Vol.7,

Neural Network can be designed to reconstruct the mass of resonance particle with large missing energy. Taking the Higgs particle search through decaying channel H⁰→τ⁺τ^- →eµx and H⁰→W⁺W^-(ZZ)→llvv at LHC collider (s TeV) as examples, neural network correctly reconstructs its mass with right peak position and better width than conventional method. The network also possesses the capability of suppressing background events. This kind of neural network can be widely used in new particle search and precise mass measurement of resonance particle.

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In the pressure range of 3〜18 MPa, high pressure steam-water two-phase flow density wave instability in vertical upward parallel pipes with inner diameter of 12 mm is studied experimentally. The oscillation curves of two-phase flow instability and the effects of several parameters on the oscillation threshold of the system are obtained. Based on the small perturbation linearization method and the stability principles of automatic control system, a mathematical model is developed to predict the characteristics of density wave instability threshold. The predictions of the model are in good agreement with the experimental results.

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Test pressures are 1.0〜4.0 MPa, heating powers 27〜190 kW, inlet subcoolings 5〜80℃, water used as coolant, and steam quality at the outlet of test section is less than 0.05. These test conditions cover the parameters for a typical 200 MW heating reactor. The experimental results show that the steam quality is the dominant factor in a natural circulation system with low pressure and low steam quality about the effect of system pressure, heating power and inlet subcooling on the flow rate, relative oscilatory amplitude and oscilatory region of flow rate.

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When using the pre-dose technique in ceramic dating, it is essential to add a calibration dose and to eliminate the background dose. For doing this measurement the sample requires multiple activation following multiple administration of a test dose to induce simulated "ancient" thermoluminescence (TL). However, the procedures introduce many factors that are difficultly corrected. This paper compares existing two kinds of measurement procedures and proposes a new procedure involving single activation following a single test dose administration. An experiment using the single activation procedure is carried out with natural fine quartz where the results obtained exhibit only 0.07 relative error. It appears that this new procedure increases the precision of the ancient TL measurement by about 0.04 and 0.11 over those of existing two kinds of procedures. In addition this method can give realistic values in TL dating for relatively "young" samples aged tens to hundreds of years where the standard high temperature TL method is relatively insensitive.

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To solve the multi-dimensional transient neutron diffusion equations, improved quasi-static Green's function method (IQS/NGFM) is adopted to deal with the temporal problem, which will increase the time step as long as possible so as to decrease the number of times of spatial calculation. The time step of IQS/NGFM can be increased to 5 ~ 10 times longer than that of full implicit differential method. In spatial calculation, the theory of NGFM is used to get the distribution of shape function, with coarse meshes which can be nearly 20 times larger than that of traditional finite differential method. So the IQS/NGFM is considered as an efficient kinetic method.

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The correlation-function potential-harmonic and generalized-Laguerre-function expansion method (CFPHGLF) of directly solving the Schrodinger equation in few-body systems is presented and applied to the n¹S (n=1-4) states of the helium atom. It can be found that the present eigenenergies for 2¹S, 3¹S and 4¹S states are much better than those from the potential-harmonic and generalized-Laguerre-function method (PHGLF) previously published in Int J Quantum Chem, 1995, 55:47; and that they agree well with the exact Hylleraas CI values. However, the eigenenergy for the ground state 1¹S is not as good as that from the PHGLF method because of omitting the potential harmonic (PH) basis relevent to electron-electron correlation. The results are also simply discussed relative to some other hyperspherical harmonic (HH) and PH methods.

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There are some original nonmagnetic point defects in the BaF₂ crystallite powder, such as interstitial and vacant F^- which can become paramagnetic centers by γ-ray-irradiation at room temperature. After γ-ray irradiation the paramagnetic point defects V_k, H, F and M centers, have been observed in the sample with experiment of electron spin resonance (ESR). Frenkel exciton, a nonmagnetic point defect, can also be induced by the γ-ray irradiation in the sample at room temperature, the existence of the Frenkel exciton is affirmed by an anomalous change of the ESR signal of V_k center with temperature. The signals of the ESR of the H, F and M centers weaken and vanish with the temperature increasing monotonously. But the ESR signal of the V_k enhances when the temperature goes up about 127°C, then weakens and vanishes. An increase in the V_k center follows an annihilation of the Frenkel exciton with heating.

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A fitted equation with least square method to describe the retention of ¹³⁴Cs in whole body is obtained by a whole body counter. That is R(t)=18.04 exp(-9.3175t) + 45.13exp(-0.0423t), where R(t) is in %, and t in d. The equation consists of two half-life components, the fast component is T_1/2=0.07d, and the slow is T_1/2=16.14d. Study on the localization of ¹³⁴Cs at cellular level was carried out by freezing microautoradiography. The results indicate that ¹³⁴Cs was chiefly in ionizing form accumulated in red as well as white blood cells. In bone marrow cells ¹³⁴Cs predominantly deposited in young cells and less in mature cells. Distribution of ¹³⁴Cs in soft tissues such as muscle, liver and cerebrum was observed. It should be noted that ¹³⁴Cs penetrated quickly into the tissue cells. The observation of investigating radioimmunotoxicological effect induced by ¹³⁴Cs shows that the inhibition of thymocytes is higher than bone marrow cells, the spleen T lymphocytes are more sensitive to ¹³⁴Cs than B lymphocytes and lymphocytes of peripheral immune cells are more sensitive to radiation than central immune cells.

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A reduction in the glutathion peroxidase (GSH-Px) activity of the blood and myocardium accompanied with an increase in the leukotriene C₄(LTC₄), free radicals and lipid peroxides (LPO) concentrations of the plasma and myocardium are found in Wistar rats fed with the low selenium (Se) and vitamin E (VE) grains from a Keshan disease (KD) endemic area for 11 weeks. The concentrations of LTC₄, free radical and LPO were decreased in these rats and the GSH-Px activity is strengthened except the group supplemented with VE alone. These results suggest that the dietary deficiencies of Se and VE might take part in the occurrence and development process of myocardial damage in KD and other ischemic and anoxic cardiomyopathy by affecting the activity of lipoxygenase in arachidonic acid metabolism and by accelerating the synthesis of LTC₄ owing to excessive free radicals and LPO.

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