329 research outputs found
Regional Environmental Change: Human Action and Adaptation. What does it take to meet the Belmont challenge?
Mobile amorphous fraction in polyaryletherketones and its influence on interlayer bonding in material extrusion
This is the final version. Available from AIP Publishing via the DOI in this record. In general, the mechanical properties of parts manufactured by material extrusion (MEX) process depend upon the interlayer bonding strength. In the case of high temperature polymers such as polyaryletherketones (PAEKs), the printing parameters,
in particular the temperatures applied within the process, become a critical factor. The printing-structure-property relationship for
these semicrystalline high temperature polymers is complex and not fully understood, often relying on statistical analysis to identify the trends between the processing parameters and the mechanical properties, while missing the microstructural interpretation
in between. By controlling the temperature settings and the printing speeds, PAEK parts can be printed in an amorphous state or
semicrystalline state. In both cases, molecular chain diffusion at the interface is crucial for achieving good mechanical properties.
Using temperature profiles directly determined by the printing parameters, the current work investigates the formation of mobile
amorphous fraction (MAF) during printing and its correlation with the correspondent Z tensile strengths. MAF is defined as the
fraction of amorphous phase with a higher mobility, which is beneficial to chain d iffusion. The conditions required to generate
MAF is explored by fast scanning calorimetry (FSC).
The MAF-Z strength correlation is aiming to provide a deeper understanding of the complete processing-structure-property relationships of the MEX process for semicrystalline polymers. It may also provide a microstructural explanation on why slow
crystallising PAEK grades are desirable in the MEX process. This study is concentrated on PAEKs which have been printed in an
amorphous state to avoid the effect of crystallisation kinetics
Standing Balance and Spatiotemporal Aspects of Gait Are Impaired Upon Nocturnal Awakening in Healthy Late Middle-Aged and Older Adults
Study Objectives: Nocturnal awakenings may constitute a unique risk for falls among older adults. We describe differences in gait and balance between presleep and midsleep testing, and whether changes in the lighting environment during the midsleep testing further affect gait and balance.
Methods: Twenty-one healthy, late middle-aged and older (64.7 ± 8.0 y) adults participated in this repeated-measures design consisting of four overnight laboratory stays. Each night, participants completed baseline visual acuity, gait, and balance testing. After a 2-h sleep opportunity, they were awakened for 13 min into one of four lighting conditions: very dim white light (\u3c 0.5 lux); dim white light (∼28.0 lux); dim orange light (∼28.0 lux); and white room-level light (∼200 lux). During this awakening, participants completed the same sequence of testing as at baseline.
Results: Low-contrast visual acuity significantly decreased with decreasing illuminance conditions (F(3,45) = 98.26, p \u3c 0.001). Our a priori hypothesis was confirmed in that variation in stride velocity and center of pressure path length were significantly worse during the mid-sleep awakening compared to presleep baseline. Lighting conditions during the awakening, however, did not influence these parameters. In exploratory analyses, we found that over one-third of the tested gait and balance parameters were significantly worse at the midsleep awakening as compared to baseline (p \u3c 0.05), and nearly one-quarter had medium to large effect sizes (Cohen d ≥ 0.5; r ≥ 0.3).
Conclusions: Balance and gait are impaired during midsleep awakenings among healthy, late middle-aged and older adults. This impairment is not ameliorated by exposure to room lighting, when compared to dim lights
The Effects of Cocaine on Different Redox Forms of Cysteine and Homocysteine, and on Labile, Reduced Sulfur in the Rat Plasma Following Active versus Passive Drug Injections
Received: 28 November 2012 / Revised: 19 April 2013 / Accepted: 6 May 2013 / Published online: 16 May 2013
The Author(s) 2013. This article is published with open access at Springerlink.comThe aim of the present studies was to evaluate
cocaine-induced changes in the concentrations of different
redox forms of cysteine (Cys) and homocysteine (Hcy),
and products of anaerobic Cys metabolism, i.e., labile,
reduced sulfur (LS) in the rat plasma. The above-mentioned
parameters were determined after i.p. acute and
subchronic cocaine treatment as well as following i.v.
cocaine self-administration using the yoked procedure.
Additionally, Cys, Hcy, and LS levels were measured
during the 10-day extinction training in rats that underwent
i.v. cocaine administration. Acute i.p. cocaine treatment
increased the total and protein-bound Hcy contents,
decreased LS, and did not change the concentrations of Cys
fractions in the rat plasma. In turn, subchronic i.p. cocaine administration significantly increased free Hcy and lowered
the total and protein-bound Cys concentrations while
LS level was unchanged. Cocaine self-administration
enhanced the total and protein-bound Hcy levels, decreased
LS content, and did not affect the Cys fractions. On the
other hand, yoked cocaine infusions did not alter the concentration
of Hcy fractions while decreased the total and
protein-bound Cys and LS content. This extinction training
resulted in the lack of changes in the examined parameters
in rats with a history of cocaine self-administration while in
the yoked cocaine group an increase in the plasma free Cys
fraction and LS was seen. Our results demonstrate for the
first time that cocaine does evoke significant changes in
homeostasis of thiol amino acids Cys and Hcy, and in some
products of anaerobic Cys metabolism, which are dependent
on the way of cocaine administration
Prevalence, Awareness, and Management of Hypertension, Dyslipidemia, and Diabetes Among United States Adults Aged 65 and Older
Perinatal Hypoxia-Ischemia Disrupts Striatal High-Affinity [ 3 H]Glutamate Uptake into Synaptosomes
: We examined the impact of hypoxia-ischemia on high-affinity [ 3 H]glutamate uptake into a synaptosomal fraction prepared from immature rat corpus striatum. In 7-day-old pups the right carotid artery was ligated, and pups were exposed to 8% oxygen for 0, 0.5, 1, or 2.5 h, and allowed to recover for up to 24 h before they were killed. High-affinity glutamate uptakes in striatal synaptosomes derived from tissue ipsilateral and contralateral to ligation were compared. After 1 h of hypoxia plus ischemia, high-affinity glutamate uptake in the striatum was reduced by 54 ± 13% compared with values from the opposite (nonischemic) side of the brain (p < 0.01, t test versus ligates not exposed to hypoxia). There were similar declines after 2.5 h of hypoxiaischemia. Activity remained low after a 1 h recovery period in room air, but after 24 h of recovery, high-affinity glutamate uptake was equal bilaterally. Kinetic analysis revealed that loss of activity could be attributed primarily to a 40% reduction in the number of uptake sites. Hypoxia alone had no effect on high-affinity glutamate uptake although it reduced synaptosomal uptake of [ 3 H]3,4-dihydroxyphenyl-ethylamine. Addition of 1 mg/ml of bovine serum albumin to the incubation medium preferentia'ly stimulated high-affinity glutamate uptake in hypoxic-ischemic brain compared with its effects in normal tissue. These studies demonstrate that hypoxia-ischemia reversibly inhibits high-affinity glutamate uptake and this occurs earlier than the time required to produce neuronal damage in the model.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66361/1/j.1471-4159.1986.tb00803.x.pd
Septic tank combined with anaerobic filter and conventional UASB: results from full scale plants
An Earth-system prediction initiative for the twenty-first century
International audienceSome scientists have proposed the Earth-System Prediction Initiative (EPI) at the 2007 GEO Summit in Cape Town, South Africa. EPI will draw upon coordination between international programs for Earth system observations, prediction, and warning, such as the WCRP, WWRP, GCOS, and hence contribute to GEO and the GEOSS. It will link with international organizations, such as the International Council for Science (ICSU), Intergovernmental Oceanographic Commission (IOC), UNEP, WMO, and World Health Organization (WHO). The proposed initiative will provide high-resolution climate models that capture the properties of regional high-impact weather events, such as tropical cyclones, heat wave, and sand and dust storms associated within multi-decadal climate projections of climate variability and change. Unprecedented international collaboration and goodwill are necessary for the success of EPI
Transformations within reach: Pathways to a sustainable and resilient world - Enhancing Governance for Sustainability
The atmospheric role in the Arctic water cycle: A review on processes, past and future changes, and their impacts
This is the final version of the article. Available from the publisher via the DOI in this record.Atmospheric humidity, clouds, precipitation, and evapotranspiration are essential components of the Arctic climate system. During recent decades, specific humidity and precipitation have generally increased in the Arctic, but changes in evapotranspiration are poorly known. Trends in clouds vary depending on the region and season. Climate model experiments suggest that increases in precipitation are related to global warming. In turn, feedbacks associated with the increase in atmospheric moisture and decrease in sea ice and snow cover have contributed to the Arctic amplification of global warming. Climate models have captured the overall wetting trend but have limited success in reproducing regional details. For the rest of the 21st century, climate models project strong warming and increasing precipitation, but different models yield different results for changes in cloud cover. The model differences are largest in months of minimum sea ice cover. Evapotranspiration is projected to increase in winter but in summer to decrease over the oceans and increase over land. Increasing net precipitation increases river discharge to the Arctic Ocean. Over sea ice in summer, projected increase in rain and decrease in snowfall decrease the surface albedo and, hence, further amplify snow/ice surface melt. With reducing sea ice, wind forcing on the Arctic Ocean increases with impacts on ocean currents and freshwater transport out of the Arctic. Improvements in observations, process understanding, and modeling capabilities are needed to better quantify the atmospheric role in the Arctic water cycle and its changes.We thank all colleagues involved in the
Arctic Freshwater Synthesis (AFS) for
fruitful discussions. In particular, John
Walsh is acknowledged for his constructive
comments on the manuscript. AFS
has been sponsored by the World
Climate Research Programme’s Climate
and the Cryosphere project (WCRP-CliC),
the International Arctic Science
Committee (IASC), and the Arctic
Monitoring and Assessment Programme
(AMAP). The work for this paper has been
supported by the Academy of Finland
(contracts 259537 and 283101), the UK
Natural Environment Research Council
(grant NE/J019585/1), the US National
Science Foundation grant ARC-1023592
and the Program “Arctic” and the Basic
Research Program of the Presidium
Russian Academy of Sciences. NCAR is
supported by the U.S. National Science
Foundation. We gratefully acknowledge
the project coordination and meeting
support of Jenny Baeseman and
Gwenaelle Hamon at the CliC
International Project Office. No new data
were applied in the manuscript. Data
applied for Figures 2 and 3 are available
from the JRA-55 archive at http://jra.
kishou.go.jp/JRA-55/index_en.
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