6801
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Li G, Li X, Zhan Y. [Female pseudohermaphroditism with a phallic urethra--a case report]. HUA XI YI KE DA XUE XUE BAO = JOURNAL OF WEST CHINA UNIVERSITY OF MEDICAL SCIENCES = HUAXI YIKE DAXUE XUEBAO 1992; 23:221-3. [PMID: 1452164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Female pseudohermaphroditism with penile urethra caused by virilizing adrenal tumor in the mother is rare. A case is reported in this article. After operation the diagnosis was verified pathologically. Exposure of a female fetus to endogenous or exogenous androgens before the seventh or eighth week of fetal age may result in male external genitalia. It is emphasized that any cryptorchid phenotypic male born to a virilized mother should be proved by sex chromatin and sex chromosomes to exclude pseudohermaphroditism and that in any case of unexplained female pseudohermaphroditism one should explore the possibility of a maternal virilizing tumor.
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6802
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Li X. [Multilocus enzyme electrophoretic types of Neisseria meningitidis serogroup B and their epidemiologic significances]. ZHONGHUA LIU XING BING XUE ZA ZHI = ZHONGHUA LIUXINGBINGXUE ZAZHI 1992; 13:129-33. [PMID: 1423533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
In order to expand the epidemiologic relationships between the strains of Neisseria meningitidis serogroup B isolated from patients and carriers, 57 cases and 45 carrier isolates were collected in 11 provinces and 2 municipalities of China since the 1970s and their multilocus enzyme electrophoretic types and clonal population structures were studied by multilocus enzyme electrophoresis. It was primarily found that the above strains could be divided into 69 electrophoretic types (ET) and 13 clones. Among others, the clone I was the most important one, because the clone I represented 63.7% of all strains tested and 77.2% of the case isolates and its district distributions were quite wide since the 1970s. In addition, it was an obvious tendency that more and more of the case isolates gathered up the clone I since 1984 and the predominant ETs also occurred in the complex ET 1 and ET 24 of the clone I. As compared with the case isolates, the above carrier isolates displayed more heterogenetic types. Only 40% of all carrier isolates belonged to the above clone I and predominant ETs.
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6803
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Li X, Huang D, Huang G, Xi D. [Uniform design for the best conditions of processing heixi in shenrong heixi pills] off. ZHONGGUO ZHONG YAO ZA ZHI = ZHONGGUO ZHONGYAO ZAZHI = CHINA JOURNAL OF CHINESE MATERIA MEDICA 1992; 17:342-3, 382. [PMID: 1418577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Uniform design has been applied to select the optimum technological conditions for processing Heixi in Shenrong Heixi Pills, using the contents of the main constituent of Heixi SNS as the optimum target. The best technological conditions have thus been found.
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6804
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Li X, Tucker J, Quan D, Duff J, Zhong R, Grant D. Alloantigen-presenting activity of cells from rat small intestine. Transplant Proc 1992; 24:1150. [PMID: 1534945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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6805
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Hamada J, Takeichi N, Okada F, Ren J, Li X, Hosokawa M, Kobayashi H. Progression of weakly malignant clone cells derived from rat mammary carcinoma by host cells reactive to plastic plates. Jpn J Cancer Res 1992; 83:483-90. [PMID: 1618698 PMCID: PMC5918850 DOI: 10.1111/j.1349-7006.1992.tb01953.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Tumor progression is the process by which tumor cells acquire more malignant properties, such as invasiveness and metastasis, during tumor development. To elucidate mechanisms of tumor progression, we examined the role of interactions between the tumor and its host by using a cloned cell line, ER-1, which was derived from a rat mammary carcinoma. ER-1 is weakly tumorigenic and non-metastatic when s.c. injected into syngeneic hosts in single cell suspension. However, ER-1 cells show a high incidence of lethal growth when s.c. implanted (5 x 10(2) cells), being attached to a 10 x 5 x 1 mm polystyrene plate. Tumor cell lines (PLT) obtained from tumors which had arisen from the plate-attached ER-1 cells no longer required plates for their growth in normal hosts, and had acquired metastatic ability to the lungs. The malignant phenotypes of PLT were stable under a usual culture condition for at least 6 months. Furthermore, the incidence of tumor development increased when small numbers of ER-1 cells were injected onto plates (or at their periphery) which had previously been implanted s.c. without tumor cells. The tumorigenicity of ER-1 cells increased after they were cocultivated for more than 30 days with host reactive cells obtained from the tissues surrounding the plates. These results suggest that host cells reactive to the foreign body (plastic plate) may not only promote the local growth of ER-1 cells but also convert them into much more malignant tumors.
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6806
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Li X, Brown SL, Hill RP. Factors influencing the thermosensitivity of two rodent tumors. Radiat Res 1992; 130:211-9. [PMID: 1574577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
When SCCVII or KHT tumors (150 mm3) growing in the dorsum of the hind feet of mice were heated in a water bath at 44 degrees C for 60 min, the local control rate was 75 or 5%, respectively. To investigate factors responsible for the differential thermosensitivity between SCCVII and KHT tumors, the intratumor temperature distributions during heating and the thermosensitivities of the tumor cells were studied. Significant temperature heterogeneity was observed in heated tumors. The thermal dose distribution during heating for the sensitive SCCVII tumors was found to be more homogeneous than that for the resistant KHT tumors. For cells grown and heated in culture, SCCVII and KHT cells had similar thermosensitivities. However, when heated in vivo, both SCCVII and KHT cells were more sensitive than their counterparts grown in culture and SCCVII cells were more sensitive than KHT cells. If cells dispersed from the tumors were cultured in medium for 6 h and then heated, both types of cells became as resistant as cells grown in culture. One possible reason for tumor cells to be more sensitive to heating in vivo than in vitro, the temperature of unheated tumors, was examined. It was found that the temperature in the same region in unheated tumors varied temporally by several degrees with an average temperature of 31-32 degrees C. We found no evidence that the temperature during tumor growth could greatly influence the thermosensitivity of the tumor cells. Our findings indicate that a more homogeneous distribution of temperature in the tumor during heating and higher in vivo thermosensitivity of the tumor cells are characteristics of the more heat-sensitive tumor.
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6807
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Xia X, Li X, Lin DL, George TF. Hole burning in the resonance fluorescence of impurity centers. PHYSICAL REVIEW. B, CONDENSED MATTER 1992; 45:8316-8320. [PMID: 10000663 DOI: 10.1103/physrevb.45.8316] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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6808
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Li X, Tan CK, So AG, Downey KM. Purification and characterization of delta helicase from fetal calf thymus. Biochemistry 1992; 31:3507-13. [PMID: 1313298 DOI: 10.1021/bi00128a027] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
A DNA helicase (delta helicase) which partially copurifies with DNA polymerase delta has been highly purified from fetal calf thymus. delta helicase differs in physical and enzymatic properties from other eukaryotic DNA helicases described thus far. The enzyme has an apparent mass of 57 kDa by gel filtration and is associated with polypeptides of 56 and 52 kDa by SDS-polyacrylamide gel electrophoresis. Photo-cross-linking of the purified enzyme with [alpha-32P]ATP resulted in labeling of a polypeptide of approximately 58 kDa, suggesting that the active site is present on the larger polypeptide. Unwinding of a partial duplex requires a nucleoside triphosphate which can be either ATP or dATP but not a nonhydrolyzable analogue of ATP. Other ribo- and deoxyribonucleoside triphosphates have little or no activity as cofactors. delta helicase also has DNA-dependent ATPase activity which has a relatively low Km for ATP (40 microM). delta helicase binds to single-stranded DNA but has little or no affinity for double-stranded DNA or single-stranded RNA. Similar to replicative DNA helicases from prokaryotes and the herpes simplex virus type 1 helicase-primase, delta helicase translocates in the 5'-3' direction along the strand to which it is bound and preferentially unwinds DNA substrates with a forklike structure.
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6809
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Li X, Wright LE, Bennhold C. Kaon photoproduction on the neutron using deuterium. PHYSICAL REVIEW. C, NUCLEAR PHYSICS 1992; 45:2011-2014. [PMID: 9967956 DOI: 10.1103/physrevc.45.2011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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6810
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Bachmann R, Li X, Ottinger C, Vilesov AF. Molecular‐beam study of the collisional intramolecular coupling of N2(B 3Πg) with the N2(A 3Σ+u) and N2(W 3Δu) states. J Chem Phys 1992. [DOI: 10.1063/1.462756] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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6811
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Hatanaka K, Uchida K, Sakai H, Kurata M, Li X, Yamamoto A. The effect of low-density lipoprotein apheresis on plasma thrombomodulating factors. ASAIO J 1992; 38:102-7. [PMID: 1384816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The authors have investigated the effects of double-membrane filtration with hollow fiber membranes made of different artificial materials and low-density lipoprotein (LDL)-adsorbent dextran sulfate cellulose (DS) columns on coagulation-related proteins and complement components to evaluate their hemocompatibility. All membrane filters showed similar sieving effects, which depended upon the molecular weights of the proteins. In the double-membrane filtration system, free protein S, protein C, antithrombin III, and alpha 1-antitrypsin were returned to the intracorporeal circulation, whereas alpha 2-macroglobulin and fibrinogen were almost completely removed from the circulation; C4b-binding protein (C4BP)-protein S complexes were also trapped by the second membrane, and in some instances were even blocked by the first membrane, if it was made of material that activated the classic pathway of the complement system. The DS column adsorbed C4BP-protein S complex, but free protein S was almost completely recovered in the eluate.
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6812
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Li X, Needs RJ, Martin RM, Ceperley DM. Green's-function quantum Monte Carlo study of a jellium surface. PHYSICAL REVIEW. B, CONDENSED MATTER 1992; 45:6124-6130. [PMID: 10000357 DOI: 10.1103/physrevb.45.6124] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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6813
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Lu JP, Li X, Martin RM. Ground state and phase transitions in solid C60. PHYSICAL REVIEW LETTERS 1992; 68:1551-1554. [PMID: 10045160 DOI: 10.1103/physrevlett.68.1551] [Citation(s) in RCA: 87] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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6814
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Abstract
Sequential effects were used to diagnose whether elements in a two-object comparison task are represented as a perceptual unit or separately. The presence of sequential effects and absence of influences of individual elements on the subsequent trial in a successive comparison task favor the hypothesis that the elements in a pair are represented as a unit, and that a response is made to the perceptual unit. The patterns of response times on same and different trials differed in several ways; these suggested that the quality of the representations of same and different trials may differ.
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6815
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Cooley BC, Hanel DP, Gould JS, Li X, Smith JW. Antithrombotic benefit of subendothelium-bound urokinase: an experimental study. J Hand Surg Am 1992; 17:235-44. [PMID: 1564269 DOI: 10.1016/0363-5023(92)90398-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
To improve the outcome of extremity replantation, microsurgeons have administered systemic antithrombotic agents (e.g., heparin, aspirin, dextran). To obviate the risks associated with systemic anticoagulation, we have investigated the use of topically applied urokinase for its binding capacity to arterial subendothelium and for its ability to prevent subsequent thrombosis. An arterial model of thrombosis associated with intimal deendothelialization was developed. Donor rat carotid arteries were everted and mechanically deendothelialized with a scalpel blade. The vessels were next subjected to one of several treatments, which included 30-minute incubation with urokinase, heparin, or vehicle (lactated Ringer's solution). The vessels were then washed, reinverted to normal orientation, sectioned into 5 mm lengths, and grafted into the femoral arteries of recipient rats. Two-hour patency rates were 25% for controls (n = 20), 10% for heparin-treated vessels (n = 10), and 55% for urokinase-treated vessels (n = 20); this last was significantly greater than the other two groups. In vitro investigations revealed that urokinase has a high capacity for binding to subendothelium, with a release half-life of approximately 20 minutes. Surface-bound urokinase was found to have proteolytic activity similar to that of urokinase in solution. These results indicate that urokinase may be a more beneficial irrigating solution additive than heparin for repair of traumatized vessels.
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6816
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Shen N, Li X, Wei S. [Relationship between height, collagen metabolism, hair zinc and excessive fluoride intake]. HUA XI YI KE DA XUE XUE BAO = JOURNAL OF WEST CHINA UNIVERSITY OF MEDICAL SCIENCES = HUAXI YIKE DAXUE XUEBAO 1992; 23:83-6. [PMID: 1398632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
After eliminating confounding factors, the study was made on the relationship between height, collagen metabolism, hair zinc and excessive fluoride intake. 140 schoolchildren aged 12-13 years born and reared in endemic fluorosis areas were surveyed. The results were as follows: 1. The average height of children with dental fluorosis III degree (DF III degree) was appreciably smaller than that of children without dental fluorosis. Among children with excessive fluoride intake, a negative correlation between the height and fluoride level in staple foods was seen. 2. The more the fluoride ingested, the higher the urinary THP excreted, showing that fluoride intoxication interfered with the collagen metabolism. 3. Among children with excessive fluoride intake, the height showed negative correlation with urinary THP/Cr, suggesting that the effect of fluoride on collagen metabolism indicated the mechanism of height retardation. 4. As compared to control group with the excessive fluoride intake but without dental fluorosis group, there was a significant reduction in hair zinc in group with DF III degree, suggesting that the zinc in the body decreased because of zinc metabolism disturbance by excessive fluoride intake. But among cases with excessive fluoride intake, no appreciable correlation between hair zinc and height was found. Therefore, it could not be confirmed that the effect of fluoride on zinc metabolism affected the height development.
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6817
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Abstract
The dual (stimulatory and inhibitory) regulation of adenylyl cyclase was studied in syncytiotrophoblast basal membranes prepared from term human placenta. Stimulation of adenylyl cyclase activity with GTP, non-hydrolyzable GTP analogs, isoproterenol and PGE1 was observed, confirming the presence of an intact stimulatory pathway in these membranes. Investigations of the inhibitory pathway revealed tight coupling of the G-protein, Gi alpha, to catalytic adenylyl cyclase, with high doses of GTP producing 80 per cent inhibition of GTP/forskolin-stimulated activity. Confirming Gi alpha involvement, pertussis toxin (PTX) treatment of basal membranes augmented the responses of adenylyl cyclase to both GTP and forskolin. In addition, immunoblotting of basal membrane proteins revealed the presence of the G-protein subunits, Gs alpha, Gi alpha, and G beta/gamma. The response of adenylyl cyclase was measured to a series of agonists known to inhibit adenylyl cyclase in other tissues, however a reproducible inhibitory effect was produced only by somatostatin (approximately 80 per cent). Treatment of basal membranes with PTX caused a degree of reversal of the somatostatin-mediated adenylyl cyclase inhibition. However, the intoxication was insufficient to restore GTP/forskolin-stimulated activity.
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6818
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Li X, Wu Y, Guo Z, Liu L. [Effect of sodium 18 beta-glycyrrhetate on experimental arrhythmia]. ZHONGGUO ZHONG YAO ZA ZHI = ZHONGGUO ZHONGYAO ZAZHI = CHINA JOURNAL OF CHINESE MATERIA MEDICA 1992; 17:176-8, inside backcover. [PMID: 1418542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The effect of sodium 18 beta-glycyrrhetate (SGA) on experimental arrhythmia was investigated. The result shows that SGA strongly counteracts arrhythmia induced by chloroform of chloroform adrenaline, lengthens the appearance time of arrhythmia induced by CaCl2, slightly retards the heart rate of rats and rabbits, and partly antagonizes the acceleration effect of isoproterenol on rabbit hearts.
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6819
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Li X, Schlafer DH. A spontaneous skin basal cell tumor in a black French minilop rabbit. LABORATORY ANIMAL SCIENCE 1992; 42:94-5. [PMID: 1316523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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6820
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Wang M, Li F, Li X, Zhang L, E Z. [Effects of ginseng volatile oil on cytochemical components of SGC-823 gastric carcinoma in cell culture]. ZHONGGUO ZHONG YAO ZA ZHI = ZHONGGUO ZHONGYAO ZAZHI = CHINA JOURNAL OF CHINESE MATERIA MEDICA 1992; 17:110-2, 128. [PMID: 1418525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
After 24, 48 and 72 hours' treatment of cells of SGC-823 gastric carcinoma in cell cultures with ginseng volatile oil, glycogen, succinate dehydrogenase and DNA in single cells were measured quantitatively with MPV2 microscope photometer. The results show that the inhibition of cancer cell growth by ginseng volatile oil may be due to the action of metabolism of DNA, carbohydrates and energy.
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6821
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Misra SK, Li X. Gd3+ EPR study of NH4Ce(SO4)2. PHYSICAL REVIEW. B, CONDENSED MATTER 1992; 45:2927-2933. [PMID: 10001841 DOI: 10.1103/physrevb.45.2927] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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6822
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Li X, Bilgutay NM, Murthy R. Spectral histogram using the minimization algorithm-theory and applications to flaw detection. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 1992; 39:279-284. [PMID: 18263148 DOI: 10.1109/58.139126] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
In ultrasonic flaw detection in large grained materials, backscattered grain noise often masks the flaw signal. To enhance the flaw visibility, a frequency diverse statistical filtering technique known as split-spectrum processing has been developed. This technique splits the received wideband signal into an ensemble of narrowband signals exhibiting different signal-to-noise ratios (SNR). Using a minimization algorithm, SNR enhancement can be obtained at the output. The nonlinear properties of the frequency diverse statistic filter are characterized based on the spectral histogram, which is the statistical distribution of the spectral windows selected by the minimization algorithm. The theoretical analysis indicates that the spectral histogram is similar in nature to the Wiener filter transfer function. Therefore, the optimal filter frequency region can be determined adaptively based on the spectral histogram without prior knowledge of the signal and noise spectra.
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6823
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Jabri MA, Li X. Predicting the number of contacts and dimensions of full-custom integrated circuit blocks using neural network techniques. IEEE TRANSACTIONS ON NEURAL NETWORKS 1992; 3:146-153. [PMID: 18276416 DOI: 10.1109/72.105428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Block layout dimension prediction is an important activity in many very large scale integration computer-aided design tasks, among them structural synthesis, floor planning and physical synthesis. Block layout dimension prediction is harder than block area prediction and has been previously considered to be intractable. The authors present a solution to this problem using a neural network machine learning approach. The method uses a neural network to predict first the number of contacts; then another neural network uses this prediction and other circuit features to predict the width and the height of its layout. The approach has produced much better results than those published-a dimension (aspect ratio) prediction average error of less than 18% with a corresponding area prediction average error of less than 15%. Furthermore, the technique predicts the number of contacts in a circuit with less than 4% error on average.
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6824
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Li X, Cooley BC, Gould JS. Influence of topical heparin on stasis-induced thrombosis of microvascular anastomoses. Microsurgery 1992; 13:72-5. [PMID: 1569883 DOI: 10.1002/micr.1920130205] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
An experiment was done to determine whether topical heparin and the association of anastomoses with dependent tissue (free flaps) exert any influences on stasis-induced microvascular thrombosis. Rat femoral vessel anastomoses with or without free flap construction were used in a total of 50 male Sprague-Dawley rats. Saline either with or without heparin was used for intralumenal irrigation during the anastomosis. Following anastomotic repair, the femoral vessels were reclamped, inducing stasis for either 2 or 4 hr. Our results showed that static blood had little adverse effect on thrombosis at the arterial anastomosis when reclamped for up to 4 hr in both standard and flap-associated anastomoses. Topical heparin significantly reduced the incidence of stasis-induced thrombosis of venous anastomoses. The venous patency rates in standard anastomoses were lower than those in flap-associated anastomoses after both 2 and 4 hr of stasis. From these results, we conclude the following. 1) Arteries may be reclamped for up to 4 hr without detriment despite static blood being in contact with the anastomotic site. 2) Topical heparin may be helpful in increasing the patency rate of venous anastomoses after a period of blood stasis. 3) Free flap construction may play a role in decreasing stasis-induced microvascular thrombosis.
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6825
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Li X, Robbins JW, Taylor KB. Effect of the levels of dissolved oxygen on the expression of recombinant proteins in four recombinantEscherichia coli strains. ACTA ACUST UNITED AC 1992; 9:1-9. [PMID: 1367973 DOI: 10.1007/bf01576362] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Four recombinant strains of Escherichia coli were examined for the effects of the dissolved oxygen level on the level of biomass, the plasmid content, and the level of recombinant protein at the stationary phase of batch growth. Strains JM101/pYEJ001, and TB-1/pYEJ001 (encoding chloramphenicol acetyltransferase), and strain TB-1/p1034, and TB-1/pUC19 (encoding beta-galactosidase) were grown at the constant dissolved oxygen levels of 0, 50, and 100% air saturation, as well as in the absence of dissolved oxygen control. The biomass of all strains under constant aerobic conditions was 12-36 times higher than that under anaerobic conditions, but was the same as or slightly higher than that without dissolved oxygen control. The plasmid content in all strains under aerobic conditions was 2.9-11.7 times higher than that under aerobic conditions. The optimal dissolved oxygen concentration for the specific activity of recombinant proteins was dependent upon the strain. In no strain were constant aerobic conditions optimal. However, because of the effect on biomass, controlled aerobic conditions were optimal for the volumetric activity of recombinant protein in all but one strain.
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