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Prematurity impacts myocardial development and may determine long-term outcomes. The objective of this study was to test the hypothesis that preterm neonates develop right ventricle dysfunction and adaptive remodelling by 32 weeks post-menstrual age that persists through 1 year corrected age.
Materials and Methods:
A subset of 80 preterm infants (born <29 weeks) was selected retrospectively from a prospectively enrolled cohort and measures of right ventricle systolic function and morphology by two-dimensional echocardiography were assessed at 32 weeks post-menstrual age and at 1 year of corrected age. Comparisons were made to 50 term infants at 1 month and 1 year of age. Sub-analyses were performed in preterm-born infants with bronchopulmonary dysplasia and/or pulmonary hypertension.
In both term and preterm infants, right ventricle function and morphology increased over the first year (p < 0.01). The magnitudes of right ventricle function measures were lower in preterm-born infants at each time period (p < 0.01 for all) and right ventricle morphology indices were wider in all preterm infants by 1 year corrected age, irrespective of lung disease. Measures of a) right ventricle function were further decreased and b) morphology increased through 1 year in preterm infants with bronchopulmonary dysplasia and/or pulmonary hypertension (p < 0.01).
Preterm infants exhibit abnormal right ventricle performance with remodelling at 32 weeks post-menstrual age that persists through 1 year corrected age, suggesting a less developed intrinsic myocardial function response following preterm birth. The development of bronchopulmonary dysplasia and pulmonary hypertension leave a further negative impact on right ventricle mechanics over the first year of age.
Multiple introductions of an exotic species can facilitate invasion success by allowing for a wider range of expressed trait values in the adventive range. Schinus terebinthifolius (Brazilian peppertree) is an invasive shrub that was introduced into Florida in two separate introductions and has subsequently hybridized, resulting in three distinct lineages (eastern, western, and hybrid). To determine whether allocation of aboveground biomass differed by introduction history, we destructively sampled 257 stems from each of six populations with differing introduction histories. The proportion of aboveground biomass allocated to fruit, wood, and leaves differed among the three populations. To determine whether the relationship between stem size and several dependent variables that measure plant performance (total dry weight, wood dry weight, number of fruits, fruit dry weight, leaf dry weight, and number of leaves) differed quantitatively by introduction history, we performed analyses of covariance. Slopes of these relationships (dependent variable vs. stem size) varied by lineage. Hybrid populations had the steepest slopes for one set of dependent variables (total dry weight, wood dry weight, and leaf dry weight), while western populations had the steepest slopes for a different set of dependent variables (number of fruits, fruit dry weight, and number of leaves). The parameterized regression equations for each dependent variable and lineage were used to nondestructively estimate different kinds of production by individuals that are part of long-term longitudinal studies to understand the demographic consequences of these different biomass allocation strategies for the performance of S. terebinthifolius individuals across the invaded range in Florida.
At the lowest radio frequencies (≤30 MHz), the Earth's ionosphere transmits poorly or not at all. This relatively unexplored region of the electromagnetic spectrum is thus an area where high resolution, high sensitivity observations can open a new window for astronomical investigations. Also, extending observations down to very low frequencies brings astronomy to a fundamental physical limit where the Milky Way becomes optically thick over relatively short path lengths due to diffuse free-free absorption.
The ALFA mission is designed to map the entire sky at frequencies between approximately 0.3 and 30 MHz with angular resolution limited by interstellar and interplanetary scattering. Most of this region of the spectrum is inaccessible from the ground because of absorption and refraction by the Earth’s ionosphere. A wide range of astrophysical questions concerning solar system, galactic, and extragalactic objects could be answered with high resolution images at low frequencies, where absorption effects and coherent emission processes become important and the synchrotron lifetimes of electrons are comparable to the age of the universe.
We have assembled a new sample of some of the most FIR-luminous galaxies in the Universe and have imaged them in 1.1 mm dust emission and measured their redshifts 1 < z < 4 via CO emission lines using the 32-m Large Millimeter Telescope / Gran Telescopio Milimétrico (LMT/GTM). Our sample of 31 submm galaxies (SMGs), culled from the Planck and Herschel all-sky surveys, includes 14 of the 21 most luminous galaxies known, with LFIR > 1014L⊙ and SFR > 104M⊙/yr. These extreme inferred luminosities – and multiple / extended 1.1 mm images – imply that most or all are strongly gravitationally lensed, with typical magnification μ ~ 10 × . The gravitational lensing provides two significant benefits: (1) it boosts the S/N, and (2) it allows investigation of star formation and gas processes on sub-kpc scales.
Dementia cases are increasing worldwide; thus, investigators seek to identify interventions that might prevent or ameliorate cognitive decline in later life. Extensive research confirms the benefits of physical exercise for brain health, yet only a fraction of older adults exercise regularly. Interactive mental and physical exercise, as in aerobic exergaming, not only motivates, but has also been found to yield cognitive benefit above and beyond traditional exercise. This pilot study sought to investigate whether greater cognitive challenge while exergaming would yield differential outcomes in executive function and generalize to everyday functioning. Sixty-four community based older adults (mean age=82) were randomly assigned to pedal a stationary bike, while interactively engaging on-screen with: (1) a low cognitive demand task (bike tour), or (2) a high cognitive demand task (video game). Executive function (indices from Trails, Stroop and Digit Span) was assessed before and after a single-bout and 3-month exercise intervention. Significant group × time interactions were found after a single-bout (Color Trails) and after 3 months of exergaming (Stroop; among 20 adherents). Those in the high cognitive demand group performed better than those in the low cognitive dose condition. Everyday function improved across both exercise conditions. Pilot data indicate that for older adults, cognitive benefit while exergaming increased concomitantly with higher doses of interactive mental challenge. (JINS, 2015, 21, 768–779)
The aim of this study was to examine whether people differed in change in performance across the first five blocks of an online flanker task and whether those trajectories of change were associated with self-reported aerobic or resistance exercise frequency according to age. A total of 8752 men and women aged 13–89 completed a lifestyle survey and five 45-s games (each game was a block of ~46 trials) of an online flanker task. Accuracy of the congruent and incongruent flanker stimuli was analyzed using latent class and growth curve modeling adjusting for time between blocks, whether the blocks occurred on the same or different days, education, smoking, sleep, caffeinated coffee and tea use, and Lumosity training status (“free play” or part of a “daily brain workout”). Aerobic and resistance exercise were unrelated to first block accuracies. For the more cognitively demanding incongruent flanker stimuli, aerobic activity was positively related to the linear increase in accuracy [B=0.577%, 95% confidence interval (CI), 0.112 to 1.25 per day above the weekly mean of 2.8 days] and inversely related to the quadratic deceleration of accuracy gains (B=−0.619% CI, −1.117 to −0.121 per day). An interaction of aerobic activity with age indicated that active participants younger than age 45 had a larger linear increase and a smaller quadratic deceleration compared to other participants. Age moderates the association between self-reported aerobic, but not self-reported resistance, exercise and changes in cognitive control that occur with practice during incongruent presentations across five blocks of a 45-s online, flanker task. (JINS, 2015, 21, 802–815)
To determine if total lifetime physical activity (PA) is associated with better cognitive functioning with aging and if cerebrovascular function mediates this association. A sample of 226 (52.2% female) community dwelling middle-aged and older adults (66.5±6.4 years) in the Brain in Motion Study, completed the Lifetime Total Physical Activity Questionnaire and underwent neuropsychological and cerebrovascular blood flow testing. Multiple robust linear regressions were used to model the associations between lifetime PA and global cognition after adjusting for age, sex, North American Adult Reading Test results (i.e., an estimate of premorbid intellectual ability), maximal aerobic capacity, body mass index and interactions between age, sex, and lifetime PA. Mediation analysis assessed the effect of cerebrovascular measures on the association between lifetime PA and global cognition. Post hoc analyses assessed past year PA and current fitness levels relation to global cognition and cerebrovascular measures. Better global cognitive performance was associated with higher lifetime PA (p=.045), recreational PA (p=.021), and vigorous intensity PA (p=.004), PA between the ages of 0 and 20 years (p=.036), and between the ages of 21 and 35 years (p<.0001). Cerebrovascular measures did not mediate the association between PA and global cognition scores (p>.5), but partially mediated the relation between current fitness and global cognition. This study revealed significant associations between higher levels of PA (i.e., total lifetime, recreational, vigorous PA, and past year) and better cognitive function in later life. Current fitness levels relation to cognitive function may be partially mediated through current cerebrovascular function. (JINS, 2015, 21, 816–830)
Airborne observations of the Trapezium region of the Orion Nebula in the 60–300 μ range have been made from 13.7 km altitude using a Michelson interferometer with the Rice University 12-in. Flying Infrared Telescope. Fourier analysis of five interferometer scans provided spectra with resolution ranging from 7 cm–1 to 20 cm–1. These spectra were compared with lunar spectra taken with the same instrument at the same altitude to correct for instrumental and atmospheric effects. A weighted combination of these scans provides a low resolution spectrum. The radiation per unit frequency interval at 190 μ was found to be at least 40% of that measured between 75 and 90 μ. Neglecting possible features in the spectrum, its general shape is consistent with a blackbody near 70 K. The resolution is inadequate to resolve spectral lines.
Latent infection from Toxoplasma gondii (T. gondii) is widespread worldwide and has been associated with cognitive deficits in some but not all animal models and in humans. We tested the hypothesis that latent toxoplasmosis is associated with decreased cognitive function in a large cross-sectional dataset, the National Health and Nutrition Examination Survey (NHANES). There were 4178 participants aged 20–59 years, of whom 19·1% had IgG antibodies against T. gondii. Two ordinary least squares (OLS) regression models adjusted for the NHANES complex sampling design and weighted to represent the US population were estimated for simple reaction time, processing speed and short-term memory or attention. The first model included only main effects of latent toxoplasmosis and demographic control variables, and the second added interaction terms between latent toxoplasmosis and the poverty-to-income ratio (PIR), educational attainment and race-ethnicity. We also used multivariate models to assess all three cognitive outcomes in the same model. Although the models evaluating main effects only demonstrated no association between latent toxoplasmosis and the cognitive outcomes, significant interactions between latent toxoplasmosis and the PIR, between latent toxoplasmosis and educational attainment, and between latent toxoplasmosis and race-ethnicity indicated that latent toxoplasmosis may adversely affect cognitive function in certain groups.
Significant new opportunities for astrophysics and cosmology have been identified at low radio frequencies. The Murchison Widefield Array is the first telescope in the southern hemisphere designed specifically to explore the low-frequency astronomical sky between 80 and 300 MHz with arcminute angular resolution and high survey efficiency. The telescope will enable new advances along four key science themes, including searching for redshifted 21-cm emission from the EoR in the early Universe; Galactic and extragalactic all-sky southern hemisphere surveys; time-domain astrophysics; and solar, heliospheric, and ionospheric science and space weather. The Murchison Widefield Array is located in Western Australia at the site of the planned Square Kilometre Array (SKA) low-band telescope and is the only low-frequency SKA precursor facility. In this paper, we review the performance properties of the Murchison Widefield Array and describe its primary scientific objectives.
We report a principle that allows writing visible light emitting semiconductor patterns of arbitrary shape down to the sub-micrometer scale. We demonstrate that porous semiconductor growth can be electrochemically initiated preferentially at surface defects created in an n-type substrate by Si++ focused ion beam bombardment. For n-type material in the dark, the electrochemical pore formation potential (Schottky barrier breakdown voltage) is significantly lower at the implanted locations than for an unimplanted surface. This difference in the threshold voltages is exploited to achieve the selectivity of the pore formation process. Visible light emitting patterns of porous Si and GaAs have been created in this way. At present, the size of the structures is limited only by the diameter of the writing ion beam, and pattern diameters in the 50–200-nm range are possible.
Major depressive disorder (MDD) is associated with deficits in recalling specific autobiographical memories (AMs). Extensive research has examined the functional anatomical correlates of AM in healthy humans, but no studies have examined the neurophysiological underpinnings of AM deficits in MDD. The goal of the present study was to examine the differences in the hemodynamic response between patients with MDD and controls while they engage in AM recall.
Participants (12 unmedicated MDD patients; 14 controls) underwent functional magnetic resonance imaging (fMRI) scanning while recalling AMs in response to positive, negative and neutral cue words. The hemodynamic response during memory recall versus performing subtraction problems was compared between MDD patients and controls. Additionally, a parametric linear analysis examined which regions correlated with increasing arousal ratings.
Behavioral results showed that relative to controls, the patients with MDD had fewer specific (p=0.013), positive (p=0.030), highly arousing (p=0.036) and recent (p=0.020) AMs, and more categorical (p<0.001) AMs. The blood oxygen level-dependent (BOLD) response in the parahippocampus and hippocampus was higher for memory recall versus subtraction in controls and lower in those with MDD. Activity in the anterior insula was lower for specific AM recall versus subtraction, with the magnitude of the decrement greater in MDD patients. Activity in the anterior cingulate cortex was positively correlated with arousal ratings in controls but not in patients with MDD.
We replicated previous findings of fewer specific and more categorical AMs in patients with MDD versus controls. We found differential activity in medial temporal and prefrontal lobe structures involved in AM retrieval between MDD patients and controls as they engaged in AM recall. These neurophysiological deficits may underlie AM recall impairments seen in MDD.
In an effort to develop alternative single buffer layer technology for YBa2Cu3O7-δ (YBCO) coated conductors, we have investigated LaMnO3 (LMO) as a potential buffer layer. High-quality LMO films were grown directly on biaxially textured Ni and Ni-W (3%) substrates using rf magnetron sputtering. YBCO films were then grown on LMO buffers using pulsed laser deposition. Detailed X-ray studies have shown that both YBCO and LMO layers were grown with a single epitaxial orientation. Rutherford backscattering spectroscopy (RBS) analyses have indicated the ratio of La to Mn ratio is 1:1. SEM micrographs indicated that 3000-Å-thick LMO films on biaxially textured Ni (100) substrates were dense, continuous and crack-free. A high Jc of over 1 MA/cm2 at 77 K and self-field was obtained on YBCO films grown on LMO-buffered Ni or Ni-W substrates. We have identified LaMnO3 as a good diffusion barrier layer for Ni and it also provides a good template for growing high current density YBCO films.
A thin-film substrate geometry is described for the study of enhanced or seeded solid-state phase transformations. As an example of this approach, thin films of hematite have been used as substrates for the study of the seeded phase transformation of a boehmite-derived transition-alumina to α-A12O3. The hematite films were grown on bulk (0001) α-A12O3 single crystal substrates by pulsed-laser ablation. A layer of a boehmite sol was then spin-coated onto the thin film. The assemblages were then heated to 950°C, or 1000°C in order to induce the phase transformation. Specimens were imaged in cross section by transmission electron microscopy. No transformation was observed for specimens heated to 950°C. In specimens heated to 1000°C, the transition alumina was found to transform to alpha-alumina, starting at the surface of the hematite film, via solid-state heteroepitaxy. In this case, islands, growing out from the hematite film into the transition alumina layer, were observed.
The point defect reaction which governs the magnetic and electrical properties of transition metal oxide spinels is the distribution of cations between tetrahedral and octahedral sublattices. Two types of redistribution occur -- ionic and electronic. The thermodynamics and kinetics of these processes can be studied via the electrical properties, thermoelectric coefficient and conductivity.
This paper describes the instrumentation and technique for the routine characterization of thin Films, multi-layers and substrates by grazing incidence X-ray reflectometry with a rotating anode and CuKα1, line source. Ge 220 channel monochromators with two reflections per channel were used with one CM placed before and the other after the specimen. In many applications the second CM could be replaced with a narrow receiving slit. The specimen holder was designed to make fine translations of the specimen for alignment, a base was designed to permit precise positioning of the diffractometer, and a high-speed Rigaku scintillation counter was used. The alignment and calibration are described and some typical data given to illustrate the capability of the method.