194 research outputs found
Maternal Depression Trajectories and Child BMI in a Multi-Ethnic Sample: A Latent Growth Modeling Analysis
Background
Perinatal (antenatal and postpartum) depression impacts approximately 12% of mothers. Perinatal depression can impact everyday functioning for mothers, and the relationship with, and development of, their children. The purpose of this study was to investigate depression trajectories from the antenatal period through 54-months postpartum and associations with child body mass index at 54-months postpartum. Methods
This study applied latent growth modeling to the Growing Up in New Zealand study, which is a longitudinal pregnancy cohort study that provides nationally representative-level data, to investigate associations between depression at three time points (antenatal, 9-months postpartum, 54-months postpartum) and child body mass index at 54-months (n=4897). Results
The average slope of depression for this sample is low and decreases over time. When child BMI was added to the model as an outcome variable, both antenatal depression (B=.25, pppχ2 (9) = 39.60, p \u3c .05, SRMR = 0.01, CFI = .99, RMSEA = 0.03, BIC=53213). Conclusions
Our findings align with the Developmental Origins of Health and Disease theory and imply that both the physical and mental health of mothers during pregnancy may be important indicators of child growth and development outcomes. Early intervention directed towards women who have even mild depression scores during pregnancy may promote healthy child development outcomes. Additionally, given the heterogeneity of depressive symptoms over time seen in this study, multiple assessment periods across the postpartum period may be valuable to adequately address and support maternal mental health
Maternal Depression Trajectories and Child BMI in a Multi-Ethnic Sample: A Latent Growth Modeling Analysis
Background
Perinatal (antenatal and postpartum) depression impacts approximately 12% of mothers. Perinatal depression can impact everyday functioning for mothers, and the relationship with, and development of, their children. The purpose of this study was to investigate depression trajectories from the antenatal period through 54-months postpartum and associations with child body mass index at 54-months postpartum. Methods
This study applied latent growth modeling to the Growing Up in New Zealand study, which is a longitudinal pregnancy cohort study that provides nationally representative-level data, to investigate associations between depression at three time points (antenatal, 9-months postpartum, 54-months postpartum) and child body mass index at 54-months (n=4897). Results
The average slope of depression for this sample is low and decreases over time. When child BMI was added to the model as an outcome variable, both antenatal depression (B=.25, pppχ2 (9) = 39.60, p \u3c .05, SRMR = 0.01, CFI = .99, RMSEA = 0.03, BIC=53213). Conclusions
Our findings align with the Developmental Origins of Health and Disease theory and imply that both the physical and mental health of mothers during pregnancy may be important indicators of child growth and development outcomes. Early intervention directed towards women who have even mild depression scores during pregnancy may promote healthy child development outcomes. Additionally, given the heterogeneity of depressive symptoms over time seen in this study, multiple assessment periods across the postpartum period may be valuable to adequately address and support maternal mental health
Switching between attractive and repulsive Coulomb-interaction-mediated drag in an ambipolar GaAs/AlGaAs bilayer device
We present measurements of Coulomb drag in an ambipolar GaAs/AlGaAs double
quantum well structure that can be configured as both an electron-hole bilayer
and a hole-hole bilayer, with an insulating barrier of only 10 nm between the
two quantum wells. The Coulomb drag resistivity is a direct measure of the
strength of the interlayer particle-particle interactions. We explore the
strongly interacting regime of low carrier densities (2D interaction parameter
up to 14). Our ambipolar device design allows comparison between the
effects of the attractive electron-hole and repulsive hole-hole interactions,
and also shows the effects of the different effective masses of electrons and
holes in GaAs.This work was financially supported by the UK Engineering and Physical Sciences Research Council. A.F.C. acknowledges financial support from Trinity College, Cambridge, and IF from Toshiba Research Europe.This is the author accepted manuscript. The final version is available from the American Institute of Physics via http://dx.doi.org/10.1063/1.494176
A complete laboratory for transport studies of electron-hole interactions in GaAs/AlGaAs ambipolar bilayers
We present GaAs/AlGaAs double quantum well devices that can operate as both electron-hole (e-h) and hole-hole (h-h) bilayers, with separating barriers as narrow as 5 nm or 7.5 nm. With such narrow barriers, in the h-h configuration, we observe signs of magnetic-field-induced exciton condensation in the quantum Hall bilayer regime. In the same devices, we can study the zero-magnetic-field e-h and h-h bilayer states using Coulomb drag. Very strong e-h Coulomb drag resistivity (up to 10% of the single layer resistivity) is observed at liquid helium temperatures, but no definite signs of exciton condensation are seen in this case. Self-consistent calculations of the electron and hole wavefunctions show this might be because the average interlayer separation is larger in the e-h case than the h-h case
Materials and Textile Architecture Analyses for Mechanical Counter-Pressure Space Suits using Active Materials
Mechanical counter-pressure (MCP) space suits have the potential to improve the mobility of astronauts as they conduct planetary exploration activities. MCP suits differ from traditional gas-pressurized space suits by applying surface pressure to the wearer using tight-fitting materials rather than pressurized gas, and represent a fundamental change in space suit design. However, the underlying technologies required to provide uniform compression in a MCP garment at sufficient pressures for space exploration have not yet been perfected, and donning and doffing a MCP suit remains a significant challenge. This research effort focuses on the novel use of active material technologies to produce a garment with controllable compression capabilities (up to 30 kPa) to address these problems. We provide a comparative study of active materials and textile architectures for MCP applications; concept active material compression textiles to be developed and tested based on these analyses; and preliminary biaxial braid compression garment modeling results.United States. National Aeronautics and Space Administration (OCT Space Technology Research Fellowship Grant NNX11AM62H)MIT-Portugal Progra
Larval dispersal and fishing pressure influence recruitment in a coral reef fishery
Understanding larval connectivity patterns in exploited fishes is a fundamental prerequisite for developing effective management strategies and assessing the vulnerability of a fishery to recruitment overfishing and localised extinction. To date, however, researchers have not considered how regional variations in fishing pressure also influence recruitment.
We used genetic parentage analyses and modelling to infer the dispersal patterns of bumphead parrotfish Bolbometopon muricatum larvae in the Kia fishing grounds, Isabel Province, Solomon Islands. We then extrapolated our Kia dispersal model to a regional scale by mapping the available nursery and adult habitat for B. muricatum in six regions in the western Solomon Islands, and estimated the relative abundance of adult B. muricatum populations in each of these regions based on available adult habitat and historical and current fishing pressure.
Parentage analysis identified 67 juveniles that were the offspring of parents sampled in the Kia fishing grounds. A fitted larval dispersal kernel predicted that 50% of larvae settled within 30 km of their parents, and 95% settled within 85 km of their parents. After accounting for unsampled adults, our model predicted that 34% of recruitment to the Kia fishery was spawned locally. Extrapolating the spatial resolution of the model revealed that a high proportion of the larvae recruiting into the Kia fishing grounds came from nearby regions that had abundant adult populations. Other islands in the archipelago provided few recruits to the Kia fishing grounds, reflecting the greater distances to these islands and lower adult abundances in some regions.
Synthesis and applications. This study shows how recruitment into a coral reef fishery is influenced by larval dispersal patterns and regional variations in historical fishing pressure. The scales of larval connectivity observed for bumphead parrotfish indicate that recruitment overfishing is unlikely if there are lightly exploited reefs up to 85 km away from a heavily fished region, and that small (<1 km2) marine-protected areas (MPAs) are insufficient to protect this species. We recommend greater efforts to understand the interactions between larval dispersal and gradients of fishing pressure, as this will enable the development of tailored fisheries management strategies
Lipoprotein ability to exchange and remove lipids from model membranes as a function of fatty acid saturation and presence of cholesterol
Lipoproteins play a central role in the development of atherosclerosis. High and low-density lipoproteins (HDL and LDL), known as 'good' and 'bad' cholesterol, respectively, remove and/or deposit lipids into the artery wall. Hence, insight into lipid exchange processes between lipoproteins and cell membranes is of particular importance in understanding the onset and development of cardiovascular disease. In order to elucidate the impact of phospholipid tail saturation and the presence of cholesterol in cell membranes on these processes, neutron reflection was employed in the present investigation to follow lipid exchange with both HDL and LDL against model membranes. Mirroring clinical risk factors for the development of atherosclerosis, lower exchange was observed in the presence of cholesterol, as well as for an unsaturated phospholipid, compared to faster exchange when using a fully saturated phospholipid. These results highlight the importance of membrane composition on the interaction with lipoproteins, chiefly the saturation level of the lipids and presence of cholesterol, and provide novel insight into factors of importance for build-up and reversibility of atherosclerotic plaque. In addition, the correlation between the results and well-established clinical risk factors suggests that the approach taken can be employed also for understanding a broader set of risk factors including, e.g., effects of triglycerides and oxidative stress, as well as local effects of drugs on atherosclerotic plaque formation
Mechanically robust cylindrical metal terahertz waveguides for cryogenic applications
As the ambition behind THz quantum cascade laser based applications continues to grow, abandoning free-space optics in favor of waveguided systems promises major improvements in targeted, easy to align, and robust radiation delivery. This is especially true in cryogenic environments, where illumination is traditionally challenging. Although the field of THz waveguides is rapidly developing, most designs have limitations in terms of mechanical stability at low temperatures, and are costly and complicated to fabricate to lengths > 1 m. In this work, we investigate readily available cylindrical metal waveguides which are suitable for effective power delivery in cryogenic environments, and explore the optimal dimensions and materials available. The materials chosen were extruded un-annealed and annealed copper, as well as stainless steel, with bore diameters of 1.75, 2.5, and 4.6 mm. Measurements were performed at three different frequencies, 2.0, 2.85 and 3.2 THz, with optimal transmission losses 1, and forms a comprehensive investigation of cryogenically compatible THz waveguides and optical couplers, paving the way for a new generation of systems to utilize THz QCLs for a host of low-temperature investigations
The effect of the gravity loading countermeasure skinsuit upon movement and strength
© 2016 National Strength and Conditioning Association. Effective countermeasures against musculoskeletal deconditioning induced by microgravity and disuse are required. A simple alternative to provision of artificial gravity by centrifugation is compressive axial loading. The Russian "Pingvin" suit was the first wearable suit to apply this concept using bungee cords tethered around the shoulders and feet. However, poor loading characteristics and severe thermal and movement discomfort were reported. The gravity loading countermeasure skinsuit (GLCS) uses a bidirectional weave to generate staged axial loading from shoulders to feet, better mimicking how Earth's gravity induces progressive loading head to foot. The Mk III GLCS's loading was evaluated and tolerability assessed during maximal joint motion, ambulation, and selected strength exercises. Eight subjects (5 male and 3 female; 28 ± 3 years; 179 ± 0.1 cm and 74.8 ± 2.9 kg), having given written informed consent, had an Mk III GLCS individually tailored. Axial loading imparted, body height, joint range of motion (ROM), ambulation, and strength tests (12 repetition maximum) were performed in the GLCS and gym attire, with subjective (rating of perceived exertion, thermal comfort, movement discomfort and body control) ratings recorded throughout. Gravity loading countermeasure skinsuit provided significant axial loading when standing but significantly reduced knee (-13°), spinal (-28°) and shoulder flexion/extension ROM (-34°/-13°), in addition to Sit and Reach (-12.8 cm). No thermal issues were reported but there was an increase in subjective discomfort. Gravity loading countermeasure skinsuit did not significantly impede strength exercise, with the exception of shoulder press. The GLCS (Mk III) demonstrates potential as a countermeasure by providing tolerable, static axial loading. Furthermore, it may serve as an elasticlike strength exercise adjunct, which may have utility as a rehabilitation modality after further design refinement
Corneal deformation dynamics are associated with the retinal nerve fiber layer progression rate in glaucoma suspects and early manifest glaucoma patients
Farshad Abedi, Antonia Kolovos, Anna Waldie, Jude Fitzgerald, Mona Awadalla, Robert Casson, Stuart L Graham, Paul R Healey, Amirul Islam, Miriam Keane, John Landers, Jamie E Crai
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