A hybrid composite architecture of carbon nanotubes (CNTs), advanced fibers and a matrix is described, from CNT synthesis and characterization through to standard mechanical and electrical laminate ...tests. Direct growth of aligned CNTs on the surface of advanced fibers in a woven fabric enables enhancement in multifunctional laminate performance, as demonstrated by a 69% increase in interlaminar shear strength and 10
6 (in-plane) and 10
8 (through-thickness) increases in laminate-level electrical conductivity. Processes developed include dip-coating of CNT growth catalyst and atmospheric-pressure chemical vapor deposition of dense aligned CNTs. A capillarity-driven mechanism is presented to explain the observed effective and uniform wetting of the aligned CNTs in the interior of the laminate by unmodified thermoset polymer resins.
Randomised controlled trials are required to address causality in the reported associations between maternal influences and offspring adiposity. The aim of this study was to determine whether an ...antenatal lifestyle intervention, associated with improvements in maternal diet and reduced gestational weight gain (GWG) in obese pregnant women leads to a reduction in infant adiposity and sustained improvements in maternal lifestyle behaviours at 6 months postpartum.
We conducted a planned postnatal follow-up of a randomised controlled trial (UK Pregnancies Better Eating and Activity Trial (UPBEAT)) of a complex behavioural intervention targeting maternal diet (glycaemic load (GL) and saturated fat intake) and physical activity in 1555 obese pregnant women. The main outcome measure was infant adiposity, assessed by subscapular and triceps skinfold thicknesses. Maternal diet and physical activity, indices of the familial lifestyle environment, were assessed by questionnaire.
A total of 698 (45.9%) infants (342 intervention and 356 standard antenatal care) were followed up at a mean age of 5.92 months. There was no difference in triceps skinfold thickness z-scores between the intervention vs standard care arms (difference -0.14 s.d., 95% confidence interval -0.38 to 0.10, P=0.246), but subscapular skinfold thickness z-score was 0.26 s.d. (-0.49 to -0.02; P=0.03) lower in the intervention arm. Maternal dietary GL (-35.34; -48.0 to -22.67; P<0.001) and saturated fat intake (-1.93% energy; -2.64 to -1.22; P<0.001) were reduced in the intervention arm at 6 months postpartum. Causal mediation analysis suggested that lower infant subscapular skinfold thickness was partially mediated by changes in antenatal maternal diet and GWG rather than postnatal diet.
This study provides evidence from follow-up of a randomised controlled trial that a maternal behavioural intervention in obese pregnant women has the potential to reduce infant adiposity and to produce a sustained improvement in maternal diet at 6 months postpartum.
Despite strong evidence that maternal influenza vaccination during pregnancy is safe, uptake of influenza vaccination during pregnancy remains low. We identified studies that assessed outcomes of ...stillbirth or spontaneous abortion after administration of influenza vaccine during pregnancy. We conducted a literature search in November 2013 that yielded 447 total citations. After removal of duplicates and studies deemed not relevant based on the title and abstract, 36 records underwent a full text review and 7 studies were included in the final review. Where possible, adjusted results were included in the meta-analysis. Women in the influenza vaccine group had a lower likelihood of stillbirth (relative risk RR, 0.73; 95% confidence interval CI, .55-.96); this association was similar when restricted to the H1N1pdm09 vaccine (RR, 0.69; 95% CI, .53-.90). The pooled estimate for spontaneous abortion was not significant (RR, 0.91; 95% CI, .68-1.22). These analyses add to the evidence base for the safety of influenza vaccination in pregnancy.
Desalination technologies can increase potable water supplies worldwide. One possible approach, capacitive deionization (CDI), could prove optimal for brackish water treatment. At present, CDI ...development has largely focused on increasing salt adsorption capacity and desalination rates of materials and devices. In addition to these metrics, ultimately, optimizing salt rejection and throughput will be essential. In this work, we present a framework for the design of flow-between CDI cells for maximum salt rejection. We developed a model that is dependent on device specific parameters (system volume, flow rate, inlet and outlet water quality), to generalize the design of a cell for any given requirement. We showed that decreasing the advection-diffusion Péclet number and increasing the aspect ratio of the electrode compared to the channel space yield the highest salt rejection. In addition, tuning the cycle frequency time for salt rejection instead of complete electrode charging can yield faster water production rates and optimal salt rejection. These modeling results were validated through experimental prototypes that made use of vertically-aligned carbon nanotube (VA-CNT) electrodes. This framework to maximize salt rejection can be extended to a multitude of porous electrodes used in flow-between CDI devices.
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•Optimizing salt rejection is dependent on CDI device parameters.•Increasing the electrode thickness to spacer ratio can increase salt rejection.•Decreasing the device Péclet number also increases salt rejection.•Throughput is maximized at cycling frequencies faster than equilibrium charge time.
We report the detection of variable emission from Sgr A* in almost all wavelength bands (i.e., centimeter, millimeter, submillimeter, near-IR, and X-rays) during a multi-wavelength observing ...campaign. Three new moderate flares are detected simultaneously in both near-IR and X-ray bands. The ratio of X-ray to near-IR flux in the flares is consistent with inverse Compton scattering of near-IR photons by submillimeter emitting relativistic particles which follow scaling relations obtained from size measurements of Sgr A*. We also find that the flare statistics in near-IR wavelengths is consistent with the probability of flare emission being inversely proportional to the flux. At millimeter wavelengths, the presence of flare emission at 43 GHz (7 mm) using the Very Long Baseline Array with milliarcsecond spatial resolution indicates the first direct evidence that hourly timescale flares are localized within the inner 30 X 70 Schwarzschild radii of Sgr A*. We also show several cross-correlation plots between near-IR, millimeter, and submillimeter light curves that collectively demonstrate the presence of time delays between the peaks of emission up to 5 hr. The evidence for time delays at millimeter and submillimeter wavelengths are consistent with the source of emission initially being optically thick followed by a transition to an optically thin regime. In particular, there is an intriguing correlation between the optically thin near-IR and X-ray flare and optically thick radio flare at 43 GHz that occurred on 2007 April 4. This would be the first evidence of a radio flare emission at 43 GHz delayed with respect to the near-IR and X-ray flare emission. The time delay measurements support the expansion of hot self-absorbed synchrotron plasma blob and weaken the hot spot model of flare emission. In addition, a simultaneous fit to 43 and 84 GHz light curves, using an adiabatic expansion model of hot plasma, appears to support a power law rather than a relativistic Maxwellian distribution of particles.
•The role of dopamine in human reward functioning is highly researched.•Drug challenge studies are translational and have good experimental control.•Dopamine drug challenge studies in healthy adults ...were summarized by reward phase.•Dopamine drugs have differing effects on various reward phases.•Drug effects are likely nonlinear and behavioral effects depend on outcome measure.
Dopamine (DA) plays a key role in reward processing and is implicated in psychological disorders such as depression, substance use, and schizophrenia. The role of DA in reward processing is an area of highly active research. One approach to this question is drug challenge studies with drugs known to alter DA function. These studies provide good experimental control and can be performed in parallel in laboratory animals and humans. This review aimed to summarize results of studies using pharmacological manipulations of DA in healthy adults. ‘Reward’ is a complex process, so we separated ‘phases’ of reward, including anticipation, evaluation of cost and benefits of upcoming reward, execution of actions to obtain reward, pleasure in response to receiving a reward, and reward learning. Results indicated that i) DAergic drugs have different effects on different phases of reward; ii) the relationship between DA and reward functioning appears unlikely to be linear; iii) our ability to detect the effects of DAergic drugs varies depending on whether subjective, behavioral, imaging measures are used.
Value of long-term ecological studies LINDENMAYER, DAVID B.; LIKENS, GENE E.; ANDERSEN, ALAN ...
Austral ecology,
November 2012, Letnik:
37, Številka:
7
Journal Article
Recenzirano
Long‐term ecological studies are critical for providing key insights in ecology, environmental change, natural resource management and biodiversity conservation. In this paper, we briefly discuss ...five key values of such studies. These are: (1) quantifying ecological responses to drivers of ecosystem change; (2) understanding complex ecosystem processes that occur over prolonged periods; (3) providing core ecological data that may be used to develop theoretical ecological models and to parameterize and validate simulation models; (4) acting as platforms for collaborative studies, thus promoting multidisciplinary research; and (5) providing data and understanding at scales relevant to management, and hence critically supporting evidence‐based policy, decision making and the management of ecosystems. We suggest that the ecological research community needs to put higher priority on communicating the benefits of long‐term ecological studies to resource managers, policy makers and the general public. Long‐term research will be especially important for tackling large‐scale emerging problems confronting humanity such as resource management for a rapidly increasing human population, mass species extinction, and climate change detection, mitigation and adaptation. While some ecologically relevant, long‐term data sets are now becoming more generally available, these are exceptions. This deficiency occurs because ecological studies can be difficult to maintain for long periods as they exceed the length of government administrations and funding cycles. We argue that the ecological research community will need to coordinate ongoing efforts in an open and collaborative way, to ensure that discoverable long‐term ecological studies do not become a long‐term deficiency. It is important to maintain publishing outlets for empirical field‐based ecology, while simultaneously developing new systems of recognition that reward ecologists for the use and collaborative sharing of their long‐term data sets. Funding schemes must be re‐crafted to emphasize collaborative partnerships between field‐based ecologists, theoreticians and modellers, and to provide financial support that is committed over commensurate time frames.
ABSTRACT We analyze Chandra X-ray images of a sample of 11 quasars that are known to contain kiloparsec scale radio jets. The sample consists of five high-redshift (z ≥ 3.6) flat-spectrum radio ...quasars, and six intermediate redshift (2.1 < z < 2.9) quasars. The data set includes four sources with integrated steep radio spectra and seven with flat radio spectra. A total of 25 radio jet features are present in this sample. We apply a Bayesian multi-scale image reconstruction method to detect and measure the X-ray emission from the jets. We compute deviations from a baseline model that does not include the jet, and compare observed X-ray images with those computed with simulated images where no jet features exist. This allows us to compute p-value upper bounds on the significance that an X-ray jet is detected in a pre-determined region of interest. We detected 12 of the features unambiguously, and an additional six marginally. We also find residual emission in the cores of three quasars and in the background of one quasar that suggest the existence of unresolved X-ray jets. The dependence of the X-ray to radio luminosity ratio on redshift is a potential diagnostic of the emission mechanism, since the inverse Compton scattering of cosmic microwave background photons (IC/CMB) is thought to be redshift dependent, whereas in synchrotron models no clear redshift dependence is expected. We find that the high-redshift jets have X-ray to radio flux ratios that are marginally inconsistent with those from lower redshifts, suggesting that either the X-ray emissions are due to the IC/CMB rather than the synchrotron process, or that high-redshift jets are qualitatively different.
Eutrophication is a widespread environmental change that usually reduces the stabilizing effect of plant diversity on productivity in local communities. Whether this effect is scale dependent remains ...to be elucidated. Here, we determine the relationship between plant diversity and temporal stability of productivity for 243 plant communities from 42 grasslands across the globe and quantify the effect of chronic fertilization on these relationships. Unfertilized local communities with more plant species exhibit greater asynchronous dynamics among species in response to natural environmental fluctuations, resulting in greater local stability (alpha stability). Moreover, neighborhood communities that have greater spatial variation in plant species composition within sites (higher beta diversity) have greater spatial asynchrony of productivity among communities, resulting in greater stability at the larger scale (gamma stability). Importantly, fertilization consistently weakens the contribution of plant diversity to both of these stabilizing mechanisms, thus diminishing the positive effect of biodiversity on stability at differing spatial scales. Our findings suggest that preserving grassland functional stability requires conservation of plant diversity within and among ecological communities.
•Women demonstrated no maladaptive HPA-axis effects to 11-month arduous military training.•The training was stressful; mood and resilience scores decreased throughout.•Saliva cortisol increased ...initially, then demonstrated habituation.•Hair cortisol increased throughout training.•Fasting cortisol decreased and stimulated cortisol increased during training.
Basic military training (BMT) is a useful model of prolonged exposure to multiple stressors. 8–12 week BMT is associated with perturbations in the hypothalamic-pituitary-adrenal (HPA) axis which could predispose recruits to injury and psychological strain. However, characterisations of HPA axis adaptations during BMT have not been comprehensive and most studies included few if any women.
We studied women undertaking an arduous, 44-week BMT programme in the UK. Anxiety, depression and resilience questionnaires, average hair cortisol concentration (HCC), morning and evening saliva cortisol and morning plasma cortisol were assessed at regular intervals throughout. A 1-h dynamic cortisol response to 1 μg adrenocorticotrophic hormone-1-24 was performed during weeks 1 and 29.
Fifty-three women (aged 24 ± 2.5 years) completed the study. Questionnaires demonstrated increased depression and reduced resilience during training (F 6.93 and F 7.24, respectively, both p < 0.001). HCC increased from 3 months before training to the final 3 months of training (median (IQR) 9.63 (5.38, 16.26) versus 11.56 (6.2, 22.45) pg/mg, p = 0.003). Morning saliva cortisol increased during the first 7 weeks of training (0.44 ± 0.23 versus 0.59 ± 0.24 μg/dl p < 0.001) and decreased thereafter, with no difference between the first and final weeks (0.44 ± 0.23 versus 0.38 ± 0.21 μg/dl, p = 0.2). Evening saliva cortisol did not change. Fasting cortisol decreased during training (beginning, mid and end-training concentrations: 701 ± 134, 671 ± 158 and 561 ± 177 nmol/l, respectively, p < 0.001). Afternoon basal cortisol increased during training while there was a trend towards increased peak stimulated cortisol (177 ± 92 versus 259 ± 13 nmol/l, p = 0.003, and 589 ± 164 versus 656 ± 135, p = 0.058, respectively).
These results suggest a normal stress response in early training was followed quickly by habituation, despite psychological and physical stress evidenced by questionnaire scores and HCC, respectively. There was no evidence of HPA axis maladaptation. These observations are reassuring for women undertaking arduous employment.
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