imaging (n=30), we did not identify the same effect (P=0.67). Patients with postoperative brain injury had elevated peak neurofilament light levels (median [inter-quartile range], 2.34 [2.24-2.64] log10 pg ml-1) compared with those without (1.86 [1.48-2.21] log10 pg ml-1; P=0.025). Delirium severity scores were higher in those with postoperative brain injury (19 [17-21]) compared with those without (7 [4-12]; P=0.01). CONCLUSION: Although limited by a small sample size, these data suggest that preoperative covert stroke occurs more commonly than previously anticipated. Plasma neurofilament light is a potential screening biomarker for postoperative ischaemic brain injury.


Asunto(s)
Lesiones Encefálicas , Accidente Cerebrovascular , Humanos , Teorema de Bayes , Filamentos Intermedios , Proyectos Piloto , Complicaciones Posoperatorias/epidemiología , Estudios Prospectivos , Anciano , Estudios Clínicos como Asunto
6.
Int J Mol Sci ; 24(3)2023 Feb 02.
Artículo en Inglés | MEDLINE | ID: mdl-36769243

RESUMEN

In vitro determination of hemolytic properties is a common and important method for preliminary evaluation of cytotoxicity of chemicals, drugs, or any blood-contacting medical device or material. The method itself is relatively straightforward, however, protocols used in the literature vary substantially. This leads to significant difficulties both in interpreting and in comparing the obtained values. Here, we examine how the different variables used under different experimental setups may affect the outcome of this assay. We find that certain key parameters affect the hemolysis measurements in a critical manner. The hemolytic effect of compounds tested here varied up to fourfold depending on the species of the blood source. The use of different types of detergents used for generating positive control samples (i.e., 100% hemolysis) produced up to 2.7-fold differences in the calculated hemolysis ratios. Furthermore, we find an expected, but substantial, increase in the number of hemolyzed erythrocytes with increasing erythrocyte concentration and with prolonged incubation time, which in turn affects the calculated hemolysis ratios. Based on our findings we propose an optimized protocol in an attempt to standardize future hemolysis studies.


Asunto(s)
Eritrocitos , Hemólisis , Humanos
7.
Child Dev ; 93(4): 1012-1029, 2022 07.
Artículo en Inglés | MEDLINE | ID: mdl-35244210

RESUMEN

Math attitudes are related to achievement, yet we do not know how the brain supports changes in math attitudes. 51 children (54.9% female, 45.1% male; 37.3% White, 33.3% Black, 11.8% Latino, 5.9% Asian, 11.8% Other) solved a multiplication task inside the scanner when they were approximately 11 (time 1; T1) and 13 (time 2; T2) years old (i.e., mean age). Results revealed clusters in the left middle to superior temporal gyri at T1 associated with math attitudes at T1 and with their longitudinal improvement. However, changes in attitudes were not associated with brain changes over time. These findings suggest that relying on the storage of arithmetic facts, involved in memory retrieval, explains the development of positive math attitudes.


Asunto(s)
Logro , Lóbulo Temporal , Encéfalo/fisiología , Niño , Preescolar , Femenino , Humanos , Masculino , Matemática , Memoria/fisiología
8.
Neuroimage ; 241: 118416, 2021 11 01.
Artículo en Inglés | MEDLINE | ID: mdl-34298084

RESUMEN

The present study examined the longitudinal relations of brain and behavior from ages 6-7.5 years old to test the bootstrapping account of language development. Prior work suggests that children's vocabulary development is foundational for acquiring grammar (e.g., semantic bootstrapping) and that children rely on the syntactic context of sentences to learn the meaning of new words (e.g., syntactic bootstrapping). Yet, little is known about the dynamics underlying semantic and syntactic development as children enter elementary school. In a series of preregistered and exploratory analyses, we tested how semantic and syntactic behavioral skills may influence the development of brain regions implicated in these processes, i.e. left posterior middle temporal gyrus (pMTG) and inferior frontal gyrus (pars opercularis, IFGop), respectively. Vice-a-versa, we tested how these brain regions may influence the development of children's semantic and syntactic behavioral skills. We assessed semantic (N = 26) and syntactic (N = 30) processes behaviorally and in the brain when children were ages 5.5-6.5 years old (Time 1) and again at 7-8 years old (Time 2). All brain-behavior analyses controlled for T1 autoregressive effects and phonological memory. Exploratory hierarchical regression analyses suggested bi-directional influences, but with greater support for syntactic bootstrapping. Across the analyses, there was a small to medium effect of change in variance in models where semantics predicted syntax. Conversely, there was medium to large change in variance in models where syntax predicted semantics. In line with prior literature, results suggest a close relationship between lexical and grammatical development in children ages 6-7.5 years old. However, there was more robust evidence for syntactic bootstrapping, suggesting that acquisition of phrase structure in school age children may allow for more effective learning of word meanings. This complements prior behavioral studies and suggests a potential shift in the early reliance on semantics to later reliance on syntax in development.


Asunto(s)
Encéfalo/diagnóstico por imagen , Encéfalo/crecimiento & desarrollo , Cognición/fisiología , Desarrollo del Lenguaje , Semántica , Vocabulario , Niño , Femenino , Humanos , Estudios Longitudinales , Imagen por Resonancia Magnética/métodos , Masculino , Desempeño Psicomotor/fisiología , Tiempo de Reacción/fisiología
9.
Neuroimage ; 235: 118021, 2021 07 15.
Artículo en Inglés | MEDLINE | ID: mdl-33836266

RESUMEN

Although behavioral studies show large improvements in arithmetic skills in elementary school, we do not know how brain structure supports math gains in typically developing children. While some correlational studies have investigated the concurrent association between math performance and brain structure, such as gray matter volume (GMV), longitudinal studies are needed to infer if there is a causal relation. Although discrepancies in the literature on the relation between GMV and math performance have been attributed to the different demands on quantity vs. retrieval mechanisms, no study has experimentally tested this assumption. We defined regions of interests (ROIs) associated with quantity representations in the bilateral intraparietal sulcus (IPS) and associated with the storage of arithmetic facts in long-term memory in the left middle and superior temporal gyri (MTG/STG), and studied associations between GMV in these ROIs and children's performance on operations having greater demands on quantity vs. retrieval mechanisms, namely subtraction vs. multiplication. The aims of this study were threefold: First, to study concurrent associations between GMV and math performance, second, to investigate the role of GMV at the first time-point (T1) in predicting longitudinal gains in math skill to the second time-point (T2), and third, to study whether changes in GMV over time were associated with gains in math skill. Results showed no concurrent association between GMV in IPS and math performance, but a concurrent association between GMV in left MTG/STG and multiplication skill at T1. This association showed that the higher the GMV in this ROI, the higher the children's multiplication skill. Results also revealed that GMV in left IPS and left MTG/STG predicted longitudinal gains in subtraction skill only for younger children (approximately 10 years old). Whereas higher levels of GMV in left IPS at T1 predicted larger subtraction gains, higher levels of GMV in left MTG/STG predicted smaller gains. GMV in left MTG/STG did not predict longitudinal gains in multiplication skill. No significant association was found between changes in GMV over time and longitudinal gains in math. Our findings support the early importance of brain structure in the IPS for mathematical skills that rely on quantity mechanisms.


Asunto(s)
Sustancia Gris/anatomía & histología , Sustancia Gris/fisiología , Matemática , Lóbulo Parietal/anatomía & histología , Lóbulo Parietal/fisiología , Solución de Problemas/fisiología , Adolescente , Mapeo Encefálico , Corteza Cerebral , Niño , Femenino , Humanos , Estudios Longitudinales , Imagen por Resonancia Magnética , Masculino , Instituciones Académicas
10.
Neuroimage ; 236: 118083, 2021 08 01.
Artículo en Inglés | MEDLINE | ID: mdl-33878381

RESUMEN

By using a longitudinal design and functional magnetic resonance imaging (fMRI), our previous study (Wang et al., 2020) found a scaffolding effect of early phonological processing in the superior temporal gyrus (STG) in 6-year-old children on later behavioral reading skill in 7.5-year-old children. Other than this previous study, nothing is known about longitudinal change in the bidirectional relation between reading skill and phonological processing in the brain. To fill this gap, in the current study, we used the same experimental paradigm as in Wang et al. (2020) to measure children's reading skill and brain activity during an auditory phonological awareness task, but with children who were 7.5 years old at Time 1 (T1) and about 1.5 years later when they were 9 years old at Time 2 (T2). The phonological awareness task included both small grain (i.e., onset) and large grain (i.e., rhyme) conditions. In a univariate analysis, we found that better reading skill at T1 predicted lower brain activation in IFG at T2 for onset processing after controlling for brain activation and non-verbal IQ at T1. This suggests that early reading ability reduces the effort of phonemic access, thus supporting the refinement hypothesis. When using general psychophysiological interaction (gPPI), we found that higher functional connectivity from IFG to STG for rhyme processing at T1 predicted better reading skill at T2 after controlling for reading skill and non-verbal IQ at T1. This suggests that the early effectiveness of accessing rhyme representations scaffolds reading acquisition. As both results did not survive multiple comparison corrections, replication of these findings is needed. However, both findings are consistent with prior studies demonstrating that phonological access in the frontal lobe becomes important in older elementary school readers. Moreover, the refinement effect for onsets is consistent with the hypothesis that learning to read allows for better access of small grain phonology, and the scaffolding effect for rhymes supports the idea that reading progresses to larger grain orthography-to-phonology mapping in older skilled readers. The current study, along with our previous study on younger children, indicates that the development of reading skill is associated with (1) the early importance of the quality of the phonological representations to later access of these representations, and (2) early importance of small grain sizes to later development of large grain ones.


Asunto(s)
Mapeo Encefálico , Desarrollo Infantil/fisiología , Corteza Prefrontal/fisiología , Psicolingüística , Lectura , Percepción del Habla/fisiología , Lóbulo Temporal/fisiología , Niño , Femenino , Humanos , Estudios Longitudinales , Imagen por Resonancia Magnética , Masculino , Fonética , Corteza Prefrontal/diagnóstico por imagen , Lóbulo Temporal/diagnóstico por imagen
11.
Artículo en Inglés | MEDLINE | ID: mdl-33431415

RESUMEN

Multidrug resistance (MDR) surveillance consists of reporting MDR prevalence and MDR phenotypes. Detailed knowledge of the specific associations underlying MDR patterns can allow antimicrobial stewardship programs to accurately identify clinically relevant resistance patterns. We applied machine learning and graphical networks to quantify and visualize associations between resistance traits in a set of 1,091 Staphylococcus aureus isolates collected from one New York hospital between 2008 and 2018. Antimicrobial susceptibility testing was performed using reference broth microdilution. The isolates were analyzed by year, methicillin susceptibility, and infection site. Association mining was used to identify resistance patterns that consisted of two or more individual antimicrobial resistance (AMR) traits and quantify the association among the individual resistance traits in each pattern. The resistance patterns captured the majority of the most common MDR phenotypes and reflected previously identified pairwise relationships between AMR traits in S. aureus Associations between ß-lactams and other antimicrobial classes (macrolides, lincosamides, and fluoroquinolones) were common, although the strength of the association among these antimicrobial classes varied by infection site and by methicillin susceptibility. Association mining identified associations between clinically important AMR traits, which could be further investigated for evidence of resistance coselection. For example, in skin and skin structure infections, clindamycin and tetracycline resistance occurred together 1.5 times more often than would be expected if they were independent from one another. Association mining efficiently discovered and quantified associations among resistance traits, allowing these associations to be compared between relevant subsets of isolates to identify and track clinically relevant MDR.


Asunto(s)
Infecciones Estafilocócicas , Staphylococcus aureus , Antibacterianos/farmacología , Antibacterianos/uso terapéutico , Farmacorresistencia Bacteriana , Resistencia a Múltiples Medicamentos , Humanos , Aprendizaje Automático , Pruebas de Sensibilidad Microbiana , New York , Infecciones Estafilocócicas/tratamiento farmacológico , Staphylococcus aureus/genética
12.
Hum Brain Mapp ; 42(11): 3534-3546, 2021 08 01.
Artículo en Inglés | MEDLINE | ID: mdl-33951259

RESUMEN

A previous functional magnetic resonance imaging (fMRI) study by Weiss et al. (Weiss et al., Human Brain Mapping, 2018, 39, 4334-4348) examined brain specialization for phonological and semantic processing of spoken words in young children who were 5 to 6 years old and found evidence for specialization in the temporal but not the frontal lobe. According to a prominent neurocognitive model of language development (Skeide & Friederici, Nature Reviews Neuroscience, 2016, 17, 323-332), the frontal lobe matures later than the temporal lobe. Thus, the current study aimed to examine if brain specialization in the frontal lobe can be observed in a slightly older cohort of children aged 7 to 8 years old using the same experimental and analytical approach as in Weiss et al. (Weiss et al., Human Brain Mapping, 2018, 39, 4334-4348). One hundred and ten typically developing children were recruited and were asked to perform a sound judgment task, tapping into phonological processing, and a meaning judgment task, tapping into semantic processing, while in the MRI scanner. Direct task comparisons showed that these children exhibited language specialization in both the temporal and the frontal lobes, with the left posterior dorsal inferior frontal gyrus (IFG) showing greater activation for the sound than the meaning judgment task, and the left anterior ventral IFG and the left posterior middle temporal gyrus (MTG) showing greater activation for the meaning than the sound judgment task. These findings demonstrate that 7- to 8-year-old children have already begun to develop a language-related specialization in the frontal lobe, suggesting that early elementary schoolers rely on both specialized linguistic manipulation and representation mechanisms to perform language tasks.


Asunto(s)
Mapeo Encefálico , Desarrollo Infantil/fisiología , Comprensión/fisiología , Juicio/fisiología , Corteza Prefrontal/fisiología , Percepción del Habla/fisiología , Lóbulo Temporal/fisiología , Niño , Femenino , Humanos , Imagen por Resonancia Magnética , Masculino , Fonética , Corteza Prefrontal/diagnóstico por imagen , Semántica , Lóbulo Temporal/diagnóstico por imagen
13.
Hum Brain Mapp ; 42(11): 3396-3410, 2021 08 01.
Artículo en Inglés | MEDLINE | ID: mdl-33978281

RESUMEN

The neurocognitive basis of elementary academic skills varies with parental socioeconomic status (SES). Little is known, however, about SES-related differences underlying higher-order cognitive skills that are critical for school success, such as reasoning. Here we used fMRI to examine how the neurocognitive basis of deductive reasoning varies as a function of parental education in school-aged children. Higher parental education was associated with greater reliance on the left inferior frontal gyrus when solving set-inclusion problems, consistent with other work suggesting that these problems might more heavily rely on verbal systems in the brain. In addition, children who are at the lower end of the parental education continuum, but have higher nonverbal skills relied on right parietal areas to a greater degree than their peers for solving set-inclusion problems. Finally, lower parental education children with higher verbal or nonverbal skill engaged dorsolateral prefrontal regions to a greater degree for set-inclusion and linear-order relations than their peers. These findings suggest that children with lower parental education rely on spatial and cognitive control mechanisms to achieve parity with their peers with parents who have more education. Better understanding variability in the neurocognitive networks that children recruit as a function of their parental factors might benefit future individualized interventions that best match children's characteristics.


Asunto(s)
Escolaridad , Red Nerviosa/fisiología , Padres , Lóbulo Parietal/fisiología , Corteza Prefrontal/fisiología , Solución de Problemas/fisiología , Adolescente , Niño , Femenino , Neuroimagen Funcional , Humanos , Imagen por Resonancia Magnética , Masculino , Red Nerviosa/diagnóstico por imagen , Lóbulo Parietal/diagnóstico por imagen , Corteza Prefrontal/diagnóstico por imagen , Clase Social
14.
Cogn Affect Behav Neurosci ; 21(5): 917-935, 2021 10.
Artículo en Inglés | MEDLINE | ID: mdl-33954927

RESUMEN

Enhancing student's math achievement is a significant educational challenge. Numerous studies have shown that math attitudes can predict improvement in math performance, but no study has yet revealed the underlying neurocognitive mechanisms explaining this effect. To answer this question, 50 children underwent functional magnetic resonance imaging (fMRI) when they were 11 (time 1; T1) and 13 (time 2; T2) years old. Children solved a rhyming judgment and a single-digit multiplication task inside the scanner at T1. The rhyming task was used to independently define a verbal region of interest in the left inferior frontal gyrus (IFG). We focused on this region because of previous evidence showing math attitudes-related effects in the left IFG for children with low math skill (Demir-Lira et al., 2019). Children completed standardized testing of math attitudes at T1 and of multiplication skill both at T1 and T2. We performed a cluster-wise regression analysis to investigate the interaction between math attitudes and improvement in multiplication skill over time while controlling for the main effects of these variables, intelligence, and accuracy on the task. This analysis revealed a significant interaction in the left IFG, which was due to improvers with positive math attitudes showing enhanced activation. Our result suggests that IFG activation, possibly reflecting effort invested in retrieving multiplication facts, is one of the possible neurocognitive mechanism by which children with positive math attitudes improve in multiplication skill. Our finding suggests that teachers and parents can help children do better in math by promoting positive math attitudes.


Asunto(s)
Imagen por Resonancia Magnética , Corteza Prefrontal , Actitud , Niño , Preescolar , Humanos , Matemática , Padres
15.
Nat Mater ; 19(2): 176-181, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31873229

RESUMEN

Epitaxial strain can unlock enhanced properties in oxide materials, but restricts substrate choice and maximum film thickness, above which lattice relaxation and property degradation occur. Here we employ a chemical alternative to epitaxial strain by providing targeted chemical pressure, distinct from random doping, to induce a ferroelectric instability with the strategic introduction of barium into today's best millimetre-wave tuneable dielectric, the epitaxially strained 50-nm-thick n = 6 (SrTiO3)nSrO Ruddlesden-Popper dielectric grown on (110) DyScO3. The defect mitigating nature of (SrTiO3)nSrO results in unprecedented low loss at frequencies up to 125 GHz. No barium-containing Ruddlesden-Popper titanates are known, but the resulting atomically engineered superlattice material, (SrTiO3)n-m(BaTiO3)mSrO, enables low-loss, tuneable dielectric properties to be achieved with lower epitaxial strain and a 200% improvement in the figure of merit at commercially relevant millimetre-wave frequencies. As tuneable dielectrics are key constituents of emerging millimetre-wave high-frequency devices in telecommunications, our findings could lead to higher performance adaptive and reconfigurable electronics at these frequencies.

16.
J Child Psychol Psychiatry ; 62(9): 1090-1099, 2021 09.
Artículo en Inglés | MEDLINE | ID: mdl-33543509

RESUMEN

BACKGROUND: Youths with autism spectrum disorder (ASD) rely more on lower-level visual processing as revealed by greater occipital activation, yet less effectively engage higher-level processing of modality-independent semantic knowledge as indicated by reduced frontal activation, compared to typically developing (TD) youths. However, little is known about age-dependent differences in neural connectivity during semantic processing in youths with ASD as compared to TD youths. METHODS: Four groups were recruited: 31 ASD children (mean age = 10.5 years old), 33 TD children (mean age = 10.4), 30 ASD adolescents (mean age = 14.9), and 34 TD adolescents (mean age = 15.1). We explored their differences in neural connectivity by using functional magnetic resonance imaging (fMRI) with psychophysiological interaction (PPI) during semantic judgments. RESULTS: In comparison with TD children, children with ASD showed greater activation in the left cuneus and weaker connectivity between the left cuneus and left middle temporal gyrus (MTG). In comparison with TD adolescents, adolescents with ASD showed less activation in the left inferior frontal gyrus (IFG) and weaker functional connectivity between the left IFG and left MTG. CONCLUSIONS: Children with ASD may rely more on visual processes in the occipital cortex that are disconnected from modality-independent semantics in the temporal cortex. However, adolescents with ASD may less effectively engage frontal mechanisms involved in the top-down control of modality-independent semantic knowledge in the temporal cortex. Our findings provide evidence of developmental differences in the neural substrates of the alterations in semantic processing in youths with ASD compared to TD youths.


Asunto(s)
Trastorno del Espectro Autista , Trastorno Autístico , Adolescente , Encéfalo/diagnóstico por imagen , Mapeo Encefálico , Niño , Humanos , Imagen por Resonancia Magnética , Vías Nerviosas , Semántica
17.
Child Dev ; 92(2): e126-e142, 2021 03.
Artículo en Inglés | MEDLINE | ID: mdl-32864778

RESUMEN

To examine whether there are common or specific deficits of reading disability (RD) in first (L1) and second languages (L2), Chinese children (9-11 years, N = 76) with or without RD who learn English as an L2 were studied during a visual word rhyming judgment task. Evidence was found for common deficits in L1 and L2 in visuo-orthographic processes in left inferior temporal gyrus and left precuneus, as well as in phonological processes in left dorsal inferior frontal gyrus as children with RD showed less activation than controls in both languages. Furthermore, the visuo-orthographic deficit appears to be a RD effect, whereas the phonological deficit appears to be a reading/performance effect. Some weak evidence for language specific effects was also found.


Asunto(s)
Dislexia/diagnóstico , Multilingüismo , Lectura , Niño , China , Humanos , Juicio , Lenguaje , Aprendizaje , Masculino , Reconocimiento Visual de Modelos/fisiología
18.
J Cogn Neurosci ; 32(1): 36-49, 2020 01.
Artículo en Inglés | MEDLINE | ID: mdl-31596168

RESUMEN

Previous studies have found specialized syntactic and semantic processes in the adult brain during language comprehension. Young children have sophisticated semantic and syntactic aspects of language, yet many previous fMRI studies failed to detect this specialization, possibly due to experimental design and analytical methods. In this current study, 5- to 6-year-old children completed a syntactic task and a semantic task to dissociate these two processes. Multivoxel pattern analysis was used to examine the correlation of patterns within a task (between runs) or across tasks. We found that the left middle temporal gyrus showed more similar patterns within the semantic task compared with across tasks, whereas there was no difference in the correlation within the syntactic task compared with across tasks, suggesting its specialization in semantic processing. Moreover, the left superior temporal gyrus showed more similar patterns within both the semantic task and the syntactic task as compared with across tasks, suggesting its role in integration of semantic and syntactic information. In contrast to the temporal lobe, we did not find specialization or integration effects in either the opercular or triangular part of the inferior frontal gyrus. Overall, our study showed that 5- to 6-year-old children have already developed specialization and integration in the temporal lobe, but not in the frontal lobe, consistent with developmental neurocognitive models of language comprehension in typically developing young children.


Asunto(s)
Mapeo Encefálico , Desarrollo Infantil/fisiología , Corteza Prefrontal/fisiología , Psicolingüística , Percepción del Habla/fisiología , Lóbulo Temporal/fisiología , Niño , Preescolar , Femenino , Humanos , Imagen por Resonancia Magnética , Masculino , Semántica
19.
Neuroimage ; 207: 116359, 2020 02 15.
Artículo en Inglés | MEDLINE | ID: mdl-31733372

RESUMEN

The objective of this study was to investigate whether phonological processes measured through brain activation are crucial for the development of reading skill (i.e. scaffolding hypothesis) and/or whether learning to read words fine-tunes phonology in the brain (i.e. refinement hypothesis). We specifically looked at how different grain sizes in two brain regions implicated in phonological processing played a role in this bidirectional relation. According to the dual-stream model of speech processing and previous empirical studies, the posterior superior temporal gyrus (STG) appears to be a perceptual region associated with phonological representations, whereas the dorsal inferior frontal gyrus (IFG) appears to be an articulatory region that accesses phonological representations in STG during more difficult tasks. 36 children completed a reading test outside the scanner and an auditory phonological task which included both small (i.e. onset) and large (i.e. rhyme) grain size conditions inside the scanner when they were 5.5-6.5 years old (Time 1) and once again approximately 1.5 years later (Time 2). To study the scaffolding hypothesis, a regression analysis was carried out by entering brain activation in either STG or IFG for either small (onset > perceptual) or large (rhyme > perceptual) grain size phonological processing at T1 as the predictors and reading skill at T2 as the dependent measure, with several covariates of no interest included. To study the refinement hypothesis, the regression analysis included reading skill at T1 as the predictor and brain activation in either STG or IFG for either small or large grain size phonological processing at T2 as the dependent measures, with several covariates of no interest included. We found that only posterior STG, regardless of grain size, was predictive of reading gains. Parallel models with only behavioral accuracy were not significant. Taken together, our results suggest that the representational quality of phonology in temporal cortex is crucial for reading development. Moreover, our study provides neural evidence supporting the scaffolding hypothesis, suggesting that brain measures of phonology could be helpful in early identification of reading difficulties.


Asunto(s)
Vías Nerviosas/fisiología , Lectura , Percepción del Habla/fisiología , Lóbulo Temporal/fisiología , Encéfalo/fisiología , Mapeo Encefálico/métodos , Niño , Preescolar , Femenino , Humanos , Aprendizaje/fisiología , Imagen por Resonancia Magnética/métodos , Masculino
20.
Learn Disabil Q ; 43(3): 179-191, 2020 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-36199479

RESUMEN

Attitudes towards math (ATM) predict math achievement. Negative ATM are associated with avoidance of math content, while positive ATM are associated with exerting more effort on math tasks. Recent literature highlights the importance of considering interactions between ATM and math skill in examining relations to achievement. This study investigated, for the first time, the effects of the interaction between math skill and ATM on the neurocognitive basis of arithmetic processing. We examined the effect of this interaction using a single-digit multiplication task in 9- to 12-year-old children. Results showed that higher math skill was correlated with less activation in the left inferior frontal gyrus (IFG), and positive ATM were correlated with less activation in the left IFG. The relation between ATM and the neural basis of multiplication varied depending on math skill. Only among children with lower math skill, positive ATM were associated with greater activation of the left IFG. The results suggest that positive ATM in low skill children might encourage them to more fully engage the neurocognitive systems underlying controlled effort and retrieval of multiplication facts. Our results highlight the importance of examining the role of both attitudinal and cognitive factors on the neural basis of arithmetic development.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA