EM and SAGE Algorithms for DOA Estimation in the Presence of Unknown Uniform Noise

The existing expectation maximization (EM) and space-alternating generalized EM (SAGE) algorithms are only applied to direction of arrival (DOA) estimation in known noise. In this paper, the two algorithms are designed for DOA estimation in unknown uniform noise. Both the deterministic and random signal models are considered. In addition, a new modified EM (MEM) algorithm applicable to the noise assumption is also proposed. Next, these EM-type algorithms are improved to ensure the stability when the powers of sources are not equal. After being improved, simulation results illustrate that the EM algorithm has similar convergence with the MEM algorithm, the SAGE algorithm outperforms the EM and MEM algorithms for the deterministic signal model, and the SAGE algorithm cannot always outperform the EM and MEM algorithms for the random signal model. Furthermore, simulation results show that processing the same snapshots from the random signal model, the SAGE algorithm for the deterministic signal model can require the fewest computations.

Three-dimensional character of the deformation twin in magnesium

Deformation twins are three-dimensional domains, traditionally viewed as ellipsoids because of their two-dimensional lenticular sections. In this work, we performed statistical analysis of twin shapes viewing along three orthogonal directions: the 'dark side' (DS) view along the twin shear direction (η₁), the twinning plane normal (TPN) view (k₁) and the 'bright side' (BS) view along the direction λ(=k₁ × η₁). Our electron back-scatter diffraction results show that twins in the DS and BS views normally exhibit a lenticular shape, whereas they show an irregular shape in the TPN view. Moreover, the findings in the TPN view revealed that twins grow faster along λ the lateral direction than along η₁ the forward propagation direction at the initial stages of twin growth. These twin sections are irregular, indicating that growth is locally controlled and the overall shape is not perfectly ellipsoidal. We explain these findings using atomistic models, and ascribe them to differences in the mobility of the edge and screw components of the twinning dislocations.

Cryosurgery for treatment of subcutaneously xenotransplanted tumors in rats and its effect on cellular immunity

Cryosurgery has shown encouraging therapeutic effects on some solid tumors but its effect on the cellular immunity remains unclear. We developed a subcutaneously xenotransplanted tumor model in SD rats to directly evaluate the immune response by detecting the serum cytokine levels, T-cell responses to tumor derived antigens, and the cytolytic activity of peripheral blood mononuclear cells against the W256 cancer line with apoptosis of cells being detected using TUNEL method. 66 SD rats were divided into 2 groups with group A having 36 rats and group B having 30 rats. 30 rats in group B were equally divided into 3 groups, tumor group B, cryosurgery group B and surgery group B, with 10 rats each. 36 rats in group A were equally divided into 2 groups, cryosurgery group A and tumor group A and treatment was done accordingly. The results showed that cryosurgery induced not only destruction of the tumor cells but also cell apoptosis around the cryosurgery foci. The apoptosis ratio reached the peak 12 h after cryosurgery, with an apoptosis rate of (68.28 ± 7.85)% .Compared with surgical resection that caused significant reduction in CD31 and CD41 cell percentages, cryosurgery resulted in significantly increased percentages of CD31 and CD41 cells (P < 0.05) with a relative increase of the CD41/CD81 cell ratio. However, sIL-2R level of peripheral blood of rats in cryosurgery group which decreased more rapidly than that in surgery group over time was significantly different 3 and 5 weeks after treatment compared to surgery group (P < 0.01). Moreover, cytotoxicity of mononuclear cell was significantly enhanced after cryosurgery, which is significantly higher in cryosurgery group (P = 0.05). These results demonstrate that in addition to tumor cell destruction, cryosurgery also results in enhanced cellular immunity and antitumor immune response of the rats with subcutaneously xenotransplanted tumor, suggesting the great potential of argon-helium cryosurgery in clinical management.

Observation of two new N* peaks in J/psi-->ppi-n and ppi+n decays

The decay J/psi-->NNpi provides an effective isospin 1/2 filter for the piN system due to isospin conservation. Using 58x10(6) J/psi decays collected with the Beijing Electromagnetic Spectrometer at the Beijing Electron Positron Collider, more than 100 thousand J/psi-->ppi-n+c.c. events are obtained. Besides the two well-known N* peaks at around 1500 MeV/c2 and 1670 MeV/c2, there are two new, clear N* peaks in the ppi invariant mass spectrum around 1360 MeV/c2 and 2030 MeV/c2 with statistical significance of 11sigma and 13sigma, respectively. We identify these as the first direct observation of the N*(1440) peak and a long-sought missing N* peak above 2 GeV/c2 in the piN invariant mass spectrum.

Observation of a threshold enhancement in the plambda invariant-mass spectrum

An enhancement near the m(p)+M(Lambda) mass threshold is observed in the combined pLambda and pLambda invariant-mass spectrum from J/psi-->pK(-)Lambda;+c.c. decays. It can be fit with an S-wave Breit-Wigner resonance with a mass m=2075+/-12(stat)+/-5(syst) MeV and a width of Gamma=90+/-35(stat)+/-9(syst) MeV; it can also be fit with a P-wave Breit-Wigner resonance. Evidence for a similar enhancement is also observed in psi(')-->pK(-)Lambda;+c.c. decays. The analysis is based on samples of 5.8x10(7)J/psi and 1.4x10(7)psi(') decays accumulated in the BES II detector at the Beijing Electron-Positron Collider.

Observation of the decay psi(2S)-->K0SK0L

The decay psi(2S)-->K(0)(S)K(0)(L) is observed using psi(2S) data collected with the Beijing Spectrometer at the Beijing Electron-Positron Collider; the branching fraction is determined to be B(psi(2S)-->K(0)(S)K(0)(L))=(5.24+/-0.47+/-0.48)x10(-5). Compared with J/psi-->K(0)(S)K(0)(L), the psi(2S) branching fraction is enhanced relative to the prediction of the perturbative QCD "12%" rule. The result, together with the branching fractions of psi(2S) decays to other pseudoscalar meson pairs (pi(+)pi(-) and K+K-), is used to investigate the relative phase between the three-gluon and the one-photon annihilation amplitudes of psi(2S) decays.

Observation of a near-threshold enhancement in the pp mass spectrum from radiative J/psi-->gammapp decays

We observe a narrow enhancement near 2m(p) in the invariant mass spectrum of pp pairs from radiative J/psi-->gammapp decays. No similar structure is seen in J/psi-->pi(0)pp decays. The results are based on an analysis of a 58 x 10(6) event sample of J/psi decays accumulated with the BESII detector at the Beijing electron-positron collider. The enhancement can be fit with either an S- or P-wave Breit-Wigner resonance function. In the case of the S-wave fit, the peak mass is below 2m(p) at M=1859(+3)(-10) (stat)+5-25(syst) MeV/c(2) and the total width is Gamma<30 MeV/c(2) at the 90% confidence level. These mass and width values are not consistent with the properties of any known particle.

Improving effects of SSF on memory deficits and pathological changes of neural and immunological systems in senescent mice

AIM

To study the effects of SSF, an effective part isolated from Scutellaria baicalensis George, on memory impairments and the pathological changes of neural and immunological systems in senescent mice induced by chronic galactose.

METHODS

Senescent performance in mice was induced by consecutive administration of D-galactose (120 mg/kg, ip) for 47 d. The behavioral tests of mice used water maze task. The neural and immunological changes were assessed by alterations of cerebral cortex morphology and immune tissue index. The improving effects of SSF (50, 100, and 200 mg/kg, ig, 47 d) on above changes in the senescent mice were detected. Piracetam (PIR) was as reference drug.

RESULTS

D-Galactose (120 mg/kg, ip, 47 d) resulted in an increase in the latencies to find the terminal platform and the number of errors entering non-exits in water maze, neuropathological changes and immune tissue index (spleen index) deducted in mice as compared with saline treated group. Both PIR (200 mg/kg, ig, 47 d) and SSF (50, 100, and 200 mg/kg, ig, 47 d) could significantly reverse the increased latencies and number of errors and improve the pathological alterations of neural and immunological systems.

CONCLUSION

SSF could ameliorate the cognitive deficits and pathological alterations of neuron and immune systems in senescent mice induced by chronic galactose.