To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure firstname.lastname@example.org
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
In this work, we propose a broadband, polarization-insensitive and wide incident angle stable metamaterial absorber (MA) based on the resistive film. The absorber consists of a three-layer structure with each layer of dielectric substrate printed with different shapes of resistive film. The multilayer structure not only extends the absorption bandwidth but also maintains high absorption under large wave incident angles. Numerical simulation shows that the absorptivity of a normal incident wave is above 90% in the frequency range 2.34–18.95 GHz, corresponding to a relative absorption bandwidth of 156%. Moreover, the whole MA structure has a total thickness of 11.3 mm, corresponding to 0.09 λ0 at its lowest absorption frequency. Due to the high symmetry of the structure, the absorber has good polarization insensitivity. In addition, for both transverse electric and transverse magnetic incidence, the proposed absorber achieves an absorptivity of more than 80% at incident angles of up to 45° and thus has good stability for wide incident angles. The absorption principle of the absorber is analyzed by the surface current and power loss density distribution. Parameter analysis is also performed for bandwidth optimization. Due to its advantages of wideband absorption with high efficiency, the proposed absorber has the potential to be applied to the energy-harvesting and electromagnetic stealth fields.
Previous studies have shown conflicting findings regarding the relationship between maternal vitamin D deficiency (VDD) and fetal growth restriction (FGR). We hypothesised that parathyroid hormone (PTH) may be an underlying factor relevant to this potential association. In a prospective birth cohort study, descriptive statistics were evaluated for the demographic characteristics of 3407 pregnancies in the second trimester from three antenatal clinics in Hefei, China. The association of the combined status of vitamin D and PTH with birth weight and the risk of small for gestational age (SGA) was assessed by a multivariate linear and binary logistic regression. We found that declined status of 25-hydroxyvitamin D is associated with lower birth weight (for moderate VDD: adjusted β = −49·4 g, 95 % CI −91·1, −7·8, P < 0·05; for severe VDD: adjusted β = −79·8 g, 95 % CI −127·2, −32·5, P < 0·01), as well as ascended levels of PTH (for elevated PTH: adjusted β = −44·5 g, 95 % CI −82·6, −6·4, P < 0·05). Compared with the non-VDD group with non-elevated PTH, pregnancies with severe VDD and elevated PTH had the lowest neonatal birth weight (adjusted β = −124·7 g, 95 % CI −194·6, −54·8, P < 0·001) and the highest risk of SGA (adjusted risk ratio (RR) = 3·36, 95 % CI 1·41, 8·03, P < 0·01). Notably, the highest risk of less Ca supplementation was founded in severe VDD group with elevated PTH (adjusted RR = 4·67, 95 % CI 2·78, 7·85, P < 0·001). In conclusion, elevated PTH induced by less Ca supplementation would further aggravate the risk of FGR in pregnancies with severe VDD through impaired maternal Ca metabolism homoeostasis.
The star formation history (SFH) of galaxies allow us to investigate when galaxies formed their stars and assembled their mass. We can constrain the SFH with high level of precision from galaxies with resolved stellar populations, since we are able to discriminate between stars of different ages from the spectrum they emit. However, the relative importance of secular evolution (nature) over nurture is not yet clear, and separating the effects of interaction-driven evolution in the observed galaxy properties is not trivial. The aim of this study is to use MaNGA (Mapping Nearby Galaxies at APO) Integral Field Unit (IFU) data, in combination with multi-wavelength data, to constrain the SFH of nearby isolated galaxies. We present here the new techniques we are developing to constrain the SFH with high level of precision from Spectral Energy Distribution (SED) fitting. This study is part of a China-Chile collaboration program where we are applying these new techniques to investigate how galaxies formed and evolve in different environments.
The derivation of accurate stellar populations of galaxies is a non-trivial task because of the well-known age-metallicity degeneracy. We aim to break this degeneracy by invoking a chemical evolution model (CEM) for isolated disk galaxy, where its metallicity enrichment history (MEH) is modelled to be tightly linked to its star formation history (SFH). Our CEM has been successfully tested on several local group dwarf galaxies whose SFHs and MEHs have been both independently measured from deep colour-magnitude diagrams of individual stars. By introducing the CEM into the stellar population fitting algorithm as a prior, we expect that the SFH of galaxies could be better constrained.
The present study was conducted to evaluate the effects of glucose, soya oil or glutamine on jejunal morphology, protein metabolism and protein expression of the mammalian target of rapamycin complex 1 (mTORC1) signalling pathway in jejunal villus or crypt compartment of piglets. Forty-two 21 d-weaned piglets were randomly allotted to one of the three isoenergetic diets formulated with glucose, soya oil or glutamine for 28 d. On day 14 or 28, the proteins in crypt enterocytes were analysed with isobaric tags for relative and absolute quantification and proteins involved in mTORC1 signalling pathway in villus or crypt compartment cells were determined by Western blotting. Our results showed no significant differences (P > 0·05) in jejunal morphology among the three treatments on day 14 or 28. The differentially expressed proteins mainly took part in a few network pathways, including antimicrobial or inflammatory response, cell death and survival, digestive system development and function and carbohydrate metabolism. On day 14 or 28, there were higher protein expression of eukaryotic initiation factor-4E binding protein-1 in jejunal crypt compartment of piglets supplemented with glucose or glutamine compared with soya oil. On day 28, higher protein expression of phosphor-mTOR in crypt compartment was observed in piglets supplemented with glucose compared with the soya oil. In conclusion, the isoenergetic glucose, soya oil or glutamine did not affect the jejunal morphology of piglets; however, they had different effects on the protein metabolism in crypt compartment. Compared with soya oil, glucose or glutamine may be better energy supplies for enterocytes in jejunal crypt compartment.
Paediatric Mycoplasma pneumoniae pneumonia (MPP) is a major cause of community-acquired pneumonia in China. Data on epidemiology of paediatric MPP from China are little known. This study retrospectively collected data from June 2006 to June 2016 in Beijing Children's Hospital, Capital Medical University of North China and aims to explore the epidemiological features of paediatric MPP and severe MPP (SMPP) in North China during the past 10 years. A total of 27 498 paediatric patients with pneumonia were enrolled. Among them, 37.5% of paediatric patients had MPP. In this area, an epidemic took place every 2–3 years at the peak, and the positive rate of MPP increased during these peak years over time. The peak age of MPP was between the ages of 6 and 10 years, accounting for 75.2%, significantly more compared with other age groups (χ2 = 1384.1, P < 0.0001). The epidemics peaked in September, October and November (χ2 = 904.9, P < 0.0001). Additionally, 13.0% of MPP paediatric patients were SMPP, but over time, the rate of SMPP increased, reaching 42.6% in 2016. The mean age of paediatric patients with SMPP (6.7 ± 3.0 years old) was younger than that of patients with non-SMPP (7.4 ± 3.2 years old) (t = 3.60, P = 0.0001). The prevalence of MPP and SMPP is common in China, especially in children from 6 to 10 years old. Paediatric patients with SMPP tend to be younger than those with non-SMPP. MPP outbreaks occur every 2–3 years in North China. September, October and November are the peak months, unlike in South China. Understanding the epidemiological characteristics of paediatric MPP can contribute to timely treatment and diagnosis, and may improve the prognosis of children with SMPP.
3D ordered bimodal mesoporous carbon (OBMC) with a high specific surface area of 1368.7 m2/g, ordered large mesopores, and small mesopores on the walls is prepared by a surfactant-free rapid method using SiO2 nanosphere arrays as templates. The resulting OBMC is then composited with sulfur to prepare S/OBMC hybrids via a simple solution infiltration method followed by a heat treatment process. In S/OBMC composite, sulfur is uniformly infiltrated inside the 3D hierarchical pores of OBMC. On the basis of this systematic design, the obtained S/OBMC cathode shows a large discharge capacity value of 1590 mA h/g at first cycle and maintains 989 mA h/g after 100 cycles at 0.2 C. Furthermore, at 1 C charge–discharge rate, a reversible discharge capacity of 733 mA h/g after 100 cycles is reached. The extraordinary electrochemical property of S/OBMC derives from the unique bimodal mesoporous structure with large mesopores and small mesopores that can facilitate the mass transfer and strict dissolution of polysulfide species into the electrolyte.
Blue compact dwarf galaxies(BCDs) are galaxies undergoing violent burst of star formation in compact regions. They are often thought of being an evolutionary stage of dwarf galaxies and thus can provide a unique window to study the formation and evolution of dwarf galaxies. We selected a sample of 48 BCDs from the SDSS-IV MaNGA survey (MPL-7) and separated the starburst(SB) components from their underlying hosts with a new algorithm. Combining the structural properties of the BCDs, we further explore the physical connections between the SB components and theirs hosts.
Ethanolamine (Etn) contained in milk is the base constituent of phosphatidylethanolamine and is required for the proliferation of intestinal epithelial cells and bacteria, which is important for maintenance of the gut microbiome and intestinal development. The present study investigated the effect of Etn on intestinal function and microbiome using 21-d-old Sprague–Dawley rats treated with 0, 250, 500 and 1000 μm Etn in drinking water for 2 weeks immediately after weaning. Growth performance, intestinal morphology, antioxidant capacity and mucosal immunity, as well as gut microbiota community composition, were evaluated. Metagenomic prediction and metabolic phenotype analysis based on 16S RNA sequencing were also carried out to assess changes in metabolic functions. We found that weaned rats administered 500 μm Etn enhanced mucosal antioxidant capacity, as evidenced by higher superoxide dismutase and glutathione peroxidase levels in the jejunum (P<0·05) compared with those in the control group. Predominant microbes including Bacteroidetes, Proteobacteria, Elusimicrobia and Tenericutes were altered by different levels of Etn compared with the control group. An Etn concentration of 500 µm shifted colonic microbial metabolic functions that are in favour of lipid- and sugar-related metabolism and biosynthesis. Etn also altered the metabolic phenotypes such as anaerobic microbial counts, and oxidative stress tolerance at over 250 µm. This is the first report for a role of Etn in modifying gut microbiota and intestinal functions. Our findings highlighted the important role of Etn in shaping gut microbial community and promotes intestinal functions, which may provide a better insight of breast-feeding to infant’s gut health.
Heading angle is a vital parameter in maintaining a vessel's track along a planned course and should be guaranteed in a stable and reliable way. An innovative method of heading determination based on a fisheye camera, which is almost totally unaffected by electromagnetism and geomagnetism, is proposed in this paper. In addition, unlike traditional astronomical methods, it also has a certain degree of adaptability to cloudy weather. Utilising the super wide Field Of View (FOV) of the camera, it is able to simultaneously image the Moon and the horizon. The Moon is treated as the observed celestial body and the horizon works as the horizontal datum. Two experiments were conducted at sea, successfully proving the feasibility of this method. The proposed heading determination system has the merits of automation, resistance to interference and could be miniaturised, making application viable.
Dietary energy density (ED) might have influences on body composition. We therefore examined whether ED is associated with body composition among Chinese adults.
We collected dietary data through validated two-day 24 h recalls. ED, defined as the amount of energy per unit weight of food consumed, was calculated based on five methods. Multiple linear regression analyses were performed to explore the associations between ED and body composition parameters, including BMI, fat mass index (FMI), fat-free mass index (FFMI), percentage body fat (%BF) and waist circumference (WC).
Chinese adults (n 1933) in 2013.
After adjusting the covariates, all ED definitions were positively associated with BMI, FMI, FFMI, %BF and WC among women (P<0·01). In men, however, ED with foods only was positively associated with BMI, FMI, FFMI and %BF (P<0·05), but not with WC (P=0·07); we also found null associations between ED with foods and all beverages and body composition among men. Additionally, ED contributed to higher increases of body composition in women than in men (P<0·01).
The present study supports the positive association between ED and body composition among adults in Southwest China, in which beverages may play an important role.
This research examined whether feeling awe weakens people's desire for money. Two experiments demonstrated that, as a self-transcendent emotion, awe decreased people's money desire. In Experiment 1, recalling a personal experience of awe makes people place less importance on money, compared with recalling an experience of happiness and recalling a neutral experience. In experiment 2, we examined different variants of awe, such as negative awe and non-nature awe. Viewing images that elicited awe, no matter what kind of awe, can induce people to put less effort into obtaining money. Process evidence suggested that awe's weakening of money desire was due to its power to make people transcend their mundane concerns. Our findings have implications for willingness to donate, price sensitivity, religious practices, and economic utilities.
We examined the in vitro developmental competence of parthenogenetic activation (PA) oocytes activated by an electric pulse (EP) and treated with various concentrations of AZD5438 for 4 h. Treatment with 10 µM AZD5438 for 4 h significantly improved the blastocyst formation rate of PA oocytes in comparison with 0, 20, or 50 µM AZD5438 treatment (46.4% vs. 34.5%, 32.3%, and 24.0%, respectively; P < 0.05). The blastocyst formation rate was higher in the group treated with AZD5438 for 4 h than in the groups treated with AZD5438 for 2 or 6 h (42.8% vs. 38.6% and 37.2%, respectively; P > 0.05). Furthermore, 66.67% of blastocysts derived from these AZD5438-treated PA oocytes had a diploid karyotype. The blastocyst formation rate of PA and somatic cell nuclear transfer (SCNT) embryos was similar between oocytes activated by an EP and treated with 2 mM 6-dimethylaminopurine for 4 h and those activated by an EP and treated with 10 µM AZD5438 for 4 h (11.11% vs. 13.40%, P > 0.05). In addition, the level of maturation-promoting factor (MPF) was significantly decreased in oocytes activated by an EP and treated with 10 µM AZD5438 for 4 h. Finally, the mRNA expression levels of apoptosis-related genes (Bax and Bcl-2) and pluripotency-related genes (Oct4, Nanog, and Sox2) were checked by RT-PCR; however, there were no differences between the AZD5438-treated and non-treated control groups. Our results demonstrate that porcine oocyte activation via an EP in combination with AZD5438 treatment can lead to a high blastocyst formation rate in PA and SCNT experiments.
A stalagmite with high 238U content from Yangkou Cave, China, revealed the evolution of the Asian summer monsoon (ASM) between 49.1 and 59.5 ka, and the δ18O values recorded Dansgaard/Oeschger (D/O) events 13–17. The Yangkou record shows a relatively gradual transition into the D/O 14 and 16 events. The discrepancy between the abrupt and gradual transitions of D/O 14 in the records from northern and southern China, respectively, suggests different responses of the ASM to climate changes in the high northern latitudes. The higher resolution δ18O record and more precise 230Th dating indicate that the timing of D/O 14 and 17 in the Hulu records at 53 and 58 ka should be shifted to 54.3 and 59 ka, respectively. The gradual strengthening of the ASM at the onsets of D/O 16 and 14 in our record is different from the abrupt temperature rise in the northern high latitudes. Some other factors must contribute to this relatively gradual ASM change in southern China, but the actual reason is still unknown.
A class of finite volume methods is developed for pricing either European or American options under jump-diffusion models based on a linear finite element space. An easy to implement linear interpolation technique is derived to evaluate the integral term involved, and numerical analyses show that the full discrete system matrices are M-matrices. For European option pricing, the resulting dense linear systems are solved by the generalised minimal residual (GMRES) method; while for American options the resulting linear complementarity problems (LCP) are solved using the modulus-based successive overrelaxation (MSOR) method, where the H+-matrix property of the system matrix guarantees convergence. Numerical results are presented to demonstrate the accuracy, efficiency and robustness of these methods.
Based on the shift-splitting technique and the idea of Hermitian and skew-Hermitian splitting, a fast shift-splitting iteration method is proposed for solving nonsingular and singular nonsymmetric saddle point problems in this paper. Convergence and semi-convergence of the proposed iteration method for nonsingular and singular cases are carefully studied, respectively. Numerical experiments are implemented to demonstrate the feasibility and effectiveness of the proposed method.
The relation between climate change and historical rhythms has long been discussed. However, this type of study still faces the lack of high-resolution data concerning long-term socio-economic processes. In this study, we collected 1586 items of direct and proffered evidence from 29 Chinese history books. We used semantic analysis to reconstruct a quantitative series of the social vicissitudes of the past 2000 yr with a 10-yr resolution to express the phase transition of the social vicissitudes of the dynasties in China. Our reconstruction demonstrates that social vicissitudes have clear cyclical features on multiple time scales. Analysis of the association of social rise and fall with climate change indicates that temperature displayed more significant effects on social vicissitudes in the long term, while precipitation displayed more significant effects on the social vicissitudes in the short term. There are great overlaps between social and climatic variables around the predominant or periodic bands. Social rise mostly occurred in the centennial-scale warm periods, whereas social decline mostly occurred in the centennial-scale cold periods. Under warm-wet conditions, social rise occurred over 57% of the time; under cold-dry conditions, the social decline occurred over 66% of the time.
CALIFA data show that isolated disk galaxies present a common gas-phase metallicity gradient, with a characteristic slope of -0.1dex/re between 0.3 and 2 disk effective radius re (Sanchez et al. 2014). Here we construct a simple model to investigate which processes regulate the formation and evolution.
The charge transport properties of anthra-tetrathiophene (ATT) and its brominated and cyanated derivatives (TBATT and TCATT) were investigated by the density functional theory (DFT) coupled with incoherent charge-hopping model. The crystal structure of TCATT is predicted by the dispersion-corrected DFT (DFT-D) method, and those of ATT and TBATT are retrieved from the Cambridge Crystallographic Data Center. The introduction of electron-withdrawing substituents of bromine and cyano decreases the frontier molecular orbital energies but increases the electron affinities, which is beneficial to electron injection and guarantees charge carrier stabilization. The π–π stacking of neighbor molecules with a short distance and large coupling area contributes to the largest transfer integral. The predicted electron mobility of TCATT reaches up to 1.851 cm2/(V·s), indicating that the cyanation of ATT is favorable for improving the electron transport. The angular dependent simulation for electron mobility shows that the electron transport is remarkably anisotropic.
The present study was conducted to investigate the anti-inflammatory effect of vitamin D both in juvenile Jian carp (Cyprinus carpio var. Jian) in vivo and in enterocytes in vitro. In primary enterocytes, exposure to 10 mg lipopolysaccharide (LPS)/l increased lactate dehydrogenase activity in the culture medium (P<0·05) and resulted in a significant loss of cell viability (P<0·05). LPS exposure increased (P<0·05) the mRNA expression of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6 and IL-8), which was decreased by pre-treatment with 1,25-dihydroxyvitamin D (1,25D3) in a dose-dependent manner (P<0·05). Further results showed that pre-treatment with 1,25D3 down-regulated Toll-like receptor 4 (TLR4), myeloid differentiation primary response gene 88 (Myd88) and NF-κB p65 mRNA expression (P<0·05), suggesting potential mechanisms against LPS-induced inflammatory response. In vivo, intraperitoneal injection of LPS significantly increased TNF-α, IL-1β, IL-6 and IL-8 mRNA expression in the intestine of carp (P<0·05). Pre-treatment of fish with vitamin D3 protected the fish intestine from the LPS-induced increase of TNF-α, IL-1β, IL-6 and IL-8 mainly by downregulating TLR4, Myd88 and NF-κB p65 mRNA expression (P<0·05). These observations suggest that vitamin D could inhibit LPS-induced inflammatory response in juvenile Jian carp in vivo and in enterocytes in vitro. The anti-inflammatory effect of vitamin D is mediated at least in part by TLR4-Myd88 signalling pathways in the intestine and enterocytes of juvenile Jian carp.