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1.
Alzheimers Dement ; 2024 Aug 14.
Artículo en Inglés | MEDLINE | ID: mdl-39140387

RESUMEN

Black women are sorely underrepresented in studies of Alzheimer's disease and related dementias (ADRD) despite higher rates of ADRD diagnoses than in non-Hispanic White women. There are many reasons for underrepresentation, including medical mistrust, limited access to clinical studies, and restrictive study inclusion criteria. These pervasive barriers to research participation are often not considered during study development and, if eventually thought of tend to be after the fact. Community-engaged research (CER) approaches are an effective method for reducing participation barriers. This article describes how CER approaches were used to develop the Black Women Inflammation and Tau Study (BWITS), a prospective study to identify biopsychosocial risk factors for ADRD in Black women. Guidelines discussed here for future ADRD research in diverse populations are informed by Community-Based Participatory Research (CBPR), the National Institute on Minority Health and Health Disparities (NIMHD), and the Patient-Centered Outcomes Research Institute (PCORI). HIGHLIGHTS: Understand the historical tragedies related to medical practices and research designs that may contribute to the underrepresentation of Black Americans in research studies today. Highlight community-engaged research approaches that effectively reduce participation barriers in minoritized groups. Review Community-Based Participatory Research, National Institute of Minority Health and Health Disparities, and the Patient-Centered Outcomes Research Institute guidelines for conducting research with minoritized communities. Describe using the three frameworks to inform the study development protocol for the Black Women Inflammation and Tau Study. Conclude by offering study design considerations that we hope can be a helpful starting point for others conducting research with minoritized communities.

2.
Ann Surg ; 274(6): 985-991, 2021 12 01.
Artículo en Inglés | MEDLINE | ID: mdl-34784665

RESUMEN

OBJECTIVE: To evaluate the association of historical racist housing policies and modern-day healthcare outcomes. SUMMARY OF BACKGROUND DATA: In 1933 the United States Government Home Owners Loan Corporation (HOLC) used racial composition of neighborhoods to determine creditworthiness and labeled them "Best", "Still Desirable", "Definitely Declining", and "Hazardous." Although efforts have been made to reverse these racist policies that structurally disadvantage those living in exposed neighborhoods, the lasting legacy on modern day healthcare outcomes is uncertain. METHODS: We performed a cross-sectional retrospective review of 212,179 Medicare beneficiaries' living in 171,930 unique neighborhoods historically labeled by the HOLC who underwent 1 of 5 of common surgical procedures - coronary artery bypass, appendectomy, colectomy, cholecystectomy, and hernia repair - between 2012 and 2018. We compared 30-day mortality, complications, and readmissions across HOLC grade and Area Deprivation Index (ADI) of each neighborhood. Outcomes were risk-adjusted using a multivariable logistical regression model accounting for patient factors (age, sex, Elixhauser comorbidities), admission type (elective, urgent, emergency), type of operation, and each neighborhoods ADI; a modern day measure of neighborhood disadvantage that includes education, employment, housing-quality, and poverty measures. RESULTS: Overall, 212,179 Medicare beneficiaries (mean age, 71.2 years; 54.2% women) resided in 171,930 unique neighborhoods historically graded by the HOLC. Outcomes worsened in a stepwise fashion across HOLC neighborhoods. Overall, 30-day postoperative mortality was 5.4% in "Best" neighborhoods, 5.8% in "Still Desirable", 6.1% in "Definitely Declining", and 6.4% in "Hazardous" (Best vs Hazardous Odds Ration: 1.23, 95% CI: 1.13-1.24, P < 0.001). The same stepwise pattern was seen from "Best" to "Hazardous" neighborhoods for complications (30.5% vs 32.2%; OR: 1.12 [95% CI: 1.07-1.17]; P < 0.001) and Readmissions (16.3% vs 17.1%; OR: 1.06 [95% CI: 1.01-1.11]; P = 0.023). After controlling for modern day deprivation using ADI, the patterns persisted with "Hazardous" neighborhoods having higher mortality (OR: 1.17 [95% CI: 1.08-1.27]; P < 0.001) and complications (OR: 1.07 [95% CI: 1.02-1.12]; P = 0.003), but not for readmissions (OR: 1.02 [95% CI: 0.97-1.07]; P = 0.546). CONCLUSIONS: Patients residing in neighborhoods previously "redlined" or labeled "Hazardous" were more likely to experience worse outcomes after inpatient hospitalization compared to those living in "Best" neighborhoods, even after taking into account modern day measures of neighborhood disadvantage.


Asunto(s)
Hospitalización/estadística & datos numéricos , Vivienda , Política Pública , Racismo , Características de la Residencia , Procedimientos Quirúrgicos Operativos , Anciano , Estudios Transversales , Escolaridad , Empleo/estadística & datos numéricos , Femenino , Humanos , Masculino , Medicare , Áreas de Pobreza , Estudios Retrospectivos , Factores Socioeconómicos , Procedimientos Quirúrgicos Operativos/mortalidad , Estados Unidos
3.
Ann Clin Psychiatry ; 28(2): 85-94, 2016 05.
Artículo en Inglés | MEDLINE | ID: mdl-27285389

RESUMEN

BACKGROUND: Medical students and physicians in training and in practice are at risk for excessive alcohol use and abuse, potentially impacting the affected individuals as well as their family members, trainees, and patients. However, several roadblocks to care, including stigma, often keep them from seeking treatment. METHODS: We analyzed data from anonymous questionnaires completed by medical students, house staff, and faculty from 2009 to 2014 as part of a depression awareness and suicide prevention program at a state-supported medical school in the United States. The authors explored associations between self-reported "drinking too much" and depression, suicidal ideation, substance use, intense affective states, and mental health treatment. RESULTS: Approximately one-fifth of the respondents reported "drinking too much." "Drinking too much" was associated with more severe depression and impairment, past suicide attempts and current suicidal ideation, intense affective states, and other substance use. Those who were "drinking too much" were more likely than others to accept referrals for mental health treatment through the anonymous interactive screening program, suggesting that this program may be effective in skirting the stigma barrier for accessing mental health care for this at-risk population. CONCLUSIONS: The self-reported prevalence of "drinking too much" among medical students, house staff, and faculty is high and associated with negative mental health outcomes. Targeted, anonymous screenings may identify at-risk individuals and provide mental health care referrals to those in need.


Asunto(s)
Centros Médicos Académicos/organización & administración , Alcoholismo/epidemiología , Derivación y Consulta , Adulto , Alcoholismo/psicología , California/epidemiología , Depresión/epidemiología , Depresión/psicología , Docentes Médicos/psicología , Femenino , Humanos , Internado y Residencia , Masculino , Medición de Riesgo , Estigma Social , Estudiantes de Medicina/psicología , Ideación Suicida , Encuestas y Cuestionarios
4.
Acad Psychiatry ; 38(5): 547-53, 2014 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-24705825

RESUMEN

OBJECTIVE: A growing body of literature documents high rates of burnout, depression, and suicidal ideation among physicians and medical students. Barriers to seeking mental health treatment in this group include concerns about time, stigma, confidentiality, and potential career impact. The authors describe a 4-year trial of the Healer Education Assessment and Referral (HEAR) program, designed to increase mental health services utilization (MHSU) and decrease suicide risk (SR) as assessed by an Interactive Screening Program (ISP)at one US medical school. METHODS: Over a 4-year period, medical students were engaged in face-to-face, campus-wide, educational group programs and were invited to complete an individual, online, and anonymous survey. This survey contained the 9-item Patient Health Questionnaire (PHQ-9) scale to assess depression and items to identify suicidal thoughts and behaviors, substance use, distressing emotional states, and the use of mental health treatment. Students who engaged in this ISP by corresponding electronically with a counselor after completing the survey were assessed and when indicated, referred to further treatment. RESULTS: The HEAR program was delivered to 1,008 medical students. Thirty-four percent (343/1,008) completed the online screening portion. Almost 8 % of respondents met the criteria for high/significant SR upon analysis of the completed screens. Ten out of 13 of the students with SR who dialogued with a counselor were not already receiving mental health treatment, indicating that this anonymous ISP identified a high proportion of an untreated, at risk, and potentially suicidal population. MHSU among medical students who completed the survey was 11.5 % in year 1 and 15.0 % by year 4. SR among medical students was 8.8 % in year 1 and 6.2 % in year 4 as assessed by the ISP. CONCLUSIONS: This novel interventional program identified at risk, potentially suicidal medical students at one institution. Based on this single-site experience, we suggest that future multisite studies incorporate a comparison group, acquire baseline (prematriculation) data regarding MHSU and SR, and use an individualized yet anonymous identification system to measure changes in individual participants' mental health status over time.


Asunto(s)
Depresión/epidemiología , Estudiantes de Medicina/psicología , Suicidio/estadística & datos numéricos , Adulto , Depresión/prevención & control , Depresión/psicología , Femenino , Encuestas Epidemiológicas , Humanos , Masculino , Servicios de Salud Mental/organización & administración , Derivación y Consulta/organización & administración , Medición de Riesgo , Estudiantes de Medicina/estadística & datos numéricos , Ideación Suicida , Suicidio/psicología , Encuestas y Cuestionarios , Estados Unidos/epidemiología , Adulto Joven , Prevención del Suicidio
5.
J Neurotrauma ; 2024 Jul 13.
Artículo en Inglés | MEDLINE | ID: mdl-38753708

RESUMEN

This review was designed to (1) determine the extent to which the clinical science on sport-related concussion treatment and rehabilitation has considered social determinants of health (SDoH) or health equity and (2) offer recommendations to enhance the incorporation of SDoH and health equity in concussion treatment research and clinical care. The Concussion in Sport Group consensus statement (2023) was informed by two systematic reviews examining prescribed rest or exercise following concussion and targeted interventions to facilitate concussion recovery. We examined 31 studies, including 2,698 participants, from those two reviews. Race (k = 6; 19.4%) and ethnicity (k = 4; 12.9%) of the study samples were usually not reported. Four studies examined ethnicity (i.e., Hispanic), exclusively as a demographic category. Five studies (16.1%) examined race as a demographic category. Three studies (9.7%) examined socioeconomic status (SES; measured as household income) as a demographic category/sample descriptor and one study (3.2%) examined SES in-depth, by testing whether the treatment and control groups differed by SES. Five studies examined an SDoH domain in a descriptive manner and four studies in an inferential/intentional manner. No study mentioned SDoH, health equity, or disparities by name. Many studies (61.3%) excluded participants based on demographic, sociocultural, or health factors, primarily due to language proficiency. The new consensus statement includes recommendations for concussion treatment and rehabilitation that rely on an evidence base that has not included SDoH or studies addressing health equity. Researchers are encouraged to design treatment and rehabilitation studies that focus specifically on underrepresented groups to determine if they have specific and unique treatment and rehabilitation needs, whether certain practical modifications to treatment protocols might be necessary, and whether completion rates and treatment adherence and response are similar.

6.
J Neurotrauma ; 40(19-20): 1977-1989, 2023 10.
Artículo en Inglés | MEDLINE | ID: mdl-37071186

RESUMEN

We conducted a content analysis of the literature underlying the Centers for Disease Control and Prevention (CDC) Guideline on the Diagnosis and Management of Mild Traumatic Brain Injury Among Children (i.e., the "Guideline") to determine the extent to which social determinants of health (SDoH) were examined or addressed. The systematic review forming the basis for the Guideline included 37 studies addressing diagnosis, prognosis, and treatment/rehabilitation. We examined those studies to identify SDoH domains derived from the U.S. Department of Health and Human Services' Healthy People 2020 and 2030 websites. No study explicitly mentioned "social determinants of health," by name, and few studies addressed SDoH domains as a primary focus (ranging from 0% to 27% of studies across SDoH domains). The most frequently represented SDoH domains, described in an inferential or a descriptive manner, were Education Access and Quality (29.7% of studies), Social and Community Context (27.0% of studies), and Economic Stability (21.6% of studies). Health Care Access (13.5% of studies) was less well represented and no studies (0%) examined Neighborhood and Built Environment. In terms of the CDC clinical questions, SDoH were only examined as predictors of outcome (prognosis) and no studies examined SDoH in relation to diagnosis or treatment/rehabilitation. The Guideline includes some commentary on health literacy and socioeconomic status. Overall, social determinants of health are largely unrepresented as important or meaningful variables influencing the Guideline on the Diagnosis and Management of Mild Traumatic Brain Injury Among Children, or in the studies that informed the Guideline.


Asunto(s)
Conmoción Encefálica , Equidad en Salud , Determinantes Sociales de la Salud , Niño , Humanos , Conmoción Encefálica/diagnóstico , Accesibilidad a los Servicios de Salud , Pronóstico , Guías de Práctica Clínica como Asunto , Revisiones Sistemáticas como Asunto
7.
Front Neurol ; 14: 1110539, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37388549

RESUMEN

Introduction: This systematic review examined whether race or ethnicity are associated with clinical outcomes (e.g., time to return to school/sports, symptom duration, vestibular deficits, and neurocognitive functioning) following sport-related concussion among child, adolescent, or college-aged student athletes. Additionally, this review assessed whether the existing literature on this topic incorporated or included broader coverage of social determinants of health. Methods: The online databases PubMed, MEDLINE®, PsycINFO®, CINAHL, Cochrane Library, EMBASE, SPORTDiscus, Scopus, and Web of Science were searched. Results: A total of 5,118 abstracts were screened and 12 studies met inclusion criteria, including 2,887 youth and young adults. Among the included articles, only 3 studies (25%) examined whether race and ethnicity were associated with outcomes following concussion as a primary objective. None of the studies assessed the association between social determinants of health and outcomes following concussion as a primary objective, although 5 studies (41.7%) addressed a social determinant of health or closely related topic as a secondary objective. Discussion: Overall, the literature to date is extremely limited and insufficient for drawing conclusions about whether race or ethnicity are categorically associated with outcomes from sport-related concussion, or more specifically, whether there are socioeconomic, structural, or cultural differences or disparities that might be associated with clinical outcome. Systematic review registration: identifier: PROSPERO, CRD42016041479, CRD42019128300.

8.
Nature ; 440(7085): 776-8, 2006 Apr 06.
Artículo en Inglés | MEDLINE | ID: mdl-16598252

RESUMEN

Differences in isotopic abundances between meteorites and rocks on Earth leave unclear the true composition of the gas out of which the Solar System formed. The Sun should have preserved in its outer layers the original composition, and recent work has indicated that the solar wind is enriched in 16O, relative to Earth, Mars and bulk meteorites. This suggests that self-shielding of CO due to photo-dissociation, which is a well understood process in molecular clouds, also led to evolution in the isotopic abundances in the early Solar System. Here we report measurements of oxygen isotopic abundances in lunar grains that were recently exposed to the solar wind. We find that 16O is underabundant, opposite to an earlier finding based on studies of ancient metal grains. Our result, however, is more difficult to understand within the context of current models, because there is no clear way to make 16O more abundant in Solar System rocks than in the Sun.

9.
Nature ; 439(7074): 314-7, 2006 Jan 19.
Artículo en Inglés | MEDLINE | ID: mdl-16421568

RESUMEN

Ocean island basalts are generally thought to be the surface expression of mantle plumes, but the nature of the components in the source regions of such mantle plumes is a subject of long-standing debate. The lavas erupted at Hawaii have attracted particular attention, as it has been proposed that coupled 186Os and 187Os anomalies reflect interaction with the Earth's metallic core. It has recently been suggested, however, that such variations could also result from addition of oceanic ferromanganese sediments to the mantle source of these lavas. Here we show that Hawaiian picrites with osmium isotope anomalies also exhibit pronounced thallium isotope variations, which are coupled with caesium/thallium ratios that extend to values much lower than commonly observed for mantle-derived rocks. This correlation cannot be created by admixing of core material, and is best explained by the addition of ferromanganese sediments into the Hawaii mantle source region. However, the lack of correlation between thallium and osmium isotopes and the high thallium/osmium ratios of ferromanganese sediments preclude a sedimentary origin for the osmium isotope anomalies, and leaves core-mantle interaction as a viable explanation for the osmium isotope variations of the Hawaiian picrites.

10.
Mult Scler Relat Disord ; 59: 103644, 2022 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-35182881

RESUMEN

BACKGROUND: The Multiple Sclerosis Performance Test (MSPT) is a self-administered, iPad®-based, computerized system for quantifying neuroperformance (cognition, upper and lower extremity motor function, and vision) in patients with multiple sclerosis (MS). OBJECTIVE: The goal of the study is to provide regression-based norms for the four MSPT test modules to adjust for the influence of demographic variables (age, education, and sex). METHODS: The MSPT was administered to 428 cognitively intact, healthy adults (ages 18 to 89 years). Participants were recruited to achieve a demographically stratified sample from four geographically diverse United States testing sites. RESULTS: The amount of shared variance in test performance accounted for by demographic variables was 18-23% for an upper extremity motor test, 31% for a walking speed test, 32% for a low contrast visual acuity test, and 48% for a cognitive test. All four test modules were significantly influenced by age (linear and non-linear effects) and education. Additionally, sex influenced performance on the cognitive and walking speed tests. CONCLUSION: This study provides regression-based equations that can enhance the clinical interpretation of MSPT scores by adjusting for the potential influences of age, education, and sex.


Asunto(s)
Esclerosis Múltiple , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Cognición , Voluntarios Sanos , Humanos , Persona de Mediana Edad , Pruebas Neuropsicológicas , Velocidad al Caminar , Adulto Joven
11.
Ann Clin Transl Neurol ; 9(7): 995-1010, 2022 07.
Artículo en Inglés | MEDLINE | ID: mdl-35702954

RESUMEN

OBJECTIVE: To assess the initial features and evolution of neurologic Postacute Sequelae of SARS-CoV-2 infection (neuro-PASC) in patients with and without prior neurologic disease. METHODS: Participants with neurologic symptoms following acute SARS-CoV-2 infection were recruited from October 9, 2020 to October 11, 2021. Clinical data included a SARS-CoV-2 infection history, neurologic review of systems, neurologic exam, Montreal cognitive assessment (MoCA), and symptom-based self-reported surveys at baseline (conducted after acute infection) and 6-month follow-up assessments. RESULTS: Fifty-six participants (69% female, mean age 50 years, 29% with prior neurologic disease such as multiple sclerosis) were enrolled, of which 27 had completed the 6-month follow-up visit in this ongoing study. SARS-CoV-2 infection severity was largely described as mild (39.3%) or moderate (42.9%). At baseline, following acute infection, the most common neurologic symptoms were fatigue (89.3%) and headaches (80.4%). At the 6-month follow-up, memory impairment (68.8%) and decreased concentration (61.5%) were the most prevalent, though on average all symptoms showed a reduction in reported severity score at the follow-up. Complete symptom resolution was reported in 33.3% of participants by 6 months. From baseline to 6 months, average MoCA scores improved overall though 26.3% of participants' scores decreased. A syndrome consisting of tremor, ataxia, and cognitive dysfunction (PASC-TAC) was observed in 7.1% of patients. INTERPRETATION: Early in the neuro-PASC syndrome, fatigue and headache are the most commonly reported symptoms. At 6 months, memory impairment and decreased concentration were most prominent. Only one-third of participants had completed resolution of neuro-PASC at 6 months, although persistent symptoms trended toward improvement at follow-up.


Asunto(s)
COVID-19/complicaciones , Enfermedades del Sistema Nervioso/etiología , SARS-CoV-2 , Progresión de la Enfermedad , Fatiga/etiología , Femenino , Cefalea/etiología , Humanos , Estudios Longitudinales , Masculino , Trastornos de la Memoria/etiología , Persona de Mediana Edad , Enfermedades del Sistema Nervioso/diagnóstico
12.
Sci Adv ; 8(39): eabq2542, 2022 Sep 30.
Artículo en Inglés | MEDLINE | ID: mdl-36170359

RESUMEN

Impact glasses found in lunar soils provide a possible window into the impact history of the inner solar system. However, their use for precise reconstruction of this history is limited by an incomplete understanding of the physical mechanisms responsible for their origin and distribution and possible relationships to local and regional geology. Here, we report U-Pb isotopic dates and chemical compositions of impact glasses from the Chang'e-5 soil and quantitative models of impact melt formation and ejection that account for the compositions of these glasses. The predominantly local provenance indicated by their compositions, which constrains transport distances to <~150 kilometers, and the age-frequency distribution are consistent with formation mainly in impact craters 1 to 5 kilometers in diameter. Based on geological mapping and impact cratering theory, we tentatively identify specific craters on the basaltic unit sampled by Chang'e-5 that may have produced these glasses and compare their ages with the impact record of the asteroid belt.

13.
Epilepsia Open ; 6(2): 266-275, 2021 06.
Artículo en Inglés | MEDLINE | ID: mdl-34033259

RESUMEN

This paper addresses the absence of an international diagnostic taxonomy for cognitive disorders in patients with epilepsy. Initiated through the 2020 Memorandum of Understanding between the International League Against Epilepsy and the International Neuropsychological Society, neuropsychological representatives from both organizations met to address the problem and consequences of the absence of an international diagnostic taxonomy for cognitive disorders in epilepsy, overview potential solutions, and propose specific solutions going forward. The group concluded that a classification of cognitive disorders in epilepsy, including an overall taxonomy and associated operational criteria, was clearly lacking and sorely needed. This paper reviews the advantages and shortcomings of four existing cognitive diagnostic approaches, including taxonomies derived from the US National Neuropsychology Network, DSM-V Neurocognitive Disorders, the Mild Cognitive Impairment classification from the aging/preclinical dementia literature, and the Research Domain Criteria Initiative. We propose a framework to develop a consensus-based classification system for cognitive disorders in epilepsy that will be international in scope and be applicable for clinical practice and research globally and introduce the International Classification of Cognitive Disorders in Epilepsy (IC-CODE) project.


Asunto(s)
Trastornos del Conocimiento , Epilepsia , Cognición , Trastornos del Conocimiento/diagnóstico , Epilepsia/diagnóstico , Epilepsia/psicología , Humanos , Pruebas Neuropsicológicas , Neuropsicología
14.
Science ; 374(6569): 887-890, 2021 Nov 12.
Artículo en Inglés | MEDLINE | ID: mdl-34618547

RESUMEN

Orbital data indicate that the youngest volcanic units on the Moon are basalt lavas in Oceanus Procellarum, a region with high levels of the heat-producing elements potassium, thorium, and uranium. The Chang'e-5 mission collected samples of these young lunar basalts and returned them to Earth for laboratory analysis. We measure an age of 1963 ± 57 million years for these lavas and determine their chemical and mineralogical compositions. This age constrains the lunar impact chronology of the inner Solar System and the thermal evolution of the Moon. There is no evidence for high concentrations of heat-producing elements in the deep mantle of the Moon that generated these lavas, so alternate explanations are required for the longevity of lunar magmatism.

15.
Nature ; 425(6958): 605-9, 2003 Oct 09.
Artículo en Inglés | MEDLINE | ID: mdl-14534583

RESUMEN

The tectonic setting in which the first continental crust formed, and the extent to which modern processes of arc magmatism at convergent plate margins were operative on the early Earth, are matters of debate. Geochemical studies have shown that felsic rocks in both Archaean high-grade metamorphic ('grey gneiss') and low-grade granite-greenstone terranes are comprised dominantly of sodium-rich granitoids of the tonalite-trondhjemite-granodiorite (TTG) suite of rocks. Here we present direct experimental evidence showing that partial melting of hydrous basalt in the eclogite facies produces granitoid liquids with major- and trace-element compositions equivalent to Archaean TTG, including the low Nb/Ta and high Zr/Sm ratios of 'average' Archaean TTG, but from a source with initially subchondritic Nb/Ta. In modern environments, basalts with low Nb/Ta form by partial melting of subduction-modified depleted mantle, notably in intraoceanic arc settings in the forearc and back-arc regimes. These observations suggest that TTG magmatism may have taken place beneath granite-greenstone complexes developing along Archaean intraoceanic island arcs by imbricate thrust-stacking and tectonic accretion of a diversity of subduction-related terranes. Partial melting accompanying dehydration of these generally basaltic source materials at the base of thickened, 'arc-like' crust would produce compositionally appropriate TTG granitoids in equilibrium with eclogite residues.

16.
Nature ; 427(6971): 234-7, 2004 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-14724635

RESUMEN

Osmium isotope ratios provide important constraints on the sources of ocean-island basalts, but two very different models have been put forward to explain such data. One model interprets (187)Os-enrichments in terms of a component of recycled oceanic crust within the source material. The other model infers that interaction of the mantle with the Earth's outer core produces the isotope anomalies and, as a result of coupled (186)Os-(187)Os anomalies, put time constraints on inner-core formation. Like osmium, tungsten is a siderophile ('iron-loving') element that preferentially partitioned into the Earth's core during core formation but is also 'incompatible' during mantle melting (it preferentially enters the melt phase), which makes it further depleted in the mantle. Tungsten should therefore be a sensitive tracer of core contributions in the source of mantle melts. Here we present high-precision tungsten isotope data from the same set of Hawaiian rocks used to establish the previously interpreted (186)Os-(187)Os anomalies and on selected South African rocks, which have also been proposed to contain a core contribution. None of the samples that we have analysed have a negative tungsten isotope value, as predicted from the core-contribution model. This rules out a simple core-mantle mixing scenario and suggests that the radiogenic osmium in ocean-island basalts can better be explained by the source of such basalts containing a component of recycled crust.

18.
Sci Rep ; 7: 44054, 2017 Mar 08.
Artículo en Inglés | MEDLINE | ID: mdl-31004127

RESUMEN

Millennial-scale cooling events termed Heinrich Stadials punctuated Northern Hemisphere climate during the last glacial period. Latitudinal shifts of the intertropical convergence zone (ITCZ) are thought to have rapidly propagated these abrupt climatic signals southward, influencing the evolution of Southern Hemisphere climates and contributing to major reorganisation of the global ocean-atmosphere system. Here, we use neodymium isotopes from a marine sediment core to reconstruct the hydroclimatic evolution of subtropical Australia between 90 to 20 thousand years ago. We find a strong correlation between our sediment provenance proxy data and records for western Pacific tropical precipitations and Australian palaeolakes, which indicates that Northern Hemisphere cooling phases were accompanied by pronounced excursions of the ITCZ and associated rainfall as far south as about 32°S. Comparatively, however, each of these humid periods lasted substantially longer than the mean duration of Heinrich Stadials, overlapping with subsequent warming phases of the southern high-latitudes recorded in Antarctic ice cores. In addition to ITCZ-driven hydroclimate forcing, we infer that changes in Southern Ocean climate also played an important role in regulating late glacial atmospheric patterns of the Southern Hemisphere subtropical regions.

19.
Brain Lang ; 170: 82-92, 2017 07.
Artículo en Inglés | MEDLINE | ID: mdl-28432987

RESUMEN

This study explored the relationships among multimodal imaging, clinical features, and language impairment in patients with left temporal lobe epilepsy (LTLE). Fourteen patients with LTLE and 26 controls underwent structural MRI, functional MRI, diffusion tensor imaging, and neuropsychological language tasks. Laterality indices were calculated for each imaging modality and a principal component (PC) was derived from language measures. Correlations were performed among imaging measures, as well as to the language PC. In controls, better language performance was associated with stronger left-lateralized temporo-parietal and temporo-occipital activations. In LTLE, better language performance was associated with stronger right-lateralized inferior frontal, temporo-parietal, and temporo-occipital activations. These right-lateralized activations in LTLE were associated with right-lateralized arcuate fasciculus fractional anisotropy. These data suggest that interhemispheric language reorganization in LTLE is associated with alterations to perisylvian white matter. These concurrent structural and functional shifts from left to right may help to mitigate language impairment in LTLE.


Asunto(s)
Corteza Cerebral/fisiopatología , Epilepsia del Lóbulo Temporal/complicaciones , Epilepsia del Lóbulo Temporal/fisiopatología , Trastornos del Lenguaje/complicaciones , Trastornos del Lenguaje/fisiopatología , Lenguaje , Imagen Multimodal , Adulto , Anisotropía , Mapeo Encefálico , Corteza Cerebral/patología , Imagen de Difusión Tensora , Epilepsia del Lóbulo Temporal/patología , Femenino , Lateralidad Funcional , Humanos , Trastornos del Lenguaje/patología , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Red Nerviosa/patología , Red Nerviosa/fisiopatología , Pruebas Neuropsicológicas , Lóbulo Temporal/patología , Lóbulo Temporal/fisiopatología , Sustancia Blanca/patología , Sustancia Blanca/fisiopatología
20.
Assessment ; 13(4): 381-4, 2006 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-17050907

RESUMEN

The sensitivity of the Paced Auditory Serial Addition Task (PASAT) to working memory deficits may be enhanced by examining "dyads" (i.e., correct responses immediately preceded by a correct response) as a complement to the traditional total correct summary score. In a sample of 397 mostly African American (79%) healthy adults, total dyad and total correct scores were highly correlated (r = .96, p < .001); however, the magnitude of this association diminished in faster stimulus presentation trials, particularly among participants with impaired working memory abilities.


Asunto(s)
Percepción Auditiva/fisiología , Trastornos de la Memoria/diagnóstico , Memoria/fisiología , Pruebas Neuropsicológicas , Adulto , Negro o Afroamericano/psicología , Femenino , Humanos , Masculino , Trastornos de la Memoria/enzimología , Procesos Mentales/fisiología , Persona de Mediana Edad , Estudios Prospectivos , Reproducibilidad de los Resultados
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