Based on the magnetic interaction energy, using derivative of the magnetic energy density, a model is proposed to compute the magnetic-induced shear modulus of magnetorheological elastomers. Taking into account the in...Based on the magnetic interaction energy, using derivative of the magnetic energy density, a model is proposed to compute the magnetic-induced shear modulus of magnetorheological elastomers. Taking into account the influences of particles in the same chain and the particles in all adjacent chains, the traditional magnetic dipole model of the magnetorheological elastomers is modified. The influence of the ratio of the distance etween adjacent chains to the distance between adjacent particles in a chain on the magnetic induced shear odulus is quantitatively studied. When the ratio is large, the multi-chain model is compatible with the single chain model, but when the ratio is small, the difference of the two models is significant and can not be neglected. Making certain the size of the columns and the distance between adjacent columns, after constructing the computational model of BCT structures, the mechanical property of the magnetorheological elastomers composed of columnar structures is analyzed. Results show that, conventional point dipole model has overrated the magnetic-induced shear modulus of the magnetorheological elastomers. From the point of increasing the magnetic-induced shear modulus, when the particle volume fraction is small, the chain-like structure exhibits better result than the columnar structure, but when the particle volume fraction is large,the columnar structure will be better.展开更多
Magnetorheological elastomer （MRE） is a new kind of smart materials, the rheological properties can be controlled rapidly by the external magnetic field. It is mainly composed of rubber and micron-sized ferromagneti...Magnetorheological elastomer （MRE） is a new kind of smart materials, the rheological properties can be controlled rapidly by the external magnetic field. It is mainly composed of rubber and micron-sized ferromagnetic particles, which forms a chain-like structure. Therefore its mechanical, electric, and magnetic properties can be changed by the applied magnetic field, which is called as the magneto-induced effect. But this effect is not remarkable enough currently for the engineering application. So it is important for material preparation to optimize parameters to enhance the magneto-induced effect. In this work, based on chain-like model, some factors influencing the magneto-induced effect of MRE were analyzed theoretically by using dipole method with the normal distribution of chain＇s angle introduced. The factors included the oblique angle of particles chains, magnetic field intensity, and shear strain, etc. Some experiments were also carried out.展开更多
In this paper, we present a Joint Source-Channel Decoding algorithm (JSCD) for Low-Density Parity Check (LDPC) codes by modifying the Sum-Product Algorithm (SPA) to account for the source redun-dancy, which results fr...In this paper, we present a Joint Source-Channel Decoding algorithm (JSCD) for Low-Density Parity Check (LDPC) codes by modifying the Sum-Product Algorithm (SPA) to account for the source redun-dancy, which results from the neighbouring Huffman coded bits. Simulations demonstrate that in the presence of source redundancy, the proposed algorithm gives better performance than the Separate Source and Channel Decoding algorithm (SSCD).展开更多
We study the one-loop contribution of the effective flavor changing neutral couplings （FCNC） tcZ on the charm quark electric dipole moment. Using the known limits on the top and charm quarks electric dipole moments,...We study the one-loop contribution of the effective flavor changing neutral couplings （FCNC） tcZ on the charm quark electric dipole moment. Using the known limits on the top and charm quarks electric dipole moments, we place limits on these FCNC anomalous couplings.展开更多
While our understanding of male reproductive strategies is informed by extensive investigations into endocrine mechanisms, the proximate mechanisms by which females compete for mates and adjust reproduction to social ...While our understanding of male reproductive strategies is informed by extensive investigations into endocrine mechanisms, the proximate mechanisms by which females compete for mates and adjust reproduction to social environment remains enigmatic. We set out to uncover endocrine correlates of mate choice, social environment, and reproductive investment in female red-backed fairy-wrens Malurus melanocephalus. In this socially monogamous, yet highly sexually promiscuous species, females experience discrete variation in the phenotype of their mates, which vary in both plumage signals and level of paternal care, and in the composition of their breeding groups, which consist of either the pair alone or with an additional cooperative auxiliary; fe- male investment varies according to these social parameters. We found that androgen, estrogen, and glucorticoid levels varied with reproductive stage, with highest androgen and estrogen concentrations during nest construction and highest corticosterone concentrations during the pre-breeding stage. These stage-dependent patterns did not vary with male phenotype or auxiliary presence, though androgen levels during pre-breeding mate selection were lower in females obtaining red/black mates than those obtaining brown mates. We found no evidence that androgen, estrogen, or corticosterone levels during the fertile period were re- lated to extra-pair young （EPY） frequency. This study demonstrates clear changes in steroid levels with reproductive stage, though it found little support for variation with social environment. We suggest hormonal responsiveness to social factors may be physiologically constrained in ways that are bypassed through exogenous hormone manipulations.展开更多
We explore the spin-boson model in a special case, i.e., with zero local field. In contrast to previous studies, we find no possibility for quantum phase transition （QPT） happening between the localized and delocali...We explore the spin-boson model in a special case, i.e., with zero local field. In contrast to previous studies, we find no possibility for quantum phase transition （QPT） happening between the localized and delocalized phases, and the behavior of the model can be fully characterized by the even or odd parity as well as the parity breaking, instead of the QPT, owned by the ground state of the system. The parity breaking mentioned in our case is completely different from the spontaneously broken symmetry relevant to the conventionally defined QPT in previous studies. Our analytical treatment about the eigensolution of the ground state of the model presents for the first time a rigorous proof of no- degeneracy for the ground state of the model, which is independent of the bath type, the degrees of freedom of the bath and the calculation precision. We argue that the QPT mentioned previously appears due to incorrect employment of the ground state of the model and/or unreasonable treatment of the infrared divergence existing in the spectral functions for Ohmic and sub-Ohmic dissipations.展开更多
Sexual isolation resulting from differences in mate choice behaviors is a hallmark of rapidly-speciating lineages. When present, asymmetrical sexual isolation may provide insights into the mechanisms responsible for t...Sexual isolation resulting from differences in mate choice behaviors is a hallmark of rapidly-speciating lineages. When present, asymmetrical sexual isolation may provide insights into the mechanisms responsible for the evolutionary change in mate signaling traits. In particular, Kaneshiro＇s hypothesis suggests that divergence in sexual characters between populations may arise in allopatry when ＇derived＇ founding populations are subject to severe population bottlenecks, accompanied by a relaxation of sexual selection relative to ＇ancestral＇ source populations. In the present study, we tested predictions of asymmetrical sexual isolation between two allopatric species of Hawaiian Laupala crickets, representing ＇ancestral＇ （L. makaio） and ＇derived＇ （L. nigra） taxa. While crickets in this genus are notable for rapid divergence of male courtship songs, these species share similar song types, thus suggesting that patterns of sexual isolation are likely due to other mating cues. Analysis of behavioral responses in conspeci- fic and heterospecific ＇no-choice＇ mating trials revealed pronounced asymmetrical isolation in the direction predicted by Kane- shiro＇s hypothesis, wherein we observed a significant reduction in mating success for crosses involving ＇derived＇ males paired with ＇ancestral＇ females, compared to the reciprocal heterospecific and both conspecific pairings. Further dissection of courtship behaviors suggested this difference did not reflect male mate choice, but rather, marked reduced spermatophore acceptance rates by ＇ancestral＇ females paired with ＇derived＇ males. The results are discussed with respect to founder effect models of speciatiou and the potential role of chemosensory signals in mate choice in these species [Current Zoology 59 （2）： 230-238, 2013].展开更多
文摘Based on the magnetic interaction energy, using derivative of the magnetic energy density, a model is proposed to compute the magnetic-induced shear modulus of magnetorheological elastomers. Taking into account the influences of particles in the same chain and the particles in all adjacent chains, the traditional magnetic dipole model of the magnetorheological elastomers is modified. The influence of the ratio of the distance etween adjacent chains to the distance between adjacent particles in a chain on the magnetic induced shear odulus is quantitatively studied. When the ratio is large, the multi-chain model is compatible with the single chain model, but when the ratio is small, the difference of the two models is significant and can not be neglected. Making certain the size of the columns and the distance between adjacent columns, after constructing the computational model of BCT structures, the mechanical property of the magnetorheological elastomers composed of columnar structures is analyzed. Results show that, conventional point dipole model has overrated the magnetic-induced shear modulus of the magnetorheological elastomers. From the point of increasing the magnetic-induced shear modulus, when the particle volume fraction is small, the chain-like structure exhibits better result than the columnar structure, but when the particle volume fraction is large,the columnar structure will be better.
基金This work was supported by the National Natural Science Foundation of China （No.50830202 and No.60804018） and the Plan of the Excellent Talent for the New Century （NCET-07-0910）. The authors also appreciate the help in the experimental instruments of Professor Xing-long Gong of University of Science and Technology of China deeply.
文摘Magnetorheological elastomer （MRE） is a new kind of smart materials, the rheological properties can be controlled rapidly by the external magnetic field. It is mainly composed of rubber and micron-sized ferromagnetic particles, which forms a chain-like structure. Therefore its mechanical, electric, and magnetic properties can be changed by the applied magnetic field, which is called as the magneto-induced effect. But this effect is not remarkable enough currently for the engineering application. So it is important for material preparation to optimize parameters to enhance the magneto-induced effect. In this work, based on chain-like model, some factors influencing the magneto-induced effect of MRE were analyzed theoretically by using dipole method with the normal distribution of chain＇s angle introduced. The factors included the oblique angle of particles chains, magnetic field intensity, and shear strain, etc. Some experiments were also carried out.
文摘In this paper, we present a Joint Source-Channel Decoding algorithm (JSCD) for Low-Density Parity Check (LDPC) codes by modifying the Sum-Product Algorithm (SPA) to account for the source redun-dancy, which results from the neighbouring Huffman coded bits. Simulations demonstrate that in the presence of source redundancy, the proposed algorithm gives better performance than the Separate Source and Channel Decoding algorithm (SSCD).
文摘We study the one-loop contribution of the effective flavor changing neutral couplings （FCNC） tcZ on the charm quark electric dipole moment. Using the known limits on the top and charm quarks electric dipole moments, we place limits on these FCNC anomalous couplings.
基金Acknowledgement We sincerely appreciate the commendable field efforts of a large number of field technicians who assisted with data collection during the course of this study, as well as logistical support provided by B. Congdon, T. Daniel, J. Lindsay and D. Westcott. We also thank members of the Schwabl and Webster labs for their valuable input throughout. Thanks also to Becca Sail＇an and Maren Vitousek for the invitation to contribute to this volume. This research was conducted with appropriate permits and permissions from the governments of Queensland and Australia, and material is based upon work supported by the National Science Foundation （USA） through grants to MSW and HS and a graduate traineeship to DGB.
文摘While our understanding of male reproductive strategies is informed by extensive investigations into endocrine mechanisms, the proximate mechanisms by which females compete for mates and adjust reproduction to social environment remains enigmatic. We set out to uncover endocrine correlates of mate choice, social environment, and reproductive investment in female red-backed fairy-wrens Malurus melanocephalus. In this socially monogamous, yet highly sexually promiscuous species, females experience discrete variation in the phenotype of their mates, which vary in both plumage signals and level of paternal care, and in the composition of their breeding groups, which consist of either the pair alone or with an additional cooperative auxiliary; fe- male investment varies according to these social parameters. We found that androgen, estrogen, and glucorticoid levels varied with reproductive stage, with highest androgen and estrogen concentrations during nest construction and highest corticosterone concentrations during the pre-breeding stage. These stage-dependent patterns did not vary with male phenotype or auxiliary presence, though androgen levels during pre-breeding mate selection were lower in females obtaining red/black mates than those obtaining brown mates. We found no evidence that androgen, estrogen, or corticosterone levels during the fertile period were re- lated to extra-pair young （EPY） frequency. This study demonstrates clear changes in steroid levels with reproductive stage, though it found little support for variation with social environment. We suggest hormonal responsiveness to social factors may be physiologically constrained in ways that are bypassed through exogenous hormone manipulations.
基金Supported by National Fundamental Research Program of China under Grant No.2012CB922102National Natural Science Foundation of China under Grant Nos.10974225 and 11004226State Key Laboratory Funding of WIPM
文摘We explore the spin-boson model in a special case, i.e., with zero local field. In contrast to previous studies, we find no possibility for quantum phase transition （QPT） happening between the localized and delocalized phases, and the behavior of the model can be fully characterized by the even or odd parity as well as the parity breaking, instead of the QPT, owned by the ground state of the system. The parity breaking mentioned in our case is completely different from the spontaneously broken symmetry relevant to the conventionally defined QPT in previous studies. Our analytical treatment about the eigensolution of the ground state of the model presents for the first time a rigorous proof of no- degeneracy for the ground state of the model, which is independent of the bath type, the degrees of freedom of the bath and the calculation precision. We argue that the QPT mentioned previously appears due to incorrect employment of the ground state of the model and/or unreasonable treatment of the infrared divergence existing in the spectral functions for Ohmic and sub-Ohmic dissipations.
文摘Sexual isolation resulting from differences in mate choice behaviors is a hallmark of rapidly-speciating lineages. When present, asymmetrical sexual isolation may provide insights into the mechanisms responsible for the evolutionary change in mate signaling traits. In particular, Kaneshiro＇s hypothesis suggests that divergence in sexual characters between populations may arise in allopatry when ＇derived＇ founding populations are subject to severe population bottlenecks, accompanied by a relaxation of sexual selection relative to ＇ancestral＇ source populations. In the present study, we tested predictions of asymmetrical sexual isolation between two allopatric species of Hawaiian Laupala crickets, representing ＇ancestral＇ （L. makaio） and ＇derived＇ （L. nigra） taxa. While crickets in this genus are notable for rapid divergence of male courtship songs, these species share similar song types, thus suggesting that patterns of sexual isolation are likely due to other mating cues. Analysis of behavioral responses in conspeci- fic and heterospecific ＇no-choice＇ mating trials revealed pronounced asymmetrical isolation in the direction predicted by Kane- shiro＇s hypothesis, wherein we observed a significant reduction in mating success for crosses involving ＇derived＇ males paired with ＇ancestral＇ females, compared to the reciprocal heterospecific and both conspecific pairings. Further dissection of courtship behaviors suggested this difference did not reflect male mate choice, but rather, marked reduced spermatophore acceptance rates by ＇ancestral＇ females paired with ＇derived＇ males. The results are discussed with respect to founder effect models of speciatiou and the potential role of chemosensory signals in mate choice in these species [Current Zoology 59 （2）： 230-238, 2013].
