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Salicylic acid (SA), a phytohormone, has been considered to be a key regulator mediating plant defence against pathogens. It is still vague how SA activates plant defence against herbivores such as chewing and sucking pests. Here, we used an aphid-susceptible wheat variety to investigate Sitobion avenae response to SA-induced wheat plants, and the effects of exogenous SA on some defence enzymes and phenolics in the plant immune system. In SA-treated wheat seedlings, intrinsic rate of natural increase (rm), fecundity and apterous rate of S. avenae were 0.25, 31.4 nymphs/female and 64.4%, respectively, and significantly lower than that in the controls (P < 0.05). Moreover, the increased activities of phenylalanine-ammonia-lyase, polyphenol oxidase (PPO) and peroxidase in the SA-induced seedlings obviously depended on the sampling time, whereas activities of catalase and 4-coumarate:CoA ligase were suppressed significantly at 24, 48 and 72 h in comparison with the control. Dynamic levels of p-coumaric acid at 96 h, caffeic acid at 24 and 72 h and chlorogenic acid at 24, 48 and 96 h in wheat plants were significantly upregulated by exogenous SA application. Nevertheless, only caffeic acid content was positively correlated with PPO activity in SA-treated wheat seedlings (P = 0.031). These findings indicate that exogenous SA significantly enhanced the defence of aphid-susceptible wheat variety against aphids by regulating the plant immune system, and may prove a potential application of SA in aphid control.
In this paper, the k-valued logic control network is introduced to study the cooperative pursuit control problem of multiple underactuated underwater vehicles (UUVs) with time delay in three-dimensional space. The semi-tensor product of matrices is used to solve the complex calculation problem of the large dimension matrix. The influence of communication delay on multiple UUVs’ optimization and cooperative pursuit control is expressed in a matrix. Under the leadership of evader UUV, the control algorithm can ensure that all the pursuit UUVs reach the desired position. The stability of the closed loop system is proved.
Multi-device radio frequency power amplifiers (PAs) often exhibit strongly non-linear behavior in combination with long-term memory effects, leading to an extremely challenging model development cycle. This paper presents a new, dynamic, behavioral modeling technique, based on a combination of the real-valued decomposed piecewise method and concepts from the field of machine learning. The underlying theory of the proposed modeling technique is provided, along with a detailed modeling procedure. Experimental results show that the proposed decomposed piecewise support vector regression (SVR) model leads to significant performance improvements when compared with standard SVR models for both single transistor and multi-transistor PAs. Different model thresholds are used to test the proposed model performance for both PA types. For the single-transistor PA, modeled using only one partition, an approximately 10 dB normalized mean square error (NMSE) reduction is seen when compared with the standard SVR model. For the same PA, when utilizing two partitions, the reduction improves to 14 dB. When applied to a multi-device Doherty PA, the NMSE between model and measurement data is −50 dB, representing more than 10 dB improvement compared with the standard SVR model.
In this study, we propose new risk measures from a regulator’s perspective on the regulatory capital requirements. The proposed risk measures possess many desired properties, including monotonicity, translation-invariance, positive homogeneity, subadditivity, nonnegative loading, and stop-loss order preserving. The new risk measures not only generalize the existing, well-known risk measures in the literature, including the Dutch, tail value-at-risk (TVaR), and expectile measures, but also provide new approaches to generate feasible and practical coherent risk measures. As examples of the new risk measures, TVaR-type generalized expectiles are investigated in detail. In particular, we present the dual and Kusuoka representations of the TVaR-type generalized expectiles and discuss their robustness with respect to the Wasserstein distance.
Data on average iodine requirements for the Chinese population are limited following implementation of long-term universal salt iodisation. We explored the minimum iodine requirements of young adults in China using a balance experiment and the ‘iodine overflow’ hypothesis proposed by our team. Sixty healthy young adults were enrolled to consume a sequential experimental diet containing low, medium and high levels of iodine (about 20, 40 and 60 μg/d, respectively). Each dose was consumed for 4 d, and daily iodine intake, excretion and retention were assessed. All participants were in negative iodine balance throughout the study. Iodine intake, excretion and retention differed among the three iodine levels (P < 0·01 for all groups). The zero-iodine balance derived from a random effect model indicated a mean iodine intake of 102 μg/d, but poor correlation coefficients between observed and predicted iodine excretion (r 0·538 for μg/d data) and retention (r 0·304 for μg/d data). As iodine intake increased from medium to high, all of the increased iodine was excreted (‘overflow’) through urine and faeces by males, and 89·5 % was excreted by females. Although the high iodine level (63·4 μg/d) might be adequate in males, the corresponding level of 61·6 μg/d in females did not meet optimal requirements. Our findings indicate that a daily iodine intake of approximately half the current recommended nutrient intake (120 μg/d) may satisfy the minimum iodine requirements of young male adults in China, while a similar level is insufficient for females based on the ‘iodine overflow’ hypothesis.
Pro-vitamin A carotenoids namely α-, β-carotene and β-cryptoxanthin have potential roles in neurocognitive development, but current literature on these carotenoids mainly focused on preventing cognitive decline in the elderly. This study examined the associations of maternal plasma pro-vitamin A carotenoids concentrations with offspring cognitive development up to 54 months in the GUSTO mother-offspring cohort study.
Materials and Methods
Maternal plasma pro-vitamin A carotenoids concentrations at delivery were determined by ultra-performance liquid chromatography. At age 24 months, the Bayley Scales of Infant and Toddler Development (BSID-III) was used to assess children's development for the following domains: cognitive, receptive and expressive language, and fine and gross motor. At age 54 months, the Kaufman Brief Intelligence Test (KBIT-2) was used to assess children's verbal and non-verbal intelligence. Associations of maternal pro-vitamin A carotenoids with offspring cognitive development at each time point were examined in 419 mother-offspring pairs using linear regressions adjusted for confounders (e.g. maternal demographics, antenatal mental health and breastfeeding duration).
Median (IQR) maternal plasma concentrations (mg/L) were: α-carotene 0.052 (0.032–0.081), β-carotene 0.189 (0.134–0.286), and β-cryptoxanthin 0.199 (0.123–0.304). In 24 months old infants, higher maternal β-cryptoxanthin (per SD increment) were associated with higher scores in most of BSID-III domains: cognitive [β 0.18, (0.08, 0.28) SD], receptive language [β 0.17 (0.07, 0.27) SD], fine motor [β 0.16 (0.06, 0.27) SD], and gross motor [β 0.16 (0.06, 0.27) SD]. Additionally, a 1-SD increment in maternal β-carotene concentrations were associated with 0.16 SD higher scores in BSID-III cognitive domain (95%: 0.04, 0.28), which was attenuated after adjusting for breastfeeding duration. No significant associations were observed between maternal α-carotene concentrations and BSID-III in children at 24 months of age, or between maternal pro-vitamin A carotenoids and KBIT-2 in children at 54 months of age.
Our study provides novel data suggesting a role of maternal pro-vitamin A carotenoids, especially β-cryptoxanthin, in offspring early cognitive development. This adds support to the importance of consuming sufficient amounts of red- and orange-coloured fruit and vegetables (rich sources of β-cryptoxanthin and β-carotene) during pregnancy. Further studies are required in other mother-offspring cohort with larger sample sizes, and intervention trials to confirm an effect of pro-vitamin A carotenoids on neurocognitive development.
We return to the long-standing question ‘Who owns the assets in a defined benefit pension plan?’ Unlike earlier studies, we condition the market's assessment of implicit property rights on the sponsoring firm's financial health. Valuations of financially strong firms, and those that are strengthening, are more responsive to pension plan funding. For these firms, each extra dollar of net plan assets is valued at between $0.50 and $1.00. In contrast, for weak and weakening firms, valuation effects are statistically indistinguishable from zero. This result is consistent with the higher likelihood that they will renege on their pension obligations.
Evidence on long-term influences of maternal vitamin B12 deficiency or concentrations on infant cognition is limited. We examined associations between maternal plasma vitamin B12 and cognitive development in 24-month-old infants. Maternal plasma vitamin B12 concentrations were measured at 26–28 weeks’ gestation; infant cognitive development was assessed with the Bayley Scales of Infant and Toddler Development-III at 24 months, for 443 mother–infant pairs from the Growing Up in Singapore Towards Healthy Outcomes cohort. Linear regressions adjusted for key confounders examined associations of maternal vitamin B12 with cognitive, receptive and expressive language, fine and gross motor subscales. Co-occurrence of maternal vitamin B12 with folate or vitamin B6 insufficiencies on child’s cognition was explored. Average maternal plasma vitamin B12 concentrations was 220·5 ± 80·5 pmol/l; 15 % and 41 % of mothers were vitamin B12 deficient (<148 pmol/l) and insufficient (148–220·9 pmol/l), respectively. Infants of mothers with vitamin B12 deficiency had 0·42 (95 % CI −0·70, −0·14) sd lower cognitive scores, compared with infants of mothers with sufficient vitamin B12. Co-occurrence of maternal vitamins B12 and B6 insufficiencies was associated with 0·37 (95 % CI −0·69, −0·06) sd lower cognitive scores in infants compared with infants of mothers sufficient in both vitamins. No significant associations were observed with other subscales. Study findings suggest the possible need to ensure adequate vitamin B12 during pregnancy. The impact of co-occurrence of maternal B-vitamins insufficiencies on early cognitive development warrants further investigation.
Parents commonly fail to correctly recognize the weight status of their child. Whether parental perception of child weight is associated with weight-related parenting behaviours and child behaviours is unclear. The present study aimed to investigate the distribution of parental perception of child weight and its associations with weight-related parenting behaviours and child behaviours in China.
Seven provinces in China.
A total of 47 417 children aged 6–17 years and their parents were included from a national survey in 2013. Parental perception of child weight, weight-related parenting behaviours and child behaviours were self-reported. Child’s weight and height were objectively measured.
A total of 30·5 % of parents underestimated and 8·7 % overestimated the child’s weight. Parental underestimation was more common among younger children, boys and children with a lower BMI Z-score. Parents who perceived that their child had a healthy weight (accurately or inaccurately) were more likely to prepare breakfast for the child, exercise with him/her, set apart his/her exercise time, restrict his/her screen time, and were less likely to store soft drinks for the child. Children perceived to have a healthy weight, regardless of their actual weight status, behaved healthier on dietary intake, physical activity and homework time.
Parental underestimation of their child’s weight was prominent in China, especially among younger children, boys and children with a lower BMI Z-score. Parental recognition of their child being overweight did not appear to translate into healthy changes in weight-related parenting behaviours or child behaviours.
Four isonitrogenous and isoenergetic purified diets containing free arachidonic acid (ARA) or EPA (control group), 0·30 % ARA, 0·30 % EPA and 0·30 % ARA+EPA (equivalent) were designed to feed juvenile grass carp (10·21 (sd 0·10) g) for 10 weeks. Only the EPA group presented better growth performance compared with the control group (P<0·05). Dietary ARA and EPA were incorporated into polar lipids more than non-polar lipids in hepatopancreas but not intraperitoneal fat (IPF) tissue. Fish fed ARA and EPA showed an increase of serum superoxide dismutase and catalase activities, and decrease of glutathione peroxidase activity and malondialdehyde contents (P<0·05). The hepatopancreatic TAG levels decreased both in ARA and EPA groups (P<0·05), accompanied by the decrease of lipoprotein lipase (LPL) activity in the ARA group (P<0·05). Fatty acid synthase (FAS), diacylglycerol O-acyltransferase and apoE gene expression in the hepatopancreas decreased in fish fed ARA and EPA, but only the ARA group exhibited increased mRNA level of adipose TAG lipase (ATGL) (P<0·05). Decreased IPF index and adipocyte sizes were found in the ARA group (P<0·05). Meanwhile, the ARA group showed decreased expression levels of adipogenic genes CCAAT enhancer-binding protein α, LPL and FAS, and increased levels of the lipid catabolic genes PPARα, ATGL, hormone-sensitive lipase and carnitine palmitoyltransferase 1 (CPT-1) in IPF, whereas the EPA group only increased PPARα and CPT-1 mRNA expression and showed less levels than the ARA group. Overall, dietary EPA is beneficial to the growth performance, whereas ARA is more potent in inducing lipolysis and inhibiting adipogenesis, especially in IPF. Meanwhile, dietary ARA and EPA showed the similar preference in esterification and the improvement in antioxidant response.
In this paper, we propose to use the interior functions of an hierarchical basis for high order BDMp elements to enforce the divergence-free condition of a magnetic field B approximated by the H(div)BDMp basis. The resulting constrained finite element method can be used to solve magnetic induction equation in MHD equations. The proposed procedure is based on the fact that the scalar (p–1)-th order polynomial space on each element can be decomposed as an orthogonal sum of the subspace defined by the divergence of the interior functions of the p-th order BDMp basis and the constant function. Therefore, the interior functions can be used to remove element-wise all higher order terms except the constant in the divergence error of the finite element solution of the B-field. The constant terms from each element can be then easily corrected using a first order H(div) basis globally. Numerical results for a 3-D magnetic induction equation show the effectiveness of the proposed method in enforcing divergence-free condition of the magnetic field.
We present a high-order discontinuous Galerkin (DG) method for the time domain Maxwell's equations in three-dimensional heterogeneous media. New hierarchical orthonormal basis functions on unstructured tetrahedral meshes are used for spatial discretization while Runge-Kutta methods for time discretization. A uniaxial perfectly matched layer (UPML) is employed to terminate the computational domain. Exponential convergence with respect to the order of the basis functions is observed and large parallel speedup is obtained for a plane-wave scattering model. The rapid decay of the out-going wave in the UPML is shown in a dipole radiation simulation. Moreover, the low frequency electromagnetic fields excited by a horizontal electric dipole (HED) and a vertical magnetic dipole (VMD) over a layered conductive half-space and a high frequency ground penetrating radar (GPR) detection for an underground structure are investigated, showing the high accuracy and broadband simulation capability of the proposed method.
This paper proposes a leader following formation tracking controller for multiple underactuated underwater vehicles (UUVs) which move in three dimensional space. In order to avoid the derivative of the virtual control signals, a control method based on filter backstepping is proposed. The method can significantly simplify the design process of the backstepping controller through the use of a filter rather than the analytic derivation directly to the virtual control variable. Furthermore, the influence of measurement noise is obviously weakened. The stability of the formation system of multiple UUVs has been proved based on Lyapunov stability theory. Simulation results illustrate that the designed controller can track a three-dimensional formation trajectory accurately.
The traditional mobile cellular networks are often designed so that a base station (BS) is always under uninterrupted working condition without considering the dynamic nature of user traffic, which results in an inefficient usage of energy. How to improve the system energy efficiency in order to achieve green networking is our major concern in this chapter. Beginning with a comprehensive review of the related works in literature, we introduce a self-organized BS virtual small networking (VSN) protocol so as to adaptively manage BSs' working states based on heterogeneity of user traffic changing in space and time. Motivated by the fact that low-traffic areas can apply a more aggressive BS-off strategy than hotspots, the proposed method is targeted at dividing BSs into groups with some similarity measurements so that the BS-off strategy can be performed more efficiently. Numerical results show that our proposals can save energy consumption on the entire cellular network to a great extent.
As demand increases for more energy-efficient technologies in wireless networks, to tackle critical issues such as boosting cost on power consumption and excessive greenhouse gas emissions, the concept of green networking has drawn great attention in recent years. In fact, during the last decades, people have witnessed that the carbon footprint of the telecommunications industry has been exponentially growing due to the explosive rise of service requirements and subscribers’ demands. The concern on reducing power consumption comes from both environmental and economical reasons. With respect to the environment, the information and communications technology (ICT) industry is responsible for approximately 2% of current global electricity demands, with 6% yearly growth in ICT-related carbon dioxide emission (CO2-e) forecast till 2020 . With respect to economics, the power consumption for operating a typical base station (BS), which needs to be connected to the electrical grid, may cost approximately $3,000/year, while off-grid BSs, generally running on diesel power generators in remote areas, may cost ten times more . As more than 120,000 new BSs are deployed annually , there is still no end in sight for the development of mobile communications with a large amount of new subscribers and a constant desire for upgrading user equipment from 2G to 3G, and then to 4G.
Optimal reinsurance from an insurer's point of view or from a reinsurer's point of view has been studied extensively in the literature. However, as two parties of a reinsurance contract, an insurer and a reinsurer have conflicting interests. An optimal form of reinsurance from one party's point of view may be not acceptable to the other party. In this paper, we study optimal reinsurance designs from the perspectives of both an insurer and a reinsurer and take into account both an insurer's aims and a reinsurer's goals in reinsurance contract designs. We develop optimal reinsurance contracts that minimize the convex combination of the Value-at-Risk (VaR) risk measures of the insurer's loss and the reinsurer's loss under two types of constraints, respectively. The constraints describe the interests of both the insurer and the reinsurer. With the first type of constraints, the insurer and the reinsurer each have their limit on the VaR of their own loss. With the second type of constraints, the insurer has a limit on the VaR of his loss while the reinsurer has a target on his profit from selling a reinsurance contract. For both types of constraints, we derive the optimal reinsurance forms in a wide class of reinsurance policies and under the expected value reinsurance premium principle. These optimal reinsurance forms are more complicated than the optimal reinsurance contracts from the perspective of one party only. The proposed models can also be reduced to the problems of minimizing the VaR of one party's loss under the constraints on the interests of both the insurer and the reinsurer.
The present study aimed to investigate the prevalence of metabolic syndrome (MetS) in 7- to 17-year-old children and adolescents in China and to examine the relationship between MetS and its associated early-life factors.
Data were collected using a standard parent/guardian questionnaire in a face-to-face interview. Each participant underwent a complete anthropometric evaluation. MetS was defined according to the criteria of the International Diabetes Federation (IDF; 2007) for children and adolescents.
Guangzhou, a large city in South China, September 2013.
A total of 1770 children and adolescents were enrolled in the study, including 913 girls (51·6 %) and 857 boys (48·4 %).
The overall prevalence of MetS in children and adolescents was 1·1 % (n 19), which was higher in boys (1·4 %) than in girls (0·8 %). Multivariate analysis indicated that high birth weight was significantly associated with abdominal obesity (OR=2·86; 95 % CI 1·62, 5·06) and MetS (OR=3·61; 95 % CI 1·33, 9·82). Furthermore, >6 months of maternal breast-feeding was inversely associated with MetS (OR=0·39; 95 % CI 0·16, 0·98).
Based on IDF criteria, the prevalence of MetS among southern Chinese children was significantly lower than that in other populations. High birth weight was significantly associated with abdominal obesity and MetS, and breast-feeding for longer than 6 months was inversely associated with MetS in South China.
Epidemiological studies have demonstrated inconsistent associations between tea consumption and mortality of all cancers, CVD and all causes. To obtain quantitative overall estimates, we conducted a dose–response meta-analysis of prospective cohort studies. A literature search in PubMed and Embase up to April 2015 was conducted for all relevant papers published. Random-effects models were used to calculate pooled relative risks (RR) with 95 % CI. In eighteen prospective studies, there were 12 221, 11 306 and 55 528 deaths from all cancers, CVD and all causes, respectively. For all cancer mortality, the summary RR for the highest v. lowest category of green tea and black tea consumption were 1·06 (95 % CI 0·98, 1·15) and 0·79 (95 % CI 0·65, 0·97), respectively. For CVD mortality, the summary RR for the highest v. lowest category of green tea and black tea consumption were 0·67 (95 % CI 0·46, 0·96) and 0·88 (95 % CI 0·77, 1·01), respectively. For all-cause mortality, the summary RR for the highest v. lowest category of green tea and black tea consumption were 0·80 (95 % CI 0·68, 0·93) and 0·90 (95 % CI 0·83, 0·98), respectively. The dose–response analysis indicated that one cup per d increment of green tea consumption was associated with 5 % lower risk of CVD mortality and with 4 % lower risk of all-cause mortality. Green tea consumption was significantly inversely associated with CVD and all-cause mortality, whereas black tea consumption was significantly inversely associated with all cancer and all-cause mortality.
To assess correlations between cruciferous vegetable intake and urinary isothiocyanate (ITC) level, in addition to glutathione S-transferase (GST) genotypes and other individual factors.
The study included cohort participants whose urinary ITC levels had been previously ascertained. Urinary ITC was assessed using HPLC. Usual dietary intake of cruciferous vegetables was assessed using a validated FFQ and total dietary ITC intake was calculated. Recent cruciferous vegetable intake was determined. GST genotypes were assessed using duplex real-time quantitative PCR assays. Spearman correlations were calculated between the covariates and urinary ITC levels and linear regression analyses were used to calculate the mean urinary ITC excretion according to GST genotype.
Urban city in China.
The study included 3589 women and 1015 men from the Shanghai Women’s and Men’s Health Studies.
Median urinary ITC level was 1·61 nmol/mg creatinine. Self-reported usual cruciferous vegetable intake was weakly correlated with urinary ITC level (rs=0·1149; P<0·0001), while self-reported recent intake was more strongly correlated with urinary ITC (rs=0·2591; P<0·0001). Overall, the GST genotypes were not associated with urinary ITC level, but significant differences according to genotype were observed among current smokers and participants who provided an afternoon urine sample. Other factors, including previous gastrectomy or gastritis, were also related to urinary ITC level.
The study suggests that urinary secretion of ITC may provide additional information on cruciferous vegetable intake and that GST genotypes are related to urinary ITC level only in some subgroups.
In this paper we investigate optimal forms of dynamic reinsurance polices among a class of general reinsurance strategies. The original surplus process of an insurance portfolio is assumed to follow a Markov jump process with state-dependent income. We assume that the insurer uses a dynamic reinsurance policy to minimize the probability of absolute ruin, where the traditional ruin can be viewed as a special case of absolute ruin. In terms of approximation theory of stochastic process, the controlled diffusion model with a general reinsurance policy is established strictly. In such a risk model, absolute ruin is said to occur when the drift coefficient of the surplus process turns negative, when the insurer has no profitability any more. Under the expected value premium principle, we rigorously prove that a dynamic excess-of-loss reinsurance is the optimal form of reinsurance among a class of general reinsurance strategies in a dynamic control framework. Moreover, by solving the Hamilton-Jacobi-Bellman equation, we derive both the explicit expression of the optimal dynamic excess-of-loss reinsurance strategy and the closed-form solution to the absolute ruin probability under the optimal reinsurance strategy. We also illustrate these explicit solutions using numerical examples.