Detection Proposal Schemes for Spectrum Sensing in Cognitive Radio

The most important components of the cognitive radio concept is its ability to measure, sense and learn. One also should be aware of the parameters related to the radio channel characteristics and the availability of spectrum and power. In cognitive radio technology, primary users can be defined as the users who have the highest priority on the usage of a specific part of the spectrum. Secondary users, have lower priority, and should not cause any interference to the primary users when using the technology. Therefore, the secondary users need to have certain cognitive radio capabilities, such as sensing the spectrum to check whether it is being used by primary user or not, and changing the radio parameters to exploit the unused part of the spectrum. In this paper we proposed a new approach for spectrum sensing, In the first approach the primary signal is known so we use the code value with match filter to detect the primary user, on the other hand, when the primary user signal is unknown we proposed a new strategy for energy detection in both non-cooperation and cooperation schemes. Then we will prove by simulation results that the new approach is better than the conventional energy detection.

High frequency electrical field-ultrashort wave therapy for treatment of cerebral ischemia/reperfusion injury in rats Histopathological evaluation

BACKGROUND： Ultrashortwave （USW） therapy may be a new method for treatment of ischemic cerebrovascular diseases. It is necessary to study its treatment time window. OBJECTIVE： To observe the effect of USW on reperfusion injury after occlusion of the middle cerebral artery （MCAO） in rats and discuss its acting mechanisms and best occasion. DESIGN： Randomized controlled observation, animal experiment. SETTING： Laboratory of Department of Rehabilitation Medicine, First Hospital Affiliated to China Medical University. MATERIALS： Sixty-six healthy Wistar rats of either gender and of clean grade, aged 18–20 weeks, weighing from 250 to 300 g, were provided by the Experimental Animal Center of China Medical University. An USW device （Shanghai Electrical Device Company） with the frequency of 40.68 MHz and the maximum output power of 40 W, and the first channel power controlled at about 11 W was used in this study. Output power was determined by photometry. METHODS： Sixty-six rats were randomly divided into 3 groups： Sham-operation group （n =6）： The suture was inserted only 1.0 depth during operation, which did not cause MACO; Model group （n =12）： The USW treatment procedure was performed with the power off on the model rats; USW treatment group （n =48）： The 48 rats were randomly divided into modeling 0, 6, 12 and 18 hours 4 subgroups. USW therapy without heat was used on the head of rats for 10 minutes at each time point. Twelve rats in USW treatment group were decapitated following treatment at each time point, and then their brain tissues were harvested. The rat brain tissues in other groups were harvested by decapitation at 24 hours after modeling. When the rats were awake, the neurologic deficit was scored by Zea-Longa five-point scale （a score of 0 indicated no neurologic deficit, a score of 1 indicated failure to extend left paw fully, a score of 2 indicated circling to the left, and a score of 3 indicated falling to the left, and rats with a score of 4 did not walk spontaneously and has a depressed level of consciousness.） Rats which still survived at 24 hours and was scored 1 and 2 on the neurologic scoring were involved in the analysis. ① Determination of cerebral water content： Cerebral water contents of healthy and injured hemisphere were determined by wet/dry weighing method. Cerebral water content （100%） =（1–dry/wet weight）×100%.②Infarction volume： The brain tissue was sliced into 2 mm sections and each section was stained with 20 g/L 2,3,5-triphenyltetrazolium chloride （TTC） by TTC staining technique for 30 minutes in a water bath at 37 ℃.Then, the section was fixed in 100 g/L formaldehyde for 10 minutes .The infarction volume was analyzed by using an imaging analyzer.③ Preparation of light microscopic sample： The rat brain tissue fixed by 100 g/L neutral formaldehyde and stained with TTC, were gradiently dehydrated with alcoholic, embedded with paraffin, sliced and stained by HE, finally, the sections were observed under the light microscope. MAIN OUTCOME MEASURES： Cerebral water content, cerebral infarction volume and cerebral histomorphology of rats in each group. RESULTS： Sixty-six rats were involved in the final analysis. ①Cerebral water content： There were no significant differences of cerebral water content in healthy hemisphere among groups （P 〉 0.05）. Cerebral water content of injured hemisphere in the model group and at modeling 0, 6, 12 and 18 hours in the USW treatment group was （81.50±0.74） %, （81.02±0.83） %, （79.78±0.70） %, （79.74±0.84） %, （79.39± 1.06） %, respectively, which was significantly higher than that in the sham-operation group [（78.09±0.52） %, P 〈 0.05]. At modeling 0, 6 and 12 hours, the cerebral water content in the injured hemisphere in the USW treatment group was significantly lower than that in the model group, respectively （P 〈 0.05）. It indicatedthat USW treatment given at 6, 12 and 18 hours after ischemia/reperfusion can lessen brain edema. ② Cerebral infarction volume： At modeling 18 hours, cerebral infarction volume in the injured hemisphere of USW treatment group was smaller than that in the model group [（191.62±121.45）,（362.03±142.01）mm3, t =2.23,P 〈 0.05]. ③ Cerebral histomorphological observation： No swelling was found in the brain tissue section of rats in the sham-operation group. In the model group, the size of infarction hemisphere was obviously increased, gyrus became flattened, cortical sulci was shallow, the color at infarct focus obviously became light, and the tissue was fragile and brittle. In the sham-operation group, it was found under the microscope that mesenchyma was highly swelled, neuronal peripheral interspace was obviously broadened, neurons presented triangle, nucleoli were reduced, condensed even disappeared, and neutrophils in the vascular cavity were obviously increased. In the USW treatment group, pathological injury was not obviously lessened at 0 hour, moderate or mild edema could be found in the injured hemisphere of USW treatment group at modeling 6,12 and 18 hours, and at this time, neutrophils in vascular cavity were increased slightly, and pathological injuries were lessened. CONCLUSION： USW may play a protective effect on cerebral ischemia/reperfusion injury by decreasing brain edema and/or cerebral infarction volume. The treatment action of USW may start at 6 hours after reperfusion, and the best occasion of application may be at 18 hours after reperfusion.

RESEARCH ON WATER QUALITY TESTS BASED ON OPTICAL WAVEGUIDE SURFACE PLASMON RESONANCE TECHNOLOGY

The water quality testing principle by surface plasmon resonance(SPR)is introduced.Using the scanning mode angular spectral testing and the CCD angular spectral testing,a kind of highresolution,wide-range,and portable optical waveguide SPR angular spectral testing system is studied,the method of improving the testing accuracy is discussed,and a long-life surface plasmon optical waveguide transducer is also proposed.Utilizing the SPR testing system,we contrastively tack some test for several sorts of solution,the results presented that significant differences of SPR peaks observed in different sorts of liquid,which indicated the effectiveness of SPR technology used in water quality testing and analysis.

Protective effect of ultrashortwave versus radix salviae miltiorrhizae on brains of rats with cerebral ischemia-reperfusion injury

BACKGROUND： HOW to control the effect of oxygen-derived free radicals on development of cerebral injury and cerebral edema is a key factor for treating cerebral ischemia-reperfusion injury. OBJECTIVE： To observe and compare the protective effects, synergistic action and mechanisms of ultrashortwave （USW） and radix salviae miltiorrhizae （RSM） on the focal cerebral ischemia-reperfusion injuries in rats. DESIGN： Randomized controlled animal study SEI-FING： Department of Rehabilitation Medicine, First Hospital affiliated to China Medical University MATERIALS： A total of 160 healthy Wistar rats of both genders and aged 18-20 weeks weighing 250-300 g of clean grade were selected in this study. 5 mL/ampoule RSM injection fluid was produced by the First Pharmaceutical Corporation of Shanghai （batch number： 011019, 0.01 mug）. The USW therapeutic device was produced by Shanghai Electronic Device Factory with the frequency of 40.68 MHz and the maximal export power of 40 W. The first channel of power after modulation was 11 W. METHODS： The experiment was carried out in the Rehabilitation Medicine Department of the First Hospital affiliated to China Medical University from May 2002 to January 2003. Focal ischemia-reperfusion model was established in rats by reversible right middle cerebral artery occlusion with filament. Right cerebral ischemia was for 2 hours and then with 24 hours reperfusion. The scores of neurological deficits were evaluated by 0 to 4 scales. After surgery, 64 successful rats models were divided into four groups according to digital table： control group, USW group, RSM group and RSM ＋ USW group with 16 cases in each group. Rats in control group were intraperitoneally injected with the same volume of saline （0.1 mL/g）; rats in USW group were given small dosage of USW on head for 10 minutes at 6 hours after reperfusion; rats in RSM group were intraperitoneally injected with 0.01 mL/g RSM solution at 30 minutes before reperfusion; rats in RSM ＋ USW group were intraperitoneally injected with 0.01 mL/g RSM parenteral solution at 30 minutes before reperfusion and given small dosage of USW on head for 10 minutes once at 6 hours after reperfusion; sixteen rats in sham operation group did not receive any treatment. All 80 rats were taken brains at 24 hours after reperfusion to measure wet and dry weights to calculate water content： Cerebral water content （%） = （1-dry/wet weight） × 100%. Superoxide dismutase （SOD） activity was measured by hydroxylamine method and malondialdehyde （MDA） content was measured by TBA photometric method. MAIN OUTCOME MEASURES ： Cerebral water content, SOD activity and MDA content RESULTS： All 160 rats except 80 failing in modeling were involved in the final analysis. （① The cerebral water content of left hemisphere made no significant difference （P 〉 0.05）. The cerebral water content of right hemisphere in the control group and the three treatment groups was obviously higher than that of the sham operation group [（81.26±0.77）%, （79.74±0.68）%, （79.76±0.81）%, （79.61±0.79）%, （77.43±0.61）%, P 〈 0.05]. The cerebral water content of right hemisphere in the three treatment groups was obviously lower than that of the control group （P〈 0.05）. There was no significant difference among the three treatment groups （P 〉 0.05）. ② Compared with the control group, SOD activity （right） of the control group decreased obviously （P 〈 0.05）, while MDA content increased obviously （P 〈 0.05）. SOD activity in the three therapeutic groups increased obviously, while MDA content decreased obviously （P 〈 0.05）; there was no significant difference among the three treatment groups （P 〉 0.05）. CONCLUSION： ① USW and RSM therapy have neuroprotective effects against focal cerebral ischemia-reperfusion injuries by means of decreasing cerebral water content and MDA and increasing the activity of SOD. ② Synergistic action was not observed between these two therapeutic methods.

Simulation and comprehensive assessment of single channel RZ-DPSK optical link by dispersion management with channel bit rate beyond 40 Gbits/s

This paper studied the influence of return to zero-differential phase-shift-keying （RZ-DPSK） data format on techniques of pre-, post- and pre/post combination dispersion compensation for faithful transmission of optical signal at 80 and 100 Gbits/s channel bit rate via simulation. The purpose of this study was to find out the dispersion compensation techniques for optimal transmis- sion with the interaction effects of self-phase modulation （SPM） and amplifier spontaneous emission （ASE） for RZ- DPSK encoded optical data. By the simulation method, it was found out that the RZ-DPSK data format can be allowed with a transmission distance of about 700 km of standard single mode fiber （SMF） at 100 Gbits/s, and it can be provided with farther transmission distance of more than 1000 km at 80 Gbits/s with the combination of the pre- and post-compensation technique. To efficiently suppress the effect of ASE and improve optical signal-to- noise ratio （OSNR）, the bandwidth frequency of optical receiver filter was found to be at least equal to bit rate.

Application of phase‑conjugate beams in beam correction and underwater optical wireless communication subject to surface wave turbulence

Water surface wave turbulence is one of the factors afecting the performances of underwater optical wireless communication(UOWC)systems.In our research,a phase-conjugate beam was used to correct the beam distortion and enhance the communication performances when a system is subject to surface wave turbulence.The phase-conjugate beam was generated by a phase-conjugate mirror(PCM),and a turbulence generator was used to generate surface wave turbulence in the experiment.We calculated the beam centroid distribution and the results showed that the phase-conjugate beam had a better propagation performance than the distorted beam at the diferent water depths.The root mean square(RMS)of the beam centroid for the phase-conjugate beam was 11 times less than that for the distorted beam,which meant that the phase-conjugate beam could efectively correct the beam drift.We further investigated the scintillation index and the signal-to-noise ratio(SNR);the results showed that the phase-conjugate beam was able to reduce the scintillation and an obvious improvement in SNR could be obtained.This research has the potential to be applied in UWC.