Carbonaceous aerosols (CA) emitted by fossil and biomass fuels consist of black carbon (BC), a strong absorber of solar radiation, and organic matter (OM). OM scatters as well as absorbs solar ...radiation. The absorbing component of OM, which is ignored in most climate models, is referred to as brown carbon (BrC). Model estimates of the global CA radiative forcing range from 0 to 0.7 Wm ⁻², to be compared with the Intergovernmental Panel on Climate Change’s estimate for the pre-Industrial to the present net radiative forcing of about 1.6 Wm ⁻². This study provides a model-independent, observationally based estimate of the CA direct radiative forcing. Ground-based aerosol network data is integrated with field data and satellite-based aerosol observations to provide a decadal (2001 through 2009) global view of the CA optical properties and direct radiative forcing. The estimated global CA direct radiative effect is about 0.75 Wm ⁻² (0.5 to 1.0). This study identifies the global importance of BrC, which is shown to contribute about 20% to 550-nm CA solar absorption globally. Because of the inclusion of BrC, the net effect of OM is close to zero and the CA forcing is nearly equal to that of BC. The CA direct radiative forcing is estimated to be about 0.65 (0.5 to about 0.8) Wm ⁻², thus comparable to or exceeding that by methane. Caused in part by BrC absorption, CAs have a net warming effect even over open biomass-burning regions in Africa and the Amazon.
Recently, deep-learning-based approaches have been proposed for the classification of neuroimaging data related to Alzheimer's disease (AD), and significant progress has been made. However, ...end-to-end learning that is capable of maximizing the impact of deep learning has yet to receive much attention due to the endemic challenge of neuroimaging caused by the scarcity of data. Thus, this study presents an approach meant to encourage the end-to-end learning of a volumetric convolutional neural network (CNN) model for four binary classification tasks (AD vs. normal control (NC), progressive mild cognitive impairment (pMCI) vs. NC, stable mild cognitive impairment (sMCI) vs. NC and pMCI vs. sMCI) based on magnetic resonance imaging (MRI) and visualizes its outcomes in terms of the decision of the CNNs without any human intervention. In the proposed approach, we use convolutional autoencoder (CAE)-based unsupervised learning for the AD vs. NC classification task, and supervised transfer learning is applied to solve the pMCI vs. sMCI classification task. To detect the most important biomarkers related to AD and pMCI, a gradient-based visualization method that approximates the spatial influence of the CNN model's decision was applied. To validate the contributions of this study, we conducted experiments on the ADNI database, and the results demonstrated that the proposed approach achieved the accuracies of 86.60% and 73.95% for the AD and pMCI classification tasks respectively, outperforming other network models. In the visualization results, the temporal and parietal lobes were identified as key regions for classification.
The absorption Ångström exponent (AAE) is an important aerosol
optical parameter used for aerosol characterization and apportionment
studies. The AAE of black carbon (BC) particles is widely accepted ...to be 1.0,
although observational estimates give quite a wide range of
0.6–1.3. With considerable uncertainties
related to observations, a numerical study is a powerful method, if not the
only one, to provide a better and more accurate understanding on BC AAE. This
study calculates BC AAE using realistic particle geometries based on fractal
aggregate and an accurate numerical optical model (namely the multiple-sphere
T-matrix method), and considers
bulk properties of an ensemble of BC particles following lognormal size
distributions. At odds with the expectations, BC AAE is not 1.0, even when BC
is assumed to have small sizes and a wavelength-independent refractive index.
With a wavelength-independent refractive index, the AAE of fresh BC is
approximately 1.05 and relatively insensitive to particle size. For BC with
geometric mean diameters larger than 0.12 µm, BC AAE becomes
smaller when BC particles are aged (compact structures or coated by other
non-absorptive materials). For coated BC, we prescribe the coating fraction
variation based on a laboratory study, where smaller BC cores are shown to
develop larger coating fractions than those of bigger BC cores. For both compact and coated BC, the AAE is highly
sensitive to particle size distribution, ranging from approximately 0.8 to
even over 1.4 with wavelength-independent refractive index. When the
refractive index is allowed to vary with wavelength, a feature with
observational backing, the BC AAE may show an even wider range. For different
BC morphologies, we derive simple empirical equations on BC AAE based on our
numerical results, which can serve as a guide for the response of BC AAE to
BC size and refractive index. Due to its complex influences, the effects of
BC geometry is better to be discussed at certain BC properties, i.e., known
size and refractive index.
Although systemic exposure to peptides, such as Gly–Pro–Hyp, Pro–Hyp, and Gly–Pro, has been reported following administration of collagen hydrolysates from fish scale and porcine skin in vivo, the ...individual peptide pharmacokinetics remain unknown. We administered the three peptides individually to rats via the intravenous (5 mg/kg) and intragastric (100 mg/kg) routes and then monitored systemic exposure and urinary excretion. The peptides in biological samples were analyzed via liquid chromatography/tandem mass spectrometry. Gly–Pro–Hyp tended to exhibit higher first‐pass metabolism than Pro–Hyp; the absolute oral bioavailabilities of Gly–Pro–Hyp and Pro–Hyp were 4.4% and 19.3%, respectively. Gly–Pro levels were very low in the systemic circulation. Pro–Hyp biotransformed from Gly–Pro–Hyp behaved similarly to Pro–Hyp alone when administered orally. Flip‐flop kinetics (elimination rate ≫ absorption rate) were evident, probably reflecting transporter‐mediated slow absorption. A double‐peak phenomenon was observed for Gly–Pro–Hyp and Pro–Hyp when administered orally, and 5.9% ± 2.6% and 1.9% ± 0.3% of each dose were excreted in urine after intravenous administration, respectively. Urinary recovery of Gly–Pro was limited to 0.4% ± 0.5% of the intravenous dose. This work represents the first individual pharmacokinetics of Gly–Pro–Hyp, Pro–Hyp, and Gly–Pro in vivo.
Throughout the year, average sea surface temperatures in the Arabian Sea are warm enough to support the development of tropical cyclones, but the atmospheric monsoon circulation and associated strong ...vertical wind shear limits cyclone development and intensification, only permitting a pre-monsoon and post-monsoon period for cyclogenesis. Thus a recent increase in the intensity of tropical cyclones over the northern Indian Ocean is thought to be related to the weakening of the climatological vertical wind shear. At the same time, anthropogenic emissions of aerosols have increased sixfold since the 1930s, leading to a weakening of the southwesterly lower-level and easterly upper-level winds that define the monsoonal circulation over the Arabian Sea. In principle, this aerosol-driven circulation modification could affect tropical cyclone intensity over the Arabian Sea, but so far no such linkage has been shown. Here we report an increase in the intensity of pre-monsoon Arabian Sea tropical cyclones during the period 1979-2010, and show that this change in storm strength is a consequence of a simultaneous upward trend in anthropogenic black carbon and sulphate emissions. We use a combination of observational, reanalysis and model data to demonstrate that the anomalous circulation, which is radiatively forced by these anthropogenic aerosols, reduces the basin-wide vertical wind shear, creating an environment more favourable for tropical cyclone intensification. Because most Arabian Sea tropical cyclones make landfall, our results suggest an additional impact on human health from regional air pollution.
Little research examines the mechanisms for the relationship between expatriate utilization and subsidiary performance. Building on the knowledge-based view of the firm, we propose a multi-stage ...mediation model to explain how expatriate staffing promotes subsidiary financial performance. Our results underscore that expatriate utilization has an indirect, mediated effect on subsidiary financial performance through its links with subsidiaries’ knowledge creation and product performance. Adopting a moderated mediation approach, we also find that the indirect relationship between expatriate utilization and subsidiary product performance via subsidiary knowledge creation is strengthened by the context of transnational strategy as a moderating contingency.
2,3-Butanediol (2,3-BD) has great potential for diverse industries, including chemical, cosmetics, agriculture, and pharmaceutical areas. However, its industrial production and usage are limited by ...the fairly high cost of its petro-based production. Several bio-based 2,3-BD production processes have been developed and their economic advantages over petro-based production process have been reported. In particular, many 2,3-BD-producing microorganisms including bacteria and yeast have been isolated and metabolically engineered for efficient production of 2,3-BD. In addition, several fermentation processes have been tested using feedstocks such as starch, sugar, glycerol, and even lignocellulose as raw materials. Since separation and purification of 2,3-BD from fermentation broth account for the majority of its production cost, cost-effective processes have been simultaneously developed. The construction of a demonstration plant that can annually produce around 300 tons of 2,3-BD is scheduled to be mechanically completed in Korea in 2019. In this paper, core technologies for bio-based 2,3-BD production are reviewed and their potentials for use in the commercial sector are discussed.
The rambling and trembling analysis separates the center of pressure (COP) fluctuations into two components: rambling (supraspinal contribution) and trembling (muscle stiffness / reflexive properties ...contribution). We examined whether the trembling component is correlated to the contractile properties (muscle stiffness and contraction time) of lower limb superficial skeletal muscles to experimentally test the rambling and trembling hypothesis. We hypothesized that muscle stiffness and contraction time, would be: (a) more correlated with; and (b) have a greater impact on the trembling component compared to the rambling component. Thirty-two healthy young adults were recruited for the study and tensiomyography was used to assess mechanical muscle responses to a single electrical stimulus to calculate muscle stiffness and contraction time based on radial muscle belly displacement measurements of lower limb muscles unilaterally. Moreover, upright postural control was assessed using a force plate to record ground reaction forces and moments and calculate the COP fluctuations during two 30 seconds trials. From the COP fluctuations, rambling and trembling time series were extracted, and all fluctuation time series were described using a number of different time-domain and frequency-domain parameters in both the anterior-posterior and medial-lateral directions. Our results demonstrated that both muscle stiffness and contraction time were moderately correlated with time-domain and frequency-domain parameters of the trembling component, as compared with those of the rambling component which was not as well correlated. Moreover, they also predicted the trembling component better. Overall, these results imply that postural control during quiet stance is, in part, related to intrinsic muscle stiffness in the lower extremities. Moreover, we showed that the rambling and trembling hypothesis is effective in separating postural sway fluctuations during upright posture to extract the contributions of muscle stiffness / reflexive properties (trembling), and likely the supraspinal contribution (rambling).
Early intervention using dietary supplements may be effective in alleviating cognitive impairment among individuals with mild cognitive impairment (MCI). This study investigated the efficacy and ...safety of
C29-fermented soybean (DW2009) as a nutritional supplement for cognitive enhancement. One hundred individuals with MCI were randomly assigned to take DW2009 (800 mg/day,
= 50) or placebo (800 mg/day,
= 50) for 12 weeks. The primary outcome measure was change in the composite score of cognitive functions related to memory and attention, measured by computerized neurocognitive function tests. Associations between changes in serum brain-derived neurotrophic factor (BDNF) levels and cognitive performance for each treatment group were evaluated. Compared to the placebo group, the DW2009 group showed greater improvements in the combined cognitive functions (
= 2.36,
for interaction = 0.02), especially in the attention domain (
= 2.34,
for interaction = 0.02). Cognitive improvement was associated with increased serum BDNF levels after consumption of DW2009 (
= 2.83,
= 0.007). The results of this clinical trial suggest that DW2009 can be safely administered to enhance cognitive function in individuals with MCI. Increased serum BDNF levels after administering DW2009 may provide preliminary insight into the underlying effects of cognitive improvement, which suggests the importance of the gut-brain axis in ameliorating cognitive deficits in MCI.
•Pozzolanic test was used to develop two measures for SCM degree of reaction.•Degree of reaction increases as temperature increases but does not depend on w/cm.•Values generally agree with those from ...literature.•Preliminary results are promising.
A pozzolanic test that can correctly identify pozzolanic materials is key in the search for alternative supplementary cementitious material (SCMs). Determination of the degree of reaction of these alternative SCMs in cementitious pastes is also important, as the reactivity of certain SCMs can be quite low. Since typical methods to determine SCM degree of reaction can be complex and laborious, the current study explores whether parameters obtained from a newly developed pozzolanic test can potentially be used to develop a simple method for determining the degree of reaction of SCMs. In the pozzolanic test, (cumulative) heat release and calcium hydroxide consumption of SCMs from a mixture of SCM and calcium hydroxide (water-to-solids ratio 0.9, pH 13.5, and testing temperature of 50 °C) are measured. Corresponding values of cumulative heat release and calcium hydroxide consumption of SCMs in a cementitious paste are also measured at two different water-cementitious materials (w/cm) ratios. The ratio between the values of cumulative heat release and the calcium hydroxide consumption in the cementitious paste and the pozzolanic test are considered to be measures of degree of reaction. Four different SCMs – class F fly ash, ground granulated blast furnace slag, metakaolin, and undensified silica fume were tested in this study. The effect of temperature and w/cm on degree of reaction were assessed. Degree of reaction values obtained from this method were compared with those from obtained from a portlandite consumption method suggested in literature and from typical values suggested in literature. Good correlation (R2 = 0.87) is obtained for the degree of reaction values determined here using the calcium hydroxide ratio and the portlandite consumption method. The degree of reaction values increase as the temperature increases but do not strongly depend on w/cm. The degree of reaction values are in general agreement with the range of values obtained from literature, however, this range is rather large, and the values depend strongly on the method used to determine degree of reaction. These preliminary results are promising and suggest that this method may potentially be used to provide information about pozzolanicity and degree of reaction of various SCMs.
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