This study explores whether the current external quality assessment(EQA)level and acceptable bias for basic semen analysis in China are clinically useful.We collected data of semen EQA from Andrology laboratories in t...This study explores whether the current external quality assessment(EQA)level and acceptable bias for basic semen analysis in China are clinically useful.We collected data of semen EQA from Andrology laboratories in the Hunan Province(China)in 2022 and searched for data in the published literature from January2000 to December 2023 in China.On the basis of these data,we analyzed the coefficients of variation and acceptable biases of different quality control materials for basic semen analysis through robust statistics.We compared these findings with quality specifications based on biological variation from optimal,desirable,and minimum levels of bias to seek a unified and more suitable semen EQAbias evaluation standard for China's national conditions.Different sources of semen quality control material exhibited considerable variation in acceptable biases among laboratories,ranging from 8.2%to 56.9%.A total of 50.0% of the laboratories met the minimum quality specifications for progressive motility(PR),whereas 100.0%and 75.0%of laboratories met only the minimum quality specifications for sperm concentration and total motility(nonprogressive[NP]+PR),respectively.The Z value for sperm concentration and PR+NP was equivalent to the desirable performance specification,whereas the Z value for PR was equivalent only to the minimum performance specification.This study highlights the feasibility of operating external quality assessment schemes for basic semen analysis using quality specifications based on biological variation.These specifications should be unified among external quality control(EQC)centers based on biological variation.展开更多
TiO_2 sols modified by rare earth (RE) ions (Ce^(4+), Eu^(3+), or Nd^(3+))were prepared by coprecipitation-peptization method. The photocatalysis activity was studied byinvestigating the photodegradation effects of ac...TiO_2 sols modified by rare earth (RE) ions (Ce^(4+), Eu^(3+), or Nd^(3+))were prepared by coprecipitation-peptization method. The photocatalysis activity was studied byinvestigating the photodegradation effects of active brilliant red dye X-3B. It is found that TiO_2sols modified by Ce^(4+), Eu^(3+), or Nd^(3+) have the anatase crystalline structure, which areprepared at 70℃. All RE^(n+)-TiO_2 sol samples have uniform nanoparticles with similar morphology,which are homogenously distributed in aqueous colloidal systems. The particle sizes are 10, 8, and12 nm for Nd^(3+)-TiO_2, Eu^(3+)-TiO_2, and Ce^(4+)-TiO_2, respectively. The character of ultrafineand positive charge sol particles contributes to the good adsorption of X-3B dye molecule on thesurface of titania (about 30% X-3B adsorption amount). Experimental results exhibit thatRE^(n+)-TiO_2 sol photocatalysts have the capability to photodegrade X-3B under visible lightirradiation. Nd^(3+)-TiO_2 and Eu^(3+)-TiO_2 show higher photocatalytic activity than Ce^(4+)-TiO_2,which is due to the difference of standard redox potential of RE^(n+)/RE^((n-1)+). RE^(n+)-TiO_2sols demonstrate more excellent interfacial adsorption and photodegradation effects to X-3B thanP_(25) TiO_2 crystallites. Moreover, the degradation mechanism of X-3B is proposed as dyephotosensitization and electron scavenging by rare earth ions.展开更多
AIM:To investigate the in vitro effects of suicide gene therapy system of herpes simplex virus thymidine kinase gene (HSV-TK) in combination with the treatment of nucleotide analog-ganciclovir (GCV) on human pancreati...AIM:To investigate the in vitro effects of suicide gene therapy system of herpes simplex virus thymidine kinase gene (HSV-TK) in combination with the treatment of nucleotide analog-ganciclovir (GCV) on human pancreatic cancer, and to provide a novel clinical therapeutic method for human pancreatic cancer.METHODS: We used a replication defective recombinant retrovirus vector GINaTK (bearing HSV-TK gene) to make packaging cell PA317 produce progeny virions. We then transferred the HSV-TK gene to target cells SW1990 using these progeny virions, and treated these gene-modified tumor cells with GCV to study the sensitivity of the cells to GCV and their bystander effects by routine MTT-method.RESULTS:Packaging cell PA317/TK was successfully constructed, and we acquired SW1990/TK through virus progeny infection. These gene-modified pancreatic cancer cells were sensitive to the treatment of GCV compared with unmodified tumor cells (t=4.15,n=10,P<0.0025). We also observed a remarkable bystander effect by mixing two kinds of cells at different ratio.CONCLUSION:Our data demonstrate that HSV-TK/GCV suicide gene therapy system is effective for treating experimental human pancreatic cancer, which is largely resistant to the common therapies,so the suicide gene therapy system may be a potential treatment approach for pancreatic cancer.展开更多
AIM:To study the effects of Kupffer cell-conditioned medium (KCCM) derived from lipopolysaccharide (LPS) treatment on proliferation of rat hepatic stellate cells (HSC).METHODS:HSC and Kupffer cells were isolated from ...AIM:To study the effects of Kupffer cell-conditioned medium (KCCM) derived from lipopolysaccharide (LPS) treatment on proliferation of rat hepatic stellate cells (HSC).METHODS:HSC and Kupffer cells were isolated from the liver of Wistar rats by in situ perfusion with pronase and collagenase and density gradient centrifugation with Nycodenz and cultured. KCCM was prepared and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay was used to detect HSC proliferation. The content of type Ⅳ collagen and laminin secreted by HSC in the HSC-conditioned medium was determined by radioimmunoassay.TGF-β1 production in the KCCM was detected by enzymelinked immunosorbent assay (ELISA).RESULTS:HSC and Kupffer cells isolated had high purity.One microgram per mililiter LPS-activated KCCM and unstimulated KCCM could significantly promote HSC proliferation [0.132±0.005 and 0.123±0.008 vscontrol group (0.100±0.003), P<0.01], and there was a difference between them (P<0.05). Ten microgram per mililiter LPS-activated KCCM (0.106±0.010) was unable to promote HSC proliferation (P>0.05). Adding anti-TGF-β1 antibodies could suppress the proliferation promoted by unstimulated KCCM and LPS(1μg/ml)-activated KCCM (0.109±0.009 vs 0.123±0.008,0.115±0.008 vs 0.132±0.005, P<0.01). LPS (1μg/ml or 10μg/ml) could not promote HSC proliferation immediately (0.096±0.003 and 0.101±0.004 vs 0.100±0.003, P>0.05). There was a parallel behavior between HSC proliferation and increased ECM level. One microgram per mililiter LPS-activated KCCM contained a larger amount of TGF-β1 than unstimulated KCCM.CONCLUSION:The technique for isolation of HSC and Kupffer cells described here is simple and reliable. KCCM stimulated by LPS may promote HSC proliferation and collagen accumulation, which are associated with hepatic fibrogenesis.展开更多
AIM: To study changes of inflammation-associated cytokine expressions during early phase of endotoxic shock in macague. METHODS: Experiments were performed in Macaque mulatta treated with LPS 2.8 mg/kg in shock model ...AIM: To study changes of inflammation-associated cytokine expressions during early phase of endotoxic shock in macague. METHODS: Experiments were performed in Macaque mulatta treated with LPS 2.8 mg/kg in shock model group or with normal saline in control group. Blood samples were collected before, or 60 min, or 120 min after LPS injection, respectively. Liver and spleen tissues were obtained at 120 min after LPS injection. The plasma levels of TNF-α,IL-1 β, IL-10 and IL-12P40 were determined by double-antibody sandwich ELISA with antibodies against human cytokines. The mRNA levels of TNF-α, IL-1 β, and IL-18 in peripheral blood mononuclear cells (PBMCs), liver and spleen were examined by real-time fluorescence semi-quantitative RT-PCR with the primers based on human genes. RESULTS: Mean systemic arterial pressure (MAP), systemicvascular resistance index (SVRI) and left ventricular work index (LVWI) of macaques were significant declined in shock model group on average 60 min after LPS injection. The plasma levels of TNF-α and IL-10 were significantly increased 60 min after LPS injection and then decreased. The plasma levels of IL-1 β and IL-12P40 were significantly increased at 120 min after LPS injection. The mRNA levels of TNF-α and IL-1 β were significantly increased 60 min after LPS stimulation in PBMCs and 120 min after LPS stimulation in livers. The mRNA level of IL-18 was significantly increased 120 rain after LPS stimulation in PBMCs and livers. But in spleen, only TNF-α mRNA level in LPS group was significantly higher 120 min after LPS stimulation, compared with that in control group. CONCLUSION: An endotoxic shock model of Macaque mulatta was successfully established. Both antibodies for ELISA and PCR primers based on human cytokine assays were successfully applied to detect macaque cytokines. In the model, inflammatory cytokines, such as TNF-α, IL-1 β,IL-12 and IL-18 as well as anti-inflammation cytokine IL-10, were released at very early phase of endotoxic shock within 120 min after LPS injection. PBMCs and liver cells might be the important sources of these cytokines.展开更多
AIM: To study the effects of phosphorus-32 glass microspheres(^32P-GMS) on human hepatocellular carcinoma in nude mice. METHODS: Human liver cancer cell line was implanted into the dorsal subcutaneous tissue of 40 BAL...AIM: To study the effects of phosphorus-32 glass microspheres(^32P-GMS) on human hepatocellular carcinoma in nude mice. METHODS: Human liver cancer cell line was implanted into the dorsal subcutaneous tissue of 40 BALB/c nude mice. Then the 40 tumor-bearing BALB/c nude mice were allocated into treatment group (n=32) and control group (n=8). In the former group different doses of ^32P-GMS were injected into the tumor mass, while in the latter nonradioactive ^31P-GMS was injected into the tumor mass. The experimental animals were sacrificed on the 14th day. The ultrastructural changes of tumor in both treatment group and control group were studied with transmission electron microscopy (TEM) and stereology. RESULTS: In treatment group, a lot of tumor cells were killed and the death rate of tumor cells was much higher (35-70%). UItrastructurally, severe nuclear damage was observed in the death cells. The characteristics of appoptosis such as margination of heterochromatin was also found in some tumor cells. Besides, well differentiated tumor cells, degenerative tumor cells and some lymphocytes were seen. The skin and musde adjacent to the tumor were normal. In control group, the tumor consisted of poorly differentiated tumor cells, in which there were only a few of dead cells (5%). Stereologicl analysis of ultrastructral morphology showed that Vv of nuclei (53.31±3.46) and Vv of nucleoli (20.40±1.84) in the control group were larger than those (30.21±3.52 and 10.96±2.52) in the treatment group respectively (P<0.01), and Vv of RER (3.21±0.54) and Vv of mitochondria (4.53±0.89) in the control group were smaller than those (8.67±1.25 and 7.12±0.95) in the treatment group respectively (P<0.01, 0.05). Sv of the membrane of microvilli and canaliculi (27.12 um^2/100 um^3±11.84 um^2/100 um^3) in the control group was smaller than that (78.81 um^2/100 um^3±19.69 um^2/100 um^3) in the treatment group (P<0.01). But Vv of lipid particles (3.71±1.97) and Vv of vacuoles (5.72±1.58)were much larger than those (0.30±0.16 and 0.35±0.15) in the treatment group respectively (P<0.05, P<0.01). CONCLUSION: The experimental results indicate that local administration of ^32P-GMS can produce obvious effect on liver cancer cells and the anticancer effect of ^32P-GMS is directly proportional to the dose administrated. UItrastructural stereology can also show the effect of ^32P-GMS on the normalization of tumor cells, which is beneficial to the prognosis and treatment of patients. Moreover, local administrtion of ^32P-GMS is also safe.展开更多
Regenerating gene (Reg or REG) family, within the superfamily of C-type lectin, is mainly involved in the liver,pancreatic, gastric and intestinal cell proliferation or differentiation. Considerable attention has focu...Regenerating gene (Reg or REG) family, within the superfamily of C-type lectin, is mainly involved in the liver,pancreatic, gastric and intestinal cell proliferation or differentiation. Considerable attention has focused on Reg family and its structurally related molecules. Over the last 15 years, 17 members of the Reg family have been cloned and sequenced. They have been considered as members of a conserved protein family sharing structural and some functional properties being involved in injury, inflammation,diabetes and carcinogenesis. We previously identified Reg Ⅳ as a strong candidate for a gene that was highly expressed in colorectal adenoma when compared to normal mucosa based on suppression subtractive hybridization (SSH),reverse Northern blot, semi-quantitative reverse transcriptase PCR (RT-PCR)and Northern blot. In situ hybridization results further support that overexpression of Reg Ⅳ may be an early event in colorectal carcinogenesis. We suggest that detection of Reg Ⅳ overexpression might be useful in the early diagnosis of carcinomatous transformation of adenoma.This review summarizes the roles of Reg family in diseases in the literature as well as our recent results of Reg Ⅳ in colorectal cancer. The biological properties of Reg family and its possible roles in human diseases are discussed. We particularly focus on the roles of Reg family as sensitive reactants of tissue injury, prognostic indicators of tumor survival and early biomarkers of carcinogenesis. In addition to our current understanding of Reg gene functions, we postulate that there might be relationships between Reg family and microsatellite instability, apoptosis and cancer with a poor prognosis. Investigation of the correlation between tumor Reg expression and survival rate, and analysis of the Reg gene status in human maliganancies, are required to elucidate the biologic consequences of Reg gene expression, the implications for Reg gene regulation of cell growth, tumorigenesis, and the progression of cancer. It needs to be further attested whether Reg gene family is applicable in early detection of cancer and whether Reg and Reg-related molecules can offer novel molecular targets for anticancer therapeutics. This has implications with regard to prognosis, such as in monitoring cancer initiation,progression and recurrence, as well as the design of chemotherapeutic drugs.展开更多
AlM: To study the expression of neurokinin-1 receptor (NK-1R) and neurokinin-2 receptor (NK-2R) in distal ileum ofacute necrotizing pancreatitis (ANP) and to evaluate therelationship between expression of these two re...AlM: To study the expression of neurokinin-1 receptor (NK-1R) and neurokinin-2 receptor (NK-2R) in distal ileum ofacute necrotizing pancreatitis (ANP) and to evaluate therelationship between expression of these two receptors andintestinal mucosal damage.METHODS: A total of 130 adult Sprague-Dawley rats wererandomly divided into two groups: the rats in ANP group(n＝80) were induced by the retrograde intraductal infusionof 30 g@L-1 sodium taurocholate. And the rats in normal controlgroup (n＝50) received laparotomy only. Sacrifices weremade 6 h, 12 h, 24 h and 48 h later in ANP and normalcontrol group after induction respectively. Intestinal mucosalpermeability was studied by intrajejunal injection of 1.SmCiradioactive isotope 99mTc-diethlene triamine pentacetic acid(DTPA) and the radioactivity of 99mTc-DTPA content in urinewas measured 6 h, 12 h, 24 h and 48 h after induction.Then the pancreas and intestine were prepared forpathology. Reverse transcription polymerase chain reaction(RT-PCR) was used to determine the mRNA expression ofNK-1R and NK-2R, and Western blot was used to investigatethe protein level of NK-1R and NK-2R.RESULTS: In ANP rats, serious histologic damages inintestinal mucosa were observed, and the radioactivity of99mTc-DTPA in urine increased significantly in the ANP group.RT-PCR revealed that NK-1R and NK-2R mRNA level wasoverexpressed in the distal ileum of ANP as compared withthe normal control group. Western blot discovered strongerNK-1R (14-fold increase) and NK-2R (9-fold increase)immunoreactivity in the intestinal mucosa of ANP rats.Moreover, the overexpression of NK-1R was associated withmucosal pathological score (r＝0.77,P＜0.01) and intestinalpermeability (r＝0.68, P＜0.01) in ANP rats.CONCLUSION: NK-1R and NK-2R contribute to disruptedneuropeptides loop balance, deteriorate intestinal damage,and are involved in pathophysiological changes in ANP.展开更多
Finite element model updating method based on global information is proposed.Prior investigation upon design space of structural parameters is performed before updating usingstatistic analysis, including parameter scr...Finite element model updating method based on global information is proposed.Prior investigation upon design space of structural parameters is performed before updating usingstatistic analysis, including parameter screening using variance analysis and response surfacefitting using regression analysis. The parameter screening method selects the design parametersconsidering the result of hypothesis testing, which is a kind of global information. Meanwhile, thetraditional updating method considers local sensitivity which only gives the information at solepoint in the design space. Response surface fitting constructs a close-form multinomial whichdescribes the relationship between concerned structural feature and selected updating parameters. Itis an approximation to finite element models(FEM) and used as a substitution in the updatingiterations. The presented updating method can be applied without the restriction of linearassumption. In addition, there is no data exchange between the updating program and the finite-element analysis program in the updating iterations. This makes the method practical inengineering. An aircraft test structure, GARTEUR, is employed to verify the effectiveness of themethod. After updating, the error of modal frequencies is less than 3 percent.展开更多
AIM: To directly investigate the relationship between telomerase activity and its subunit expression and the inhibitory effect of antisense hTR on pancreatic carcinogenesis.METHODS: We examined the telomerase activity...AIM: To directly investigate the relationship between telomerase activity and its subunit expression and the inhibitory effect of antisense hTR on pancreatic carcinogenesis.METHODS: We examined the telomerase activity and its subunit expression by cell culture, polymerase chain reaction (PCR), PCR-silver staining, PCR-ELISA, DNA sequencing, MTT and flow cytometry methods.RESULTS: PCR-silver staining and PCR-ELISA methods had the same specificity and sensitivity as the TRAP method.Telomerase activity was detected in the extract of the 10th,20th and 30th passages of P3 cells,while it was absent in fibroblasts. Furthermore, after the 30th generation, the proliferation period of fibroblast cells was significantly prolonged. Telomerase activity and hTERTmRNA were detected in two pancreatic carcinoma cell lines, but were found to be negative in human fibroblast cells. Telomerase activity and hTERTmRNA were tested in pancreatic carcinoma specimens of 24 cases. The telomerase activity was positive in 21 of the 24 cases (87.5 %), and the hTERTmRNA in 20 cases (83.3 %). In adjacent normal tissues positive rates were both 12.5 %. There was a significant difference between the two groups. This indicated a significant correlation between the expression level of telomerase activity and histologic differentiation,metastasis and advanced clinical stage of pancreatic carcinoma. Our findings showed that the expressions of hTR and TP1mRNA were not correlated with the activity of telomerase but the expression of hTERTmRNA was. After treatment with PS-ODNs, telomerase activity in P3 cells weakened and the inhibiting effect became stronger with an increase in PS-ODNs concentration. There was a significant difference between different PS-ODN groups (P＜0.05). Inhibition of telomerase activity occurred most significant with PS-ODN1.The results of the FCM test of pancreatic cancer P3 cells showed an increase in the apoptotic rate with increasing PS-ODN1 and PS-ODN2concentrations.CONCLUSION: The expression of telomerase activity has a significant relationship to carcinogenesis. A strong correlation exists between telomerase activity and hTERTmRNA expression. The up-regulation of hTERTmRNA expression may play a critical role in human carcinogenesis.The expression of telomerase activity and its subunit level in pancreatic carcinoma significantly correlate with the clinical stage of pancreatic carcinoma and hence, may be helpful in its diagnosis and prognosis. The anti-hTR complementary to the template region of hTR is sufficient to inhibit P3 cell telomerase activity and cell proliferation in vitro, and can lead to a profound induction of programmed cell death.展开更多
To evaluate the clinic outcome of off-pump coronary bypass grafting (OPCABG) of patients with coronary heart disease and chronic obstructive pulmonary disease, we collected and analyzed 1998-2002 data on 28 patients w...To evaluate the clinic outcome of off-pump coronary bypass grafting (OPCABG) of patients with coronary heart disease and chronic obstructive pulmonary disease, we collected and analyzed 1998-2002 data on 28 patients with these two diseases who had received off-pump coronary bypass operation in our hospital, and compared with data on those who also had the same two diseases but received on-pump coronary artery bypass at same time. There were no operation-related death;one died of respiratory failure 14 days after operation while staying in hospital; there were more respiratory complications in the conventional coronary artery bypass grafting group (CCABG) than in the OPCABG group; and the PaO2/FiO2 in the CCABG group was higher than that in the OPCABG group during operation because of CPB, but lower than that in the OPCABG group 6-12 hours after operation. OPCABG seemed more suitable than CCABG for coronary artery disease patients with chronic obstructive pulmonary disease due to less damage to their oxygen-exchange capability and the fewer respiratory complications.展开更多
A new closed-loop driving scheme for the silicon micromachined vibratory gyroscope (SMVG) is proposed. The push-pull driving is adopted and in-phase AC and reverse-phase DC voltages are applied in the driving electrod...A new closed-loop driving scheme for the silicon micromachined vibratory gyroscope (SMVG) is proposed. The push-pull driving is adopted and in-phase AC and reverse-phase DC voltages are applied in the driving electrodes placed in both sides of the active combs, respectively. Driving performance analyses show that the frequency spectrum between driving moments and noise signals is separated. Therefore, the model of the closed-loop control is set up with the phase lock loop (PLL). The requirements for phases and gains of the sinusoidal selfdrive-oscillation are met by PLL, thus the closed-loop circuit reaches the self-drive-oscillation. Phase conditions of the sinusoidal self-drive-oscillation and the characteristic of phase discrimination of the PLL are used to eliminate the coupling between driving and sense signals, and noise signals. Finally, experimental results show that the variations of both the driving frequency and the amplitude are all under 0.02%. The precision and the reliability of the gyroscope are greatly improved.展开更多
AIM: Aberrant DNA methylation of CpG site is among the earliest and most frequent alterations in cancer. Several studies suggest that aberrant methylation of the CpG sites of the tumor suppressor gene is closely assoc...AIM: Aberrant DNA methylation of CpG site is among the earliest and most frequent alterations in cancer. Several studies suggest that aberrant methylation of the CpG sites of the tumor suppressor gene is closely associated with carcinogenesis. However, large-scale analysis of candidate genes has so far been hampered by the lack of highthroughput approach for analyzing DNA methylation. The aim of this study was to describe a microarray-based method for detecting changes of DNA methylation in cancer.METHODS: This method used bisulfite-modified DNA as a template for PCR amplification, resulting in conversion of unmethylated cytosine, but not methylated cytosine, into thymine within CpG islands of interest. Therefore, the amplified product might contain a pool of DNA fragments with altered nucleotide sequences due to differential methylation status.Nine sets of oligonucleotide probes were designed to fabricate a DNA microarray to detect the methylation changes of p16 gene CpG islands in gastric carcinomas. The results were further validated by methylation-specific PCR (MSP).RESULTS: The experimental results showed that the microarray assay could successfully detect methylation changes of p16 gene in 18 gastric tumor samples. Moreover,it could also potentially increase the frequency of detecting p16 methylation from tumor samples than MSP.CONCLUSION: Microarray assay could be applied as a useful tool for mapping methylation changes in multiple CpG loci and for generating epigenetic profiles in cancer.展开更多
Discrete-rate adaptive modulation （AM） scheme for distributed antenna system （DAS） with imperfect channel state information （CSI） is developed, and the corresponding performance is investigated in composite Rayl...Discrete-rate adaptive modulation （AM） scheme for distributed antenna system （DAS） with imperfect channel state information （CSI） is developed, and the corresponding performance is investigated in composite Rayleigh channel. Subject to target bit error rate （BER） constraint, an improved fixed switching threshold （FST） for the AM scheme is presented by means of tightly-approximate BER expression, and it can avoid the performance loss fxom conventional FST. Based on the imperfect CSI, the variable switching threshold （VST） is derived by utilizing the maximum a posteriori method. This VST includes the improved FST as a special case, and may lower the impact of estimation error on the performance. By the switching thresholds, the spectrum efficiency （SE） and average BER of the system are respectively derived, and resulting closed- form expressions are attained. With these expressions, the system performance can be effectively evaluated. Simulation results show that the derived theoretical SE and BER can match the simulations well. Moreover, the AM with the presented FST has higher SE than that with the conventional one, and the AM with VST can tolerate the large estimation error while maintaining the target BER.展开更多
For the purpose of making the best use of the mine frequency resource and realizing the instruction idea “to exchange bandwidth for distance" a W-CDMA mine spread spectrum mobile communication scheme based on sp...For the purpose of making the best use of the mine frequency resource and realizing the instruction idea “to exchange bandwidth for distance" a W-CDMA mine spread spectrum mobile communication scheme based on spread spectrum communication technique and the propagation characteristic of electromagnetic wave along laneways is proposed.The structure and make up of the system are studied and the working frequency and channels are assigned.Analysis indicates the scheme is a simple one that can fulfill the mine saying requirement.展开更多
A completely new finite element software, Finite ElementProgram Generator (FEPG), is introduced and its designing thought and organizing structure is presented.FEPG uses the method of components and the technique of a...A completely new finite element software, Finite ElementProgram Generator (FEPG), is introduced and its designing thought and organizing structure is presented.FEPG uses the method of components and the technique of artificial intelligence to generate finite element program automatically by a computer according to the general principles of mathematic and internal rules of finite element method,as is similar to the deduction of mathematics.FEPG breaks through the limitation of present finite element software,which only applies to special discipline,while FEPG is suitable for all kinds of differential equations solved by finite element method.Now FEPG has been applied to superconductor research,electromagnetic field study,petroleum exploration,transportation,structure engineering,water conservancy,ship mechanics, solid-liquid coupling problems and liquid dynamics,etc.in China.展开更多
We try to apply a constituent quark model (a variety chiral constituent quark model) and the resonating group approach for the multi-quark problems to compute the effective potential between the NN- in S-wave (the qua...We try to apply a constituent quark model (a variety chiral constituent quark model) and the resonating group approach for the multi-quark problems to compute the effective potential between the NN- in S-wave (the quarks in the nucleons N and N-, and the two nucleons relatively as well, are in S wave) so as to see the possibility if there may be a tight bound state of six quarks as indicated by a strong enhancement at threshold of pp- in J/ψ and B decays. The effective potential which we obtain in terms of the model and approach shows if the experimental enhancement is really caused by a tight S-wave bound state of six quarks, then the quantum number of the bound state is very likely to be I = 1, JPC= 0-+.展开更多
Web information extraction is viewed as a classification process and a competing classification method is presented to extract Web information directly through classification. Web fragments are represented with three ...Web information extraction is viewed as a classification process and a competing classification method is presented to extract Web information directly through classification. Web fragments are represented with three general features and the similarities between fragments are then defined on the bases of these features. Through competitions of fragments for different slots in information templates, the method classifies fragments into slot classes and filters out noise information. Far less annotated samples are needed as compared with rule-based methods and therefore it has a strong portability. Experiments show that the method has good performance and is superior to DOM-based method in information extraction. Key words information extraction - competing classification - feature extraction - wrapper induction CLC number TP 311 Foundation item: Supported by the National Natural Science Foundation of China (60303024)Biography: LI Xiang-yang (1974-), male, Ph. D. Candidate, research direction: information extraction, natural language processing.展开更多
Adaptive control of a flexible beam system preceded by an unknown dead-zonein the driving motor is investigated in state space form. By introducing an important lemma forsimplifying error equation between the flexible...Adaptive control of a flexible beam system preceded by an unknown dead-zonein the driving motor is investigated in state space form. By introducing an important lemma forsimplifying error equation between the flexible beam model and the matching reference model, arobust adaptive control scheme is developed by involving the dead-zone inverse terms. The newadaptive control law ensures global stability of the entire system and achieves desired trackingprecision even when the slopes of the dead-zone are not equal. Simulations performed on a typicalflexible beam system illustrate and clarify the validity of this approach.展开更多
基金supported by the Hunan Province Municipal Natural Science Foundation(2022JJ30018)the Hunan Province Health Commission Science Foundation(B202301037899)to WNL。
文摘This study explores whether the current external quality assessment(EQA)level and acceptable bias for basic semen analysis in China are clinically useful.We collected data of semen EQA from Andrology laboratories in the Hunan Province(China)in 2022 and searched for data in the published literature from January2000 to December 2023 in China.On the basis of these data,we analyzed the coefficients of variation and acceptable biases of different quality control materials for basic semen analysis through robust statistics.We compared these findings with quality specifications based on biological variation from optimal,desirable,and minimum levels of bias to seek a unified and more suitable semen EQAbias evaluation standard for China's national conditions.Different sources of semen quality control material exhibited considerable variation in acceptable biases among laboratories,ranging from 8.2%to 56.9%.A total of 50.0% of the laboratories met the minimum quality specifications for progressive motility(PR),whereas 100.0%and 75.0%of laboratories met only the minimum quality specifications for sperm concentration and total motility(nonprogressive[NP]+PR),respectively.The Z value for sperm concentration and PR+NP was equivalent to the desirable performance specification,whereas the Z value for PR was equivalent only to the minimum performance specification.This study highlights the feasibility of operating external quality assessment schemes for basic semen analysis using quality specifications based on biological variation.These specifications should be unified among external quality control(EQC)centers based on biological variation.
基金This work was financially supported by the Hi-Tech Research and Development Program (863 Program) of China (No. 2002AA302304)the National Natural Science Foundation of China (No. 60121101)the Education Department Foundation of Jiangsu Province (JHOl-
文摘TiO_2 sols modified by rare earth (RE) ions (Ce^(4+), Eu^(3+), or Nd^(3+))were prepared by coprecipitation-peptization method. The photocatalysis activity was studied byinvestigating the photodegradation effects of active brilliant red dye X-3B. It is found that TiO_2sols modified by Ce^(4+), Eu^(3+), or Nd^(3+) have the anatase crystalline structure, which areprepared at 70℃. All RE^(n+)-TiO_2 sol samples have uniform nanoparticles with similar morphology,which are homogenously distributed in aqueous colloidal systems. The particle sizes are 10, 8, and12 nm for Nd^(3+)-TiO_2, Eu^(3+)-TiO_2, and Ce^(4+)-TiO_2, respectively. The character of ultrafineand positive charge sol particles contributes to the good adsorption of X-3B dye molecule on thesurface of titania (about 30% X-3B adsorption amount). Experimental results exhibit thatRE^(n+)-TiO_2 sol photocatalysts have the capability to photodegrade X-3B under visible lightirradiation. Nd^(3+)-TiO_2 and Eu^(3+)-TiO_2 show higher photocatalytic activity than Ce^(4+)-TiO_2,which is due to the difference of standard redox potential of RE^(n+)/RE^((n-1)+). RE^(n+)-TiO_2sols demonstrate more excellent interfacial adsorption and photodegradation effects to X-3B thanP_(25) TiO_2 crystallites. Moreover, the degradation mechanism of X-3B is proposed as dyephotosensitization and electron scavenging by rare earth ions.
基金Supported by the Scienceand Teclmology Foundation of Southeast University
文摘AIM:To investigate the in vitro effects of suicide gene therapy system of herpes simplex virus thymidine kinase gene (HSV-TK) in combination with the treatment of nucleotide analog-ganciclovir (GCV) on human pancreatic cancer, and to provide a novel clinical therapeutic method for human pancreatic cancer.METHODS: We used a replication defective recombinant retrovirus vector GINaTK (bearing HSV-TK gene) to make packaging cell PA317 produce progeny virions. We then transferred the HSV-TK gene to target cells SW1990 using these progeny virions, and treated these gene-modified tumor cells with GCV to study the sensitivity of the cells to GCV and their bystander effects by routine MTT-method.RESULTS:Packaging cell PA317/TK was successfully constructed, and we acquired SW1990/TK through virus progeny infection. These gene-modified pancreatic cancer cells were sensitive to the treatment of GCV compared with unmodified tumor cells (t=4.15,n=10,P<0.0025). We also observed a remarkable bystander effect by mixing two kinds of cells at different ratio.CONCLUSION:Our data demonstrate that HSV-TK/GCV suicide gene therapy system is effective for treating experimental human pancreatic cancer, which is largely resistant to the common therapies,so the suicide gene therapy system may be a potential treatment approach for pancreatic cancer.
文摘AIM:To study the effects of Kupffer cell-conditioned medium (KCCM) derived from lipopolysaccharide (LPS) treatment on proliferation of rat hepatic stellate cells (HSC).METHODS:HSC and Kupffer cells were isolated from the liver of Wistar rats by in situ perfusion with pronase and collagenase and density gradient centrifugation with Nycodenz and cultured. KCCM was prepared and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay was used to detect HSC proliferation. The content of type Ⅳ collagen and laminin secreted by HSC in the HSC-conditioned medium was determined by radioimmunoassay.TGF-β1 production in the KCCM was detected by enzymelinked immunosorbent assay (ELISA).RESULTS:HSC and Kupffer cells isolated had high purity.One microgram per mililiter LPS-activated KCCM and unstimulated KCCM could significantly promote HSC proliferation [0.132±0.005 and 0.123±0.008 vscontrol group (0.100±0.003), P<0.01], and there was a difference between them (P<0.05). Ten microgram per mililiter LPS-activated KCCM (0.106±0.010) was unable to promote HSC proliferation (P>0.05). Adding anti-TGF-β1 antibodies could suppress the proliferation promoted by unstimulated KCCM and LPS(1μg/ml)-activated KCCM (0.109±0.009 vs 0.123±0.008,0.115±0.008 vs 0.132±0.005, P<0.01). LPS (1μg/ml or 10μg/ml) could not promote HSC proliferation immediately (0.096±0.003 and 0.101±0.004 vs 0.100±0.003, P>0.05). There was a parallel behavior between HSC proliferation and increased ECM level. One microgram per mililiter LPS-activated KCCM contained a larger amount of TGF-β1 than unstimulated KCCM.CONCLUSION:The technique for isolation of HSC and Kupffer cells described here is simple and reliable. KCCM stimulated by LPS may promote HSC proliferation and collagen accumulation, which are associated with hepatic fibrogenesis.
基金Supported by the Foundation of the Municipal Government of Nanjing,No.ZKG9809 and Health Bureau of Jiangsu Province,No.TS9904
文摘AIM: To study changes of inflammation-associated cytokine expressions during early phase of endotoxic shock in macague. METHODS: Experiments were performed in Macaque mulatta treated with LPS 2.8 mg/kg in shock model group or with normal saline in control group. Blood samples were collected before, or 60 min, or 120 min after LPS injection, respectively. Liver and spleen tissues were obtained at 120 min after LPS injection. The plasma levels of TNF-α,IL-1 β, IL-10 and IL-12P40 were determined by double-antibody sandwich ELISA with antibodies against human cytokines. The mRNA levels of TNF-α, IL-1 β, and IL-18 in peripheral blood mononuclear cells (PBMCs), liver and spleen were examined by real-time fluorescence semi-quantitative RT-PCR with the primers based on human genes. RESULTS: Mean systemic arterial pressure (MAP), systemicvascular resistance index (SVRI) and left ventricular work index (LVWI) of macaques were significant declined in shock model group on average 60 min after LPS injection. The plasma levels of TNF-α and IL-10 were significantly increased 60 min after LPS injection and then decreased. The plasma levels of IL-1 β and IL-12P40 were significantly increased at 120 min after LPS injection. The mRNA levels of TNF-α and IL-1 β were significantly increased 60 min after LPS stimulation in PBMCs and 120 min after LPS stimulation in livers. The mRNA level of IL-18 was significantly increased 120 rain after LPS stimulation in PBMCs and livers. But in spleen, only TNF-α mRNA level in LPS group was significantly higher 120 min after LPS stimulation, compared with that in control group. CONCLUSION: An endotoxic shock model of Macaque mulatta was successfully established. Both antibodies for ELISA and PCR primers based on human cytokine assays were successfully applied to detect macaque cytokines. In the model, inflammatory cytokines, such as TNF-α, IL-1 β,IL-12 and IL-18 as well as anti-inflammation cytokine IL-10, were released at very early phase of endotoxic shock within 120 min after LPS injection. PBMCs and liver cells might be the important sources of these cytokines.
基金Supported by the Science and Technology commission of JiangsuProvince,No.B J93007 and Natural Science Foundation of JiangsuProvince,No.BK2001003
文摘AIM: To study the effects of phosphorus-32 glass microspheres(^32P-GMS) on human hepatocellular carcinoma in nude mice. METHODS: Human liver cancer cell line was implanted into the dorsal subcutaneous tissue of 40 BALB/c nude mice. Then the 40 tumor-bearing BALB/c nude mice were allocated into treatment group (n=32) and control group (n=8). In the former group different doses of ^32P-GMS were injected into the tumor mass, while in the latter nonradioactive ^31P-GMS was injected into the tumor mass. The experimental animals were sacrificed on the 14th day. The ultrastructural changes of tumor in both treatment group and control group were studied with transmission electron microscopy (TEM) and stereology. RESULTS: In treatment group, a lot of tumor cells were killed and the death rate of tumor cells was much higher (35-70%). UItrastructurally, severe nuclear damage was observed in the death cells. The characteristics of appoptosis such as margination of heterochromatin was also found in some tumor cells. Besides, well differentiated tumor cells, degenerative tumor cells and some lymphocytes were seen. The skin and musde adjacent to the tumor were normal. In control group, the tumor consisted of poorly differentiated tumor cells, in which there were only a few of dead cells (5%). Stereologicl analysis of ultrastructral morphology showed that Vv of nuclei (53.31±3.46) and Vv of nucleoli (20.40±1.84) in the control group were larger than those (30.21±3.52 and 10.96±2.52) in the treatment group respectively (P<0.01), and Vv of RER (3.21±0.54) and Vv of mitochondria (4.53±0.89) in the control group were smaller than those (8.67±1.25 and 7.12±0.95) in the treatment group respectively (P<0.01, 0.05). Sv of the membrane of microvilli and canaliculi (27.12 um^2/100 um^3±11.84 um^2/100 um^3) in the control group was smaller than that (78.81 um^2/100 um^3±19.69 um^2/100 um^3) in the treatment group (P<0.01). But Vv of lipid particles (3.71±1.97) and Vv of vacuoles (5.72±1.58)were much larger than those (0.30±0.16 and 0.35±0.15) in the treatment group respectively (P<0.05, P<0.01). CONCLUSION: The experimental results indicate that local administration of ^32P-GMS can produce obvious effect on liver cancer cells and the anticancer effect of ^32P-GMS is directly proportional to the dose administrated. UItrastructural stereology can also show the effect of ^32P-GMS on the normalization of tumor cells, which is beneficial to the prognosis and treatment of patients. Moreover, local administrtion of ^32P-GMS is also safe.
基金National Natural Science Foundation of China,No.30200333 and No.30371605
文摘Regenerating gene (Reg or REG) family, within the superfamily of C-type lectin, is mainly involved in the liver,pancreatic, gastric and intestinal cell proliferation or differentiation. Considerable attention has focused on Reg family and its structurally related molecules. Over the last 15 years, 17 members of the Reg family have been cloned and sequenced. They have been considered as members of a conserved protein family sharing structural and some functional properties being involved in injury, inflammation,diabetes and carcinogenesis. We previously identified Reg Ⅳ as a strong candidate for a gene that was highly expressed in colorectal adenoma when compared to normal mucosa based on suppression subtractive hybridization (SSH),reverse Northern blot, semi-quantitative reverse transcriptase PCR (RT-PCR)and Northern blot. In situ hybridization results further support that overexpression of Reg Ⅳ may be an early event in colorectal carcinogenesis. We suggest that detection of Reg Ⅳ overexpression might be useful in the early diagnosis of carcinomatous transformation of adenoma.This review summarizes the roles of Reg family in diseases in the literature as well as our recent results of Reg Ⅳ in colorectal cancer. The biological properties of Reg family and its possible roles in human diseases are discussed. We particularly focus on the roles of Reg family as sensitive reactants of tissue injury, prognostic indicators of tumor survival and early biomarkers of carcinogenesis. In addition to our current understanding of Reg gene functions, we postulate that there might be relationships between Reg family and microsatellite instability, apoptosis and cancer with a poor prognosis. Investigation of the correlation between tumor Reg expression and survival rate, and analysis of the Reg gene status in human maliganancies, are required to elucidate the biologic consequences of Reg gene expression, the implications for Reg gene regulation of cell growth, tumorigenesis, and the progression of cancer. It needs to be further attested whether Reg gene family is applicable in early detection of cancer and whether Reg and Reg-related molecules can offer novel molecular targets for anticancer therapeutics. This has implications with regard to prognosis, such as in monitoring cancer initiation,progression and recurrence, as well as the design of chemotherapeutic drugs.
基金the scientific research funding for the returned overseas Chinese scholars,State Personnel Ministry,No.7690004027
文摘AlM: To study the expression of neurokinin-1 receptor (NK-1R) and neurokinin-2 receptor (NK-2R) in distal ileum ofacute necrotizing pancreatitis (ANP) and to evaluate therelationship between expression of these two receptors andintestinal mucosal damage.METHODS: A total of 130 adult Sprague-Dawley rats wererandomly divided into two groups: the rats in ANP group(n＝80) were induced by the retrograde intraductal infusionof 30 g@L-1 sodium taurocholate. And the rats in normal controlgroup (n＝50) received laparotomy only. Sacrifices weremade 6 h, 12 h, 24 h and 48 h later in ANP and normalcontrol group after induction respectively. Intestinal mucosalpermeability was studied by intrajejunal injection of 1.SmCiradioactive isotope 99mTc-diethlene triamine pentacetic acid(DTPA) and the radioactivity of 99mTc-DTPA content in urinewas measured 6 h, 12 h, 24 h and 48 h after induction.Then the pancreas and intestine were prepared forpathology. Reverse transcription polymerase chain reaction(RT-PCR) was used to determine the mRNA expression ofNK-1R and NK-2R, and Western blot was used to investigatethe protein level of NK-1R and NK-2R.RESULTS: In ANP rats, serious histologic damages inintestinal mucosa were observed, and the radioactivity of99mTc-DTPA in urine increased significantly in the ANP group.RT-PCR revealed that NK-1R and NK-2R mRNA level wasoverexpressed in the distal ileum of ANP as compared withthe normal control group. Western blot discovered strongerNK-1R (14-fold increase) and NK-2R (9-fold increase)immunoreactivity in the intestinal mucosa of ANP rats.Moreover, the overexpression of NK-1R was associated withmucosal pathological score (r＝0.77,P＜0.01) and intestinalpermeability (r＝0.68, P＜0.01) in ANP rats.CONCLUSION: NK-1R and NK-2R contribute to disruptedneuropeptides loop balance, deteriorate intestinal damage,and are involved in pathophysiological changes in ANP.
基金This project is supported by National Natural Science Foundation of China (No. 20010227012)
文摘Finite element model updating method based on global information is proposed.Prior investigation upon design space of structural parameters is performed before updating usingstatistic analysis, including parameter screening using variance analysis and response surfacefitting using regression analysis. The parameter screening method selects the design parametersconsidering the result of hypothesis testing, which is a kind of global information. Meanwhile, thetraditional updating method considers local sensitivity which only gives the information at solepoint in the design space. Response surface fitting constructs a close-form multinomial whichdescribes the relationship between concerned structural feature and selected updating parameters. Itis an approximation to finite element models(FEM) and used as a substitution in the updatingiterations. The presented updating method can be applied without the restriction of linearassumption. In addition, there is no data exchange between the updating program and the finite-element analysis program in the updating iterations. This makes the method practical inengineering. An aircraft test structure, GARTEUR, is employed to verify the effectiveness of themethod. After updating, the error of modal frequencies is less than 3 percent.
基金the Applied Basic Research Programs of Science and Technology Commission Foundation of Jiangsu Province,No BJ98080(1998-2001)
文摘AIM: To directly investigate the relationship between telomerase activity and its subunit expression and the inhibitory effect of antisense hTR on pancreatic carcinogenesis.METHODS: We examined the telomerase activity and its subunit expression by cell culture, polymerase chain reaction (PCR), PCR-silver staining, PCR-ELISA, DNA sequencing, MTT and flow cytometry methods.RESULTS: PCR-silver staining and PCR-ELISA methods had the same specificity and sensitivity as the TRAP method.Telomerase activity was detected in the extract of the 10th,20th and 30th passages of P3 cells,while it was absent in fibroblasts. Furthermore, after the 30th generation, the proliferation period of fibroblast cells was significantly prolonged. Telomerase activity and hTERTmRNA were detected in two pancreatic carcinoma cell lines, but were found to be negative in human fibroblast cells. Telomerase activity and hTERTmRNA were tested in pancreatic carcinoma specimens of 24 cases. The telomerase activity was positive in 21 of the 24 cases (87.5 %), and the hTERTmRNA in 20 cases (83.3 %). In adjacent normal tissues positive rates were both 12.5 %. There was a significant difference between the two groups. This indicated a significant correlation between the expression level of telomerase activity and histologic differentiation,metastasis and advanced clinical stage of pancreatic carcinoma. Our findings showed that the expressions of hTR and TP1mRNA were not correlated with the activity of telomerase but the expression of hTERTmRNA was. After treatment with PS-ODNs, telomerase activity in P3 cells weakened and the inhibiting effect became stronger with an increase in PS-ODNs concentration. There was a significant difference between different PS-ODN groups (P＜0.05). Inhibition of telomerase activity occurred most significant with PS-ODN1.The results of the FCM test of pancreatic cancer P3 cells showed an increase in the apoptotic rate with increasing PS-ODN1 and PS-ODN2concentrations.CONCLUSION: The expression of telomerase activity has a significant relationship to carcinogenesis. A strong correlation exists between telomerase activity and hTERTmRNA expression. The up-regulation of hTERTmRNA expression may play a critical role in human carcinogenesis.The expression of telomerase activity and its subunit level in pancreatic carcinoma significantly correlate with the clinical stage of pancreatic carcinoma and hence, may be helpful in its diagnosis and prognosis. The anti-hTR complementary to the template region of hTR is sufficient to inhibit P3 cell telomerase activity and cell proliferation in vitro, and can lead to a profound induction of programmed cell death.
文摘To evaluate the clinic outcome of off-pump coronary bypass grafting (OPCABG) of patients with coronary heart disease and chronic obstructive pulmonary disease, we collected and analyzed 1998-2002 data on 28 patients with these two diseases who had received off-pump coronary bypass operation in our hospital, and compared with data on those who also had the same two diseases but received on-pump coronary artery bypass at same time. There were no operation-related death;one died of respiratory failure 14 days after operation while staying in hospital; there were more respiratory complications in the conventional coronary artery bypass grafting group (CCABG) than in the OPCABG group; and the PaO2/FiO2 in the CCABG group was higher than that in the OPCABG group during operation because of CPB, but lower than that in the OPCABG group 6-12 hours after operation. OPCABG seemed more suitable than CCABG for coronary artery disease patients with chronic obstructive pulmonary disease due to less damage to their oxygen-exchange capability and the fewer respiratory complications.
文摘A new closed-loop driving scheme for the silicon micromachined vibratory gyroscope (SMVG) is proposed. The push-pull driving is adopted and in-phase AC and reverse-phase DC voltages are applied in the driving electrodes placed in both sides of the active combs, respectively. Driving performance analyses show that the frequency spectrum between driving moments and noise signals is separated. Therefore, the model of the closed-loop control is set up with the phase lock loop (PLL). The requirements for phases and gains of the sinusoidal selfdrive-oscillation are met by PLL, thus the closed-loop circuit reaches the self-drive-oscillation. Phase conditions of the sinusoidal self-drive-oscillation and the characteristic of phase discrimination of the PLL are used to eliminate the coupling between driving and sense signals, and noise signals. Finally, experimental results show that the variations of both the driving frequency and the amplitude are all under 0.02%. The precision and the reliability of the gyroscope are greatly improved.
基金Supported by the National Natural Science Foundation of China,No.60121101the National High Technology ResearchDevelopment Program of China,No.2002AA2Z2004
文摘AIM: Aberrant DNA methylation of CpG site is among the earliest and most frequent alterations in cancer. Several studies suggest that aberrant methylation of the CpG sites of the tumor suppressor gene is closely associated with carcinogenesis. However, large-scale analysis of candidate genes has so far been hampered by the lack of highthroughput approach for analyzing DNA methylation. The aim of this study was to describe a microarray-based method for detecting changes of DNA methylation in cancer.METHODS: This method used bisulfite-modified DNA as a template for PCR amplification, resulting in conversion of unmethylated cytosine, but not methylated cytosine, into thymine within CpG islands of interest. Therefore, the amplified product might contain a pool of DNA fragments with altered nucleotide sequences due to differential methylation status.Nine sets of oligonucleotide probes were designed to fabricate a DNA microarray to detect the methylation changes of p16 gene CpG islands in gastric carcinomas. The results were further validated by methylation-specific PCR (MSP).RESULTS: The experimental results showed that the microarray assay could successfully detect methylation changes of p16 gene in 18 gastric tumor samples. Moreover,it could also potentially increase the frequency of detecting p16 methylation from tumor samples than MSP.CONCLUSION: Microarray assay could be applied as a useful tool for mapping methylation changes in multiple CpG loci and for generating epigenetic profiles in cancer.
基金National Natural Science Foundation of China，Open Research Fund of National Mobile Communications Research Laboratory of Southeast University，Qing Lan Project of Jiangsu Province,the Fundamental Research Funds for the Central Universities,Research Founding of Graduate Innovation Center in NUAA，Innovation Fund of College of Electronic and Information Engineering of NUAA
文摘Discrete-rate adaptive modulation （AM） scheme for distributed antenna system （DAS） with imperfect channel state information （CSI） is developed, and the corresponding performance is investigated in composite Rayleigh channel. Subject to target bit error rate （BER） constraint, an improved fixed switching threshold （FST） for the AM scheme is presented by means of tightly-approximate BER expression, and it can avoid the performance loss fxom conventional FST. Based on the imperfect CSI, the variable switching threshold （VST） is derived by utilizing the maximum a posteriori method. This VST includes the improved FST as a special case, and may lower the impact of estimation error on the performance. By the switching thresholds, the spectrum efficiency （SE） and average BER of the system are respectively derived, and resulting closed- form expressions are attained. With these expressions, the system performance can be effectively evaluated. Simulation results show that the derived theoretical SE and BER can match the simulations well. Moreover, the AM with the presented FST has higher SE than that with the conventional one, and the AM with VST can tolerate the large estimation error while maintaining the target BER.
文摘For the purpose of making the best use of the mine frequency resource and realizing the instruction idea “to exchange bandwidth for distance" a W-CDMA mine spread spectrum mobile communication scheme based on spread spectrum communication technique and the propagation characteristic of electromagnetic wave along laneways is proposed.The structure and make up of the system are studied and the working frequency and channels are assigned.Analysis indicates the scheme is a simple one that can fulfill the mine saying requirement.
文摘A completely new finite element software, Finite ElementProgram Generator (FEPG), is introduced and its designing thought and organizing structure is presented.FEPG uses the method of components and the technique of artificial intelligence to generate finite element program automatically by a computer according to the general principles of mathematic and internal rules of finite element method,as is similar to the deduction of mathematics.FEPG breaks through the limitation of present finite element software,which only applies to special discipline,while FEPG is suitable for all kinds of differential equations solved by finite element method.Now FEPG has been applied to superconductor research,electromagnetic field study,petroleum exploration,transportation,structure engineering,water conservancy,ship mechanics, solid-liquid coupling problems and liquid dynamics,etc.in China.
文摘We try to apply a constituent quark model (a variety chiral constituent quark model) and the resonating group approach for the multi-quark problems to compute the effective potential between the NN- in S-wave (the quarks in the nucleons N and N-, and the two nucleons relatively as well, are in S wave) so as to see the possibility if there may be a tight bound state of six quarks as indicated by a strong enhancement at threshold of pp- in J/ψ and B decays. The effective potential which we obtain in terms of the model and approach shows if the experimental enhancement is really caused by a tight S-wave bound state of six quarks, then the quantum number of the bound state is very likely to be I = 1, JPC= 0-+.
文摘Web information extraction is viewed as a classification process and a competing classification method is presented to extract Web information directly through classification. Web fragments are represented with three general features and the similarities between fragments are then defined on the bases of these features. Through competitions of fragments for different slots in information templates, the method classifies fragments into slot classes and filters out noise information. Far less annotated samples are needed as compared with rule-based methods and therefore it has a strong portability. Experiments show that the method has good performance and is superior to DOM-based method in information extraction. Key words information extraction - competing classification - feature extraction - wrapper induction CLC number TP 311 Foundation item: Supported by the National Natural Science Foundation of China (60303024)Biography: LI Xiang-yang (1974-), male, Ph. D. Candidate, research direction: information extraction, natural language processing.
基金This project is supported by National Natural Science Foundation of China (No. 59885002).
文摘Adaptive control of a flexible beam system preceded by an unknown dead-zonein the driving motor is investigated in state space form. By introducing an important lemma forsimplifying error equation between the flexible beam model and the matching reference model, arobust adaptive control scheme is developed by involving the dead-zone inverse terms. The newadaptive control law ensures global stability of the entire system and achieves desired trackingprecision even when the slopes of the dead-zone are not equal. Simulations performed on a typicalflexible beam system illustrate and clarify the validity of this approach.
