Mean-variance model based on filters of minimum spanning tree

This study aims to reduce the statistical uncertainty of the correlation coefficient matrix in the mean-variance model of Markowitz. A filtering algorithm based on minimum spanning tree (MST) is proposed. Daily data of the 30 stocks of the Hang Seng Index (HSI) and Dow Jones Index (DJI) from 2004 to 2009 are selected as the base dataset. The proposed algorithm is compared with the Markowitz method in terms of risk, reliability, and effective size of the portfolio. Results show that (1) although the predicted risk of portfolio built with the MST is slightly higher than that of Markowitz, the realized risk of MST filtering algorithm is much smaller; and (2) the reliability and the effective size of filtering algorithm based on MST is apparently better than that of the Markowitz portfolio. Therefore, conclusion is that filtering algorithm based on MST improves the mean-variance model of Markowitz.     

Characterization of an endo-1,4-β-glucanase from Lilium longiflorum that functioned in pollen germination and pollen tube growth

Endo-β-glucanases play vital roles in the regulation of pollen tube growth. Here, a previously identified endo-l,4-β-glucanase from Lilium Iongiflorum （lily）, named LlpCell, was expressed in Escherichia coli, purified, and further investigated for its physiological function. The recombinant LlpCell protein hydrolyzed carboxy-methylcellulose （CMC） and exhibited activity towards laminarin from Eisenia. arborea and 1,3：l,4-β-glucan of barley. The pH for the optimum activity was 6.0 and the value of Km calculated from CMC was 5.0 mg/mL. Adding EDTA resulted in the total loss of the enzymatic activity, and this effect could be restored by the addition of Ca^2＋. Western blotting analysis showed that LlpCell protein was present in pollen grains and rehydrated pollen grains, and the amount of the protein was increased during pollen germinating, but not in the pollen tube. Consistently, the immunofluorescence labeling study with the antibody against LIpCell also indicated the presence of LIpCell at the begin-ning of germination, but not in the elongating pollen tube. Furthermore, incubation of LlpCell with pollen at the beginning of pollen germination increased the germination percentage and the length of pollen tube. All of these results suggested that LlpCell could play an important role in the regulation of lily pollen germination and the initiation of pollen tube growth.     

Electromagnetic behavior of two-dimensional quasi-crystal left-handed materials with dendritic unit

We demonstrated a two-dimensional quasi-crystal dendritic structure model with negative permeability. The microwave transmission and reflection properties of periodic and quasi-crystal dendritic structure mediums with varied angle incidence were measured. The results showed that the resonant peaks of quasi-crystal negative permeability samples and left-handed samples had tiny shift with the altering of incident angle. Because of the influence of coupling between quasi-crystal dendritic cells, the resonance of the entire material was enhanced or weakened. The quasi-crystal dendritic structure model will provide an easy method to design isotropic left-handed materials （LHMs）.     

Soluble Jagged 1/Fc chimera protein induces the differentiation and maturation of bone marrow-derived dendritic cells

A soluble Jagged 1/Fc chimera protein （Jagged 1/Fc） was directly used to induce differentiation and maturation of bone marrow-derived dendritic cells （DCs） in mice in vitro. A model of inducing and amplifying DCs in vitrowas established. The effect of Jagged 1/Fc on morphology of DCs induced by both rmGM-CSF and rmlL-4 was observed under a confocal microscope. A fluorescein-labeled monoclonal antibody staining combined with flow cytometry was applied to detect the effect of Jagged 1/Fc on the expression of CD11c, MHC-Ⅱ, CD86, CD80 and CD40 molecules on the surface of DCs. The results showed that Jagged 1/Fc did not affect the morphological properties of DC differentiation induced by both rmGM-CSF and rmlL-4. But it could promote the differentiation and maturation of DCs induced by both. The effect of it was strikingly different in the expression profile of co-stimulating molecules and the morphologic properties of DCs from lipopolysaccharide （LPS）. The levels of MHC-Ⅱ and CD40 molecule expression on the surface of DCs stimulated by Jagged 1/Fc were significantly lower than those stimulated by LPS, and the level of CD80 expression on the surface of DCs induced by Jagged 1/Fc was near to that induced by LPS. Jagged 1/Fc had no influence on the expression of CD86 molecule on the surface of DCs. Jagged 1/Fc when used alone could not maintain the growth, differentiation and maturation of DCs. All the findings indicate that Jagged 1/Fc influences the differentiation and maturation of DCs, which is not markedly similar to LPS, providing important evidence for its development and application as a novel immunosuppressant.     

Lithium bond structures of HnY （n=2, 3; Y=O,S, N）…LiNH2 and the abnormal blue shift of N-Li bond

The optimized geometries of the complexes between HnY （n=2, 3; Y=O, S, N） and LiNH2 have been calculated at the B3LYP/6-311＋＋G^＊＊ and MP2/6-311＋＋G^＊＊ levels. Three stable complexes were obtained. Frequency analysis showed that the enlarged 2N-4Li presents the abnormal blue shift in three complexes. The calculated binding energy with basis set super-position error （BSSE） and zero-point vibrational energy （ZPE） corrections of complex Ⅰ-Ⅲ is -58.65, -31.66 and -69.59 kJ·mol^-1 （MP2）, respectively. Natural bond orbital theory （NBO） analysis has been performed, and the results revealed that the H2O…LiNH2 （complex I） and H3N…LiNH2 （complex Ⅲ） are formed with coexisting σ-s and n-s type lithium bond interactions, complex Ⅱ is formed with ττ-s type lithium bond interaction between HnY （n=2,3; Y=O, N） and LiNH2, and H2S…LiNH2 （complex Ⅱ） is formed with n-s type lithium bond interaction between H2S and LiNH2. Natural resonance theory （NRT） and atom in molecule （AIM） theory have also been studied to investigate the bond order and topological properties of the lithium bond structures.     

Preparation and luminescence characteristics of Sr3SiO5：Eu^2＋ phosphor for white LED

The Sr3SiO5：Eu^2＋ phosphor was synthesized by high temperature solid-state reaction. The emission spectrum of Sr3SiO5：Eu^2＋ shows two bands centered at 487 and 575 nm, which well agree with the theoretic values of emission spectrum. The excitation spectrum for 575 nm emission center has several excitation bands at 365, 418, 458 and 473 nm. And the results show that the emission spectrum of Sr3SiO5：Eu^2＋ is influenced by the Eu^2＋ concentration. The relative emission spectra of the white-emitting InGaN-based YAG：Ce^3＋ LED and Sr3SiO5：Eu^2＋ LED were investigated. The results show that the color development of InGaN-based Sr3SiO5：Eu^2＋ is better than that of InGaN-based YAG：Ce^3＋, and the CIE chromaticity of InGaN-based Sr3SiO5：Eu^2＋ is （x=0.348, y=0.326）.     

Drifting bands of solar radio spikes

The solar flare （1N/C5.3） occurred in NOAA 8742 on October 27, 1999, end the accompanied complex radio burst was observed by the spectrometer with both high temporal （5 ms） end frequency （10 MHz） resolutions at Purple Mountain Observatory （PMO）. It started at 04：27：42 UT, peaked at 04：28：42 UT end ended at 04：29：18 UT. The most significant feature of the event might be the sequential spikes in both time and frequency to form three slow drift bands over the frequency range of -5 to ≥7.5 GHz with almost the same drift rate about 2.7 GHz/s. The relative bandwidth for the individual spikes varied from 1.6% to 4.9%, typically 3.3%. Based on electron cyclotron maser action driven by loss-cone enisotropy, the rare phenomena of slow drift band consisting of spikes were interpreted by spike source moving back and forth along the magnetic loop. Also, the estimations of the narrow bandwidths of spike given by electron cyclotron maser theory coincided well with the observations.     

Development of <Emphasis Type="Italic">Gossypium barbadense</Emphasis> chromosome segment substitution lines in the genetic standard line TM-1 of <Emphasis Type="Italic">Gossypium hirsutum</Emphasis>

Chromosome segment substitution lines （CSSL） consist of a battery of near-isogenic lines that have been developed and cover the entire genome of some crops. With the exception of one homozygous chromosome segment transferred from a donor parent, the remaining genome of each CSSL line is the same as the recipient parent. It is an ideal material for genome research and particularly QTL mapping. In the present study, we first developed one set of CSSL lines using G hirsutum acc. TM-1 （the genetic standard）, as the recipient parent and G barbadense cv. Hai7124 as the donor parent using molecular assistedlselection in BC5S1-3 generations. The CSSL consisted of 330 different lines, in which 1-4 different lines had the same or overlapping substituted segments. The genetic length of the substituted segments covered 5271.9 cM with an average segment distance of 10.9 cM, 1.5 times the total genetic length of Upland cotton （3514.6 cM）. The substituted segments of each line varied in length, ranging from 3.5 cM for the shortest segment to 23.2 cM in the longest segment. Our CSSL have not yet to cover the entire tetraploid cotton genome, due to the absence of some donor parent interval segments.     

Effects of dietary nickel on detoxification enzyme activities in the midgut of <Emphasis Type="Italic">Spodoptera litura</Emphasis> Fabricius larvae

Nickel accumulated in midugt of Spodoptera litura Fabricius could induce the expression of metallothionein, one of the most important detoxification proteins in organisms. In the present study, the effects of dietary nickel on the activities of detoxification enzymes, such as carboxylesterase （CarE） and giutathione S-transferase （GST） in the midgut of S. litura larvae have been studied to get an understanding of the detoxification mechanisms of S. litura larvae to excessive nickel. Results showed that CarE activities in the midgut of the 5th instar larvae decreased at lower levels of nickel （≤5 mg/kg）, while increased with increasing nickel doses at higher levels of nickel （≥10 mg/kg） exposure in successive 3 generations. CarE activities of the 6th instar larvae were also characterized as inhibited at low levels of nickel exposure, and improved at higher levels in the 1st generation. CarE activities of 6th instar larvae in the 2nd and 3rd generations were all lower than that in control. However, GST activities in the midgut of the 5th and 6th instar larvae all increased with increasing nickel doses （1 --20 mg/kg） in diets.