1,941 research outputs found
Pedunculopontine-Induced cortical decoupling as the neurophysiological locus of dissociation
Mounting evidence suggests an association between aberrant sleep phenomena and dissociative experiences. However, no wake-sleep boundary theory provides a compelling explanation of dissociation or specifies its physiological substrates. We present a theoretical account of dissociation that integrates theories and empirical results from multiple lines of research concerning the domain of dissociation and the regulation of rapid eye movement (REM) sleep.
This theory posits that individual differences in the circuitry governing the REM sleep promoting Pedunculopontine Nucleus and Laterodorsal Tegmental Nucleus determine the degree of similarity in the cortical connectivity profiles of wakefulness and REM sleep. We propose that a latent trait characterized by elevated dissociative experiences emerges from the decoupling of frontal executive regions due to a REM sleep-like aminergic/cholinergic balance. The
Pedunculopontine Induced Cortical Decoupling Account of Dissociation (PICDAD) suggests multiple fruitful lines of inquiry and provides novel insights
Numerical Simulations of Supernova Dust Destruction. II. Metal-Enriched Ejecta Knots
Following our previous work, we investigate through hydrodynamic simulations
the destruction of newly-formed dust grains by sputtering in the reverse shocks
of supernova remnants. Using an idealized setup of a planar shock impacting a
dense, spherical clump, we implant a population of Lagrangian particles into
the clump to represent a distribution of dust grains in size and composition.
We vary the relative velocity between the reverse shock and ejecta clump to
explore the effects of shock-heating and cloud compression. Because supernova
ejecta will be metal-enriched, we consider gas metallicities from Z/Zsun = 1 to
100 and their influence on cooling properties of the cloud and the thermal
sputtering rates of embedded dust grains. We post-process the simulation output
to calculate grain sputtering for a variety of species and size distributions.
In the metallicity regime considered in this paper, the balance between
increased radiative cooling and increased grain erosion depends on the impact
velocity of the reverse shock. For slow shocks (velocity less than or equal to
3000 km/s), the amount of dust destruction is comparable across metallicities,
or in some cases is decreased with increased metallicity. For higher shock
velocities (velocity greater than or equal to 5000 km/s), an increase in
metallicity from Z/Zsun = 10 to 100 can lead to an additional 24% destruction
of the initial dust mass. While the total dust destruction varies widely across
grain species and simulation parameters, our most extreme cases result in
complete destruction for some grain species and only 44% dust mass survival for
the most robust species. These survival rates are important in understanding
how early supernovae contribute to the observed dust masses in high-redshift
galaxies.Comment: 10 pages, 6 figures, 2 tables, changes made to the text and figures
as suggested by the anonymous referee, accepted by the Astrophysical Journa
Numerical Simulations of Supernova Dust Destruction. I. Cloud-crushing and Post-processed Grain Sputtering
We investigate through hydrodynamic simulations the destruction of
newly-formed dust grains by sputtering in the reverse shocks of supernova
remnants. Using an idealized setup of a planar shock impacting a dense,
spherical clump, we implant a population of Lagrangian particles into the clump
to represent a distribution of dust grains in size and composition. We then
post-process the simulation output to calculate the grain sputtering for a
variety of species and size distributions. We explore the parameter space
appropriate for this problem by altering the over-density of the ejecta clumps
and the speed of the reverse shocks. Since radiative cooling could lower the
temperature of the medium in which the dust is embedded and potentially protect
the dust by slowing or halting grain sputtering, we study the effects of
different cooling methods over the time scale of the simulations. In general,
our results indicate that grains with radii less than 0.1 microns are sputtered
to much smaller radii and often destroyed completely, while larger grains
survive their interaction with the reverse shock. We also find that, for high
ejecta densities, the percentage of dust that survives is strongly dependent on
the relative velocity between the clump and the reverse shock, causing up to
50% more destruction for the highest velocity shocks. The fraction of dust
destroyed varies widely across grain species, ranging from total destruction of
Al2O3 grains to minimal destruction of Fe grains (only 20% destruction in the
most extreme cases). C and SiO2 grains show moderate to strong sputtering as
well, with 38% and 80% mass loss. The survival rate of grains formed by early
supernovae is crucial in determining whether or not they can act as the "dust
factories" needed to explain high-redshift dust.Comment: 18 pages, 16 figures, 2 tables, changes make to the text and figures
as suggested by the anonymous referee, accepted by the Astrophysical Journa
Case Report Buttock Necrosis after Uterine Artery Embolization for Delayed Hysterectomy in Placenta Percreta
Background. Morbidly adherent placenta (MAP) is increasing in incidence and is commonly associated with maternal hemorrhage and cesarean hysterectomy. Uterine artery embolization (UAE) may be utilized in the conservative management of placenta percreta to potentially reduce blood loss. The incidence of complications from UAE in the conservative management of placenta percreta is poorly described. To our knowledge, we present the first reported case of buttock necrosis in this setting. Case. A 39-year-old gravida nine para two with placenta percreta who underwent conservative management with UAE complicated by right buttock necrosis. Conclusion. While UAE may potentially decrease blood loss, it is not without risk. More studies must be performed in order to quantify those risks and determine the clinical utility of UAE
Ethnic differences in do-not-resuscitate orders after intracerebral hemorrhage.
OBJECTIVE: To explore ethnic differences in do-not-resuscitate orders after intracerebral hemorrhage.
DESIGN: Population-based surveillance.
SETTING: Corpus Christi, Texas.
PATIENTS: All cases of intracerebral hemorrhage in the community of Corpus Christi, TX were ascertained as part of the Brain Attack Surveillance in Corpus Christi (BASIC) project.
INTERVENTIONS: None.
MEASUREMENTS AND MAIN RESULTS: Medical records were reviewed for do-not-resuscitate orders. Unadjusted and multivariable logistic regression were used to test for associations between ethnicity and do-not-resuscitate orders, both overall ( any do-not-resuscitate ) and within 24 hrs of presentation ( early do-not-resuscitate ), adjusted for age, gender, Glasgow Coma Scale, intracerebral hemorrhage volume, intraventricular hemorrhage, infratentorial hemorrhage, modified Charlson Index, and admission from a nursing home. A total of 270 cases of intracerebral hemorrhage from 2000-2003 were analyzed. Mexican-Americans were younger and had a higher Glasgow Coma Scale than non-Hispanic whites. Mexican-Americans were half as likely as non-Hispanic whites to have early do-not-resuscitate orders in unadjusted analysis (odds ratio 0.45, 95% confidence interval 0.27, 0.75), although this association was not significant when adjusted for age (odds ratio 0.61, 95% confidence interval 0.35, 1.06) and in the fully adjusted model (odds ratio 0.75, 95% confidence interval 0.39, 1.46). Mexican-Americans were less likely than non-Hispanic whites to have do-not-resuscitate orders written at any time point (odds ratio 0.37, 95% confidence interval 0.23, 0.61). Adjustment for age alone attenuated this relationship although it retained significance (odds ratio 0.49, 95% confidence interval 0.29, 0.82). In the fully adjusted model, Mexican-Americans were less likely than non-Hispanic whites to use do-not-resuscitate orders at any time point, although the 95% confidence interval included one (odds ratio 0.52, 95% confidence interval 0.27, 1.00).
CONCLUSIONS: Mexican-Americans were less likely than non-Hispanic whites to have do-not-resuscitate orders after intracerebral hemorrhage although the association was attenuated after adjustment for age and other confounders. The persistent trend toward less frequent use of do-not-resuscitate orders in Mexican-Americans suggests that further study is warranted
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Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109317/1/ana24280.pd
Architecture Optimization Dramatically Improves Reverse Bias Stability in Perovskite Solar Cells: A Role of Polymer Hole Transport Layers
We report that device architecture engineering has a substantial impact on
the reverse bias instability that has been reported as a critical issue in
commercializing perovskite solar cells. We demonstrate breakdown voltages
exceeding -15 V in typical pin structured perovskite solar cells via two steps:
i) using polymer hole transporting materials; ii) using a more
electrochemically stable gold electrode. While device degradation can be
exacerbated by higher reverse bias and prolonged exposure, our as-fabricated
perovskite solar cells completely recover their performance even after
stressing at -7 V for 9 hours both in the dark and under partial illumination.
Following these observations, we systematically discuss and compare the reverse
bias driven degradation pathways in perovskite solar cells with different
device architectures. Our model highlights the role of electrochemical reaction
rates and species in dictating the reverse bias stability of perovskite solar
cells
Epigenomics and Metabolomics Reveal the Mechanism of the \u3cem\u3eAPOA2\u3c/em\u3e-Saturated Fat Intake Interaction Affecting Obesity
Background: The putative functional variant −265T \u3e C (rs5082) within the APOA2 promoter has shown consistent interactions with saturated fatty acid (SFA) intake to influence the risk of obesity.
Objective: The aim of this study was to implement an integrative approach to characterize the molecular basis of this interaction.
Design: We conducted an epigenome-wide scan on 80 participants carrying either the rs5082 CC or TT genotypes and consuming either a low-SFA (\u3c 22 g/d) or high-SFA diet (≥ 22 g/d), matched for age, sex, BMI, and diabetes status in the Boston Puerto Rican Health Study (BPRHS). We then validated the findings in selected participants in the Genetics of Lipid Lowering Drugs and Diet Network (GOLDN) Study (n = 379) and the Framingham Heart Study (FHS) (n = 243). Transcription and metabolomics analyses were conducted to determine the relation between epigenetic status, APOA2 mRNA expression, and blood metabolites.
Results: In the BPRHS, we identified methylation site cg04436964 as exhibiting significant differences between CC and TT participants consuming a high-SFA diet, but not among those consuming low-SFA. Similar results were observed in the GOLDN Study and the FHS. Additionally, in the FHS, cg04436964 methylation was negatively correlated with APOA2 expression in the blood of participants consuming a high-SFA diet. Furthermore, when consuming a high-SFA diet, CC carriers had lower APOA2 expression than those with the TT genotype. Lastly, metabolomic analysis identified 4 pathways as overrepresented by metabolite differences between CC and TT genotypes with high-SFA intake, including tryptophan and branched-chain amino acid (BCAA) pathways. Interestingly, these pathways were linked to rs5082-specific cg04436964 methylation differences in high-SFA consumers.
Conclusions: The epigenetic status of the APOA2 regulatory region is associated with SFA intake and APOA2 -265T \u3e C genotype, promoting an APOA2 expression difference between APOA2 genotypes on a high-SFA diet, and modulating BCAA and tryptophan metabolic pathways. These findings identify potential mechanisms by which this highly reproducible gene-diet interaction influences obesity risk, and contribute new insights to ongoing investigations of the relation between SFA and human health. This study was registered at clinicaltrials.gov as NCT03452787
Epigenomics and metabolomics reveal the mechanism of the APOA2-saturated fat intake interaction affecting obesity
Background: The putative functional variant -265T\u3eC (rs5082) within the APOA2 promoter has shown consistent interactions with saturated fatty acid (SFA) intake to influence the risk of obesity.
Objective: The aim of this study was to implement an integrative approach to characterize the molecular basis of this interaction.
Design: We conducted an epigenome-wide scan on 80 participants carrying either the rs5082 CC or TT genotypes and consuming either a low-SFA (\u3c22 g/d) or high-SFA diet (≥22 g/d), matched for age, sex, BMI, and diabetes status in the Boston Puerto Rican Health Study (BPRHS). We then validated the findings in selected participants in the Genetics of Lipid Lowering Drugs and Diet Network (GOLDN) Study (n = 379) and the Framingham Heart Study (FHS) (n = 243). Transcription and metabolomics analyses were conducted to determine the relation between epigenetic status, APOA2 mRNA expression, and blood metabolites.
Results: In the BPRHS, we identified methylation site cg04436964 as exhibiting significant differences between CC and TT participants consuming a high-SFA diet, but not among those consuming low-SFA. Similar results were observed in the GOLDN Study and the FHS. Additionally, in the FHS, cg04436964 methylation was negatively correlated with APOA2 expression in the blood of participants consuming a high-SFA diet. Furthermore, when consuming a high-SFA diet, CC carriers had lower APOA2 expression than those with the TT genotype. Lastly, metabolomic analysis identified 4 pathways as overrepresented by metabolite differences between CC and TT genotypes with high-SFA intake, including tryptophan and branched-chain amino acid (BCAA) pathways. Interestingly, these pathways were linked to rs5082-specific cg04436964 methylation differences in high-SFA consumers.
Conclusions: The epigenetic status of the APOA2 regulatory region is associated with SFA intake and APOA2 -265T\u3eC genotype, promoting an APOA2 expression difference between APOA2 genotypes on a high-SFA diet, and modulating BCAA and tryptophan metabolic pathways. These findings identify potential mechanisms by which this highly reproducible gene-diet interaction influences obesity risk, and contribute new insights to ongoing investigations of the relation between SFA and human health. This study was registered at clinicaltrials.gov as NCT03452787
Persistent ischemic stroke disparities despite declining incidence in Mexican Americans
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/102622/1/ana23972.pd
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