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In this paper, we compute the Bowley solution of a one-period, mean–variance Stackelberg game in insurance, in which a buyer and a seller of insurance are the two players, and they act in a certain order. First, the seller offers the buyer any (reasonable) indemnity policy in exchange for a premium computed according to the mean–variance premium principle. Then, the buyer chooses an indemnity policy, given that premium rule. To optimize the choices of the two players, we work backwards. Specifically, given any pair of parameters for the mean–variance premium principle, we compute the optimal insurance indemnity to maximize a mean–variance functional of the buyer’s terminal wealth. Then, we compute the parameters of the mean–variance premium principle to maximize the seller’s expected terminal wealth, given the foreknowledge of what the buyer will choose when offered that premium principle. This pair of optimal choices, namely, the optimal indemnity and the optimal parameters of the premium principle, constitute a Bowley solution of this Stackelberg game. We illustrate our results via numerical examples.

The environmental stressors associated with the cross-provincial transfer of coal resource-based enterprises (CREs) have become a critical concern for the green, sustainable, and high-quality development of resource-rich areas in central and western regions. This study referred to socioeconomic statistics and carried out an interview survey, literature review, and systematic analysis to clarify the mechanism underlying environmental stressors arising from the cross-provincial transfer of CREs. The intervention factors associated with such environmental stressors were identified, and the study conducted an empirical analysis of relevant data related to the coal-resources industry in three central and western provinces in China for the period 1997-2016. Research findings: (1) The intensity ranking of the influencing factors associated with environmental stressors caused by cross-provincial transfers of CREs has certain rules. The 'level of the enterprise's investment in environmental protection' is the weakest, the 'enterprise's development mode level' is slightly stronger, the 'enterprise scale' is stronger, and 'environmental regulation' is the strongest. (2) Stricter endogenous and exogenous policy regulations for environmental governance in rich coal resource-based regions are associated with weaker negative externalities in respect of resource development and the intensity of stressors. (3) Larger CREs are associated with a better green mining capacity, environmental repair cost advantages, social constraints, self-discipline, and thus, a weaker stress effect. (4) CREs that adopt more superior modes of development that focus on the utilization of the 'three wastes' are associated with a weaker stress effect. (5) The higher the level of investment by CREs in environmental protection technology, facilities, and equipment, the weaker the stress effect. The conclusions of the study can provide a theoretical basis to assist the Chinese government to develop relevant regulations to control inter-provincial transfers by CREs and to thereby diminish environmental stressor effects.

In this paper, we consider the equilibrium excess-of-loss reinsurance and investment problem for both an insurer and a reinsurer. The risk process of the insurer is described by a classical Cramer-...

In this paper, we consider a dynamic Pareto optimal risk‐sharing problem under the time‐consistent mean‐variance criterion. A group of n insurers is assumed to share an exogenous risk whose dynamics is modeled by a Levy process. By solving the extended Hamilton–Jacobi–Bellman equation using the Lagrange multiplier method, an explicit form of the time‐consistent equilibrium risk‐bearing strategy for each insurer is obtained. We show that equilibrium risk‐bearing strategies are mixtures of two common risk‐sharing arrangements, namely, the proportional and stop‐loss strategies. Their explicit forms allow us to thoroughly examine the analytic properties of the equilibrium risk‐bearing strategies. We later consider two extensions to the original model by introducing a set of financial investment opportunities and allowing for insurers' ambiguity towards the exogenous risk distribution. We again explicitly solve for the equilibrium risk‐bearing strategies and further examine the impact of the extension component (investment or ambiguity) on these strategies. Finally, we consider an application of our results in the classical risk‐sharing problem of a pure exchange economy.

Background: Sarin is a nerve agent which is lethal to people due to its high toxicity. According to its extreme toxicity, sarin, relatively lack of color, highly toxic, miscible in water, poses viable threats to potable water sources. Therefore, there is an urgent need for portable, rapid and yet reliable methods to monitor for adulteration of potable water sources by sarin on spot. Methods: A stock solution of 30 mg/L sarin was prepared daily by dissolving 300 μg of sarin in 10 mL isopropanol. A certain amount of sarin was added to the glass tube, and then o-dianisidine and hydrogen peroxide were added. The pH value of the solution was adjusted to 9.8. The solution was transferred to the test tube after 10 minutes. A test tube of 2 mL was placed between the light source and the RGB color sensor. The LED light source illuminates directly over the test tube while the RGB sensor obtained the generated spectral response. This RGB voltage output is connected to the ADC and microcontroller to convert these analog voltages to three digital data. This RGB digital data is linked to the microcomputer through the serial port that is interfaced with the user interface. The data thus obtained in the sensor can be processed to display the sarin concentration. Results: Under the optimum conditions as described above, the calibration curve of chromaticity value versus sarin concentration was linear in the range of 0.15 mg/L to 7.8 mg/L. According to the IUPAC definition, theoretical detection limits of this method were 0.147 mg/L and 0.140 mg/L for R and B values, respectively. The practical detection limit was 0.15 mg/L. The sensor was successfully applied to the determination of sarin in artificial water samples and the recoveries were between 86.0% to 95.9%. Conclusion: The results in the present work have demonstrated the feasibility to design a new portable colorimetric sensor based on the RGB chromaticity method for quantitative determination of sarin in water. The influences of chromogenic reagent, oxidant, reaction time, o-dianisidine concentration, hydrogen peroxide concentration, reaction temperature, pH on the chromaticity values were investigated. The results showed that the sensor possessed high selectivity, sensitivity and good repeatability. The method would be potentially applied to the analysis of other toxic compounds in environment, such as other chemical warfare agents.

Ion-exchange polymer and modified carbonization bacterial cellulose (CBC) electrodes were fabricated using varying amounts of cation-exchange polymers (glutaric acid (GA) and sulfosuccinic acid (SSA)) and assembled within an asymmetric capacitive deionization unit (p-CDI). The performance of selective NO 2 − electro-adsorption was studied. The AC/CBC-SSA group showed a better salt adsorption capacity (14.56 mg/g) and nitrite removal efficiency (71.01%) than the AC/CBC-GA (10.72 mg/g, 47.83%) and AC/AC (4.81 mg/g, 12.74%) groups. It was confirmed that the CBC-SSA/GA electrodes enhanced nitrite selectivity and increased the adsorption capacity, and the total amounts of adsorbed anions increased when the applied voltage was increased from 0.8 to 1.2 V, while the molar fraction of nitrate decreased. The competitive and preferential adsorption of anions was further investigated using different binary solutions of anions and occurred in the following sequence: NO 2 − > SO 4 2 − > NO 3 − > F − ≈ Cl − . Furthermore, the p-CDI units were applied to remove nitrite in real wastewater samples, and the results showed that they had excellent reusability and application for use in dyeing wastewater treatment.

Flow electrode capacitive deionization (FCDI) utilizes flowable electrodes to obtain a continuous and extensible desalination approach, eliminating the discharging step. However, the poor conductivity of flow electrode slurry and high clogging risk during the desalting process can limit desalination performance. Thus, we prepare the C2N@rGO material as a flow electrode to solve the channel blocking problem and improve the salt ion removal performance, maximizing the amount of active particles that can be added to the deionization process by forming a conductive network. The as-synthetized material possesses a large specific surface area, rich micropores, high N-doping, and tunable graphitization structure, which can further enhance the desalination properties of the as-prepared electrode. The results indicate that C2N@rGO-4% has an optimal porous structure (812.3 m2 g−1) and chemical composition (29.5%, N-doping), and the highest specific capacitance (236.6 F g−1). The FCDI results reveal that C2N@rGO-4% has a high salt ion adsorption capacity (180.72 mg g−1), salt ion adsorption rate (0.3043 mg min−1 cm2), salt ion removal efficiency (49.93%), and current efficiency (65.22%) under a 1.81 g L−1 NaCl solution at 1.0 V. Moreover, the results also indicate that the FCDI performance partly relies on the synergistic effect between the porous structure and chemical composition. Therefore, as an electrode material, C2N@rGO has strong potential for application in FCDI systems.

Service has become an important factor that affects insurance holders’ purchase behaviors, competition and even the survival of insurers. This paper introduces value-added service into the optimal ...

It has become a key issue and policy focus for the Chinese government to support the regionally-coordinated and high-quality development of coal resource-exhausted enterprises (CRE) in Eastern China, and the industrial upgrading required in the coal resource-rich regions (CRR) in Midwestern China. In this study, in accordance with economic statistics and the endogenous economic growth theory, we analyzed the mechanism of the horizontal spillage and vertical spillage in the CRE that are experiencing the effect of science and technology project funding sponsored by the government. We combined the theoretical analysis with empirical tests. Relevant data on the coal enterprises transferred from Eastern China to Shaanxi Province during 1997–2016 were selected for the empirical tests. Our results were as follows. (1) There were both horizontal and vertical spillage effects from the inter-regional transfer behavior (ITB) of the CRE in Eastern China. (2) The science and technology project fund sponsored by the government in the CRR of Midwestern China had a significant role in promoting the total factor productivity (TFP) of the enterprises inside and outside the local coal industry. (3) The strength of the horizontal spillage effect of the ITB of the Eastern China CRE was obviously stronger than that of the vertical spillage effect. (4) The effects of the fixed asset investments and labor inputs in the CRR of Midwestern China on the TFP of the enterprises were minimal. Our results provided the theoretical bases for the making of policies related to regulating the ITB of CRE. These data may be used to promote innovative, coordinated, and high-quality development in the region.

We solve an optimal robust reinsurance problem for an ambiguity-averse insurer, who worries about ambiguity in the rate of claim occurrence and who develops an optimal robust reinsurance strategy to minimize the penalized discounted probability of ruin, in which we discount for the time of ruin. Specifically, we minimize the expectation of e − δ τ 1 { τ ∞ } , in which τ equals the time of ruin and δ measures the insurer’s time value. Moreover, we penalize this expectation with an entropic term that accounts for the insurer’s ambiguity concerning the claim rate. We suppose that the insurer is allowed to purchase per-claim reinsurance to transfer its risk exposure to a reinsurer. We derive the optimal robust reinsurance strategy and the corresponding value function by applying stochastic dynamic programming and by solving the corresponding boundary-value problem. We prove that, when the reinsurance premium is computed according to the mean–variance premium principle, the optimal robust reinsurance strategy is piecewise linear with respect to the claim size. Under the special case of the expected-value premium principle, excess-of-loss reinsurance is optimal, but under the special case of the variance premium principle, proportional reinsurance is not optimal due to the ambiguity. We also present and discuss two numerical examples to illustrate our results.

Novel two-dimensional carbon nitride hexagonal-like sheets were fabricated from thermal condensation, which uses hexaazatriphenylene-based precursor prepared microporous and oxidation resistant carbons materials (HAT-CN). The results show that the as-prepared HAT-CN is the first electrode utilized in capacitive deionization, due to the rich heteroatom and border-group content, as well as the potential collaborative effect of C and N atoms, displaying the quick ion diffusion and strong charge transfer performance. Additionally, the capacitive deionization performance of HAT-CN is improved by the synergistic contribution of a large accessible surface area, large pore volume, and high graphitization. The electrode of HAT-CN was carbonized at 550 °C which display an excellent specific capacitance of 179.2 F g−1 in 1-M NaCl solution at a scan rate of 5 mV s−1. Subsequently, a high salt adsorption capacity of 24.66 mg g−1 was attained for an applied voltage of 1.2 V in 500 mg L−1 NaCl solution, showing good cyclic stability at 30 cycles. Considering those excellent properties of the prepared HAT-CN, the capacitive deionization electrode should be an ideal candidate for high-performance deionization application.

A key issue for the Chinese government entails managing the coordinated regional implementation of a program designed to achieve the sustainable development of coal resource-exhausted enterprises in eastern China and the industrial upgrading in coal resource-rich regions in midwest China. Based on systems engineering and synergetics, this study analyzes the coupled correlations between coal resources-exhausted enterprises in eastern China and the midwest regions with rich coal resources by utilizing relevant index data samples for the Xuzhou Mining Group as well as Guizhou, Qinghai and Xinjiang during the period 2005–2015 for empirical testing. The results reveal the following: (1) The coupling of the advantages between coal resources-exhausted enterprises from eastern China and the coal resource-rich regions in midwest China is essential for inter-district shifts by coal resources-exhausted enterprises from eastern China. (2) The likelihood of an inter-district shift by coal resources-exhausted enterprises from eastern China depends on their degree of coupling. (3) The degree of coupling can be used as a scientific basis to select targets for inter-district transfers. The degree of coupling between Xuzhou Mining Group and Xinjiang is higher than that between Xuzhou Mining Group and Guizhou, Qinghai. Thus, shifts to Xinjiang may be awarded priority. (4) Both sides should focus on overcoming their disadvantages in order to improve their degree of coupling and strengthen the driving force of inter-district transfers and regional coordinated development.

The discovery of functional genes underlying agronomic traits is of great importance for wheat improvement. Here we designed a new wheat exome capture probe panel based on IWGSC RefSeq v1.0 genome sequence information and developed an effective algorithm varBScore that can sufficiently reduce the background noise in gene mapping and identification. An effective method, termed bulked segregant exome capture sequencing (BSE-Seq) for identifying causal mutations or candidate genes was established by combining the use of new designed wheat exome capture panel, sequencing of bulked segregant pools from segregating populations, and the robust algorithm varBScore. We evaluated the effectiveness of varBScore algorithm on SNP call using the published dataset for mapping and cloning the yellow rust resistance gene Yr7 in wheat. Furthermore, using BSE-Seq, we rapidly identified a wheat yellow leaf mutant gene ygl1 in an ethyl methanesulfonate (EMS) mutant population and found that a single mutation of G to A at 921 position in the wild type YGL1 gene encoding magnesium-chelatase subunit chlI caused the leaf yellowing phenotype. We further showed that mutation of YGL1 through CRISPR/Cas9 gene editing led to a yellow phenotype on the leaves of transgenic wheat, indicating that ygl1 is the correct causal gene responsible for the mutant phenotype. In summary, our approach is highly efficient for discovering the causal mutation or gene cloning in wheat.

This paper focuses on the optimal reinsurance problem with consideration of joint interests of an insurer and a reinsurer. In our model, the risk process is assumed to follow a Brownian motion with drift. The insurer can transfer the risk to the reinsurer via proportional reinsurance, and the reinsurance premium is calculated according to the variance and standard deviation premium principles. The objective is to maximize the expected exponential utility of the weighted sum of the insurer’s and the reinsurer’s terminal wealth, where the weight can be viewed as a regularization parameter to measure the importance of each party. By applying stochastic control theory, we establish the Hamilton–Jacobi–Bellman equation and obtain explicit expressions of optimal reinsurance strategies and optimal value functions. Furthermore, we provide some numerical simulations to illustrate the effects of model parameters on the optimal reinsurance strategies.

This paper focuses on a stochastic differential game played between two insurance companies, a big one and a small one. In our model, the basic claim process is assumed to follow a Brownian motion with drift. Both of two insurance companies purchase the reinsurance, respectively. The big company has sufficient asset to invest in the risky asset which is described by the constant elasticity of variance (CEV) model and acquire new business like acting as a reinsurance company of other insurance companies, while the small company can invest in the risk-free asset and purchase reinsurance. The game studied here is zero-sum where there is a single exponential utility. The big company is trying to maximize the expected exponential utility of the terminal wealth to keep its advantage on surplus while simultaneously the small company is trying to minimize the same quantity to reduce its disadvantage. In this paper, we describe the Nash equilibrium of the game and prove a verification theorem for the exponential utility. By solving the corresponding Fleming-Bellman-Isaacs equations, we derive the optimal reinsurance and investment strategies. Furthermore, numerical examples are presented to show our results.

Perfluorooctane sulfonate (PFOS) is a persistent organic pollutant and can cause oxidative stress in animals. Wood vinegar (WV) is the water condensate of smoke produced during wood carbonization. It was used for antibacterial application, pest control, and antioxidant. In the study, PFOS and WV were used to treat the planarian, and then the oxidative stress induced by PFOS on the planarian (Dugesia japonica) and the protective effects of WV on lipid peroxidation, related antioxidant enzyme activity, and mRNA expression in the planarian were studied. PFOS caused an increase in malondialdehyde (MDA) contents, a decrease in superoxide dismutase (SOD) and catalase (CAT) activities, and a change in glutathione peroxidase (GPx), glutathione S-transferase (GST), glutathione reductase (GR) activities. The mRNA levels of glutathione peroxidase gene (gpx), glutathione S-transferase enzyme gene (gst), and glutathione reductase gene (gr) are upregulated or downregulated to varying degrees. The WV and co-treatment planarians reduced MDA levels, increased the activities of oxidative stress biomarker enzymes, and restored gene expression levels. Our results show that low concentration of WV has protective effects on the oxidative damage caused by PFOS in the planarian.

This paper considers the derivative-based optimal investment strategies for an asset–liability management (ALM) problem under the mean–variance criterion in the presence of stochastic volatility. Specifically, an asset–liability manager is allowed to invest not only in a risk-free bond and a stock, but also in a derivative, whose price depends on the underlying price of the stock and its volatility. By solving a system of two backward stochastic differential equations, we derive the explicit expressions of the efficient strategies and the corresponding efficient frontiers in two cases, with and without the derivative asset. Moreover, we consider the special case of an optimal investment problem with no liability commitment, which is also not studied in the literature. We also provide some numerical examples to illustrate our results and find that the efficient frontier of the case with the derivative is always better than that of the case without the derivative. Moreover, under the same variance, the expectation of the case with the derivative can reach up to as twice as that of the case without the derivative in some situations.

Experiments were carried out to study the effects of nitrification inhibitors (NI) on the transformation of soil nitrogen (N) in purple soil and the effects on the N accumulation in different organs of citrus seedlings. In incubation and pot experiments, the rate of nitrification inhibitors 2-chloro-6-trichloro-methyl pyridine (Nitrapyrin), 3,4-dimethylpyrazole phosphate (DMPP) and dicyandiamide (DCD) was 2.4%, 1.0% and 5.0% of N rate, respectively. The trend of different nitrification inhibitors on ammonium nitrogen ( NH+4-N ), nitrate nitrogen ( NO-3-N ) content and pH was compared in incubation experiment; and the effect of different NI on the dry matter quality, N uptake of citrus seedling was studied in pot experiment. The results showed that NI could significantly inhibit soil nitrification in the early culture period (p DMPP > En (calculated as nitrogen application rate). Application of NI increased the height and dry matter accumulation, N accumulation of citrus seedling grown in pot experiment. Thus, application of NI would be helpful for improving N use efficiency in purple soil which is one of major soil types for citrus production in China.

Insurance contracts pricing, that is determining the risk loading added to the expected loss, plays a fundamental role in insurance business. It covers the loss from adverse claim experience and generates a profit. As market competition is a key component in the pricing exercise, this paper proposes a novel dynamic pricing game model with multiple insurers who are competing with each other to sell insurance contracts by controlling their insurance premium. Different with the existing works assuming deterministic surplus/loss, we consider stochastic surplus and adopt the linear Brownian motion model, i.e., a diffusion approximation to the classical Cramer–Lundberg model, for the aggregate claim amount. The risk exposure of an insurer is assumed to be affected by all insurers in the market. By solving a system of Hamilton–Jacobi–Bellman (HJB) equations, Nash equilibrium premium strategies are explicitly obtained for the insurers who are aiming to maximize their expected terminal exponential utilities. The representation form of the equilibrium strategies relates to the so-called M-matrix, which appears in many economic models. To investigate the robustness of equilibrium pricing strategies under model uncertainty, we further extend the model by allowing insurers to perceive ambiguity towards the aggregate claim loss. Closed-form expression for the robust premium strategies are obtained and comparative statics are carried out for model parameters.

In this paper, the mesoporous NiO nanowires (NWs) were synthesized by using SBA-15 silica as the hard templates with the nanocasting method, and then calcined from 550 to 750 °C. X-ray diffraction, transmission electron microscopy (TEM), nitrogen adsorption/desorption isotherm and UV-vis spectrum were used to characterize the morphology, phase structure and microstructure of the as-prepared samples. All results indicated that the calcination temperature greatly affected crystallization degree and specific surface area of the as-prepared NiO NWs. And the crystallization degree increased and specific surface area decreased with the calcination temperature. The higher specific surface area created more active sites for the surface redox reaction, while the higher crystallization degree led to the wider bandgap and made the charge carriers transport easily. It was concluded that the calcination temperature of NiO NWs greatly affected the gas-sensing performance. The optimized results from the gas-sensing behavior indicated that NiO NWs-650 based sensor exhibited the highest sensitivity to ethanol for the suitable calcination temperature. Furthermore, NiO NWs-650 sensor exhibited a better selectivity to ethanol than n-hexane, methanol, acetone and formaldehyde.

The mesoporous α-Fe 2 O 3 nanowires (NWs) were successfully synthesized by changing the calcination temperature from 550 to 750 °C (marked NWs-550, NWs-650 and NWs-750) via using SBA-15 silica as the hard templates with the nanocasting method. The characterization results indicated that the bandgap of the as-prepared samples hardly changed and the high BET surface areas changed a little with the calcination temperature from 550 to 750 °C. Mesoporous α-Fe 2 O 3 NWs had been found to possess the remarkable gas-sensing performance to ethanol gas. The gas-sensing behavior indicated that α-Fe 2 O 3 NWs-650 exhibited the higher response than that of α-Fe 2 O 3 NWs-550 and α-Fe 2 O 3 NWs-750. The calcination-temperature-dependent gas-sensing properties were mainly attributed to the competition of surface defects and body defects by the crystallization temperature. The lower calcination temperature could create more surface defects to improve the gas-sensing response, while the higher temperature would reduce the body defect and make the charge carriers transport easily. As the result, the suitable calcination temperature was desired to optimize the defects of nanostructures to improve the gas sensitivity.

In this paper, we study an insurer’s reinsurance–investment problem under a mean–variance criterion. We show that excess-loss is the unique equilibrium reinsurance strategy under a spectrally negative Levy insurance model when the reinsurance premium is computed according to the expected value premium principle. Furthermore, we obtain the explicit equilibrium reinsurance–investment strategy by solving the extended Hamilton–Jacobi–Bellman equation.

Nickel oxides (NiO) nanowires were synthesized using the ordered mesoporous silica SBA-15 as hard templates with the nanocasting method, and then mesoporous NiO nanowires (NiO MNWs) were separated from the dispersed NiO nanowires (NiO DNWs) by the centrifugation technique. XRD, TEM, nitrogen adsorption/desorption isotherm and UV–vis spectrum were used to characterize the phase structure and microstructure. Both samples existed in bundles with the different grain size and NiO MNWs with the larger grain size presented the higher mesopores percent. The specific surface area (92.61 m 2 /g) and bandgap (3.31 eV) of NiO MNWs were higher than those of NiO DNWs for the higher mesoporous-structure. Therefore, the NiO MNWs based sensor exhibited the good sensitivity and fast response-recovery to ethanol at 340 °C. The gas-sensing properties of NiO MNWs were better than those of the NiO DNWs, which should be attributed to the higher surface area and wider bandgap.

The production of high purity hydrogen via the sorption-enhanced steam reforming of acetic acid, a model compound of bio-oil, was investigated in this work. A bi-functional catalyst with stable catalytic activity and CO 2 -capture ability, Ni/Ce x Zr 1−x O 2 -CaO, was prepared by a sol–gel method and characterized in details by BET, XRD, TPR and SEM-EDX analytic techniques. The characterization of these materials showed that the catalysts were mainly composed of Ni, Ce x Zr 1−x O 2 and CaO. As CaO loading increased, a new species, CaZrO 3, with a perovskite structure was formed. The presence of CaZrO 3 in the catalysts acted as a barrier to CaO grain growth at high temperatures and thus improved the CO 2 -capture stability. These catalysts exhibited good CO 2 sorption capacity in 15 consecutive carbonation–calcination cycles, even at a high calcination temperature of 900 °C. Particularly, in case of the Ni/CZC-2.5 catalyst, 98% high purity H 2 could be obtained during the prebreakthrough stage when the catalysts were tested in the SESR of acetic acid at 550 °C with an S/C ratio of 4. In addition, high hydrogen purity was maintained over 15 cyclic reaction-calcination operations, which was mainly attributed to the uniform distribution of Ni, CaO, Ce x Zr 1−x O 2 and CaZrO 3 in the catalysts. These results indicated the great potential of the SESR technique for hydrogen production from bio-oil.

This paper considers an optimal investment problem for a defined contribution (DC) pension plan with default risk in a mean–variance framework. In the DC plan, contributions are supposed to be a predetermined amount of money as premiums and the pension funds are allowed to be invested in a financial market which consists of a risk-free asset, a defaultable bond and a risky asset satisfied a constant elasticity of variance (CEV) model. Notice that a part of pension members could die during the accumulation phase, and their premiums should be withdrawn. Thus, we consider the return of premiums clauses by an actuarial method and assume that the surviving members will share the difference between the return and the accumulation equally. Taking account of the pension fund size and the volatility of the accumulation, a mean–variance criterion as the investment objective for the DC plan can be formulated, and the original optimization problem can be decomposed into two sub-problems: a post-default case and a pre-default case. By applying a game theoretic framework, the equilibrium investment strategies and the corresponding equilibrium value functions can be obtained explicitly. Economic interpretations are given in the numerical simulation, which is presented to illustrate our results.

In this paper, we derive and study a pair of optimal reinsurance–investment strategies under the two-sided exit framework which aims to (1) maximize the probability that the surplus reaches the target b before ruin occurs over the time horizon [ 0 , e λ ] (where e λ is an independent exponentially distributed random time); (2) minimize the probability that ruin occurs before the surplus reaches the target b over the time horizon [ 0 , e λ ] . We assume the insurer can purchase proportional reinsurance and invest its wealth in a financial market consisting of a risk-free asset and a risky asset, where the dynamics of the latter is assumed to be correlated with the insurance surplus. By solving the associated Hamilton–Jacobi–Bellman (HJB) equation via a dual argument, an explicit expression for the optimal reinsurance–investment strategy is obtained. We find that the optimal strategy of objective (1) (objective (2) resp.) is always more aggressive (conservative resp.) than the strategy of minimizing the infinite-time ruin probability of Promislow and Young (2005). Due to the presence of the time factor e λ , the optimal strategy under objective (1) or (2) may lead to more aggressive positions as the wealth level increases, a behavior which may be more consistent with industry practices.

A new mononuclear ternary La(III) complex with mixed ligands of salicylic acid (Hsal) and 1,10-phenanthroline (phen), namely [La(sal)3(phen)2], has been synthesized and characterized. The structure of the La(III) complex was studied by elemental analysis, thermal analysis, infrared, UV–visible, and fluorescence spectroscopy, single-crystal X-ray diffraction, and tight-binding quantum chemical calculation. The crystal structure analysis reveals the La center was chelated by two phen and three sal ligands. Comparative studies on the bacteriostatic and bactericidal activities of the La(III) complex, ligands, and the lanthanum salt were completed against gram-positive and gram-negative bacteria. These studies demonstrate that the La(III) complex has efficient antibacterial activities toward the selected bacteria. The safety profile of the complex was studied using mice as animal models. The results show that the La(III) complex has low toxicity. The morphology of bacteria was observed by field emission scanning electron microscopy, showing that the La(III) complex may act on the cell envelope of bacteria to achieve good bactericidal effects. The results suggest that the La(III) complex may be developed as effective antibacterial drug candidates.

The dispersed and uniform hematite nanowires (α-Fe 2 O 3 NWs) with the different diameter were synthesized using SBA-15 as hard templates by the nanocasting method, and the diameter of α-Fe 2 O 3 NWs was about 4, 6 and 8 nm, respectively. The BET surface area of α-Fe 2 O 3 NWs changed a little, while the bandgap decreased from 2.07, 2.03 to 1.91 eV with the increasing diameter according to quantum size effect. Compared all samples, the sensitivity of α-Fe 2 O 3 NWs based gas-sensors increased from 10.64 to 11.43 with the bandgap and BET surface area α-Fe 2 O 3 NWs in 100 ppm ethanol at 300 °C, and the response–recovery time was also improved for the good crystallinity. It's concluded that the surface area greatly affected the gas-sensing performance of α-Fe 2 O 3 NWs based sensors, while the bandgap and crystallinity also influenced the gas-sensing behavior to some extent. The α-Fe 2 O 3 NWs based gas-sensors exhibited the high sensitivity, fast response–recovery and good selectivity to ethanol.

This article considers an optimal excess-of-loss reinsurance–investment problem for a mean–variance insurer, and aims to develop an equilibrium reinsurance–investment strategy. The surplus process is assumed to follow the classical Cramer–Lundberg model, and the insurer is allowed to purchase excess-of-loss reinsurance and invest her surplus in a risk-free asset and a risky asset. The market price of risk depends on a Markovian, affine-form and square-root stochastic factor process. Under the mean–variance criterion, equilibrium reinsurance–investment strategy and the corresponding equilibrium value function are derived by applying a game theoretic framework. Finally, numerical examples are presented to illustrate our results.

Inspired by the α -maxmin expected utility, we propose a new class of mean-variance criterion, called α -maxmin mean-variance criterion, and apply it to the reinsurance-investment problem. Our model allows the insurer to have different levels of ambiguity aversion (rather than only consider the extremely ambiguity-averse attitude as in the literature). The insurer can purchase proportional reinsurance and also invest the surplus in a financial market consisting of a risk-free asset and a risky asset, whose dynamics is correlated with the insurance surplus. Closed-form equilibrium reinsurance-investment strategy is derived by solving the extended Hamilton–Jacobi–Bellman equation. Our results show that the equilibrium reinsurance strategy is always more conservative if the insurer is more ambiguity-averse. When the dependence between insurance and financial risks are weak, the equilibrium investment strategy is also more conservative if the insurer is more ambiguity-averse. However, in order to diversify the portfolio, a more ambiguity-averse insurer may adopt a more aggressive investment strategy if the insurance market is very ambiguous. For an ambiguity-neutral insurer, the investment strategy is identical to the non-robust investment strategy.

This paper aims to derive the time-consistent investment strategy for the defined contribution (DC) pension plan under the mean-variance criterion. The financial market consists of a risk-free asset and a risky asset of which price process satisfies the constant elasticity of variance (CEV) model. Compared with the geometric Brownian motion model, the CEV model has the ability of capturing the implied volatility skew and explaining the volatility smile. The authors assume that the contribution to the pension fund is a constant proportion of the pension member’s salary. Meanwhile, the salary is stochastic and its volatility arises from the price process of the risky asset, which makes the proposed model different from most of existing researches and more realistic. In the proposed model, the optimization problem can be decomposed into two sub-problems: Before and after retirement cases. By applying a game theoretic framework and solving extended Hamilton-Jacobi-Bellman (HJB) systems, the authors derive the time-consistent strategies and the corresponding value functions explicitly. Finally, numerical simulations are presented to illustrate the effects of model parameters on the time-consistent strategies.

700-nm-thick silicon nitride-on-insulator (SNOI) is widely used for nonlinear applications due to its broadband nearly zero flattened dispersion. In this paper, we present a grating coupler for the TE mode of strip waveguides on 700-nm-thick SNOI. Focusing grating structure and inverse taper are combined to reduce the footprint to 70.2 μm × 19.7 μm. The peak coupling efficiency is -3.7 dB and the 1-dB bandwidth is 54 nm. The fabrication process is CMOS-compatible with only one additional etching step required.

This paper analyzes the equilibrium strategy of a robust optimal reinsurance-investment problem under the mean–variance criterion in a model with jumps for an ambiguity-averse insurer (AAI) who worries about model uncertainty. The AAI’s surplus process is assumed to follow the classical Cramer–Lundberg model, and the AAI is allowed to purchase proportional reinsurance or acquire new business and invest in a financial market to manage her risk. The financial market consists of a risk-free asset and a risky asset whose price process is described by a jump-diffusion model. By applying stochastic control theory, we establish the corresponding extended Hamilton–Jacobi–Bellman (HJB) system of equations. Furthermore, we derive both the robust equilibrium reinsurance-investment strategy and the corresponding equilibrium value function by solving the extended HJB system of equations. In addition, some special cases of our model are provided, which show that our model and results extend some existing ones in the literature. Finally, the economic implications of our findings are illustrated, and utility losses from ignoring model uncertainty, jump risks and prohibiting reinsurance are analyzed using numerical examples.

Chlorobenzenes (CBs) present in synthetic dyes are discharged into natural waters during the treatment of textile dyeing wastewater, which may have adverse effects on human and environment. In this study, the existence and removal of 12 CBs in different units of five treatment plants were examined. The ecological risk of CBs in textile dyeing wastewater was assessed by ambient severity (AS) and risk quotients (RQs). The results showed that trichlorobenzene, tetrachlorobenzene, pentachlorobenzene and hexachlorobenzene were ubiquitous in textile dyeing wastewater, and their distribution was similar. In one of the plants, the content of hexachlorobenzene was found to be as high as 9.277 μg/L in the raw water, which was an oil-water mixture. In other plants, there was no significant difference in the content and composition of CBs among influent and effluent suggesting that the conventional wastewater treatment plants cannot improve the existence of them. Monochlorobenzene and dichlorobenzene were not detected, which may have been related to strong volatility, biochemical properties, and weak instrument sensitivity. In the treatment process and effluent, trichlorobenzene is the main pollutant and accounted for 39.51% of all CB. CB removal was found only in the anaerobic system, while the aerobic system did not have the corresponding removal effect on CB and total organic carbon. According to ecological risk assessment, CBs in effluent has not been found the significant potential harm to human health (AS 1), but posed moderate ecological risk to aquatic ecosystem (RQs 0.1).

Whether the trans-regional transfer of resource-oriented enterprises produces a stress effect is a major issue concerning the green, sustainable, and high-quality development of resource-rich areas in the mid-west of China. Using the system engineering concept and socioeconomic statistics, in combination with a theoretical analysis and empirical testing, this study analyzed the functional characteristics of the natural environment in the region and clarified the mechanism characteristics by which a natural environment functional stress effect could be caused by the trans-regional transfer of resource-oriented enterprises. Resource-orientated industry data from 2000 to 2015 in the three mid-western provinces of Shanxi, Shaanxi, and Guizhou were selected for empirical testing. Several key findings were made. (1) The trans-regional transfer of resource-oriented enterprises had a significant strengthening effect on the five stress indicators of land subsidence, solid waste, waste water, waste gas, and dust in the three provinces of mid-west China. (2) The trans-regional transfer of resource-oriented enterprises led to the restoration of the natural environment in mining areas, which was coordinated by relevant governments and enterprises, resulting in a significant weakening of the land subsidence, solid waste, and waste water stress in the three provinces of the mid-west, as well as a significant weakening of the waste gas stress in Shaanxi Province and dust stress in Guizhou Province. (3) The trans-regional transfer of resource-oriented enterprises had a higher positive intensification effect than a negative weakening effect on the natural environment functional stress in the three provinces of the mid-west. (4) In a comparison of the effects of natural environment function stress due to the trans-regional transfer of resource-oriented enterprises there were large differences among the three provinces in terms of the intensifying and weakening flows of stress. The conclusions provide a theoretical basis for the formulation of relevant policies to regulate the trans-regional transfer of resource-oriented enterprises and reduce the stress effect.

We demonstrate an automated wavelength calibration scheme for a dual-ring based silicon electro-optic switch. By using an improved saddle point searching algorithm, the calibration over a full free spectral range of 6 nm is achieved.

This paper focuses on the optimal management problem for a general insurance company which holds shares of an insurance company and a reinsurance company. The general company aims to maximize the expected exponential utility of the weighted sum of the insurance company’s and the reinsurance company’s terminal wealth. In our model, the risk process is assumed to follow a jump-diffusion risk model in which the surplus process is a compound Poisson risk process perturbed by a diffusion. The insurance company transfers part of the risk due to insurance claims via the proportional reinsurance to the reinsurance company. In addition, both the insurance company and the reinsurance company are allowed to invest in a risk-free asset and a risky asset whose price process is described by the Heston model, respectively. By applying the method of stochastic control, we establish the Hamilton–Jacobi–Bellman equation and obtain the optimal reinsurance and investment strategies for the insurance company and the reinsurance company. Furthermore, numerical simulations are provided to illustrate the effects of model parameters on the optimal reinsurance and investment strategies.

Collaborative graph-based discriminant analysis (CGDA) has been recently proposed for dimensionality reduction and classification. It uses available samples to construct sample collaboration via L2 norm minimization-based representation, thus showing great computational efficiency. However, CGDA only constructs the intra-class graph, so it only takes into account local geometry and ignores the separability for samples in different classes. In this paper, we propose a novel method termed as collaborative representation based neighborhood preserving projection (CRNPP) for dimensionality reduction. By incorporating the intra-class and inter-class discriminant information into the graph construction of collaborative representation coefficients, CRNPP not only maintains the same level of time cost as CGDA, but also preserves both global and local geometry of the data simultaneously. In this way, the collaborative relationship of the data from the same class is strengthened while the collaborative relationship of the data from different classes is inhibited in the projection subspace. Experiments on benchmark face databases validate the effectiveness and efficiency of the proposed method.

Subspace clustering refers to the task of clustering a collection of points drawn from a high-dimensional space into a union of multiple subspaces that best fits them. State-of-the-art approaches have been proposed for tackling this clustering problem by using the low-rank or sparse optimization techniques. However, most of the traditional subspace clustering methods are developed for single-view data and are not directly applicable to the multi-view scenario. In this paper, we present a Manifold Regularized Multi-view Subspace Clustering (MRMSC) method to better incorporate the correlated and complementary information from different views. MRMSC yields a unified affinity representation by joint optimization across different views. To respect the data manifold locally, the graph Laplacian is constructed to maintain the intrinsic geometrical structure of each view. In the multi-view integration, a sparsity constraint is imposed to the unified affinity representation in order to better reflect the data relationship from multiple views or features. In experiments, we compared the performance of clustering using MRMSC with the single-view and concatenate-multi-view methods on different datasets. The results showed that better clustering performance can be achieved by fusing the multiple features with a unified affinity representation by MRMSC.

Bisphenol A (BPA), an endocrine-disrupting chemical, has received much attention from researchers and the general public. In this paper, a novel method of determining BPA at trace levels was developed, using magnetic reduced graphene oxide (rGO-Fe3O4)-based solid-phase extraction coupled with dispersive liquid–liquid microextraction (DLLME), followed by high-performance liquid chromatographic determination. The rGO-Fe3O4 was prepared and then characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, and vibrating sample magnetometry. The greatest saturation magnetization of rGO-Fe3O4 was up to 43.8 emu g−1, which allowed rapid isolation of the rGO-Fe3O4 from solutions upon applying an appropriate magnetic field. The effects of solution pH, adsorbent amount, type and volume of eluent and extraction solvent, extraction time, and salt concentration on the extraction efficiency of BPA were examined and optimized. Under the optimum conditions, an enrichment factor of 5217 and an LOD of 0.01 μg L−1 for BPA were obtained. The reusability of rGO-Fe3O4 for at least 12 repeated cycles without any significant decrease in the extraction recovery of BPA was demonstrated. The proposed method was applied to the determination of BPA in different real water samples, with relative recoveries of 84.8–104.9 % and RSDs of 0.8–8.3 % in the spiked concentration range 1–10 μg L−1.

International audience; AbstractBiofortification is a strategy for overcoming human zinc (Zn) deficiency, especially in rural areas of developing countries. Actually, biofortification by foliar Zn application has been demonstrated at small scale, but not at large scale due to the absence of economic analysis. Therefore, here, we conducted the first cost-effectiveness analysis using the method of “disability-adjusted life year” measuring the health burden. We thus quantified the cost of agronomic biofortification of wheat with Zn in three major wheat-growing regions of China. Our results show that the current annual health burden due to human Zn deficiency, defined as numbers of disability-adjusted life years lost, is 0.21 million years for the region under single wheat plantation, 0.79 million years for the region under wheat-maize rotation, and 0.38 million years for the region under wheat-rice rotation. Comparing with traditional wheat diets in these three regions, the consumption of agronomically Zn-biofortified wheat diets could increase the daily Zn intakes of infants and children under 5 years of age. These increased daily Zn intakes consequently reduce the health burden due to human Zn deficiency in these regions by up to 56.6 %. According to cost-effectiveness analysis, the cost for saving one disability-adjusted life year in these regions ranges from US$ 226 to US$ 594 for foliar Zn application alone. The cost ranges from US$ 41 to US$ 108 when foliar Zn and pesticide applications are combined to reduce labor costs. This cost of US$ 41–108 under the combined application of foliar Zn plus pesticide is lower than the World Bank’s standard.

In this study, α-Fe2O3 nanowires were synthesized using mesoporous SBA-15 silica as the hard templates with the nanocasting method, and then mesoporous α-Fe2O3 nanowire bundles (NWBs) were separated from the well-dispersed α-Fe2O3 nanowires (NWs) by the centrifugation technique. Both samples were characterized by x-ray diffraction, transmission electron microscopy (TEM), nitrogen adsorption/desorption isotherm and UV-vis spectra. All results indicated that the α-Fe2O3 NWBs with mesoporous structure presented a higher BET surface area (95 m(2) g(-1)) and wider bandgap (2.08 eV) than those of α-Fe2O3 NWs (32 m(2) g(-1) and 1.91 eV). The bandgap of α-Fe2O3 NWBs was in accordance with the bulk α-Fe2O3, while the BET surface area was much higher. The results from the gas-sensing measurement revealed that the α-Fe2O3 NWBs based gas sensor exhibited a high sensitivity of 21.7, fast response-recovery of 7.5 s and 1 s, and good selectivity to ethanol at 340 °C. The sensitivity (21.7) for ethanol of α-Fe2O3 NWBs was much better than that of the α-Fe2O3 NWs (12.2), which should be attributed to the higher BET surface area and wider bandgap of α-Fe2O3 NWBs.

In this paper, we present a single microring resonator structure formed by incorporating a reflectivity-tunable loop mirror for the tuning of resonance spacing. Based on the optical mode-splitting in the resonator structure, spacing between two adjacent resonances can be tuned from zero to one whole free spectral range (FSR) by controlling the coupling strength between the two counter-propagating degenerate modes in the microring resonator. In experiment, by integrating metallic microheater, the resonance-spacing tuning over the whole FSR (1.17 nm) is achieved within 9.82 mW heating power dissipation. The device is expected to have potential applications in reconfigurable optical filtering and microwave photonics.

Thick Silicon nitride-on-insolater (SNOI) is widely used for nonlinear applications due to its broadband nearly-zero flattened dispersion. In this paper, we present a grating coupler for strip waveguides on 700-nm-thick SNOI. Focusing grating structure and inverse taper are combined to minify the footprint to 70μm × 19μm. The peak couplin g efficiency is −3.7dB and the 1-dB bandwidth is 54nm.

Iron (Fe) and zinc (Zn) are essential micronutrient for both human and plants, but Fe and Zn deficiency is prevalent in the world especially developing countries including India and China. Biofortification is considered the most promising approach to alleviate Fe and Zn malnutrition. Thus this study was mainly conducted to review the recent progresses on the strategies of the processes affecting Fe and Zn accumulation in edible portion of crops at genetic and physiological levels. While agricultural approaches are useful to gain Fe and Zn enriched cereals, therefore agro-biofortification of Fe and Zn by agricultural approaches was also reviewed for possible solution in intensive agriculture system.