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Sample records for delayed hbeag seroconversion

  1. Relative predictive factors for hepatocellular carcinoma after HBeAg seroconversion in HBV infection

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    Kazumoto Murata; Kazushi Sugimoto; Katsuya Shiraki; Takeshi Nakano

    2005-01-01

    AIM: To determine the predictive factors forhepatocellular carcinoma (HCC) development in patientsafter spontaneous or therapeutic HBeAg seroconversion.METHODS: In 48 patients who seroconverted to anti-HBe positive during follow-up, the background factors forHCC development were analyzed.RESULTS: HCC was developed in six patients duringfollow-up (average follow-up after HBeAg seroconversion:10.9±5.4 years). The incidence of HCC evaluated byKaplan-Meier analysis was significantly higher in patientswith abnormal aspartate aminotransferase (AST>40 IU/L) level, lower platelet counts (PLT<10×104/μL),lower albumin level (Alb<30 g/L), positive HBV-DNA or older age at seroconversion (>40 years). However, lower platelet count was the only predictive factor for HCC development shown by multivariate proportional-hazard analysis.CONCLUSION: Active hepatitis or advanced hepatitis at HBeAg seroconversion or progressive hepatitis even after HBeAg seroconversion would be the risk factors for HCC development. These predictive factors should be taken into account in determining the frequency of biochemical study or imaging studies for HCC surveillance.

  2. HBcrAg Identifies Patients Failing to Achieve HBeAg Seroconversion Treated with Pegylated Interferon Alfa-2b

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    Hui Ma

    2016-01-01

    Conclusions: Effective antiviral treatment can decrease HBcrAg levels in the serum. The NPVs of HBcrAg for predicting HBeAg seroconversion at 24-week follow-up was 100%, but the PPVs were not satisfactory (all <31%. The serum HBcrAg levels of the patients with HBeAg seroconversion at the end of the 24-week follow-up steadily declined or even became undetectable during the LTFU.

  3. Slow reduction of IP-10 Levels predicts HBeAg seroconversion in chronic hepatitis B patients with 5 years of entecavir treatment.

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    Guo, Renyong; Mao, Hejun; Hu, Xiao; Zheng, Nengneng; Yan, Dong; He, Jianqin; Yang, Jiezuan

    2016-11-15

    The aim of this study was to determine the correlation between dynamic changes in serum cytokine/chemokine expression levels in response to entecavir (ETV) treatment and HBV e antigen (HBeAg) seroconversion in patients with chronic hepatitis B (CHB). Four cytokines (interleukin [IL]-4, IL-6, IL-8, and interferon-γ) and five chemokines (macro-phage inflammatory protein [MIP]-1α, MIP-1β, platelet derived growth factor-BB, and interferon-inducible protein 10 [IP-10]) before ETV therapy and at 3, 6, 12, 24, 36 and 60 months during therapy in 105 CHB patients were analyzed. The results showed that the low decrease rate of IP-10 levels after 1 year of ETV treatment was an independent predictor of HBeAg seroconversion at year 5 (Hazard ratio = 0.972). The area under the receiver operating characteristic curves for the decrease rate of IP-10 levels after 1 year of treatment to discriminate a year-5 HBeAg seroconversion was 0.752 (p = 0.005). The results indicate that higher IP-10 level at year one of ETV treatment is associated with an increased probability of HBeAg seroconversion. Quantification of IP-10 during ETV treatment may help to predict long-term HBeAg seroconversion in patients with CHB.

  4. Predictive value of serum ALT and T-cell receptor beta variable chain for HBeAg seroconversion in chronic hepatitis B patients during tenofovir treatment

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    Yang, Jiezuan; Yan, Dong; Guo, Renyong; Chen, Jiajia; Li, Yongtao; Fan, Jun; Fu, Xuyan; Yao, Xinsheng; Diao, Hongyan; Li, Lanjuan

    2017-01-01

    Abstract Effective antiviral therapy plays a key role in slowing the progression of chronic hepatitis B (CHB). Identification of serum indices, including hepatitis B e antigen (HBeAg) expression and seroconversion, will facilitate evaluation of the efficacy of antiviral therapy in HBeAg-positive CHB patients. The biochemical, serological, virological parameters, and the frequency of circulating CD4+CD25+ regulatory T cell (Treg) in 32 patients were measured at baseline and every 12 weeks during 96 weeks of tenofovir disoproxil fumarate (TDF) treatment. The relationship between the hepatitis B virus (HBV) deoxyribonucleic acid (DNA) and Treg and alanine aminotransferase (ALT) levels was analyzed, respectively. The molecular profiles of T-cell receptor beta variable chain (TRBV) were determined using gene melting spectral pattern. For the seroconverted 12 patients, ALT declined to normal levels by week 24 and remained at this level in subsequent treatment; moreover, the predictive cutoff value of ALT for HBeAg seroconversion (SC) was 41.5 U/L at week 24. The positive correlation between HBV DNA and Treg and ALT was significant in SC patients, but not in non-SC patients. Six TRBV families (BV3, BV11, BV12, BV14, BV20, and BV24) were predominantly expressed in SC patients at baseline. The decline of ALT could be used to predict HBeAg seroconversion for CHB patients during TDF treatment. In addition, the profile of Tregs and TRBVs may be associated with HBeAg seroconversion and could also be a potential indicator for predicting HBeAg SC and treatment outcome for CHB patients. PMID:28272219

  5. Predictive value of serum ALT and T-cell receptor beta variable chain for HBeAg seroconversion in chronic hepatitis B patients during tenofovir treatment.

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    Yang, Jiezuan; Yan, Dong; Guo, Renyong; Chen, Jiajia; Li, Yongtao; Fan, Jun; Fu, Xuyan; Yao, Xinsheng; Diao, Hongyan; Li, Lanjuan

    2017-03-01

    Effective antiviral therapy plays a key role in slowing the progression of chronic hepatitis B (CHB). Identification of serum indices, including hepatitis B e antigen (HBeAg) expression and seroconversion, will facilitate evaluation of the efficacy of antiviral therapy in HBeAg-positive CHB patients. The biochemical, serological, virological parameters, and the frequency of circulating CD4CD25 regulatory T cell (Treg) in 32 patients were measured at baseline and every 12 weeks during 96 weeks of tenofovir disoproxil fumarate (TDF) treatment. The relationship between the hepatitis B virus (HBV) deoxyribonucleic acid (DNA) and Treg and alanine aminotransferase (ALT) levels was analyzed, respectively. The molecular profiles of T-cell receptor beta variable chain (TRBV) were determined using gene melting spectral pattern. For the seroconverted 12 patients, ALT declined to normal levels by week 24 and remained at this level in subsequent treatment; moreover, the predictive cutoff value of ALT for HBeAg seroconversion (SC) was 41.5 U/L at week 24. The positive correlation between HBV DNA and Treg and ALT was significant in SC patients, but not in non-SC patients. Six TRBV families (BV3, BV11, BV12, BV14, BV20, and BV24) were predominantly expressed in SC patients at baseline. The decline of ALT could be used to predict HBeAg seroconversion for CHB patients during TDF treatment. In addition, the profile of Tregs and TRBVs may be associated with HBeAg seroconversion and could also be a potential indicator for predicting HBeAg SC and treatment outcome for CHB patients.

  6. HBeAg Seroconversion in HBeAg-Positive Chronic Hepatitis B Patients Receiving Long-Term Nucleos(t)ide Analog Treatment: A Systematic Review and Network Meta-Analysis

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    Xing, Tongjing; Xu, Hongtao; Cao, Lin; Ye, Maocong

    2017-01-01

    Background HBeAg seroconversion is an important intermediate outcome in HBeAg-positive chronic hepatitis B (CHB) patients. This study aimed to compare the effect of nucleos(t)ide analogs (NAs) on HBeAg seroconversion in treating CHB with lamivudine, adefovir, telbivudine, entecavir, and tenofovir. Methods Network meta-analysis of NA treatment-induced HBeAg seroconversion after 1–2 years of treatment was performed. In addition, NA treatment-induced HBeAg seroconversion after 3–5 years of treatment was systematically evaluated. Results A total of 31 articles were included in this study. Nine and five studies respectively reporting on 1- and 2-year treatment were included in our network meta-analysis. In addition, 6, 5, and 5 studies, respectively reporting on 3-, 4-, and 5-year treatment were included in our systematic evaluation. Telbivudine showed a significantly higher HBeAg seroconversion rate after a 1 year treatment period compared to the other NAs (odds ratio (OR) = 3.99, 95% CI 0.68–23.6). This was followed by tenofovir (OR = 3.36, 95% CI 0.70–16.75). Telbivudine also showed a higher seroconversion rate compared to the other NAs after a 2 year treatment period, (OR = 1.38, 95% CI 0.92–2.22). This was followed by entecavir (OR = 1.14, 95% CI 0.72–1.72). No significant difference was observed between spontaneous induction and long-term telbivudine treatment-induced HBeAg seroconversion. However, entecavir and tenofovir treatment-induced HBeAg seroconversions were significantly lower than spontaneous seroconversion. Conclusion Long-term treatment with potent anti-HBV drugs, especially tenofovir and entecavir, may reduce HBeAg seroconversion compared with spontaneous HBeAg seroconversion rate. Telbivudine treatment, whether short term or long term, is associated with higher HBeAg seroconversion compared with the other NAs. However, the high rates of drug resistance likely limit the application of telbivudine. PMID:28107377

  7. Serum HBV core-related antigen is a good predictor for spontaneous HBeAg seroconversion in chronic hepatitis B patients.

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    Song, Guangjun; Yang, Ruifeng; Rao, Huiying; Feng, Bo; Ma, Hui; Jin, Qian; Wei, Lai

    2017-03-01

    Early prediction of spontaneous hepatitis B virus e antigen (HBeAg) seroconversion is pivotal in the prevention of unnecessary drug prescription, corresponding financial burden, and adverse reactions. One hundred and thirteen chronic hepatitis B patients with HBeAg-positive in the immune active phase were followed up for about 1.5 years. Patients were classified into two groups: spontaneous HBeAg seroconversion group (group A, n = 18) and non-spontaneous HBeAg seroconversion group. Among the non-spontaneous HBeAg seroconversion group, 35 patients were selected as controls (group B, n = 35). At week 12, there was a significant difference in hepatitis B core-related antigen (HBcrAg) levels between the two groups (group A 4.32 ± 1.05 log10  kU/ml, and group B 5.16 ± 0.53 log10  kU/ml, P = 0.004), and this significance magnified at week 28. Only two variables, HBcrAg level and the reduction in the HBcrAg levels (ΔHBcrAg) at week 28 were enrolled, with the odds ratio of 4.19 and 0.21, respectively. The optimal cutoffs of HBcrAg levels and the ΔHBcrAg at week 28 were 4.90 and 2.00 log10  kU/ml, respectively. The positive predictive value and negative predictive value of HBcrAg levels at week 28 were 73.9% and 96.7%, respectively. The positive predictive value and negative predictive value of the ΔHBcrAg at week 28 were 76.2% and 93.8%, respectively. The measurement of HBcrAg is useful for monitoring the natural course of chronic hepatitis B virus infection. The dynamics of HBcrAg levels could accurately predict the spontaneous HBeAg seroconversion. J. Med. Virol. 89:463-468, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  8. Quantitative HBsAg and HBeAg predict hepatitis B seroconversion after initiation of HAART in HIV-HBV coinfected individuals.

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    Gail V Matthews

    Full Text Available OBJECTIVE: Anti-HBe seroconversion and HBsAg loss are important therapeutic endpoints in patients with hepatitis B virus (HBV infection. Quantitative measures of hepatitis B surface antigen (qHBsAg and e antigen (qHBeAg have been identified as potentially useful indicators of therapeutic response in HBV monoinfection. The aim of this study was to examine serological change including quantitative biomarkers in HIV-HBV coinfected patients initiating HBV active antiretroviral therapy (ART. METHODS: HIV-HBV coinfected individuals from Thailand were followed for up to 168 weeks post ART. Rates and associations of qualitative serological change were determined. Longitudinal changes in qHBsAg and qHBeAg were measured and their utility as predictors of response examined. RESULTS: Forty seven patients were included of whom 27 (57% were HBeAg positive at baseline. Median CD4 count was 48 cells/mm(3. Over a median follow-up of 108 weeks 48% (13/27 lost HBeAg, 12/27 (44% achieved anti-HBe seroconversion and 13% (6/47 HBsAg loss. Anti-HBe seroconversion was associated with higher baseline ALT (p = 0.034, lower qHBsAg (p = 0.015, lower qHBeAg (p = 0.031 and greater HBV DNA decline to week 24 (p = 0.045. Sensitivity and specificity for qHBsAg and qHBeAg decline of >0.5 log at week 12 and >1.0 log at week 24 were high for both anti-HBe seroconversion and HBsAg loss. CONCLUSIONS: Rates of serological change in these HIV-HBV coinfected individuals with advanced immunodeficiency initiating HBV-active ART were high. Baseline and on treatment factors were identified that were associated with a greater likelihood of subsequent anti-HBe seroconversion, including both quantitative HBsAg and HBeAg, suggesting these biomarkers may have utility in this clinical setting.

  9. High-Throughput Analysis of the T Cell Receptor Beta Chain Repertoire in PBMCs from Chronic Hepatitis B Patients with HBeAg Seroconversion

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    Yachao Qu

    2016-01-01

    Full Text Available T lymphocytes are the most important immune cells that affect both the development and treatment of hepatitis B. We used high-throughput sequencing to determine the diversity in the V and J regions of the TCRβ chain in 4 chronic hepatitis B patients before and after HBeAg seroconversion. Here, we demonstrate that the 4 patients expressed Vβ12-4 at the highest frequencies of 10.6%, 9.2%, 17.5%, and 7.5%, and Vβ28 was the second most common, with frequencies of 7.8%, 6.7%, 5.3%, and 10.9%, respectively. No significant changes were observed following seroconversion. With regard to the Jβ gene, Jβ2-1 was the most commonly expressed in the 4 patients at frequencies of 5.8%, 6.5%, 11.3%, and 7.3%, respectively. Analysis of the V-J region genes revealed several differences, including significant increases in the expression levels of V7-2-01-J2-1, V12-4-J1-1, and V28-1-J1-5 and a decrease in that of V19-01-J2-3. These results illustrate the presence of biased TCRVβ and Jβ gene expression in the chronic hepatitis B patients. TRBVβ12-4, Vβ28, Jβ2-1, V7-2-01-J2-1, V12-4-J1-1, and V28-1-J1-5 may be associated with the development and treatment of CHB.

  10. High-Throughput Analysis of the T Cell Receptor Beta Chain Repertoire in PBMCs from Chronic Hepatitis B Patients with HBeAg Seroconversion

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    Huang, Yong; Liu, Di; Huang, Yinuo; Zhang, Zhiyi

    2016-01-01

    T lymphocytes are the most important immune cells that affect both the development and treatment of hepatitis B. We used high-throughput sequencing to determine the diversity in the V and J regions of the TCRβ chain in 4 chronic hepatitis B patients before and after HBeAg seroconversion. Here, we demonstrate that the 4 patients expressed Vβ12-4 at the highest frequencies of 10.6%, 9.2%, 17.5%, and 7.5%, and Vβ28 was the second most common, with frequencies of 7.8%, 6.7%, 5.3%, and 10.9%, respectively. No significant changes were observed following seroconversion. With regard to the Jβ gene, Jβ2-1 was the most commonly expressed in the 4 patients at frequencies of 5.8%, 6.5%, 11.3%, and 7.3%, respectively. Analysis of the V-J region genes revealed several differences, including significant increases in the expression levels of V7-2-01-J2-1, V12-4-J1-1, and V28-1-J1-5 and a decrease in that of V19-01-J2-3. These results illustrate the presence of biased TCRVβ and Jβ gene expression in the chronic hepatitis B patients. TRBVβ12-4, Vβ28, Jβ2-1, V7-2-01-J2-1, V12-4-J1-1, and V28-1-J1-5 may be associated with the development and treatment of CHB. PMID:27818694

  11. Hepatitis B virus genotype has no impact on hepatitis B e antigen seroconversion after lamivudine treatment

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    Henry Lik-Yuen Chan; May-Ling Wong; Alex Yui Hui; Angel Mei-Ling Chim; Ada Mei-Ling Tse; Lawrence Cheung-Tsui Hung; Francis Ka-Leung Chan; Joseph Jao-Yiu Sung

    2003-01-01

    AIM: To investigate the association of hepatitis B virus (HBV) genotype and HBeAg seroconversion after nucleotide analogue treatment.METHODS: Chronic hepatitis B patients receiving lamivudine followed up for at least 6 months post-treatment were studied. Consecutive treatment-naive patients who were prospectively followed up in the clinic for at least 18 months were studied as controls. HBeAg seroconversion was defined as loss of HBeAg, appearance of anti-HBe and normalization of alanine aminotransferase for at least 6 months.RESULTS: Thirty-five patients on lamivudine and 96 control patients followed up for 39 (18-49) months were studied.Lamivudine was given for 12 (10-18) months, and patients were followed up for 15 (6-34) months after drug cessation.Genotype B and C HBV were found in 43 and 88 patients and HBeAg seroconversion occurred in 12 (28 %) and 16(18 %) patients, respectively (P=0.30). There was no difference in HBeAg seroconversion between patients infected by genotype B and C HBV in the control (35 % vs 21%, P=0.25) and lamivudine-treated (14 % vs 10 %,P=1.00) groups.CONCLUSION: HBeAg seroconversion after treatment by lamivudine was not influenced by the HBV genotype.

  12. Delayed Seroconversion to HTLV-II Is Associated with a Stop-Codon Mutation in the pol Gene.

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    Dube, Syamalima; Dube, Dipak K; Abbott, Lynn; Glaser, Jordan; Poiesz, Bernard J

    2017-05-01

    A known HIV-1-positive intravenous drug user was found to be human T cell lymphoma/leukemia virus-II (HTLV-II) DNA positive by polymerase chain reaction but seronegative in a screening ELISA. He was consistently DNA positive but took 2 years to fully seroconvert. Sequencing of the HTLV-II strain in his cultured T lymphocytes indicated that it is a prototypical type A strain with no major differences in the long terminal repeat DNA sequence, nor major amino acid differences in the Gag, Env, Tax, and Rex proteins. However, a mutation in its pol gene created a stop codon at amino acid 543 of the Pol protein, a region that encodes for the RNase function. This mutation may account for the subject's slow seroconversion.

  13. Association between single-nucleotide polymorphisms and early spontaneous hepatitis B virus e antigen seroconversion in children.

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    Komatsu, Haruki; Murakami, Jun; Inui, Ayano; Tsunoda, Tomoyuki; Sogo, Tsuyoshi; Fujisawa, Tomoo

    2014-11-06

    The disease progression following hepatitis B virus (HBV) infection is associated with single-nucleotide polymorphisms (SNPs). However, the role of SNPs in chronic HBV infection in children remains unclear. Here, we investigate the association between SNPs and early spontaneous hepatitis B e antigen (HBeAg) seroconversion in children with chronic hepatitis B infection. This was a retrospective cohort study. We genotyped seven SNPs in the following genes, interleukin (IL)-10 (rs1800871 and rs1800872), human leukocyte antigen (HLA)-DPA1 (rs3077), HLA-DPB1 (rs9277535), HLA-DQB2 (rs7453920), HLA-DQB1 (rs2856718), and IL28B (rs8099917), in patients with chronic HBV infection using PCR and sequencing. These variants were analyzed for an association with early HBeAg seroconversion in children. Of 225 Japanese patients with chronic hepatitis B virus infection (male/female: 105/120, median age at initial visit: 6 years; range 0-44 years), 52 achieved spontaneous HBeAg seroconversion at the age of 10 years or younger (G1: early seroconversion group), and 57 did not achieve spontaneous HBeAg seroconversion under the age of 20 years (G2: late or no seroconversion group). Of the seven SNPs, only the HLA-DPA1 SNP displayed a low p-value (P = 0.070), but not significant, to have early HBeAg seroconversion in the dominant model and in the allele model (P = 0.073) using the chi-square test. The association study found a low p-value, but not significant, to have early HBeAg seroconversion in the dominant model for HLA-DPA1 (genotype TC + TT vs. CC, P = 0.070, odds ratio: 2.016, 95% confidence interval: 0.940-4.323) using a logistic regression model. Although the HLA-DPA1 SNP did not show a statistically significant association with early HBeAg seroconversion in this study, the HLA-DPA1 SNP might increase the likelihood of achieving early spontaneous HBeAg seroconversion in children.

  14. Durability of viral response after off-treatment in HBeAg positive chronic hepatitis B

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    Myeong Jun Song; Do Seon Song; Hee Yeon Kim; Sun Hong Yoo; Si Hyun Bae; Jong Young Choi; Seung Kew Yoon

    2012-01-01

    AIM:To evaluate the durability in hepatitis B e antigen (HBeAg) positive chronic hepatitis B patients who discontinued antiviral treatment.METHODS:A total of 48 HBeAg positive chronic hepatitis B patients who were administered nucleoside analogues and maintained virological response for ≥6 mo [hepatitis B virus (HBV) DNA < 300 copies/mL and HBeAg seroconversion] before cessation of treatment were enrolled between February 2007 and January 2010.The criteria for the cessation of the antiviral treatment were defined as follows:(1) achievement of virological response; and (2) duration of consolidation therapy (≥ 6 mo).After treatment cessation,the patients were followed up at 3-6 mo intervals.The primary endpoint was serologic and virologic recurrence rates after withdrawal of antiviral treatment.Serologic recurrence was defined as reappearance of HBeAg positivity after HBeAg seroconversion.Virologic recurrence was defined as an increase in HBV-DNA level >104 copies/mL after HBeAg seroconversion with previously undetectable HBV-DNA level.RESULTS:During the median follow-up period of 18.2 mo (range:5.1-47.5 mo) after cessation of antiviral treatment,the cumulative serological recurrence rate was 15 % at 12 mo.The median duration between the cessation of antiviral treatment and serologic recurrence was 7.2 mo (range:1.2-10.9 mo).Of the 48 patients with HBeAg positive chronic hepatitis,20 (41.6%)showed virological recurrence.The cumulative virologic recurrence rates at 12 mo after discontinuing the antiviral agent were 41%.The median duration between off-treatment and virologic recurrence was 7.6 mo (range:4.3-27.1 mo).The mean age of the virological recurrence group was older than that of the non-recurrence group (46.7 ± 12.1 years vs 38.8 ± 12.7 years,respectively; P =0.022).Age (> 40 years) and the duration of consolidation treatment (≥ 15 mo) were significant predictive factors for offtreatment durability in the multivariate analysis [P =0

  15. Hepatitis B surface antigen quantification at hepatitis B e antigen seroconversion predicts virological relapse after the cessation of entecavir treatment in hepatitis B e antigen-positive patients

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    Yuan-wang Qiu

    2016-02-01

    Conclusions: HBsAg levels can help guide the timing of cessation of ETV treatment. HBsAg levels of 2.5 log10 IU/ml at HBeAg seroconversion may be a useful marker to predict virological relapse after the cessation of ETV treatment in HBeAg-positive CHB patients.

  16. [The HBeAg/antiHBe seroconversion as a result of lamivudine treatment in children with chronic hepatitis B unresponsive to previous interferon alpha therapy].

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    Lebensztejn, Dariusz Marek; Skiba, Elzbieta; Sobaniec-Lotowska, Maria; Kaczmarski, Maciej

    2004-06-01

    The aim of the study was evaluation the HBeAg/antiHBe seroconversion frequency as a result of lamivudine treatment in children who are nonresponders to previous IFN-alpha therapy. The observation was carried out on 41 children, aged 4-17 years, with biopsy-proven chronic hepatitis B (HBeAg+) treated with lamivudine 3-4 mg/kg/d (max. 100 mg/d) for 12 months. After 6 months of lamivudine therapy 59.3% children normalized GPT activity and only 1 child (2.5%) lost HBeAg. At the end of 12 months of therapy 81.5% normalized GPT activity and 4 of them (10%) lost HBeAg and seroconverted to antiHBe. None of treated children lost HBsAg. The age, sex, pretreatment GPT activity and active histological disease were not predictors of lamivudine-induced HBeAg loss. There were no side effects of lamivudine therapy except one boy who had severe thrombocytopenia. The HBeAg/antiHBe seroconversion rate after one year trial of lamivudine in children with chronic hepatitis B unresponsive to previous IFN alpha therapy was 10%. The age, sex, pretreatment GPT activity and active histologic disease were not predictors of lamivudine-induced HBeAg loss.

  17. On-treatment HBV DNA level could predict HBeAg seroclearance in patients with HBeAg-positive chronic hepatitis B with entecavir therapy.

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    Huang, Yi-Jie; Chang, Chi-Sen; Peng, Yen-Chun; Yeh, Hong-Zen; Yang, Sheng-Shun

    2017-06-01

    Hepatitis B e antigen (HBeAg) status is associated with clinical outcomes, and seroconversion of HBeAg is one of the treatment goals. In this study, we determined the association of on-treatment serum hepatitis B virus (HBV) DNA levels in HBeAg-positive chronic hepatitis B patients who were receiving entecavir (ETV) treatment. A retrospective cohort study was conducted involving 135 (78 male and 57 female; mean age, 42.3 ± 13 years) patients with HBeAg-positive chronic hepatitis B (CHB). Between August 2008 and March 2014, each patient was treated with ETV for at least 96 weeks, and their HBV DNA levels were evaluated every 3-6 months. HBeAg seroclearance at the 96(th) week was defined as an absence of serum HBeAg within 96 weeks after ETV treatment. Univariate and multivariate logistic regression analysis was used to identify the predictors of 96(th) week HBeAg seroclearance, and a multivariable model was constructed. Among the 135 ETV-treated HBeAg-positive CHB patients, 37 patients achieved HBeAg seroclearance (Group 1), whereas 98 patients had persistent HBeAg-positive status (Group 2) at the 96(th) week check-up. The baseline laboratory data was not significantly different between both the two groups. At the 24(th) and 48(th) weeks, there were significant differences between Group 1 and Group 2 in the percentage of patients with HBV DNA levels < 20 IU/mL [17/77 (22.1%) and 11/23 (47.8%), p = 0.032; 45/89 (50.6%) and 26/35 (74.3%), p = 0.028, respectively). Our study demonstrated that HBV DNA levels < 20 IU/mL at the 24(th) and 48(th) weeks could predict serum HBeAg loss in ETV-treated HBeAg-positive patients with CHB. Copyright © 2017. Published by Elsevier Taiwan LLC.

  18. Association of core promoter mutations of hepatitis B virus and viral load is different in HBeAg(+) and HBeAg(-) patients

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    Andi Utama; Benyamin Lukito; Tantoro Harmono; Nasrul Zubir; Julius; Soewignjo Soemohardjo; Laurentius Adrianus Lesmana; Ali Sulaiman; Susan Tai; Marlinang Diarta Siburian; Sigit Purwantomo; Mariana Destila Bayu Intan; Tri Shinta Kurniasih; Rino Alvani Gani; Wenny Astuti Achwan; Arnelis; Syafruddin AR Lelosutan

    2011-01-01

    AIM: To identify the prevalence of hepatitis B e antigen (HBeAg) and to assess the association of hepatitis B virus (HBV) core promoter mutations and viral load in Indonesian patients.METHODS: Sixty-four patients with chronic hepatitis,65 with liver cirrhosis and 50 with hepatocellular carcinoma were included in this study. HBeAg and hepatitis B e antibody (HBeAb) tests were performed using enzyme-linked immunosorbent assay and the mutations were analyzed by sequencing. Viral load was measured by real-time polymerase chain reaction.RESULTS: Of 179 patients, 108 (60.3%) were HBeAg(-) and 86 (79.6%) of these HBeAg(-) patients had been seroconverted. The A1896 mutation was not found in HBeAg(+) patients, however, this mutation was detected in 70.7% of HBeAg(-) patients. This mutation was frequently found when HBeAg was not expressed (87.7%), compared to that found in HBeAg seroconverted patients (65.1%). The A1899 mutation was also more prevalent in HBeAg(-) than in HBeAg(+) patients (P = 0.004). The T1762/A1764 mutation was frequently found in both HBeAg(+) and HBeAg(-) patients, however,the prevalence of this mutation did not significantly differ among the two groups (P = 0.054). In HBeAg(+)patients, the T1762/A1764 mutation was correlated with lower HBV DNA (P < 0.001). The A1899 mutation did not correlate with HBV DNA (P = 0.609). In HBeAg(-)patients, the T1762/A1764 mutation alone was not correlated with HBV DNA (P = 0.095), however, the presence of either the T1762/A1764 or A1896 mutations was associated with increased HBV DNA (P < 0.001).CONCLUSION: The percentage of HBeAg(-) patients is high in Indonesia, and most of the HBeAg(-) patients had been seroconverted. The A1896 mutation was most likely the major cause of HBeAg loss. The T1762/A1764 mutation alone was associated with lower viral loads in HBeAg(+) patients, but not in HBeAg(-) patients.

  19. Differential plasma microRNA profiles in HBeAg positive and HBeAg negative children with chronic hepatitis B.

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    Thilde Nordmann Winther

    Full Text Available BACKGROUND AND AIM: Children chronically infected with hepatitis B virus (HBV are at high risk of progressive liver disease. However, no treatment is available that is consistently effective in curing chronic hepatitis B (CHB in children. Improved understanding of the natural course of disease is warranted. Identification of specific microRNA (miRNA profiles in children chronically infected with HBV may provide insight into the pathogenesis of CHB and lead to advances in the management of children with CHB. PATIENTS AND METHODS: MiRNA PCR panels were employed to screen plasma levels of 739 miRNAs in pooled samples from HBeAg positive, HBeAg negative, and healthy children. The three groups' plasma miRNA profiles were compared, and aberrantly expressed miRNAs were identified. The identified miRNAs were then validated. Individual RT-qPCRs were performed on plasma from 34 HBeAg positive, 26 HBeAg negative, and 60 healthy children. RESULTS: A panel of 16 plasma miRNAs were identified as aberrantly expressed in HBeAg positive and HBeAg negative children (p<0.001. Levels of all of the miRNAs were upregulated in HBeAg positive children compared with in HBeAg negative children. A positive correlation was furthermore found between plasma levels of the identified miRNAs and HBV DNA (p<0.001. CONCLUSION: We are the first to investigate the plasma miRNA profile of children chronically infected with HBV. Our data indicates the existence of a relationship between abundance of circulating miRNAs and immunological stages in the natural course of disease. Certain miRNAs may contribute to the establishment and maintenance of CHB in children. Further studies are warranted to advance understanding of miRNAs in the pathogenesis of CHB, hopefully leading to the identification of future therapeutic targets.

  20. Survival analysis on aggregate data to assess time to sero-conversion after experimental infection with Bovine Leukemia virus.

    Science.gov (United States)

    Monti, G E; Frankena, K

    2005-05-10

    Bovine Leukemia virus (BLV) is a ubiquitous retrovirus that affects mainly cattle. Knowledge of the precise moment of infection is fundamental for identification and evaluation of factors related to BLV transmission. Systematic reviews and meta-analyses provide good evidence on the effects of medical interventions. The objectives were to estimate time to sero-conversion after experimental infection using data from retrieved literature and to detect factors that may influence the length of that interval using survival analysis on pooled data. An analysis using aggregate data from 36 studies totalling 438 observations was performed. From this, four sets were created and analysed by interval-censored accelerated failure time models (AFT) with different distributions (exponential, Weibull, log-logistic, lognormal and generalized gamma), and some variants of the Cox model (Andersen-Gill, smoothing splines) with and without a frailty effect. The AFT gamma model fit best and the estimated median time to sero-conversion in the null model was 57 days (95% confidence interval (CI): 49; 75) using all data and 47 days (95% CI: 39; 55) when only studies using experimental inoculation were considered. Some factors were consistently associated with time to sero-conversion. These included exposure by animal-to-animal contact (resulting in a seven-fold increase in time to sero-conversion compared to direct inoculation), diagnostic method to detect sero-conversion (time to sero-conversion was 1.4 times shorter when AGID was used compared to ELISA), and transmission by insect bites (biological media) delayed sero-conversion 2.3 times compared transmission via needles or other inanimate media. After fitting a frailty Cox model, results showed that sero-conversion in susceptible animals after infection using donors, in which presence of virus before the experiment started was confirmed, increased the hazard of sero-conversion two times in comparison with donors in which virus presence

  1. Child mortality related to seroconversion or lack of seroconversion after measles vaccination

    DEFF Research Database (Denmark)

    Aaby, Peter; Pedersen, I R; Knudsen, K

    1989-01-01

    When blood samples were analyzed for seroconversion after measles vaccination, it was discovered that the vaccine had been ineffective for a certain period. During the 2 years between vaccination and the time of seroanalysis, nonseroconverters had a significantly higher mortality than...... children) were excluded from the analysis (P less than 0.01). The difference in mortality was particularly marked among children vaccinated in the age group 9 to 11 months. This as well as other community studies suggest that measles vaccination reduces child mortality from the age of vaccination...

  2. 免疫学应答与慢性乙型肝炎血清学转换的关系%The relationship between immune response and chronic hepatitis B seroconversion

    Institute of Scientific and Technical Information of China (English)

    李智彬; 刘永明; 苏何玲; 钟彦伟

    2013-01-01

    乙型肝炎病毒(HBV)感染是全球性的卫生问题,每年有将近100万人死于HBV感染所致的肝衰竭等肝脏疾病。大部分的慢性乙型肝炎(CHB)患者经过抗病毒治疗后可以达到持久的免疫,小部分的还可以达到临床治愈。理想的抗病毒治疗过程一般经过三个重要转折点,分别是 HBV DNA 转阴, HBeAg血清学转换及HBsAg血清学转换。长效干扰素治疗的患者只有40%左右的患者出现HbeAg血清学转化,因此,对CHB患者或许可采取调整患者免疫功能从而达到临床治愈。%HBV infection is a global healthy question. Every year almost one million people are dead from HBV related diseases, such as hepatic failure or liver cirrhosis. The majority of the chronic hepatitis B (CHB) patients, who had received antiviral therapy, will get the ability of antiviral persistence immunity while the minority of these patients came up to the standard of clinical cure. The ideal process of antiviral therapy has three important turning points, including HBV DNA seroconversion, HBeAg seroconversion and HBsAg seroconversion. However, only 40%patients who received pegylated interferon therapy have the effect of HBeAg seroconversion. Thus, the CHB patients may achieve clinical cure by regulating their immune functions.

  3. Child mortality related to seroconversion or lack of seroconversion after measles vaccination

    DEFF Research Database (Denmark)

    Aaby, Peter; Pedersen, I R; Knudsen, K

    1989-01-01

    When blood samples were analyzed for seroconversion after measles vaccination, it was discovered that the vaccine had been ineffective for a certain period. During the 2 years between vaccination and the time of seroanalysis, nonseroconverters had a significantly higher mortality than seroconvert......When blood samples were analyzed for seroconversion after measles vaccination, it was discovered that the vaccine had been ineffective for a certain period. During the 2 years between vaccination and the time of seroanalysis, nonseroconverters had a significantly higher mortality than...... seroconverters (P less than 0.05). The incidence of measles among nonseroconverters was 30% during the period. Between 9 months and 3 years of age, cumulative mortality was 15.1% for nonseroconverters and 4.5% for seroconverters. The difference in mortality was larger when high risk groups (twins, motherless...... children) were excluded from the analysis (P less than 0.01). The difference in mortality was particularly marked among children vaccinated in the age group 9 to 11 months. This as well as other community studies suggest that measles vaccination reduces child mortality from the age of vaccination...

  4. [Bilateral amyotrophic neuralgia (Parsonage Turner syndrome) with HIV seroconversion].

    Science.gov (United States)

    Louis, E; Touzé, E; Piketty, M L; Salmon-Céron, D; Zuber, M

    2003-07-01

    We report a unusual case of neuralgic amyotrophy (NA) occurring during the seroconversion stage of an HIV infection. Combined with previously published cases, our observation suggests that NA associated with HIV could belong to the group of early multiplex mononeuritis. Neurologists should be aware of HIV infection when managing a patient with NA.

  5. Acanthamoeba polyphaga mimivirus virophage seroconversion in travelers returning from Laos.

    Science.gov (United States)

    Parola, Philippe; Renvoisé, Aurélie; Botelho-Nevers, Elisabeth; La Scola, Bernard; Desnues, Christelle; Raoult, Didier

    2012-09-01

    During January 2010, a husband and wife returned from Laos to France with probable parasitic disease. Increased antibodies against an Acanthamoeba polyphaga mimivirus virophage indicated seroconversion. While in Laos, they had eaten raw fish, a potential source of the virophage. This virophage, associated with giant viruses suspected to cause pneumonia, could be an emerging pathogen.

  6. Dengue Virus Seroconversion in Travelers to Dengue-Endemic Areas.

    Science.gov (United States)

    Olivero, Rosemary M; Hamer, Davidson H; MacLeod, William B; Benoit, Christine M; Sanchez-Vegas, Carolina; Jentes, Emily S; Chen, Lin H; Wilson, Mary E; Marano, Nina; Yanni, Emad A; Ooi, Winnie W; Karchmer, Adolf W; Kogelman, Laura; Barnett, Elizabeth D

    2016-11-02

    We conducted a prospective study to measure dengue virus (DENV) antibody seroconversion in travelers to dengue-endemic areas. Travelers seen in the Boston Area Travel Medicine Network planning to visit dengue-endemic countries for ≥ 2 weeks were enrolled from 2009 to 2010. Pre- and post-travel blood samples and questionnaires were collected. Post-travel sera were tested for anti-DENV IgG by indirect IgG enzyme-linked immunosorbent assay (ELISA) and anti-DENV IgM by capture IgM ELISA. Participants with positive post-travel anti-DENV IgG or IgM were tested for pre-travel anti-DENV IgG and IgM; they were excluded from the seroconversion calculation if either pre-travel anti-DENV IgG or IgM were positive. Paired sera and questionnaires were collected for 62% (589/955) of enrolled travelers. Most participants were 19-64 years of age, female, and white. The most common purposes of travel were tourism and visiting friends and relatives; most trips were to Asia or Africa. Median length of travel was 21 days. DENV antibody seroconversion by either anti-DENV IgM or IgG ELISA was 2.9-6.8%; lower range percent excluded potential false-positive anti-DENV IgG due to receipt of yellow fever or Japanese encephalitis vaccines at enrollment; upper range percent excluded proven false-positive anti-DENV IgM. Eighteen percent of those with seroconversion reported dengue-like symptoms. Seroconversion was documented for travel to Africa as well as countries and regions known to be highly dengue endemic (India, Brazil, southeast Asia). Given widespread risk of dengue, travel medicine counseling should include information on risk of dengue in endemic areas and advice on preventing insect bites and seeking prompt medical attention for febrile illness.

  7. Hepatitis C seroconversions in HIV infection across Europe

    DEFF Research Database (Denmark)

    Boesecke, Christoph; Grint, Daniel; Soriano, Vincent

    2015-01-01

    BACKGROUND & AIMS: In the last decade, several outbreaks of sexually acquired acute hepatitis C (HCV) infection have been described in HIV-positive men who have sex with men (MSM). The aims of this study were to determine whether there has been an increase in the number of acute HCV infections...... HCV seroconversions were observed from 16,188 tests [1.38% (95%CI 1.20-1.56)] among 5736 patients between 2002 and 2013. Overall the odds of acquiring HCV infection increased by 4% per year (OR 1.04 [95%CI 0.99-1.09]; P = 0.10). Overall 63.2% (141/223) of all seroconversions were seen among MSM...

  8. Haemorrhagic enteritis seroconversion in turkey breeders: field observations

    Directory of Open Access Journals (Sweden)

    Raffaella Ceruti

    2010-01-01

    Full Text Available Seroconversion to viral haemorrhagic enteritis (HE was studied in seven flocks of turkey breeders (17.974 birds in total, after 20 weeks of the onset of egg production. They showed no clinical signs, and mortality rate was normal. However, the infection caused a drop in egg production lasting about five weeks (-2.32 eggs laid during this period, but had no effect on hatching parameters.

  9. G1896A Precore Mutation and Association With HBeAg Status, Genotype and Clinical Status in Patients With Chronic Hepatitis B

    Directory of Open Access Journals (Sweden)

    Suppiah

    2015-10-01

    Full Text Available Background Precore stop codon (G1896A mutation is one of the commonest mutations found in patients with chronic hepatitis B. However, over the years, this mutation was not reported much in Malaysia. Objectives We therefore investigated the presence of G1896A mutation in Malaysian population and its association with HBeAg status, clinical stage, hepatitis B virus (HBV genotype and e-seroconversion rate. Patients and Methods Serum samples from 93 patients confirmed as hepatitis B carriers were collected for molecular assay. The whole genome of HBV was amplified by polymerase chain reaction and directly sequenced. The precore and basal core promoter regions were analyzed for presence of mutations. Results The most commonly observed mutation in the precore region was C1858T with 64.5% prevalence. The precore mutation of interest (G1896A was identified in 25.8% of isolates. The basal core promoter mutations detected were A1762T-G1764A (26.9%, C1653T (8.6%, A1752G (10.8% and C1766T (2.2%. No significant association was observed between G1896A mutation and HBeAg-negativity. Nonetheless, G1896A was highly prevalent among HBV genotype B. Clinical association revealed that subjects with G1896A mutations were mainly detected in asymptomatic chronic hepatitis B (58.3% and liver cirrhosis (41.7%. One subject was diagnosed with fulminant hepatitis (4.2% and 8.3% had hepatocellular carcinoma (HCC. Conclusions Our data suggested an intermediate prevalence of G1896A mutation among Malaysian hepatitis B carriers. The stop codon mutation has a significant association with genotype B and patients with chronic hepatitis B and liver cirrhosis.

  10. Biochemical response to lamivudine treatment in HBeAg negative chronic hepatitis B patients in Iran

    Institute of Scientific and Technical Information of China (English)

    Amir Houshang Mohammad Alizadeh; Mitra Ranjbar; Babak Karimi; Saeed Hatami

    2006-01-01

    AIM: To study the effect of a one-year lamivudine regimen in patients with chronic hepatitis B.METNODS: Medical records of HBeAg negative hepatitis B patients who attended a hepatitis clinic in Tehran between March 2002-March 2004 were evaluated. The patients received 100 mg lamivudine tablets once daily for at least 12 mo. Liver enzymes and complete blood count were checked at baseline and the end of treatment (12th mo) and 6 mo after discontinuation of treatment.RESULTS: Of all patients, 24 were excluded. Of 71patients left, 58 (81.7%) were men. Mean age of the patients was 38 ± 14 years. Mean level of ALT in serum was 1437 ± 205 nkat/L at baseline with a significant reduction at the end of treatment to a mean level of 723± 92 nkat/L (P = 0.002). In 38 patients (53.5%), the ALT level was normal after one-year treatment. Five patients (7.3%) relapsed (biochemically) within 6 mo after discontinuing lamivudine therapy (the patients with good end of treatment response). Mean level of AST in serum was 1060 ± 105 nkat/L at baseline which decreased significantly to 652 ± 75 nkat/L at the end of treatment (P = 0.002).CONCLUSION: Over half (53.5%) of chronic hepatitis B patients with HBeAg negative have normal liver enzyme level at 12-mo lamivudine therapy.

  11. Measles Vaccine : A Study On Seroconversion And Side Effects

    Directory of Open Access Journals (Sweden)

    Malik Abida

    1998-01-01

    Full Text Available Research Question: 1. What is the extent of immune response of Edmonston Zagreb Strain in children? 2. What are the side effects of this vaccine? Objectives: 1. To follow up children after Edmonston Zagreb strain vaccination for evaluation of seroconverstion. Study: Cross sectional Setting: Well Baby Clinic of pediatrics OPD at J.N. Medical College, A.M.U., Aigarh (U.P participants: Children between 9-15 months. Sample Size: 100 consecutive children coming for routine immunization. Study variable: Malnourished and poor socio-economic status Outcome variable: Extent of seroconversion with no statistical significant difference between malnourished and socio-economically poor children. 26% showed minor self-limiting post vaccination reactions in all age groups. Recommendations: Edmonston Zagreb measles vaccine is recommended since it has very good immunogenic activity and post vaccination reactions.

  12. HBV-DNA level at 6 months of entecavir treatment predicts HBeAg loss in HBeAg-positive chronic hepatitis B patients

    Directory of Open Access Journals (Sweden)

    Cheng-Yuan Peng

    2015-04-01

    Conclusion: On-treatment complete virological response at Month 6 is a favorable factor predictive of HBeAg loss at 2 years of entecavir therapy. Therefore, measurement of serum HBV-DNA level at 6 months of entecavir therapy is optimal to predict HBeAg loss at 2 years of therapy in HBeAg-positive CHB patients.

  13. Longitudinal serum HIV RNA quantification: correlation to viral phenotype at seroconversion and clinical outcome

    DEFF Research Database (Denmark)

    Katzenstein, T L; Pedersen, C; Nielsen, C

    1996-01-01

    OBJECTIVE: To investigate the longitudinal changes in serum HIV RNA, and to clarify whether the viral load early in infection has a predictive value for the clinical outcome; also, to correlate viral phenotype at seroconversion and changes in CD4 cell counts with viral burden. DESIGN: Twenty...... seroconverters with HIV isolates available at seroconversion had HIV RNA quantified by polymerase chain reaction (PCR) at seroconversion and thereafter every 6 months. Mean follow-up time was 65 months. Patients were classified according to viral phenotype at seroconversion, time to AIDS progression, serum viral....... Harbouring syncytium-inducing (SI) virus at seroconversion was associated with faster progression to AIDS than non-SI (NSI; P RNA. CONCLUSION: Serum HIV RNA is high around the time...

  14. Extremely prolonged HIV seroconversion associated with an MHC haplotype carrying disease susceptibility genes for antibody deficiency disorders.

    Science.gov (United States)

    Padiglione, Alex; Aleksic, Eman; French, Martyn; Arnott, Alicia; Wilson, Kim M; Tippett, Emma; Kaye, Matthew; Gray, Lachlan; Ellett, Anne; Crane, Megan; Leslie, David E; Lewin, Sharon R; Breschkin, Alan; Birch, Chris; Gorry, Paul R; McPhee, Dale A; Crowe, Suzanne M

    2010-11-01

    Severe immunodeficiency during primary human immunodeficiency virus (HIV) infection is unusual. Here, we characterized viral and immunological parameters in a subject presenting with Pneumocystis jirovecii pneumonia in the setting of prolonged primary HIV illness and delayed seroconversion. HIV antibody was only detected by enzyme-linked immunosorbent assay 12 months after presentation, and Western blot profiles remain indeterminate. Isolated virus was of R5 phenotype, exhibited poor viral fitness, but was otherwise unremarkable. Analysis of HIV antibody isotypes showed failure to mount a detectable HIV IgG response over nearly 2 years of infection, in particular IgG(1)- and IgG(3)-specific responses, despite normal responses to common infections and vaccines. Genetic analysis demonstrated homozygosity for part of an MHC haplotype containing susceptibility genes for common variable immunodeficiency (CVID) syndrome and other antibody deficiency disorders. Thus, a primary disorder of specific antibody production may explain exceptionally slow antibody development in an otherwise severe seroconversion illness. This highlights the need for multiparameter testing, in particular use of a fourth generation HIV test, for confirming HIV infection and underscores the importance of host factors in HIV pathogenesis. Copyright © 2010 Elsevier Inc. All rights reserved.

  15. Seroconversion Following Anal and Genital HPV Infection in Men: The HIM Study

    Science.gov (United States)

    Giuliano, Anna R.; Viscidi, Raphael; Torres, B. Nelson; Ingles, Donna J.; Sudenga, Staci L.; Villa, Luisa L.; Baggio, Maria Luiza; Abrahamsen, Martha; Quiterio, Manuel; Salmeron, Jorge; Lazcano-Ponce, Eduardo

    2015-01-01

    Background Protection from naturally acquired human papillomavirus (HPV) antibodies may influence HPV infection across the lifespan. This study describes seroconversion rates following genital, anal, and oral HPV 6/11/16/18 infections in men and examines differences by HPV type and anatomic site. Methods Men with HPV 6/11/16/18 infections who were seronegative for those genotypes at the time of DNA detection were selected from the HPV Infection in Men (HIM) Study. Sera specimens collected ≤36 months after detection were analyzed for HPV 6/11/16/18 antibodies using a virus-like particle-based ELISA. Time to seroconversion was separately assessed for each anatomic site, stratified by HPV type. Results Seroconversion to ≥1 HPV type (6/11/16/18) in this sub-cohort (N=384) varied by anatomic site, with 6.3, 18.9, and 0.0% seroconverting following anal, genital, and oral HPV infection, respectively. Regardless of anatomic site, seroconversion was highest for HPV 6 (19.3%). Overall, seroconversion was highest following anal HPV 6 infection (69.2%). HPV persistence was the only factor found to influence seroconversion. Conclusions Low seroconversion rates following HPV infection leave men susceptible to recurrent infections that can progress to HPV-related cancers. This emphasizes the need for HPV vaccination in men to ensure immune protection against new HPV infections and subsequent disease. PMID:26688833

  16. Measles mimicking HIV seroconversion syndrome: a case report

    Directory of Open Access Journals (Sweden)

    Brook Gary

    2010-02-01

    Full Text Available Abstract Introduction Measles is on the rise in the United Kingdom and must be considered in the differential diagnosis of any patient presenting with fever and rash. As a highly infectious disease, identified patients must be isolated in the hospital setting. Case presentation A 28-year-old Polish woman presented ill to the accident and emergency department of a district general hospital. She had painful genital ulceration, oral soreness, fever, and a facial rash. She became hypoxic within 24 hours of presentation and began to tire, thus requiring noninvasive ventilation. Her respiratory symptoms were out of proportion to the findings of her chest radiograph, which remained virtually normal. Human immunodeficiency virus seroconversion syndrome complicated by Pneumocystis carinii pneumonia was high among the differential diagnoses. She was given cotrimoxazole, high-dose steroids, broad spectrum antibiotics, and anti fungal cover. Human immunodeficiency virus polymerase chain reaction came back as negative and her symptoms resolved within 10 days of presentation. She was taken off all treatment and discharged home feeling well. Serological measles was confirmed as part of a viral screen, but its clinical suspicion was low. Conclusion The presentation of measles in this patient was unique and atypical. With its incidence rising in the United Kingdom, measles must be increasingly considered as a differential diagnosis in patients presenting with fever and rash.

  17. The Change of Quantitative of HBeAg Can Predict the Efficacy of Peg-IFN-α 2a in HBeAg-positive CHB Patients

    Institute of Scientific and Technical Information of China (English)

    Yong-jian Ji; Wan-hua Ren; Fei-fei Li; Jian-ting Fang; Xi-zhen Sun; Cheng-yong Qin

    2013-01-01

    Objective To investigate the quantitation of hepatitis B e antigen (HBeAg) at week 24 in predicting the efifcacy of pegylated-interferon alfa-2a (Peg-IFN-α2a) in HBeAg-positive chronic hepatitis B (CHB) patients at week 48 and to find a useful predictor for treatment efficacy and investigate individualized treatment of antiviral therapy. Methods Ninety-six HBeAg-positive CHB patients with detectable HBeAg who were treated with Peg-IFN-α2a were enrolled in this trial. They were categorized into 3 groups according to the changes of HBeAg in week 24:HBeAg decline>2 log10 group (group A), HBeAg decline between 1 1og10-2 log10 (group B), HBeAg decline Results At week 48, mean reduction of serum HBV DNA:group A:5.8 log10 copies/ml, group B:3.8 log10 copies/ml, group C1:2.8 log10 copies/ml, group C2:5.7 log10 copies/ml, the reduction of HBV DNA in group A was greater than groups B and C1 (P Conclusions HBeAg decline > 2 log10 at week 24 in Peg-IFN-α 2a-treated hepatitis B patients suggested a better efficacy at week 48; HBeAg decline < 2 log10 at week 24 suggests a worse efficacy at week 48, the combined therapy of Peg-IFN-α and lamivudine could improve the clinical responses. The change of quantitative of HBeAg at week 24 may be used as a predictor of treatment effects at week 48.

  18. Reverse seroconversion of hepatitis B virus after hematopoietic stem cell transplantation.

    Science.gov (United States)

    Goyama, S; Kanda, Y; Nannya, Y; Kawazu, M; Takeshita, M; Niino, M; Komeno, Y; Nakamoto, T; Kurokawa, M; Tsujino, S; Ogawa, S; Aoki, K; Chiba, S; Motokura, T; Shiratori, Y; Hirai, H

    2002-11-01

    Hepatitis B virus (HBV) reactivation in patients previously positive for hepatitis B surface antibody (HBsAb), so-called reverse seroconversion, has been considered to be a rare complication after hematopoietic stem cell transplantation (HSCT). We experienced two patients who developed reverse seroconversion among nine who were HBsAb positive and Hepatitis B core antibody (HBcAb) positive before HSCT; one after autologous bone marrow transplantation (BMT) and another after allogeneic peripheral blood stem cell transplantation (PBSCT). We reviewed the literature and considered that reverse seroconversion of HBV after HSCT is not uncommon among HBsAb positive recipients. The use of corticosteroids, the lack of HBsAb in donor, and a decrease in serum HBsAb and HBcAb levels may predict reverse seroconversion after HSCT.

  19. Evaluation of antineutrophil cytoplasmic antibody seroconversion induced by minocycline, sulfasalazine, or penicillamine

    NARCIS (Netherlands)

    Choi, HK; Slot, MC; Pan, GL; Weissbach, CA; Niles, JL; Merkel, PA

    2000-01-01

    Objective, Case reports have suggested that minocycline, sulfasalazine, and penicillamine are associated with antineutrophil cytoplasmic antibody (ANCA)-positive vasculitis, This study evaluated ANCA seroconversion due to these agents in serum samples prospectively collected in randomized, double-bl

  20. The Vancouver Lymphadenopathy-AIDS Study: 6. HIV seroconversion in a cohort of homosexual men.

    Science.gov (United States)

    Schechter, M T; Boyko, W J; Douglas, B; Willoughby, B; McLeod, A; Maynard, M; Craib, K J; O'Shaughnessy, M

    1986-12-15

    In an ongoing prospective study of homosexual men conducted since November 1982 in Vancouver, we identified 345 men who did not have antibody to human immunodeficiency virus (HIV) at the time of enrolment and for whom results of follow-up serologic testing were available. A total of 66 cases of seroconversion were documented among the 345 men between November 1982 and October 1985. Methods of survival data analysis that take into account the varying durations of follow-up were used to study the epidemiologic features of seroconversion in this group. The probability of seroconversion during the entire observation period was 23.1%. The seroconversion rates remained stable, at 10.5% and 10.0% during the last 2 years of the observation period. Cox regression analysis revealed the following variables to be independently associated with risk of seroconversion: frequent receptive anal intercourse, elevated number of male sexual partners in the year before enrolment, use of illicit drugs, a history of gonorrhea and age less than 30 years in November 1982. Multivariate analysis failed to reveal any role of oral sexual activity in the transmission of HIV. Oral ingestion of semen was not associated with seroconversion in either univariate or multivariate analysis. The observation that younger men were more likely to seroconvert suggests that young homosexual men were less likely than older men to modify their sexual behaviour.

  1. Hepatitis B e antigen polypeptides isolated from sera of individuals infected with hepatitis B virus: comparison with HBeAg polypeptide derived from Dane particles.

    Science.gov (United States)

    Takahashi, K; Imai, M; Gotanda, T; Sano, T; Oinuma, A; Mishiro, S; Miyakawa, Y; Mayumi, M

    1980-09-01

    Hepatitis B e antigen (HBeAg) occurs in the serum of individuals infected with hepatitis B virus both free and in association with IgG. Utilizing a succession of steps involving salt precipitation, affinity chromatography, ion-exchange chromatography and isoelectrofocusing, we isolated free and IgG-bound forms of HBeAg from the sera of infected individuals with an overall gain in specific activity of 3000-fold and 540-fold, respectively. Polypeptide profiles of purified HBeAg preparations were studied by SDS-polyacrylamide gel electrophoresis in the presence of 2-mercaptoethanol. Both free and IgG-bound preparations revealed polypeptides with mol. wt. of 15500 (P15.5) and 16 500 (P16.5), and HBeAg activity was detected corresponding to their positions. The HBeAg polypeptides (P15.5/16.5) derived from sera were physicochemically different from the two polypeptides with HBeAg activity (P19 and P45) liberated from Dane particle cores by the conventional method involving incubation with Nonidet P40 and 2-mercaptoethanol. However, when core particles were prepared in the presence of a proteolytic enzyme, in addition to Nonidet P40 and 2-mercaptoethanol, they gave rise to HBeAg polypeptides with mol. wt. of 31000 (P31) and 15 500. Furthermore, P31 split into P15.5 when heated at 100 degrees C for 2 min. On the basis of these results, P15.5 may be assumed to be the essential polypeptide bearing HBeAg activity in the serum and also in Dane particles.

  2. The risk of perinatal hepatitis B virus transmission: hepatitis B e antigen (HBeAg prevalence estimates for all world regions

    Directory of Open Access Journals (Sweden)

    Ott Jördis J

    2012-06-01

    Full Text Available Abstract Background HBeAg presence in childbearing-age women is a major determinant of perinatal hepatitis B virus (HBV transmission. The risk of developing chronic HBV infection and liver disease is highest at young age. Our aim was to assess perinatal HBV transmission risk by means of estimating age- and region-specific HBeAg prevalence. Methods Based on observed HBeAg seroprevalence data obtained from a systematic literature review, we modeled HBeAg prevalence using an empirical Bayesian hierarchical model. Age- and region-specific estimates were generated for 1990 and 2005. Results Globally, highest HBeAg prevalence of over 50 % was found in 0–9 years old girls. At reproductive age, HBeAg prevalence was 20-50 %. Prevalence was highest in young females in East Asia in 1990 (78 %, the infection was less common in Sub-Saharan and North Africa. Regional differences in prevalence were smaller in 2005. There was an overall decrease in HBeAg between 1990 and 2005, which was strongest among girls in Oceania (23.3 % decline, South and South-East Asia (14 % decline. However, in these regions, prevalence remained high at 67 % among young females in 2005. Smaller decreases were observed in women at reproductive age, at which 24-32 % of all HBsAg-positive women were HBeAg-positive in 2005, with lowest prevalence in Southern Sub-Saharan Africa and highest prevalence in Oceania and South-East Asia. Conclusions HBeAg estimates are crucial for understanding the epidemiology of HBV and for prioritizing implementation of WHO`s prevention recommendations for all infants to receive the first dose of hepatitis B vaccine within 24 hours of birth. Results will have importance as access to treatment for chronic HBV infection is expanded.

  3. PREVALENCE, SEROCONVERSION AND RISK FACTORS OF HEPATITIS B AND C INFECTION IN PATIENTS ON MAINTENANCE HEMODIALYSIS

    Directory of Open Access Journals (Sweden)

    Vikas

    2014-10-01

    Full Text Available : BACKGROUND: HBV and HCV infections pose a great threat to patients on hemodialysis and studies have been conducted regarding the prevalence and seroconversion rates. The present study was conducted to demonstrate the prevalence and seroconversion rate in patients with chronic hemodialysis and also the incidence of liver function derangement in patients with Hepatitis B and C. METHODS: HBV and HCV status of patients who were on hemodialysis irrespective of serological status and etiology of renal failure were observed. 205 patients were followed up for a period of one year and the incidence, prevalence and seroconversion of HBV and HCV was estimated through HbsAg and Anti-HCV ELISA tests. T-test was used to compare different biochemical and other parameters among two groups (Reactive and Non-reactive. Linear regression was used to calculate the relationship between the parameters and seroconversion rates. RESULTS: 205 patients were observed in the study. The prevalence and seroconversion rates were 11.22% and 4.8% in HBV patients and 18.54% and 6.8% in HCV patients respectively, at the end of the study. There was a significant correlation of the prevalence with average number of blood transfusion and elevated ALT levels in HbsAg reactive patients. Additionally, anti-HCV reactive patients correlated significantly with average number of blood transfusion and elevated ALT levels. There was significant correlation with mean duration of haemodialysis and i.v drug abuse in anti-HCV reactive patients. Regarding the seroconversion status only the average number of blood transfusions was having a significant correlation in both HbsAg and anti-HCV reactive patients. CONCLUSION: The prevalence and seroconversion rates were 11.22% and 4.8% in HBV patients and 18.54% and 6.8% in HCV patients respectively. Safety can be improved with the availability of more sensitive tests, increasing use of erythropoietin, timely vaccination for hepatitis B and adopting

  4. Seroconversion for West Nile and St. Louis encephalitis viruses among sentinel horses in Colombia.

    Science.gov (United States)

    Mattar, Salim; Komar, Nicholas; Young, Ginger; Alvarez, Jaime; Gonzalez, Marco

    2011-12-01

    We prospectively sampled flavivirus-naïve horses in northern Colombia to detect West Nile virus (WNV) and St. Louis encephalitis virus (SLEV) seroconversion events, which would indicate the current circulation of these viruses. Overall, 331 (34.1%) of the 971 horses screened were positive for past infection with flaviviruses upon initial sampling in July 2006. During the 12-month study from July 2006-June 2007, 33 WNV seroconversions and 14 SLEV seroconversions were detected, most of which occurred in the department of Bolivar. The seroconversion rates of horses in Bolivar for the period of March-June 2007 reached 12.4% for WNV and 6.7% for SLEV. These results comprise the first serologic evidence of SLEV circulation in Colombia. None of the horses sampled developed symptoms of encephalitis within three years of initial sampling. Using seroconversions in sentinel horses, we demonstrated an active circulation of WNV and SLEV in northern Colombia, particularly in the department of Bolivar. The absence of WNV-attributed equine or human disease in Colombia and elsewhere in the Caribbean Basin remains a topic of debate and speculation.

  5. Seroconversion for west Nile and St. Louis encephalitis viruses among sentinel horses in Colombia

    Directory of Open Access Journals (Sweden)

    Salim Mattar

    2011-12-01

    Full Text Available We prospectively sampled flavivirus-naïve horses in northern Colombia to detect West Nile virus (WNV and St. Louis encephalitis virus (SLEV seroconversion events, which would indicate the current circulation of these viruses. Overall, 331 (34.1% of the 971 horses screened were positive for past infection with flaviviruses upon initial sampling in July 2006. During the 12-month study from July 2006-June 2007, 33 WNV seroconversions and 14 SLEV seroconversions were detected, most of which occurred in the department of Bolivar. The seroconversion rates of horses in Bolivar for the period of March-June 2007 reached 12.4% for WNV and 6.7% for SLEV. These results comprise the first serologic evidence of SLEV circulation in Colombia. None of the horses sampled developed symptoms of encephalitis within three years of initial sampling. Using seroconversions in sentinel horses, we demonstrated an active circulation of WNV and SLEV in northern Colombia, particularly in the department of Bolivar. The absence of WNV-attributed equine or human disease in Colombia and elsewhere in the Caribbean Basin remains a topic of debate and speculation.

  6. Seroconversion for infectious pathogens among UK military personnel deployed to Afghanistan, 2008-2011.

    Science.gov (United States)

    Newman, Edmund N C; Johnstone, Penelope; Bridge, Hannah; Wright, Deborah; Jameson, Lisa; Bosworth, Andrew; Hatch, Rebecca; Hayward-Karlsson, Jenny; Osborne, Jane; Bailey, Mark S; Green, Andrew; Ross, David; Brooks, Tim; Hewson, Roger

    2014-12-01

    Military personnel are at high risk of contracting vector-borne and zoonotic infections, particularly during overseas deployments, when they may be exposed to endemic or emerging infections not prevalent in their native countries. We conducted seroprevalence testing of 467 UK military personnel deployed to Helmand Province, Afghanistan, during 2008-2011 and found that up to 3.1% showed seroconversion for infection with Rickettsia spp., Coxiella burnetii, sandfly fever virus, or hantavirus; none showed seroconversion for infection with Crimean-Congo hemorrhagic fever virus. Most seroconversions occurred in personnel who did not report illness, except for those with hantavirus (70% symptomatic). These results indicate that many exposures to infectious pathogens, and potentially infections resulting from those exposures, may go unreported. Our findings reinforce the need for continued surveillance of military personnel and for education of health care providers to help recognize and prevent illnesses and transmission of pathogens during and after overseas deployments.

  7. Seroconversion for Infectious Pathogens among UK Military Personnel Deployed to Afghanistan, 2008–2011

    Science.gov (United States)

    Johnstone, Penelope; Bridge, Hannah; Wright, Deborah; Jameson, Lisa; Bosworth, Andrew; Hatch, Rebecca; Hayward-Karlsson, Jenny; Osborne, Jane; Bailey, Mark S.; Green, Andrew; Ross, David; Brooks, Tim; Hewson, Roger

    2014-01-01

    Military personnel are at high risk of contracting vector-borne and zoonotic infections, particularly during overseas deployments, when they may be exposed to endemic or emerging infections not prevalent in their native countries. We conducted seroprevalence testing of 467 UK military personnel deployed to Helmand Province, Afghanistan, during 2008–2011 and found that up to 3.1% showed seroconversion for infection with Rickettsia spp., Coxiella burnetii, sandfly fever virus, or hantavirus; none showed seroconversion for infection with Crimean-Congo hemorrhagic fever virus. Most seroconversions occurred in personnel who did not report illness, except for those with hantavirus (70% symptomatic). These results indicate that many exposures to infectious pathogens, and potentially infections resulting from those exposures, may go unreported. Our findings reinforce the need for continued surveillance of military personnel and for education of health care providers to help recognize and prevent illnesses and transmission of pathogens during and after overseas deployments. PMID:25418685

  8. Revised cutoff values of ALT and HBV DNA level can better differentiate HBeAg (- chronic inactive HBV patients from active carriers

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    Gull Sana

    2011-02-01

    Full Text Available Abstract Background and Aims ELISA is still used as primary test for diagnosis HBV disease. However, ELISA-positive patients were marked as HBV inactive after confirmation with PCR and vice versa. Our aim was to assess the performance of new cut-off value of ALT, HBV DNA load and significance of AST as screening tool for HBeAg (- chronic active or inactive patients in Pakistani population. Materials and methods In a cross-sectional, cohort study, 567 HBeAg (- patients followed for one year were selected. Patients with persistent elevated ALT than normal and HBV DNA ≥ 100,000 copies/mL were taken as active chronic. Diagnostic values for ALT, AST and HBV DNA load in HBV HBeAg (- chronic active and inactive patients compared using receiver operation characteristic (ROC curves. Results Of 567 HBeAg (- patients, 228 were classified as chronic inactive and 339 as active. HBV infection was dominant in male. Serum ALT, AST and HBV DNA levels showed significant and high AUROC to differentiate chronic HBeAg (- inactive patients from active. AUROC for Serum ALT, AST and HBV DNA were observed 0.997, 0.969 and 1.000, respectively. For revised cut off value for ALT (30 IU/L for male and 19 IU/L for female and HBV DNA load ≥100,000 copies/mL, a PPV of 97%, NPV of 94%, a sensitivity of 98%, and a specificity of 92% was observed to discriminate active carriers from inactive carriers. We also observed 93.5% specificity, 83.1% sensitivity, 82% PPV and 89.5% NPV for AST ≤20 IU/L to differentiate inactive carriers from active ones in our study group. Conclusions Revised cut off value of ALT and NIH derived HBV DNA value can better discriminate between HBeAg (- chronic active and inactive patients.

  9. Relationship between HBV DNA and HBeAg in serum and HBcAg and inflammation grad in liver tissue among patients with chronic hepatiti B

    Institute of Scientific and Technical Information of China (English)

    刘兴祥

    2014-01-01

    Objective To investigate the relationship between HBV DNA and HBeAg in serum and HBcAg and inflammation grade in liver tissue among chronic hepatitis B(CHB)patients.Methods A retrospective analysis was performed on 250 CHB patients who underwent liver biopsy.These patients were divided into three groups according to serum levels of HBV

  10. 原核和真核细胞表达HBeAg的应用研究%Application of HBeAg produced in prokaryotic cells and eukaryotic cells

    Institute of Scientific and Technical Information of China (English)

    何亮; 邓小昭; 刁振宇; 周宗安; 郑纪山; 高健

    2001-01-01

    Objectives: To express HBeAg in prokaryotic and eukaryotic cells and compare the two types of HBeAg in the anti-HBeAg testing. Methods: HBeAg was expressed both in E.coli cells and in silk worm cells, purified by Sephacryl S-200.HBeAg protein concentration and antigenic titer were determined respectively by ultraviolet-spectroscopy and EIA. Results: HBeAg produced by E.coli cells: Activation ratio was 10 000/mg, HBeAg/HBcAg = 50; The specificity in testing anti-HbeAg was 96%;HBeAg produced by silk worm cells: Activation ratio was 160 000/mg, HBeAg/HBcAg = 5 000, The specificity in testing anti-HbeAg was 100%. Conclusions: HBeAg produced by eukaryotic cells contained much lower proportion of HbcAg and higher activation ratio, which therefore bring about a possibility to improve the quality of the kit for testing Anti-HBe.%目的:将原核细胞和真核细胞分别克隆表达生产的HBeAg,经适当纯化后进行检测分析,并在乙型肝炎抗HBe检测中进行应用和比较。方法:分别用大肠杆菌和家蚕细胞表达生产HBeAg,并用Saphacryl S-200 柱层析进行纯化;紫外分光光度法测定表达产物的蛋白含量;EIA法测定HBeAg和HBcAg效价及评估HBeAg 的应用效果。结果:原核细胞HBeAg:比活性为10 000 /mg,HBeAg/HBcAg=50,用于抗HBe 的检测时特异性为96%,灵敏度符合国家卫生部panel要求。真核细胞HBeAg:比活性为 160 000/mg,HBeAg / HBcAg =5 000,用于抗HBe 的检测时特异性为100%,灵敏度高于国家卫生部panel要求的1~2个滴度。结论:真核细胞表达的HBeAg比活性高而HBcAg含量低,在抗HBe检测时的应用效果优于原核细胞。

  11. Predictors of HBeAg status and hepatitis B viraemia in HIV-infected patients with chronic hepatitis B in the HAART era in Brazil

    Directory of Open Access Journals (Sweden)

    Leite Andréa G

    2011-09-01

    Full Text Available Abstract Background HBV-HIV co-infection is associated with an increased liver-related morbidity and mortality. However, little is known about the natural history of chronic hepatitis B in HIV-infected individuals under highly active antiretroviral therapy (HAART receiving at least one of the two drugs that also affect HBV (TDF and LAM. Information about HBeAg status and HBV viremia in HIV/HBV co-infected patients is scarce. The objective of this study was to search for clinical and virological variables associated with HBeAg status and HBV viremia in patients of an HIV/HBV co-infected cohort. Methods A retrospective cross-sectional study was performed, of HBsAg-positive HIV-infected patients in treatment between 1994 and 2007 in two AIDS outpatient clinics located in the São Paulo metropolitan area, Brazil. The baseline data were age, sex, CD4 T+ cell count, ALT level, HIV and HBV viral load, HBV genotype, and duration of antiretroviral use. The variables associated to HBeAg status and HBV viremia were assessed using logistic regression. Results A total of 86 HBsAg patients were included in the study. Of these, 48 (56% were using combination therapy that included lamivudine (LAM and tenofovir (TDF, 31 (36% were using LAM monotherapy, and 7 patients had no previous use of either one. Duration of use of TDF and LAM varied from 4 to 21 and 7 to 144 months, respectively. A total of 42 (48. 9% patients were HBeAg positive and 44 (51. 1% were HBeAg negative. The multivariate analysis revealed that the use of TDF for longer than 12 months was associated with undetectable HBV DNA viral load (serum HBV DNA level p = 0. 047. HBeAg positivity was associated with HBV DNA > 60 UI/ml (p = 0. 001 and ALT levels above normality (p = 0. 038. Conclusion Prolonged use of TDF containing HAART is associated with undetectable HBV DNA viral load. HBeAg positivity is associated with HBV viremia and increased ALT levels.

  12. Human immunodeficiency virus type 1 seroconversion in women with genital ulcers.

    Science.gov (United States)

    Plourde, P J; Pepin, J; Agoki, E; Ronald, A R; Ombette, J; Tyndall, M; Cheang, M; Ndinya-Achola, J O; D'Costa, L J; Plummer, F A

    1994-08-01

    Genital ulcers are implicated as a risk factor enhancing susceptibility to human immunodeficiency virus type 1 (HIV-1) infection. A prospective study to determine the incidence of and risk factors associated with acquisition of HIV-1 in women with genital ulcers was done. HIV-1-seronegative women with genital ulcers attending a clinic for sexually transmitted diseases in Nairobi were followed to HIV-1 seroconversion over a 6-month period. Of 81 women, 10 seroconverted to HIV-1. The crude 6-month incidence of HIV-1 infection was 12%. Risk factors associated with seroconversion included cervical ectopy (rate ratio [RR], 4.9; 95% confidence interval [CI], 1.5-15.6) and pelvic inflammatory disease (RR, 6.3; 95% CI, 1.9-20.4). Thus, cervical ectopy and pelvic inflammatory disease may increase susceptibility to HIV-1 in women with genital ulcers.

  13. HIV sero-conversion during late pregnancy – when to retest

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    Emma Kalk

    2013-06-01

    Full Text Available The South African National Prevention of Mother-to-Child Transmission of HIV programme has resulted in significant reductions in vertical transmission, but new infant HIV infections continue to occur. We present two cases of HIV seroconversion during late pregnancy, demonstrating the limitations of the current programme. These could be mitigated by expanding the programme to include maternal testing at delivery and at immunisation clinic visits as we pursue the elimination of mother-to-child transmission.

  14. 母儿HBeAg的相关性及乙肝疫苗效果的随访研究%Study on the correlation between maternal HBeAg and infantile HBeAg and follow -up of the effect of hepatitis B vaccine

    Institute of Scientific and Technical Information of China (English)

    董洁敏; 阎娟娟; 高向东; 冯丽萍; 汪波; 王素萍

    2012-01-01

    目的:探讨乙肝表面抗原阳性孕妇HBeAg与其子代HBeAg、HBsAb的关系.方法:从太原市传染病院收集的表面抗原阳性孕妇及其新生儿共84对母儿作为研究对象,将84例HBsAg阳性孕妇分为HBeAg阳性组和HBeAg阴性组,出生24h内的新生儿定义为新生儿组,并对其进行随访,随访结果进入婴儿组.收集孕妇分娩前或分娩后24 h内的肘静脉血和出生24h内的新生儿及其随访时的股静脉血,采用化学发光法检测乙肝标志物.结果:母亲HBeAg阳性组的官内感染率显著高于HBeAg阴性组.HBeAg阳性组新生儿HBeAg阳性率明显高于HBeAg阴性组(x2=17.336,P<0.01).婴儿的HBeAg阳性率与母亲HBeAg无统计学相关性(P>0.05).母亲、新生儿的HBeAg均与婴儿HBsAb无统计学相关性(P>0.05).婴儿HBeAg与婴儿表面抗体有统计学差异(x2=5.687,P<0.05).结论:母亲HBeAg可能是官内感染的重要因素.新生儿HBeAg阳性可能与母亲HBeAg阳性有关,婴儿HBsAb与母亲、新生儿的HBeAg无关联,婴儿HBeAg阳性可能会降低婴儿HBsAb水平.%Objective: To explore the relationship between maternal HBeAg among the pregnant women with positive HBsAg and infantile HBeAg and HBsAb. Methods: A total of 84 pregnant women with positive HBsAg and their neonates were collected from hospital for infectious diseases in Taiyuan city as study objects, then 84 pregnant women with positive HBsAg were divided into HBeAg - positive group and HBeAg - negative group. The neonates within 24 hours after birth were designed as neonate group, then they were followed up, the results of follow - up entered into infant group. The blood samples of anconal vein of pregnant women before delivery and within 24 hours after delivery and the blood samples of femoral vein of the neonates within 24 hours after birth and during follow - up period were collected, chemi-luminescence was used to detect hepatitis B markers. Results; Among the pregnant women, the incidence of

  15. [Seroconversion in response to a reinforced primary hepatitis B vaccination in children with cancer].

    Science.gov (United States)

    Villena, Rodolfo; Zubieta, Marcela; Hurtado, Carmen; Salgado, Carmen; Silva, Gladys; Fernández, Jazmine; Villarroel, Milena; Fernández, Marisol; Brahm, Javier; O'Ryan, Miguel; Santolaya, María Elena

    2015-01-01

    Immune response against vaccine antigens may be impaired in children with cancer. The aim of this study was to evaluate the seroconversion response against hepatitis B vaccination (HBV) at the time of chemotherapy onset and/or remission in children with cancer. Prospective, two-centre, controlled, non-randomised study conducted on children recently diagnosed with cancer, paired with healthy subjects. Cases received HBV at time 0, 1 and 6 months with DNA recombinant HBV at a dose of 20 and 40 μg if than 10 years of age, respectively, at the time of diagnosis for solids tumours and after the remission in case of haematological tumours. Controls received the same schedule, but at of 10 and 20 μg doses, respectively. HBs antibodies were measured in serum samples obtained at 2, 8 and 12 months post-vaccination. Protective titres were defined as > 10 mIU/ml at 8th month of follow up. A total of 78 children with cancer and 25 healthy controls were analysed at month 8th of follow up. Seroconversion rates in the cancer group reached 26.9%, with no differences by age, gender or type of tumour (P = .13, .29, and .44, respectively). Control group seroconversion was 100% at the 8th month, with P 10 mIU/ml. Vaccination against hepatitis B with three doses of DNA recombinant vaccine at an increased concentration, administrated at the time of onset of chemotherapy and/or remission provided an insufficient immune response in a majority of children with cancer. More immunogenic vaccines should be evaluated in this special population, such as a third generation, with more immunogenic adjuvants, enhanced schedules at 0, 1, 2, 6 month, evaluation of antibody titres at month 8 and 12h to evaluate the need for further booster doses. Copyright © 2015 Sociedad Chilena de Pediatría. Publicado por Elsevier España, S.L.U. All rights reserved.

  16. Detection of seroconversion to West Nile virus, Usutu virus and Sindbis virus in UK sentinel chickens

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    Dawson Alistair

    2006-09-01

    Full Text Available Summary We previously reported evidence of West Nile virus (WNV circulation in UK birds, probably introduced by migratory birds from overseas. We now demonstrate WNV-specific seroconversion in sentinel chickens raised on an English farm. Maternal neutralizing antibodies to WNV in hatchlings declined within three weeks. During the following months, healthy chickens developed WNV neutralizing antibodies that were confirmed by immunoblotting and indirect immunofluorescence tests using WNV antigens. The proportion of seropositive chickens was higher for WNV than for Usutu virus or Sindbis virus. Attempts to isolate infectious virus or to detect viral RNA in the sera, failed.

  17. X-linked Agammaglobulinemia With Normal Immunoglobulin and Near-Normal Vaccine Seroconversion.

    Science.gov (United States)

    Preece, Kahn; Lear, Graeme

    2015-12-01

    We present a 22-month-old boy with X-linked agammaglobulinemia masked by normal immunoglobulin levels and vaccine seroconversion. Diagnosis was made after strong clinical suspicion of immune deficiency led to identification of markedly reduced B-cell numbers and confirmation with identification of a novel Bruton tyrosine kinase gene mutation. He was commenced on replacement immunoglobulin therapy with excellent clinical improvement. This case highlights the variability of phenotypic presentation and apparent disunity between routine immunologic investigations and severe disease in X-linked agammaglobulinemia, necessitating clinical acumen to make the diagnosis.

  18. The Vancouver Lymphadenopathy-AIDS Study: 6. HIV seroconversion in a cohort of homosexual men.

    OpenAIRE

    1986-01-01

    In an ongoing prospective study of homosexual men conducted since November 1982 in Vancouver, we identified 345 men who did not have antibody to human immunodeficiency virus (HIV) at the time of enrolment and for whom results of follow-up serologic testing were available. A total of 66 cases of seroconversion were documented among the 345 men between November 1982 and October 1985. Methods of survival data analysis that take into account the varying durations of follow-up were used to study t...

  19. Dengue virus serological prevalence and seroconversion rates in children and adults in Medellin, Colombia: implications for vaccine introduction

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    Mabel Carabali

    2017-05-01

    Conclusions: These laboratory-based findings could inform dengue vaccine decisions, as they provide age-specific seroprevalence and seroconversion data, evidencing permanent and ongoing dengue transmission in the study area. This study provides evidence for the existing rates of secondary and heterotypic responses, presenting a challenge that must be addressed adequately by the new vaccine candidates.

  20. 抗病毒治疗后慢性乙型肝炎患者外周血免疫细胞的改变与HBeAg血清学阴转的关系%Relationship between the changes in immune cells and HBeAg loss following antiviral treatment in chronic hepatitis B patients

    Institute of Scientific and Technical Information of China (English)

    郑琦; 朱月永; 陈靖; 刘豫瑞; 游佳; 曾达武; 林苏; 江家骥

    2012-01-01

    HBeAg-positive patients (n =20) throughout the 48-week course of ADV therapy (10 mg/d).HBV-specific T cell reactivity to HBV core antigen (HBcAg) was assessed by enzymelinked immunosorbent spot assay and cell proliferation assay at pre-treatment (baseline) and post-treatment weeks 4,12,24,36,and 48.Percentage of regulatory T cells (Tregs),as well as activated peripheral natural killer (NK) cells (expressing the NKG2D receptor),was measured by flow cytometry.Comparisons of means were performed by the two-tailed t-test or the Mann-Whitney rank sum test.Results After 48 weeks of ADV therapy,HBeAg loss was observed in six of the 20 (30%) patients and 14 patients remained HBeAg-positive.In the patients with HBeAg loss,the viral load reduction was accompanied by a significantly enhanced response rate of HBV-specific interferon (IFN)-gamma-producing CD4+ T cells [measured as (spot forming cells/peripheral blood mononuclear cells); baseline:(661.25 ± 281.97) × 10-6 vs.week 48:(280.75 ± 104.33) ×10-6,P =0.045].In contrast,patients without HBeAg loss showed no significant differences in T cell response rates.The patient groups with and without HBeAg loss showed similar proportions of peripheral blood Tregs during the treatment course,which included a trend of gradual decrease from baseline to week 4 with steady levels thereafter.In addition,both groups showed a similar increase in NKG2D expression that began at week 12 and peaked at week 48.Conclusion HBV-specific T cell reactivity temporally increases in some ADV-treated chronic hepatitis B patients,and this trend is strongly associated with HBeAg loss.Furthermore,recovery of HBV-specific T cell reactivity promotes viral clearance and HBeAg seroconversion.

  1. Rainfall and sentinel chicken seroconversions predict human cases of Murray Valley encephalitis in the north of Western Australia.

    Science.gov (United States)

    Selvey, Linda A; Johansen, Cheryl A; Broom, Annette K; Antão, Catarina; Lindsay, Michael D; Mackenzie, John S; Smith, David W

    2014-12-10

    Murray Valley encephalitis virus (MVEV) is a flavivirus that occurs in Australia and New Guinea. While clinical cases are uncommon, MVEV can cause severe encephalitis with high mortality. Sentinel chicken surveillance is used at many sites around Australia to provide an early warning system for risk of human infection in areas that have low population density and geographical remoteness. MVEV in Western Australia occurs in areas of low population density and geographical remoteness, resulting in logistical challenges with surveillance systems and few human cases. While epidemiological data has suggested an association between rainfall and MVEV activity in outbreak years, it has not been quantified, and the association between rainfall and sporadic cases is less clear. In this study we analysed 22 years of sentinel chicken and human case data from Western Australia in order to evaluate the effectiveness of sentinel chicken surveillance for MVEV and assess the association between rainfall and MVEV activity. Sentinel chicken seroconversion, human case and rainfall data from the Kimberley and Pilbara regions of Western Australia from 1990 to 2011 were analysed using negative binomial regression. Sentinel chicken seroconversion and human cases were used as dependent variables in the model. The model was then tested against sentinel chicken and rainfall data from 2012 and 2013. Sentinel chicken seroconversion preceded all human cases except two in March 1993. Rainfall in the prior three months was significantly associated with both sentinel chicken seroconversion and human cases across the regions of interest. Sentinel chicken seroconversion was also predictive of human cases in the models. The model predicted sentinel chicken seroconversion in the Kimberley but not in the Pilbara, where seroconversions early in 2012 were not predicted. The latter may be due to localised MVEV activity in isolated foci at dams, which do not reflect broader virus activity in the region

  2. Risk factors for seroconversion by Leishmania infantum in a cohort of dogs from an endemic area of Brazil.

    Directory of Open Access Journals (Sweden)

    Wendel Coura-Vital

    Full Text Available Visceral leishmaniasis (VL has recently emerged in various urban and peri-urban areas of Brazil and other countries. Understanding the urbanization of VL requires identification of risk factors associated with human and canine infection. To determine the predictors of risk for canine VL, a survey was conducted of 1,443 dogs, from which a cohort was selected (n = 455 and evaluated for approximately 26 months. Serology was conducted with two enzyme-linked immunosorbent assays (ELISA: one conducted in the Laboratory of Zoonosis of the Belo Horizonte Health Department (LZOON and the other in the Laboratory of Immunopathology of the Federal University of Ouro Preto (LIMP. A molecular diagnostic method (PCR-restriction fragment length polymorphism and a structured questionnaire were also used. To identify the factors associated with seroconversion, two time-dependent Cox regression models were performed with different sensitivities (model 1, seroconversion by ELISA/LZOON; model 2, seroconversion by ELISA/LIMP. The overall incidences of seroconversion were 6.5/1000 dogs-months and 11.2/1000 dogs-months for ELISA/LZOON and ELISA/LIMP, respectively. Increased risk of seroconversion was associated with short fur (model 1: hazard ratio [HR] 1.9, the presence of dry leaves (model 1: HR 2.8 or manure (model 1: HR 3.5 in the backyard, dogs sleeping predominantly in the backyard (model 2: HR 2.1, the presence of symptoms (model 2: HR 2.0, and positive molecular results during follow-up (model 2: HR 1.5. Decreased risk was associated with insecticide spraying in the house (model 2: HR 0.5. These results indicate that more-vulnerable domiciles, certain dog behaviors, lack of vector control measures, and positive molecular results were associated with the occurrence of canine VL. Furthermore, it is important to emphasize that PCR-positive dogs should be monitored, owing to the possibility of seroconversion. Identifying risk factors for seroconversion in dogs is

  3. Alteration of the glycan profile of serum glycoproteins during the seroconversion process in hepatitis B virus-infected patients treated with antiviral therapy and its clinical significance%抗HBV治疗后血清学转换中血清糖蛋白聚糖谱的变化及其临床意义

    Institute of Scientific and Technical Information of China (English)

    古幼兰; 汤宇文; 周晓东; 刘银坤

    2014-01-01

    Objective To use a lectin microarray to study the alteration of glycan affinity profiles of serum glycoproteins during the hepatitis B e antigen (HBeAg) and hepatitis B surface antigen (HBsAg) seroconversion in patients with chronic hepatitis B (CHB) following treatment with antiviral therapy,and to explore its biological significance.Methods CHB patients were divided into the following four groups:untreated HBeAg-positive,HBeAg seroconversion after anti-HBV therapy,HBsAg loss after anti-HBV therapy,and healthy individuals (controls).Serum samples were collected from each participant,depleted of high abundance proteins and analyzed by a lectin microarray containing 50 lectins.The lectin-affinity glycan profiles of serum proteins were partially verified by lectin blotting.Between-group differences were analyzed by one-way analysis of variance,and pairwise comparisons were carried out with the Student-Newman-Keuls (SNK) method.Results The results from the lectin microarray and lectin blotting assay showed significantly reduced affinity for 16 lectins in the untreated HBeAg-positive group compared to the control group (P<0.05);in addition,the specific glycan profiles of the untreated HBeAg-positive group included decreased terminal and core fructose,GalNAc α-Thr/Ser (T,Tn-antigen),GalNac α,terminal β1-4,and β-D galactose,bisecting and/or GlcNAc,mannose and Sia.However,the HBeAg seroconversion after anti-HBV therapy group showed enhanced binding of PSA,MPL and the above-mentioned 16 lectins (P < 0.05),suggesting that the reduced serum glycoprotein glycan structures returned to normal or slightly higher than healthy levels after the therapy-induced seroconversion.Comparison of the group with HBsAg loss after anti-HBV therapy to the group with HBeAg seroconversion after anti-HBV therapy showed the binding ability of ten lectins (AAL,ACL,HAL,HPL,RCA-I,LEL,STL,PHA-E,NML and PCL) were weakened to near control levels and six lectins (VAL,LCA,GNL,PSA,MPL and JAC) were

  4. Anti-virus prophylaxis withdrawal may be feasible in liver transplant recipients whose serum HBeAg and HBV DNA are negative.

    Science.gov (United States)

    Geng, Lei; Lin, Bing-Yi; Shen, Tian; Guo, Hua; Ye, Yu-Fu; Zheng, Shu-Sen

    2016-06-01

    Anti-virus prophylactic therapy may be not necessary for the prevention of hepatitis B virus (HBV) recurrence after HBV-related liver transplantation (LT). However, studies on completely stopping the hepatitis B immune globulin (HBIG) and nucleos(t)ide analogs (NUC) after LT are few. The aim of the current study was to evaluate the safety of anti-virus prophylaxis withdrawal in liver recipients whose serum hepatitis B e antigen (HBeAg) and HBV DNA are negative. We analyzed 190 patients undergone LT for HBV-related liver disease from 2006 to 2012 and found that 10 patients completely stopped the HBIG and NUC due to poor compliance. These patients were liver biopsied and checked monthly with serum HBV markers, HBV DNA and liver function. Among the 10 patients, 9 did not show the signs of HBV recurrence after a mean follow-up of 51.6 months (range 20-73) after withdrawal of the HBIG and NUC. The average time from LT to the withdrawal of the anti-virus drug was 23.8 (13-42) months; one patient showed hepatitis B surface antigen-positive and detectable HBV DNA after stopping anti-virus drugs and this patient was successfully treated with entecavir. Our data suggested that complete withdrawal of anti-virus prophylaxis was safe and feasible for patients whose serum HBeAg and HBV DNA were negative at the time of LT.

  5. Barebacking e a possibilidade de soroconversão Barebacking and the possibility of seroconversion

    Directory of Open Access Journals (Sweden)

    Luís Augusto Vasconcelos da Silva

    2009-06-01

    Full Text Available Este artigo discute a produção de sentidos sobre a possibilidade de soroconversão nas práticas de barebacking, bem como a dinâmica do bug chasing e suas ambigüidades no contexto brasileiro. Nessa perspectiva, algumas justificativas para a realização do barebacking, de modo geral definido como o sexo anal desprotegido entre homens que fazem sexo com homens de forma intencional, serão focalizadas. Durante a minha trajetória de pesquisa, foram acompanhadas algumas comunidades e fóruns de discussão no Orkut sobre o barebacking, como também desenvolvidas entrevistas online, abertas, no MSN, com barebackers oriundos de distintos estados do país, principalmente de São Paulo e Rio de Janeiro, Brasil. A busca pela soroconversão também esteve presente nos contextos de interação online do cenário brasileiro, embora haja muito mais uma multiplicidade de interesses e modalidades de barebacking entre os diversos interlocutores online. Como será discutido neste artigo, mais do que adquirir o HIV, existe uma preocupação excessiva por acumular ou intensificar sensações.This article discusses the production of meanings concerning the possibility of HIV seroconversion in bareback sex practices, as well as the dynamics of bug chasing and its ambiguities in the Brazilian context. The article emphasizes several reasons for engaging in barebacking, generally defined as the intentional nonuse of condoms during anal sex among men who have sex with men. During the course of my research, some Orkut communities and chat forums on barebacking were followed, and open online interviews via MSN Messenger were conducted with barebackers from different States of Brazil, mainly São Paulo and Rio de Janeiro. Pursuit of seroconversion was also present in the contexts of online interaction in the Brazilian scenario, although there was much more of a multiplicity of interests and barebacking modalities across the various on-line interlocutors. As discussed

  6. Human immunodeficiency virus seroconversion presenting with acute inflammatory demyelinating polyneuropathy: a case report

    Directory of Open Access Journals (Sweden)

    Sloan Derek J

    2008-12-01

    Full Text Available Abstract Introduction Acute Human Immunodeficiency Virus infection is associated with a range of neurological conditions. Guillain-Barré syndrome is a rare presentation; acute inflammatory demyelinating polyneuropathy is the commonest form of Guillain-Barré syndrome. Acute inflammatory demyelinating polyneuropathy has occasionally been reported in acute Immunodeficiency Virus infection but little data exists on frequency, management and outcome. Case presentation We describe an episode of Guillain-Barré syndrome presenting as acute inflammatory demyelinating polyneuropathy in a 30-year-old man testing positive for Immunodeficiency Virus, probably during acute seroconversion. Clinical suspicion was confirmed by cerebrospinal fluid analysis and nerve conduction studies. Rapid clinical deterioration prompted intravenous immunoglobulin therapy and early commencement of highly active anti-retroviral therapy. All symptoms resolved within nine weeks. Conclusion Unusual neurological presentations in previously fit patients are an appropriate indication for Immunodeficiency-Virus testing. Highly active anti-retroviral therapy with adequate penetration of the central nervous system should be considered as an early intervention, alongside conventional therapies such as intravenous immunoglobulin.

  7. Seroconversion to Japanese Encephalitis Virus among U.S. Infantry Forces in Korea

    Science.gov (United States)

    Eick-Cost, Angelia A.; Hu, Zheng; Klein, Terry A.; Putnak, Robert J.; Jarman, Richard G.

    2015-01-01

    Japanese encephalitis virus (JEV) is endemic in the Republic of Korea (ROK), posing a medical threat to more than 29,000 U.S. Forces military personnel currently deployed in the ROK. The objective of this study was to provide data on the risk of JEV exposure among U.S. Forces in the ROK. One thousand U.S. Army Soldiers were randomly selected for the study from the cohort of infantry Soldiers deployed in the ROK for a period of at least 330 days from 2008 to 2011. Pre- and post-deployment serum specimens were tested for the presence of JEV antibodies by plaque reduction neutralization test. A total of 2/1,000 (0.2%) U.S. Army Soldiers post-deployment specimens tested positive for JEV antibody. Results from the pre-deployment specimens indicated one true seroconversion and one with titers suggestive of a JEV infection. These results indicate a low, but nonzero risk of JEV exposure among U.S. Army Soldiers in the ROK. PMID:26240157

  8. Postvaccination seroconversion against the surface antigen of Hepatitis B virus, in nursing students

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    Gladys Amanda Mera-Urbano

    2013-09-01

    Full Text Available Objective: To determine the status of seroconversion after vaccination against the surface antigen of hepatitis B virus in nursing students, University of Cauca. Methods: Cross sectional study in students of V and VI semester. The sample was taken from 37 students, 15 of V and 22 of VI semester. The instrument used was a survey that included 11 questions of multiple selections. Records for weight, height and laboratory results were collected; blood samples for antibody titers were performed with informed consent. The data were tabulated and analyzed using SPSS, version 17.0. Results: 89.2% of students had levels of antibodies to the surface antigen. This value was greater than 10 mUI/ml, considered by the scientific community as a protector value of Hepatitis B. 10.8% of had lesser values. Regarding vaccination scheme, 24% had a dose, 19% two, 48% three and 8% had a one dose. The population with 3 doses and reinforcement seroconverted by 100%. Conclusion: This study demonstrated failings in the scheme of vaccination of the students of nursing and that 10.8 % presented lower values than 10 mIU/ml. It is necessary to apply the institutional rules with more strength as a preventive measure for hepatitis B.

  9. Temporal Trends in Postseroconversion CD4 Cell Count and HIV Load: The Concerted Action on Seroconversion to AIDS and Death in Europe Collaboration, 1985-2002

    National Research Council Canada - National Science Library

    Maria Dorrucci; Giovanni Rezza; Kholoud Porter; Andrew Phillips

    2007-01-01

    ... (Concerted Action on Seroconversion to AIDS and Death in Europe Collaboration). We focused on individuals seroconverting between 1985 and 2002 who had the first CD4 cell count (n = 3687) or HIV load (n = 1584...

  10. Incidence of syphilis seroconversion among HIV-infected persons in Asia: results from the TREAT Asia HIV Observational Database

    Science.gov (United States)

    Ahn, Jin Young; Boettiger, David; Kiertiburanakul, Sasisopin; Merati, Tuti Parwati; Huy, Bui Vu; Wong, Wing Wai; Ditangco, Rossana; Lee, Man Po; Oka, Shinichi; Durier, Nicolas; Choi, Jun Yong

    2016-01-01

    Introduction Outbreaks of syphilis have been described among HIV-infected men who have sex with men (MSM) in Western communities, whereas reports in Asian countries are limited. We aimed to characterize the incidence and temporal trends of syphilis among HIV-infected MSM compared with HIV-infected non-MSM in Asian countries. Methods Patients enrolled in the TREAT Asia HIV Observational Database cohort and with a negative non-treponemal test since enrolment were analyzed. Incidence of syphilis seroconversion, defined as a positive non-treponemal test after previously testing negative, was evaluated among patients at sites performing non-treponemal tests at least annually. Factors associated with syphilis seroconversion were investigated at sites doing non-treponemal testing in all new patients and subsequently testing routinely or when patients were suspected of having syphilis. Results We included 1010 patients from five sites that performed non-treponemal tests in all new patients; those included had negative non-treponemal test results during enrolment and subsequent follow-ups. Among them, 657 patients were from three sites conducting regular non-treponemal testing. The incidence of syphilis seroconversion was 5.38/100 person-years (PY). Incidence was higher in MSM than non-MSM (7.64/100 PY vs. 2.44/100 PY, p<0.001). Among MSM, the incidence rate ratio (IRR) for every additional year from 2009 was 1.19 (p=0.051). MSM status (IRR 3.48, 95% confidence interval (CI) 1.88–6.47), past syphilis diagnosis (IRR 5.15, 95% CI 3.69–7.17) and younger age (IRR 0.84 for every additional 10 years, 95% CI 0.706–0.997) were significantly associated with syphilis seroconversion. Conclusions We observed a higher incidence of syphilis seroconversion among HIV-infected MSM and a trend to increasing annual incidence. Regular screening for syphilis and targeted interventions to limit transmission are needed in this population. PMID:27774955

  11. Incidence of syphilis seroconversion among HIV-infected persons in Asia: results from the TREAT Asia HIV Observational Database

    Directory of Open Access Journals (Sweden)

    Jin Young Ahn

    2016-10-01

    Full Text Available Introduction: Outbreaks of syphilis have been described among HIV-infected men who have sex with men (MSM in Western communities, whereas reports in Asian countries are limited. We aimed to characterize the incidence and temporal trends of syphilis among HIV-infected MSM compared with HIV-infected non-MSM in Asian countries. Methods: Patients enrolled in the TREAT Asia HIV Observational Database cohort and with a negative non-treponemal test since enrolment were analyzed. Incidence of syphilis seroconversion, defined as a positive non-treponemal test after previously testing negative, was evaluated among patients at sites performing non-treponemal tests at least annually. Factors associated with syphilis seroconversion were investigated at sites doing non-treponemal testing in all new patients and subsequently testing routinely or when patients were suspected of having syphilis. Results: We included 1010 patients from five sites that performed non-treponemal tests in all new patients; those included had negative non-treponemal test results during enrolment and subsequent follow-ups. Among them, 657 patients were from three sites conducting regular non-treponemal testing. The incidence of syphilis seroconversion was 5.38/100 person-years (PY. Incidence was higher in MSM than non-MSM (7.64/100 PY vs. 2.44/100 PY, p<0.001. Among MSM, the incidence rate ratio (IRR for every additional year from 2009 was 1.19 (p=0.051. MSM status (IRR 3.48, 95% confidence interval (CI 1.88–6.47, past syphilis diagnosis (IRR 5.15, 95% CI 3.69–7.17 and younger age (IRR 0.84 for every additional 10 years, 95% CI 0.706–0.997 were significantly associated with syphilis seroconversion. Conclusions: We observed a higher incidence of syphilis seroconversion among HIV-infected MSM and a trend to increasing annual incidence. Regular screening for syphilis and targeted interventions to limit transmission are needed in this population.

  12. Frequent transient hepatitis C viremia without seroconversion among healthcare workers in Cairo, Egypt.

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    Aline Munier

    Full Text Available BACKGROUNDS: With 10% of the general population aged 15-59 years chronically infected with hepatitis C virus (HCV, Egypt is the country with the highest HCV prevalence worldwide. Healthcare workers (HCWs are therefore at particularly high risk of HCV infection. Our aim was to study HCV infection risk after occupational blood exposure among HCWs in Cairo. METHODOLOGY/PRINCIPAL FINDINGS: The study was conducted in 2008-2010 at Ain Shams University Hospital, Cairo. HCWs reporting an occupational blood exposure at screening, having neither anti-HCV antibodies (anti-HCV nor HCV RNA, and exposed to a HCV RNA positive patient, were enrolled in a 6-month prospective cohort with follow-up visits at weeks 2, 4, 8, 12 and 24. During follow-up, anti-HCV, HCV RNA and ALT were tested. Among 597 HCWs who reported a blood exposure, anti-HCV prevalence at screening was 7.2%, not different from that of the general population of Cairo after age-standardization (11.6% and 10.4% respectively, p = 0.62. The proportion of HCV viremia among index patients was 37%. Of 73 HCWs exposed to HCV RNA from index patients, nine (12.3%; 95%CI, 5.8-22.1% presented transient viremia, the majority of which occurred within the first two weeks after exposure. None of the workers presented seroconversion or elevation of ALT. CONCLUSIONS/SIGNIFICANCE: HCWs of a general University hospital in Cairo were exposed to a highly viremic patient population. They experienced frequent occupational blood exposures, particularly in early stages of training. These exposures resulted in transient viremic episodes without established infection. These findings call for further investigation of potential immune protection against HCV persistence in this high risk group.

  13. Assessment of seroconversion against peste des petits ruminants vaccine among sheep and goats in Buchanan, Liberia

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    BO Olugasa

    2012-12-01

    Full Text Available Serological response to a live commercial vaccine of Peste des petits ruminants (PPR virus administered to sheep and goats in Buchanan, the capital city of Grand Bassa County, Liberia was assessed in view of its importance for effective restocking of small ruminants in the city. Forty-four paired serum samples (pre- and post-vaccination were collected from vaccinated sheep and goats during a nation-wide campaign for food security promotion from March to October, 2011. Sheep and goats were vaccinated against PPR in late April, 2011. Pre-vaccination samples were collected in mid-April, 2011. Post-vaccination samples were collected in mid-October 2011 from the same groups of sheep and goats (6 months after vaccination. Paired serum samples gathered were stored at -4 0C until tested. Competitive Enzyme Linked Immunosorbent Assay (c-ELISA was used to determine antibody levels against PPR virus. Only 34(77.3% out of 44 paired serum samples were adequate in quantity and quality for the test. Test results indicated 27(79.4% out of 44 paired serum samples increased significantly in antibody levels from pre-vaccination to post-vaccination levels that were equal or above threshold of Percentage Inhibition (PI > 50% against PPR vaccine. The importance of these findings to effective veterinary services delivery for the control of this neglected animal disease in Liberia is discussed. The present seroconversion status against PPR virus is considered to be a milestone in rebuilding veterinary services systems in Liberia towards national efforts for food security after prolonged civil war (1989-2003 in the country.

  14. The intracellular HBV DNAs as novel and sensitive biomarkers for the clinical diagnosis of occult HBV infection in HBeAg negative hepatocellular carcinoma in China.

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    Hui Wang

    Full Text Available This study aimed to investigate the virological status in liver (both tumor and adjacent non-tumor tissue, the clinical features and the contribution of occult HBV infection (OBI to postoperative prognosis in HBeAg-negative(- hepatocellular carcinoma (HCC patients in China. Using quantitative TaqMan fluorescent real-time PCR assays, HBV covalently closed circular DNA (cccDNA and total DNA (tDNA were both quantified in 11 (HBsAg(- and 57 (HBsAg-positive(+ pairs of tumor tissue (TT and adjacent non-tumor tissue (ANTT obtained from HBeAg(- HCC patients who received no antiviral treatment and were negative for anti-HCV before surgical treatment. Of 11 HBsAg(- patients, 36% were with HBsAb(+ HBeAb(+ HBcAb(+. However, only 9% of the HBsAg(- patients were HBsAb(- HBeAb(+ HBcAb(+, which accounted for the majority (93% in the HBsAg(+ group. TT and ANTT HBV tDNAs in 11 HCC patients with HBsAg (- and HBeAg (- were all detectable. HBV cccDNA and tDNA were all lower in the HBsAg(- group than those in the HBsAg(+ group. By Kaplan-Meier analysis, patients with OBI were associated with a lower risk of cirrhosis and better overall survival (OS. The intracellular HBV DNAs, such as HBV cccDNA and tDNA are valuable biological markers for the diagnosis of occult HBV infection in HCC patients. This would assist the clinical implementation of a more personalized therapy for viral re-activation control and improve the survival rate of OBI patients.

  15. [Correlation of serum chemokine RANTES level with serum biochemical indices, HBeAg and HBV DNA load in patients with chronic hepatitis B].

    Science.gov (United States)

    Zhang, Ka; Xu, Qi-Huan; Chen, Lu-Biao; Shu, Xin; Chen, Ni; Li, Gang

    2009-06-01

    To investigate the level of the serum chemokine RANTES and its correlation with serum biochemical indices of liver function test, HBeAg and HBV DNA load in patients with chronic hepatitis B. 144 patients with chronic hepatitis B (observed group) and 18 normal cases (control group) were enrolled in this study. The serum level of chemokine RANTES was detected with an ABC-ELISA assay. Statistical analysis was performed on the software of SPSS13.0. The serum chemokine RANTES level in the observed group (3930.12 ng/ml 2856.96) ng/ml was significantly higher than that in the control group (329.46 ng/ml +/- 152.23) ng/ml. The results from the observed group indicated the positive correlation of serum RANTES level with indices of liver function test, including ALT (r = 0.197, P = 0.018), AST(r = 0.239, P = 0.004) and TBil (r = 0.316, P = 0.001), but did not with PTA (r = - 0.078, P = 0.357). Neither difference of serum chemokine RANTES level between HBeAg-positive group and HBeAg-negative group nor that between high HBV DNA load group (> or = 10(5) copies/ml) and low HBV DNA load group (hepatitis B elevates significantly and is not affected by HBeAg or HBV DNA load. Its positive correlation with indices of liver function test indicates that RANTES might play an important role in the pathogenesis of chronic hepatitis B.

  16. Anti-virus prophylaxis withdrawal may be feasible in liver transplant recipients whose serum HBeAg and HBV DNA are negative

    Institute of Scientific and Technical Information of China (English)

    Lei Geng; Bing-Yi Lin; Tian Shen; Hua Guo; Yu-Fu Ye; Shu-Sen Zheng

    2015-01-01

    Anti-virus prophylactic therapy may be not nec-essary for the prevention of hepatitis B virus (HBV) recur-rence after HBV-related liver transplantation (LT). However, studies on completely stopping the hepatitis B immune globu-lin (HBIG) and nucleos(t)ide analogs (NUC) after LT are few. The aim of the current study was to evaluate the safety of anti-virus prophylaxis withdrawal in liver recipients whose serum hepatitis Be antigen (HBeAg) and HBV DNA are negative. We analyzed 190 patients undergone LT for HBV-related liver dis-ease from 2006 to 2012 and found that 10 patients completely stopped the HBIG and NUC due to poor compliance. These patients were liver biopsied and checked monthly with serum HBV markers, HBV DNA and liver function. Among the 10 patients, 9 did not show the signs of HBV recurrence after a mean follow-up of 51.6 months (range 20-73) after with-drawal of the HBIG and NUC. The average time from LT to the withdrawal of the anti-virus drug was 23.8 (13-42) months;one patient showed hepatitis B surface antigen-positive and detectable HBV DNA after stopping anti-virus drugs and this patient was successfully treated with entecavir. Our data sug-gested that complete withdrawal of anti-virus prophylaxis was safe and feasible for patients whose serum HBeAg and HBV DNA were negative at the time of LT.

  17. Anti-virus prophylaxis withdrawal may be feasible in liver transplant recipients whose serum HBeAg and HBV DNA are negative

    Institute of Scientific and Technical Information of China (English)

    Lei Geng; Bing-Yi Lin; Tian Shen; Hua Guo; Yu-Fu Ye; Shu-Sen Zheng

    2016-01-01

    Anti-virus prophylactic therapy may be not nec-essary for the prevention of hepatitis B virus (HBV) recur-rence after HBV-related liver transplantation (LT). However, studies on completely stopping the hepatitis B immune globu-lin (HBIG) and nucleos(t)ide analogs (NUC) after LT are few. The aim of the current study was to evaluate the safety of anti-virus prophylaxis withdrawal in liver recipients whose serum hepatitis Be antigen (HBeAg) and HBV DNA are negative. We analyzed 190 patients undergone LT for HBV-related liver dis-ease from 2006 to 2012 and found that 10 patients completely stopped the HBIG and NUC due to poor compliance. These patients were liver biopsied and checked monthly with serum HBV markers, HBV DNA and liver function. Among the 10 patients, 9 did not show the signs of HBV recurrence after a mean follow-up of 51.6 months (range 20-73) after with-drawal of the HBIG and NUC. The average time from LT to the withdrawal of the anti-virus drug was 23.8 (13-42) months;one patient showed hepatitis B surface antigen-positive and detectable HBV DNA after stopping anti-virus drugs and this patient was successfully treated with entecavir. Our data sug-gested that complete withdrawal of anti-virus prophylaxis was safe and feasible for patients whose serum HBeAg and HBV DNA were negative at the time of LT.

  18. Hepatitis B Virus Expression in Villi from Paternal HBeAg Positive Early Abortion Embryo%父系HBeAg阳性流产胚胎绒毛中HBV-DNA的表达

    Institute of Scientific and Technical Information of China (English)

    林淑仪; 李芳; 陈励和; 崔咏怡; 禤庆山

    2012-01-01

    Objective: To investigate hepatitis B virus (HBV-DNA) expression in villi from paternal HBeAg positive early abortion embryo. Methods: Early abortion embryos, whose paternal serum HBsAg positive and maternal serum HBsAg negative, were collected. They were divided into G1 paternal HBeAg (+)and maternal HBsAb (+), G2 paternal HBeAg (+) and maternal HBsAb (-), G3 paternal HBeAg (-) and maternal HBsAb (+), and G4 maternal HBsAb (-) and paternal HbeAg (-). parents serum HBV antigen and antibody measurement was performed by ELISA, HBV-DNA expression in villi was measured by fluori-metric quantitative PCR. Results: Among 142 villi from paternal HBsAg positive early abortion embryo, 3 of 84 villi from paternal HBeAg positive early abortion embryo were detected for HBV-DNA expression. The positive rate was 3.57%. 2 cases in G2 paternal HBeAg (+) and maternal HBsAb (-), and 1 case in Gl paternal HBeAg (+) and maternal HBsAb (+). In groups whose paternal HBeAg were positive (G1 and G2), there was no significant difference for villi HBV-DNA expressing rate (P>0.05). Conclusion: Hepatitis B virus might more likely transmit vertically to early embryo villi in paternal HBeAg positive cases.%目的:探讨在父系HBeAg阳性的流产胚胎中,乙型肝炎病毒在绒毛中的表达.方法:募集仅父系感染乙型肝炎病毒组合,即母HBsAg(-)且父HBsAg(+)流产胚胎.接以下组合将入选对象分为4组:组1为父HBeAg(+)母HBsAb(+);组2为父HBeAg(+)母HBsAb(-);组3为父HBeAg(-)母HBsAb(+);组4为父HBeAg(-)母HBsAb(-),采用酶联免疫吸附实验(ELISA)对胎儿父、母亲血清进行乙肝抗原、抗体检测,并使用荧光定量PCR法对胚胎绒毛进行HBV DNA检测.结果:父系感染乙型肝炎病毒的142例胚胎中,仅在父系HBeAg阳性组别(1、2组)84例胚胎中发现3例绒毛HBV-DNA升高,阳性率为3.57%.其中父HBeAg(+)母HBsAb(-)组合中2例,父HBeAg(+)母HBsAb(+)组合中1例.父系HBeAg均阳性,母系HBsAb阳性与阴性组间

  19. Delayed Puberty

    DEFF Research Database (Denmark)

    Kolby, Nanna; Busch, Alexander Siegfried; Juul, Anders

    2017-01-01

    Delayed puberty can be a source of great concern and anxiety, although it usually is caused by a self-limiting variant of the normal physiological timing named constitutional delay of growth and puberty (CDGP). Delayed puberty can, however, also be the first presentation of a permanent condition ...... mineral density) and psychological (e.g., low self-esteem) and underline the importance of careful clinical assessment of the patients.......Delayed puberty can be a source of great concern and anxiety, although it usually is caused by a self-limiting variant of the normal physiological timing named constitutional delay of growth and puberty (CDGP). Delayed puberty can, however, also be the first presentation of a permanent condition...

  20. Delayed fission

    Energy Technology Data Exchange (ETDEWEB)

    Hatsukawa, Yuichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-07-01

    Delayed fission is a nuclear decay process that couples {beta} decay and fission. In the delayed fission process, a parent nucleus undergoes {beta} decay and thereby populates excited states in the daughter. If these states are of energies comparable to or greater than the fission barrier of the daughter, then fission may compete with other decay modes of the excited states in the daughter. In this paper, mechanism and some experiments of the delayed fission will be discussed. (author)

  1. 核苷(酸)类似物停药后 HBeAg 阴性慢性乙型肝炎复发的临床研究%Relapse of patients with HBeAg negative chronic hepatitis B after nucleos(t) ide analogues drug withdrawal

    Institute of Scientific and Technical Information of China (English)

    浦永兰; 李明; 王杰; 龚银花; 朱莉; 李国勇

    2016-01-01

    Objective To analyze the relapse and related factors of the HBeAg negative chronic hepatitis B after nu-cleos(t)ide analogues(NUCs)drug withdrawal. Methods A total of 39 patients with HBeAg negative chronic hepatitis B after NUCs drug withdrawal in the First People's Hospital of Taicang City and the Fifth People's Hospital of Suzhou City from June 2011 to June 2015 were selected,they were divided into A group(with relapse after standard drug discontinuance,n =16)and B group(with relapse after non standard drug discontinuance,n = 23). A total of 9 patients with HBeAg negative chronic hepatitis B treated by NUCs(without relapse within 1 year of drug discontinuance)were selected as C group at the same time. The incidence of relapse and related factors were analyzed. Results Baseline serum HBV DNA of C group was lower than A,B group(P ﹤ 0. 05),baseline serum HBV DNA between A group and B group showed no significant differences( P ﹥0. 05);baseline serum HBsAg of C group was lower than B group(P ﹤ 0. 05),but compared with A group,the differences were not statistically significant(P ﹥ 0. 05);serum HBsAg of C group was lower than the A,B group(P ﹤ 0. 05),serum HBsAg between A group and B group showed no significant differences(P ﹥ 0. 05). Conclusion HBeAg negative chronic hep-atitis B patients taking NUCs with standard drug discontinuance or not appear relapse within 1 year,patients with non - standard drug has high recurrence rate within the six months baseline serum HBV DNA,baseline serum HBsAg or discontinuation of ser-um HBsAg levels maybe associated with recurrence.%目的:观察 HBeAg 阴性慢性乙型肝炎患者核苷(酸)类似物(NUCs)停药后病情复发情况,分析相关因素。方法选择2011年6月—2015年6月在太仓市第一人民医院和苏州市第五人民医院住院及门诊服用 NUCs停药后复发的 HBeAg 阴性慢性乙型肝炎患者39例,分为规范停药后复发组(A 组)16例和不规

  2. Rapid assessment of malaria transmission using age-specific sero-conversion rates.

    Directory of Open Access Journals (Sweden)

    Laveta Stewart

    Full Text Available BACKGROUND: Malaria transmission intensity is a crucial determinant of malarial disease burden and its measurement can help to define health priorities. Rapid, local estimates of transmission are required to focus resources better but current entomological and parasitological methods for estimating transmission intensity are limited in this respect. An alternative is determination of antimalarial antibody age-specific sero-prevalence to estimate sero-conversion rates (SCR, which have been shown to correlate with transmission intensity. This study evaluated SCR generated from samples collected from health facility attendees as a tool for a rapid assessment of malaria transmission intensity. METHODOLOGY AND PRINCIPAL FINDINGS: The study was conducted in north east Tanzania. Antibodies to Plasmodium falciparum merozoite antigens MSP-1(19 and AMA-1 were measured by indirect ELISA. Age-specific antibody prevalence was analysed using a catalytic conversion model based on maximum likelihood to generate SCR. A pilot study, conducted near Moshi, found SCRs for AMA-1 were highly comparable between samples collected from individuals in a conventional cross-sectional survey and those collected from attendees at a local health facility. For the main study, 3885 individuals attending village health facilities in Korogwe and Same districts were recruited. Both malaria parasite prevalence and sero-positivity were higher in Korogwe than in Same. MSP-1(19 and AMA-1 SCR rates for Korogwe villages ranged from 0.03 to 0.06 and 0.07 to 0.21 respectively. In Same district there was evidence of a recent reduction in transmission, with SCR among those born since 1998 [MSP-1(19 0.002 to 0.008 and AMA-1 0.005 to 0.014 ] being 5 to 10 fold lower than among individuals born prior to 1998 [MSP-1(19 0.02 to 0.04 and AMA-1 0.04 to 0.13]. Current health facility specific estimates of SCR showed good correlations with malaria incidence rates in infants in a contemporaneous

  3. 2009 A(H1N1 seroconversion rates and risk factors among the general population in Vientiane Capital, Laos.

    Directory of Open Access Journals (Sweden)

    Alexia Kieffer

    Full Text Available OBJECTIVE: To assess 2009 A(H1N1 seroconversion rates and their determinants within an unvaccinated population in Vientiane Capital, Laos. METHODS: CoPanFlu Laos, a general population cohort of 807 households and 4,072 participants was established in March 2010. Sociodemographic data, epidemiological data, and capillary blood samples were collected from all the household members in March, and again in October 2010, in order to assess the level of antibodies to 2009 A(H1N1 with the haemagglutination inhibition assay. 2009 A(H1N1 seroconversion was defined as a fourfold or greater increase in titre between inclusion and follow-up. Determinants for pandemic influenza infection were studied using the generalized estimating equations model, taking household clustering into account. RESULTS: Between March and November 2010, 3,524 paired sera were tested. Prior to the pandemic, our cohort was almost completely vaccine-naive for seasonal influenza. The overall seroconversion rate among nonvaccinated individuals (n = 2,810 was 14.3% (95%CI [13.0, 15.6], with the highest rate for participants under 20 yo (19.8%, 95%CI [17.4, 22.4] and the lowest rate for participants over 60 yo (6.5%, 95%CI [3.7, 10.4]. Participants with lower baseline titres had significantly higher infection rates, with a dose-effect relationship. Odds ratios (ORs ranged from 76.5 (95%CI [27.1, 215.8], for those with a titre at inclusion of 1∶10, to 8.1 (95%CI [3.3, 20.4], for those with a titre of 1∶40. Having another household member with a titre ≥1∶80 was associated with a higher likelihood of immunity (OR = 3.3, 95%CI [2.8, 3.9]. CONCLUSION: The determinants and age distribution for seroconversion within a vaccine-naive population were similar to those found in developed countries. This pandemic was characterized by strong epidemiological determinants, regardless of geographical zone and level of development. Moreover, we detected pre-existing cross

  4. Transmission and control implications of seroconversion to Maedi-Visna virus in Basque dairy-sheep flocks.

    Science.gov (United States)

    Berriatua, Eduardo; Alvarez, Vega; Extramiana, Belén; González, Lorenzo; Daltabuit, Mara; Juste, Ramón

    2003-09-12

    A retrospective analysis of seroconversion to Maedi-Visna virus (MVV) was carried out for 10 infected semi-intensively reared dairy-sheep flocks that were tested annually between 1994 and 1999. Four of the flocks raised replacement lambs artificially with bovine colostrum and milk replacement to avoid lactogenic MVV infection but did not prevent aerosol contact between replacements and other sheep in the flock. Flock culling percentages ranged between 14 and 25% and in eight flocks the number of sheep that seroconverted was similar to or lower than the number of sheep culled--suggesting that incidence could be reduced by culling seropositive sheep without increasing average culling percentages. Random-effects logistic regression indicated that seroconversion was associated positively with increasing contact with infected sheep and with lifetime MV-serological status of the dam (used as a proxy measure of genetic susceptibility), but not with mode of rearing pre-weaning (artificially or with a seropositive or seronegative dam). Our results indicate that when conditions allow efficient horizontal transmission, there is no evidence that lactogenic infection increases the risk of MV infection and that there is an important inheritable component of disease resistance or susceptibility.

  5. Time before anti-Toxoplasma IgG seroconversion detection by 7 commercial assays in French pregnant women.

    Science.gov (United States)

    Armengol, Catherine; Cassaing, Sophie; Roques-Malecaze, Christine; Chauvin, Pamela; Iriart, Xavier; Berry, Antoine; Fillaux, Judith

    2017-02-01

    We assessed the ability to early detect a toxoplasmic seroconversion between 1 immunoblot (LDBIO II®) and 6 automated assays (TGS TA®, Architect®, Vidas II®, Liaison II®, Platelia®, and Elecsys®), comparing the time before anti-Toxoplasma gondii IgG detection during infection in pregnant women. From 2007 to 2015, 620 sera of 269 women were included. The median durations before positive IgG detection with Vidas II®, Liaison II®, Platelia®, and Elecsys® were significantly longer than Architect® with differential times from 11 to 28days (P<0.001). This time was significantly shortened by the use of LDBIO®, resulting in a saving of 13days (P<0.001). The detection of a positive rate of IgG with TGS TA® was as early as Architect® (P=0.105). The ability to early detect a toxoplasmic seroconversion is not equivalent between the assays and has to be considered when selecting the reagents to reduce the time to therapeutic intervention.

  6. HBeAg can up regulate regulatory T cell in cord blood%HBeAg能上调新生儿脐带血中调节性T细胞的表达

    Institute of Scientific and Technical Information of China (English)

    许晓梅; 施可庆; 刘建; 孙江川; 刘菊莲; 冯丽娟; 张大志

    2011-01-01

    Objective:To detect the frequency of CD4+CD25+CD127low- regulatory T cell ( Treg )in cord blood born from HBsAg positive mother and to determine the relationship between mother's HBeAg and HBV persistent infection after the children were born.Methods:According to mother's HBeAg status,63 cord blood of neonates delivered by H BsAg positive mothers were divided into group A ( HBeAg positive )and group B(HBeAg negative).22 cases of cord blood of neonates from HBsAg negative mother were served as group C ( healthy controls ).The frequency of Treg was analyzed by three-color immunofluorescence flow cytometry.HBV serum markers and HBVDNA level both in cord blood and mother's peripheral blood were detected. Results:In group A, 24 of 33 cord blood of neonates were HBeAg positive,but none of them were HBeAg positive in group B and group C.AII of the cord blood were HBVDNA negative.There was no relationship about the HBeAg quantity between mother's peripheral blood and cord blood(P>O.OS).Compared with group B and group C, the percentage of Treg significantly increased in group h ( P<0.05 ) , hut the number was not dramatically different between group B and group C (P>0.05).The frequency of Treg did not relate to HBVDNA level and HBeAg quantity either in mother's peripheral blood or in cord blood. Conclusion: HBeAg may have substantial impact on the development of fetal immune system and bring on their immunotolerance to HBV by upregulating Treg in cord blood.%目的:观察HBsAg阳性产妇新生儿脐带血CD4+CD25+CD127low/-调节性T细胞(Regulatory T cell,Treg)的数量,探讨HBeAg在新生儿HBV持续性感染中的作用.方法:共收集63例HBsAg阳性产妇新生儿脐带血,按照产妇产前HBeAg状态分为A组33例HBeAg阳性,B组30例HBeAg阴性,C组22例HBsAg阴性产妇做为对照组.利用三色流式分析法分析新生儿脐带血单个核细胞(Cord blood monocytes,CBMCs)中的Treg的频数.并检测产妇及其脐带

  7. Anti-cyclic citrullinated peptide antibodies – a role in rheumatoid arthritis and the possibility of seroconversion: A focus on abatacept

    Directory of Open Access Journals (Sweden)

    N. V. Chichasova

    2017-01-01

    Full Text Available The detection of anti-cyclic citrullinated peptide (anti-CCP antibodies plays a diagnostic and statistical predictive role in rheumatoid arthritis (RA. The decreased concentration of anti-CCP antibodies or their seroconversion is observed for not all groups of anti-inflammatory drugs. Seropositivity for anti-CCP antibodies is a predictor of the higher efficacy of abatacept (ABC. The possibility of seroconversion of anti-CCP antibodies, like rheumatoid factor, during treatment with ABC is associated with the more pronounced suppression of clinical symptoms of RA activity and progressive joint destruction, with remission achievement in a large proportion of patients.

  8. The G1613A mutation in the HBV genome affects HBeAg expression and viral replication through altered core promoter activity.

    Directory of Open Access Journals (Sweden)

    Man-Shan Li

    Full Text Available Infection of hepatitis B virus (HBV causes acute and chronic hepatitis and is closely associated with the development of cirrhosis and hepatocellular carcinoma (HCC. Previously, we demonstrated that the G1613A mutation in the HBV negative regulatory element (NRE is a hotspot mutation in HCC patients. In this study, we further investigated the functional consequences of this mutation in the context of the full length HBV genome and its replication. We showed that the G1613A mutation significantly suppresses the secretion of e antigen (HBeAg and enhances the synthesis of viral DNA, which is in consistence to our clinical result that the G1613A mutation associates with high viral load in chronic HBV carriers. To further investigate the molecular mechanism of the mutation, we performed the electrophoretic mobility shift assay with the recombinant RFX1 protein, a trans-activator that was shown to interact with the NRE of HBV. Intriguingly, RFX1 binds to the G1613A mutant with higher affinity than the wild-type sequence, indicating that the mutation possesses the trans-activating effect to the core promoter via NRE. The trans-activating effect was further validated by the enhancement of the core promoter activity after overexpression of RFX1 in liver cell line. In summary, our results suggest the functional consequences of the hotspot G1613A mutation found in HBV. We also provide a possible molecular mechanism of this hotspot mutation to the increased viral load of HBV carriers, which increases the risk to HCC.

  9. Adherence to chemoprophylaxis and Plasmodium falciparum anti-circumsporozoite seroconversion in a prospective cohort study of Dutch short-term travelers

    NARCIS (Netherlands)

    Belderok, S.M.; Hoek, A.; Roeffen, W.F.; Sauerwein, R.; Sonder, G.J.

    2013-01-01

    BACKGROUND: We conducted a prospective study in a cohort of short-term travelers assessing the incidence rate of anti-circumsporozoite seroconversion, adherence to chemoprophylaxis, symptoms of malaria during travel, and malaria treatment abroad. METHODS: Adults were recruited from the travel clinic

  10. Safety and Efficacy of Nucleic Acid Polymers in Monotherapy and Combined with Immunotherapy in Treatment-Naive Bangladeshi Patients with HBeAg+ Chronic Hepatitis B Infection.

    Directory of Open Access Journals (Sweden)

    Mamun Al-Mahtab

    Full Text Available Previous in vivo studies have suggested that nucleic acid polymers (NAPs may reduce circulating levels of HBsAg in the blood by blocking its release from infected hepatocytes and that this effect may have clinical benefit. NAP treatment, was evaluated in two clinical studies in patients with HBeAg positive chronic HBV infection. The REP 101 study examined REP 2055 monotherapy in 8 patients and the REP 102 study examined REP 2139-Ca, in monotherapy in 12 patients, 9 of which transitioned to short term combined treatment with pegylated interferon alpha 2a or thymosin alpha 1. In both studies NAP monotherapy was accompanied by 2-7 log reductions of serum HBsAg, 3-9 log reductions in serum HBV DNA and the appearance of serum anti-HBsAg antibodies (10-1712 mIU / ml. Eight of the 9 patients transitioning to combined treatment with immunotherapy (pegylated interferon or thymosin alpha 1 in the REP 102 study experienced HBsAg loss and all 9 patients experienced substantial increases in serum anti-HBsAg antibody titers before withdrawal of therapy. For 52 weeks after removal of REP 2055 therapy, rebound of serum viremia (HBV DNA > 1000 copies / ml, HBsAg > 1IU / ml was not observed in 3 / 8 patients. Suppression of serum virema was further maintained for 290 and 231 weeks in 2 of these patients. After withdrawal of all therapy in the 9 patients that transitioned to combination therapy in the REP 102 study, 8 patients achieved HBV DNA < 116 copies / ml after treatment withdrawal. Viral rebound occurred over a period of 12 to 123 weeks in 7 patients but was still absent in two patients at 135 and 137 weeks of follow-up. Administration tolerability issues observed with REP 2055 were rare with REP 2139-Ca but REP 2139-Ca therapy was accompanied by hair loss, dysphagia and dysgeusia which were considered related to heavy metal exposure endemic at the trial site. These preliminary studies suggest that NAP can elicit important antiviral responses during

  11. Imputation of the Date of HIV Seroconversion in a Cohort of Seroprevalent Subjects: Implications for Analysis of Late HIV Diagnosis

    Directory of Open Access Journals (Sweden)

    Paz Sobrino-Vegas

    2012-01-01

    Full Text Available Objectives. Since subjects may have been diagnosed before cohort entry, analysis of late HIV diagnosis (LD is usually restricted to the newly diagnosed. We estimate the magnitude and risk factors of LD in a cohort of seroprevalent individuals by imputing seroconversion dates. Methods. Multicenter cohort of HIV-positive subjects who were treatment naive at entry, in Spain, 2004–2008. Multiple-imputation techniques were used. Subjects with times to HIV diagnosis longer than 4.19 years were considered LD. Results. Median time to HIV diagnosis was 2.8 years in the whole cohort of 3,667 subjects. Factors significantly associated with LD were: male sex; Sub-Saharan African, Latin-American origin compared to Spaniards; and older age. In 2,928 newly diagnosed subjects, median time to diagnosis was 3.3 years, and LD was more common in injecting drug users. Conclusions. Estimates of the magnitude and risk factors of LD for the whole cohort differ from those obtained for new HIV diagnoses.

  12. Anti-HBs seroconversion during treatment with entecavir in a patient with chronic hepatitis B virus infection on hemodialysis.

    Science.gov (United States)

    Spaziante, Martina; Biliotti, Elisa; Grieco, Stefania; Palazzo, Donatella; Esvan, Rozenn; Taliani, Gloria

    2014-01-01

    Hepatitis B (HBV) virus infection is one of the most important causes of liver disease in patients with end-stage renal failure on hemodialysis. The natural history of chronic HBV infection acquired in childhood starts with an immune tolerant phase, followed by an immune clearance phase that may lead to the inactive carrier state or the development of chronic liver disease. Information on antiviral therapy administered very early during the immune clearance phase are lacking and no data exist on the treatment of early immune activation in the hemodialysis setting. This report describes the case of a patient affected by end-stage renal failure and HBeAg-positive chronic HBV virus infection treated very early during the immune clearance phase of HBV infection with an adjusted-dose of nucleoside analogue entecavir. The patient achieved a very rapid HBV-DNA undetectability, anti-HBe, and anti-HBs seroconversion. This is the first report of antiviral therapy with entecavir started during the immune reactive phase of HBV infection in a patient on hemodialysis and it suggests that antiviral treatment can enhance the effects of host immune activation resulting in biochemical, serological, and viral response, even in end-stage renal failure patients with partial immunodeficiency. Antiviral therapy with entecavir in the setting of hemodialysis was safe and well tolerated.

  13. A community-based survey of human toxoplasmosis in rural Amazonia: seroprevalence, seroconversion rate, and associated risk factors.

    Science.gov (United States)

    Ferreira, Marcelo U; Hiramoto, Roberto M; Aureliano, Débora P; da Silva-Nunes, Mônica; da Silva, Natal S; Malafronte, Rosely S; Muniz, Pascoal T

    2009-07-01

    IgG antibodies to Toxoplasma gondii were detected in, March-April 2004, in 65.8% (95% confidence interval, 60.8-70.8%) of 342 systematically sampled subjects 5-90 years of age (87.5% of the eligible) living in a rural settlement in Amazonia, with a seroconversion rate of 9% over 1 year of follow-up of 99 seronegative subjects. Multiple logistic regression analysis identified age as the only significant independent predictor of seropositivity at the baseline. Each additional year of age increases the odds of being seropositive by 6%, and 76.8% of the subjects are expected to be seropositive at 30 years of age. A single high-prevalence spatial cluster, comprising 11.9% of the seropositive subjects, was detected in the area; households in the cluster were less likely to have dogs as pets and their heads had a lower education level, when compared with households located outside the cluster. The challenges for preventing human toxoplasmosis in tropical rural settings are discussed.

  14. The study on the relativity among HBeAg, HBV-DNA and PreS1-antigen%乙型肝炎血清前S1抗原与HBV-DNA和HBeAg相关性分析

    Institute of Scientific and Technical Information of China (English)

    邓芝云; 董菊子; 朱发仁; 张方信

    2011-01-01

    Objective To study the clinical application value of Presl-antigen. Methods The HBV markers and Presl-antigen were detected by enzyme linked immunosorbent assay ( ELISA) and the HBV-DNA was detected by fluorescent quantitation poly-merase chain reaction (FQ-PCR) in 365 patients with hepatitis B. Results The positive rates of the HBV-DNA and Presl were 86.4% and 89.1% in 110 patients of HBsAg+ , HBeAg+ and HBcAb + ; 36.4% and 40.9% in 66 patients of HBsAg+ ,HBeAb + and HBcAb + ;32.4% and 41.7% in 37 patients of HBsAg + and HBcAb + ;15.4% and 15.4% in 39 patients of HeAg + and HBcAb + ;5.3% and 8.0% in 113 patients of HBsAb +. The positive rates of HBeAg and PreSlAg increased with increasing HBV-DNA, PreS1 Ag was increased significantly compared with HBeAg ( P < 0.05 ). Conclusion Presl and HBV-DNA are the sensitive index for HBV replication, though PreSlAg and HBeAg Presl increased with increasing HBV-DNA, PreSlAg is more sensitive than HBeAg, and it is valuable in clinical application.%目的 探讨乙型肝炎血清前S1抗原(PreS1Ag)临床应用的价值.方法 对365例乙型肝炎患者血清,采用酶联免疫吸附试验(ELISA)检测HBV血清标志物和PreS1 Ag,用荧光定量聚合酶链反应(FQ-PCR)方法 检测HBV-DNA.结果 HBV-DNA和PreS1Ag的阳性率在110例HBV大三阳中,分别为86.4%和89.1%;在66例HBV小三阳中,分别为36.4%和40.9%;在37例HBsAg、HBcAb中,分别为32.4%和41.7%;在39例HBeAg、HBcAb阳性中,分别为15.4%和15.4%;在113例HBsAb阳性中,分别为5.3%和8.0%.HBeAg、PreS1Ag阳性率随不同载量HBV-DNA升高而增高,但PreS1Ag比HBeAg增高更明显(P<0.05).结论 PreS1 Ag和HBV-DNA一样都是乙型肝炎病毒复制的敏感指标,虽然PreS1Ag和HBeAg都随HBV-DNA载量增加而升高,但PreS1Ag较HBeAg更能敏感,因此PreS1 Ag具有重要的临床应用价值.

  15. Delayed childbearing.

    Science.gov (United States)

    Francis, H H

    1985-06-01

    In many Western nations, including England and Wales, Sweden, and the US, there is a current trend towards delayed childbearing because of women's pursuit of a career, later marriage, a longer interval between marriage and the 1st birth, and the increasing number of divorcees having children in a 2nd marriage. Wives of men in social classes I and II in England and Wales are, on average, having their 1st child at 27.9 years, 1.6 years later than in 1973, and in social classes IV and V, 1.0 years later than in 1973, at a mean age of 23.7 years. Consequently, the total period fertility rate for British women aged 30-34 years, 35-39 years, and 40 and over increased by 4%, 2%, and 4%, respectively, between 1982-83, in contrast to reductions of 2% and 3%, respectively, in the 15-19 year and 20-24 year age groups, with the 25-29-year-olds remaining static. The average maternal mortality for all parties in England and Wales during 1976-78 was 106/million for adolescents, 70.4/million for 20-24 year-olds, and 1162/million for those aged 40 years and older. The specific obstetric and allied conditions which increase with age are the hypertensive diseases of pregnancy, hemorrhage, pulmonary embolism, abortion, cardiac disease, caesarean section, ruptured uterus, and amniotic fluid embolism. The Swedish Medical Birth Registry of all live births and perinatal deaths since 1973 has shown that the risk of late fetal death is significantly greater in women aged 30-39 years than in those of the same parity and gravidity aged 20-24 years. The risk of giving birth to low birth weight babies preterm and at term and of premature labor are similarly increased. The early neonatal death rate also was increased for primigravidas and nulliparas in the 30-39 year age group but not in parous women. This is, in part, due to the rise in incidence of fetal abnormalities with advancing maternal age because of chromosomal and nonchromosomal anomalies. These also appear to be the cause of the

  16. HBeAg阴性乙型肝炎患者HBV-LP及HBV-DNA检测分析%Detection of serum HBV-LP and HBV-DNA in hepatitis B patients of negative HBeAg

    Institute of Scientific and Technical Information of China (English)

    刘鸿生; 胡志刚; 俞蕾; 周颖

    2012-01-01

    目的 分析HBeAg阴性的乙型肝炎患者血清HBV-LP及HBV-DNA检测的价值.方法 收集64份HBeAg阴性的乙型肝炎患者血清标本,分别采用实时荧光定量PCR检测HBV-DNA、ELISA法检测HBV-LP.结果 64例HBeAg阴性的乙型肝炎患者血清中,HBV-DNA阳性36例,总检出率为56.3%;HBV-LP阳性44例,总检出率为68.8%;HBV-DNA与PreS1抗原具有较好的相关性,HBeAg阴性的乙型肝炎患者血清HBV-DNA、HBV-LP阳性率差异无统计学意义,HBV-DNA复制拷贝数为<103、103-5、106-7、>107拷贝/ml,HBV-LP 检出率分别为60.7%、82.6%、60.0%、66.7%.结论 HBeAg阴性的乙型肝炎患者血清中HBV-LP检测可以作为HBV-DNA检测的有效补充.%OBJECTIVE To analyze the clinical significance of detection of serum HBV-LP and HBV-DNA in patients with hepatitis B whose HBeAg were negative. METHODS A total of 64 serum specimens of hepatitis B patients with negative HBeAg were collected. HBV-DNA was detected using the real-time fluorescent quantitative PCR and HBV-LP was measured by ELISA. RESULTS Of the 64 serum specimens, 36 were positive for HBV-DNA and 44 were positive for HBV-LP with the detection rates of 56. 3% and 68. 8%, respectively. It showed that HBV-LP and HBV-DNA were related but there was no significant difference between their own positivity. The HBV-DNA copies being 107 copy/ml, the detection rates of HBV-LP were 60. 7%,82. 5%,60. 0% and 66. 7%, respectively. CONCLUSION Detection of HBV-LP can serve as an effective complement to the measurement of HBV-DNA in patients with Hepatitis B whose HBeAg were negative.

  17. D-Dimer Levels before HIV Seroconversion Remain Elevated Even after Viral Suppression and Are Associated with an Increased Risk of Non-AIDS Events.

    Science.gov (United States)

    Freiberg, Matthew S; Bebu, Ionut; Tracy, Russell; So-Armah, Kaku; Okulicz, Jason; Ganesan, Anuradha; Armstrong, Adam; O'Bryan, Thomas; Rimland, David; Justice, Amy C; Agan, Brian K

    2016-01-01

    The mechanism underlying the excess risk of non-AIDS diseases among HIV infected people is unclear. HIV associated inflammation/hypercoagulability likely plays a role. While antiretroviral therapy (ART) may return this process to pre-HIV levels, this has not been directly demonstrated. We analyzed data/specimens on 249 HIV+ participants from the US Military HIV Natural History Study, a prospective, multicenter observational cohort of >5600 active duty military personnel and beneficiaries living with HIV. We used stored blood specimens to measure D-dimer and Interleukin-6 (IL-6) at three time points: pre-HIV seroconversion, ≥6 months post-HIV seroconversion but prior to ART initiation, and ≥6 months post-ART with documented HIV viral suppression on two successive evaluations. We evaluated the changes in biomarker levels between time points, and the association between these biomarker changes and future non-AIDS events. During a median follow-up of 3.7 years, there were 28 incident non-AIDS diseases. At ART initiation, the median CD4 count was 361cells/mm3; median duration of documented HIV infection 392 days; median time on ART was 354 days. Adjusted mean percent increase in D-dimer levels from pre-seroconversion to post-ART was 75.1% (95% confidence interval 24.6-148.0, p = 0.002). This increase in D-dimer was associated with a significant 22% increase risk of future non-AIDS events (p = 0.03). Changes in IL-6 levels across time points were small and not associated with future non-AIDS events. In conclusion, ART initiation and HIV viral suppression does not eliminate HIV associated elevation in D-dimer levels. This residual pathology is associated with an increased risk of future non-AIDS diseases.

  18. Seroprevalence and sero-conversion after vaccination against Peste des Petits Ruminants in sheep and goats from Awash Fentale District, Afar, Ethiopia.

    Science.gov (United States)

    Faris, D; Yilkal, A; Berhe, G; Kelay, B

    2012-02-01

    A cross-sectional epidemiological study followed by vaccination and postvaccinal serum antibody assessment against Peste des Petits Ruminants (PPR) in small ruminant population of Awash Fentale District, Afar, Ethiopia, was conducted from September 2006 to June 2007 with the aim of investigating seroprevalence and post-vaccination sero-conversion rate. A total of 1239 sera collected from sheep and goats which were not vaccinated, were screened by using nucleoprotein-based competitive enzyme-linked immunosorbent assay (c-ELISA). Only 21 (1.70%) animals were found to be positive. Following the base-line seroprevalence study, small ruminants in the area were vaccinated using the attenuated homologous PPR virus (Nigeria 75/1) strain vaccine, produced at National Veterinary Institute (NVI) in Debre-Zeit, Ethiopia. A total of 1096 small ruminants were resampled from the vaccinated population fourteen days after vaccination. The postvaccination sero-conversion rate in the population was found to be 61.13%, indicating a relatively weak herd immunity. The main reason for the low sero-conversion could be the thermolabile nature of the vaccine, since no statistically significant difference was observed between small ruminants vaccinated by Veterinary Professionals and Community Animal Health Workers (CAHWs), using Chi-squared test at 95% CI (P>0.05). This signifies the need for thermostable vaccine that could potentially increase the herd immunity in addition to that being administered by CAHWs independently. The current finding indicated that CAHWs could participate in vaccination campaigns in such areas as Afar, where there are few veterinarians despite of the huge livestock populations, as means of pastoralists' livelihood. Copyright © 2011 Elsevier B.V. All rights reserved.

  19. Intra-unit correlations in seroconversion to Actinobacillus pleuropneumoniae and Mycoplasma hyopneumoniae at different levels in Danish multi-site pig production facilities

    DEFF Research Database (Denmark)

    Vigre, Håkan; Dohoo, I.R.; Stryhn, H.;

    2004-01-01

    2) and Mycoplasma hyopneumoniae (Mh). Based on the estimated variances, three newly described computational methods (model linearisation, simulation and linear modelling) and the standard method (latent-variable approach) were used to estimate the correlations (intra-class correlation components......, ICCs) between pigs in the same production unit regarding seroconversion. Substantially different values of ICCs were obtained from the four methods. However, ICCs obtained by the simulation and the model linearisation were quite consistent. Data used for estimation were collected from 1161 pigs from...

  20. Critical peripheral ischemia precipitated by severe episode of Raynaud's phenomenon in a patient with aPL-positive systemic lupus erythematosus, upon high titer anti-RNP seroconversion.

    Science.gov (United States)

    Levy, O; Maslakov, I; Vosco, S; Markov, A; Amit-Vazina, M; Tishler, M

    2015-03-01

    A 35-year-old female with long standing aPL-positive lupus without history of thromboembolic events, who has developed critical peripheral ischemia (CPI) is described. An episode of severe Raynaud's phenomenon rapidly progressed to an extensive digit-threatening ischemia, involving bilateral hands and feet. She was successfully treated with corticosteroids, anticoagulation, iloprost, sildenafil, and nifedipine. Her serological studies were remarkable for the emergence of high titer anti-RNP seroconversion and an increase in aPL titer, suggesting that these autoantibodies played a role in the pathogenesis of CPI. It is important to note that such observation should herald this potentially devastating complication of systemic lupus erythematosus.

  1. 40岁以上HBeAg阳性和阴性慢性乙型肝炎病毒感染者的临床特点比较%Clinical differences between HBeAg - positive and - negative chronic hepatitis B patients over 40 - years - old

    Institute of Scientific and Technical Information of China (English)

    李春霞; 徐光华; 潘怀强; 刘娜

    2012-01-01

    Objective To determine the differential clinical characteristics between hepatitis B e antigen (HBeAg) - positive and - negative patients with chronic hepatitis B virus (HBV) infection who are over 40 - years - old. Methods A total of 186 patients with chronic HBV and over 40 - years - old were analyzed, including 93 HBeAg - positive patients and 93 HBeAg - negative patients. Results In the HBeAg - positive group, 76.34% were male and 78.49% had a family history of HBV infection. The HBeAg - positive group had higher levels of HBV DNA and ALT, and a higher proportion of cirrhosis cases, than the HBeAg - negative group. Ascites were detected in patients from both groups diagnosed with decompensated cirrhosis. Upper gastrointestinal bleeding was more frequent in the HBeAg - negative group. Conclusion In our study of chronic HBV patients over 40 - years - old, HBeAg - positivity was more frequent in males with a family history of HBV. HBeAg - negativity was more frequently associated with liver cirrhosis. It is possible that progression of chronic HBV may be related to high levels of HBV DNA and persistent liver inflammation;%目的 探讨40岁以上HBeAg阳性和HBeAg阴性慢性HBV感染者的临床特点.方法 收集40岁以上慢性HBV感染者共186例,其中HBeAg阳性组93例,HBeAg阴性组93例.结果 40岁以上HBeAg阳性慢性HBV感染者男性为多(76.34%),并且多有乙型肝炎家族聚集现象( 78.49%);40岁以上HBeAg阳性慢性HBV感染者的HBV DNA水平与ALT水平均高于HBeAg阴性慢性HBV感染者;40岁以上乙型肝炎肝硬化患者中,HBeAg阳性者占少数;40岁以上乙型肝炎肝硬化失代偿期患者中,HBeAg阳性者多合并腹水形成,而HBeAg阴性者既可见腹水形成,又可见上消化道出血.结论 40岁以上HBeAg阳性慢性HBV感染者多见于男性,多具有家族聚集现象,HBeAg阳性肝硬化患者所占比率较低,但HBV DNA水平较高,肝脏的炎症活动明显,病情进展可能较快.

  2. The Right Delay

    NARCIS (Netherlands)

    Datadien, A.H.R.; Haselager, W.F.G.; Sprinkhuizen-Kuyper, I.G.

    2011-01-01

    Axonal conduction delays should not be ignored in simulations of spiking neural networks. Here it is shown that by using axonal conduction delays, neurons can display sensitivity to a specific spatio-temporal spike pattern. By using delays that complement the firing times in a pattern, spikes can ar

  3. Preliminary results of sero-conversion of kids and lambs vaccinated with Brucella melitensis rev -1 strain. Current achievements and feature challenges on brucellosis

    Directory of Open Access Journals (Sweden)

    XHELIL KOLECI

    2014-06-01

    Full Text Available Sheep and goat brucellosis is an endemic and most important infectious disease of livestock in Albania. It continues to remain a frequent zoonotic disease and an important public health issue. Among available strategies, mass vaccination is an acceptable, cost effective approach, and is a widely used strategy in many countries including some neighbouring Balkan countries. Albanian veterinary services supported by the European Union-funded PAZA project (Protection Against Zoonotic diseases, Albania applied two successive annual mass vaccination campaigns that aimed to vaccinate all small ruminants in the country. These two campaigns aimed at significantly reducing disease spread, however, a small number of infection foci could remain and persist in some parts of country. Post-vaccination surveillance is essential for early detection and proper control of cases of brucellosis that might re-emerge. Limitation major complication arising from mass vaccination is the difficulty of interpretation of the results of serological tests conducted to diagnose the disease. The aim of this study was to evaluate the proportion of vaccinated animals that showed sero-conversion and the duration of detectable levels of agglutinins (antibody against brucellosis in vaccinated animals. Methods. In total, 69 individual animals, 23 lambs and 46 kids aged from 4 to 7 months, were sampled at monthly intervals. Jugular blood was collected before vaccination and at intervals thereafter and tested by means of the Rose Bengal test. All animals were serologically negative before vaccination with modified live Brucella melitensis Rev.1 strain vaccine. Rose Bengal test was performed before vaccination, 18 days, 2, 3 and 4 months after vaccination. Results. Eighteen days after vaccination, 63 out of 69 animals (91.3% 82.6% of lambs (19 out of 23 lambs and 95.6% of goat kids (44 out of 46 showed strong sero-conversion in Rose Bengal test. The proportion of positive vaccinated

  4. An Analytical Delay Model

    Institute of Scientific and Technical Information of China (English)

    MIN Yinghua; LI Zhongcheng

    1999-01-01

    Delay consideration has been a majorissue in design and test of high performance digital circuits. Theassumption of input signal change occurring only when all internal nodesare stable restricts the increase of clock frequency. It is no longertrue for wave pipelining circuits. However, previous logical delaymodels are based on the assumption. In addition, the stable time of arobust delay test generally depends on the longest sensitizable pathdelay. Thus, a new delay model is desirable. This paper explores thenecessity first. Then, Boolean process to analytically describe thelogical and timing behavior of a digital circuit is reviewed. Theconcept of sensitization is redefined precisely in this paper. Based onthe new concept of sensitization, an analytical delay model isintroduced. As a result, many untestable delay faults under thelogical delay model can be tested if the output waveforms can be sampledat more time points. The longest sensitizable path length is computedfor circuit design and delay test.

  5. HIV testing of male partners of pregnant women in Porto Alegre, Brazil: a potential strategy for reduction of HIV seroconversion during pregnancy.

    Science.gov (United States)

    Yeganeh, Nava; Simon, Mariana; Dillavou, Claire; Varella, Ivana; Santos, Breno Riegel; Melo, Marineide; Fonseca, Rosana; Lira, Rita; Gorbach, Pamina; Nielsen-Saines, Karin

    2014-01-01

    Pregnant women have a significantly higher risk of HIV acquisition during gestation than their non-pregnant counterparts due to behavioral and biological factors. Acute seroconversion during gestation results in increased HIV mother-to-child transmission rates and has been identified as a major public health challenge. In order to address potential HIV seroconversion in our pregnant patients, we conducted a prospective cohort study to evaluate the acceptability of offering HIV testing to sexual partners of HIV-negative pregnant women receiving antenatal care at two hospitals in Porto Alegre, Brazil. Over a 14-month study period, HIV-negative pregnant women at two hospital-based clinic sites were encouraged to bring their stable sexual partner for HIV voluntary counseling and testing during prenatal care. Women were re-interviewed following delivery to measure success of the intervention. Of the 1223 HIV-negative pregnant women enrolled in the study, 663 (54%) of their male sexual partners received HIV testing during antenatal care and 4 (0.6%) were diagnosed with HIV infection. A total of 645 women were interviewed at the time of delivery, with 620 (97%) confirming that HIV testing was suggested to their partner. The most common reason provided by women as to why partners did not come for testing was work (69%) and lack of perceived risk (14%). Independent predictors of successful partner testing included being white (odds ratio [OR] 1.59, 95% confidence interval [CI] 1.18-2.12), married (OR 1.78, 95% CI 1.08-2.94), having an older age of sexual debut (OR 0.94, 95% CI 0.9-0.98), and being recruited at Hospital Conceiçao (OR 2.1, 95% CI 1.52-2.88). We conclude that HIV partner testing during prenatal care is acceptable, rendering this intervention attractive to public health programs targeting prevention of sexually transmitted infections.

  6. Adherence to chemoprophylaxis and Plasmodium falciparum anti-circumsporozoite seroconversion in a prospective cohort study of Dutch short-term travelers.

    Directory of Open Access Journals (Sweden)

    Sanne-Meike Belderok

    Full Text Available BACKGROUND: We conducted a prospective study in a cohort of short-term travelers assessing the incidence rate of anti-circumsporozoite seroconversion, adherence to chemoprophylaxis, symptoms of malaria during travel, and malaria treatment abroad. METHODS: Adults were recruited from the travel clinic of the Public Health Service Amsterdam. They kept a structured daily travel diary and donated blood samples before and after travel. Blood samples were serologically tested for the presence of Plasmodium falciparum anti-circumsporozoite antibodies. RESULTS: Overall, the incidence rate (IR of anti-circumsporozoite seroconversion was 0.8 per 100 person-months. Of 945 travelers, 620 (66% visited high-endemic areas and were advised about both chemoprophylaxis and preventive measures against mosquito bites. Most subjects (520/620 = 84% took at least 75% of recommended prophylaxis during travel. Travel to Africa, use of mefloquine, travel duration of 14-29 days in endemic areas, and concurrent use of DEET (N,N-diethyl-meta-toluamide were associated with good adherence practices. Four travelers without fever seroconverted, becoming anti-circumsporozoite antibody-positive. All four had been adherent to chemoprophylaxis; two visited Africa, one Suriname, one India. Ten subjects with fever were tested for malaria while abroad and of these, three received treatment. All three were adherent to chemoprophylaxis and tested negative for anti-circumsporozoite antibodies. CONCLUSION: Travel to Africa, using mefloquine, travel duration of 14-29 days in endemic areas, and use of DEET were associated with good adherence to chemoprophylaxis. The combination of chemoprophylaxis and other preventive measures were sufficient to protect seroconverting travelers from clinical malaria. Travelers who were treated for malaria abroad did not seroconvert.

  7. Estimation of the time of seroconversion to the New Jersey serotype of vesicular stomatitis virus in sentinel cattle of dairy herds located at high and low elevations in southern Mexico

    Science.gov (United States)

    To estimate time to seroconversion to vesicular stomatitis 1 New Jersey virus (VSNJV) in sentinel cattle in southern Mexico, ninety-two sentinel cattle in four free-ranging dairy herds at high- (=500 mts) and low-elevation (<500 mts) locations in southern Mexico were studied. A prospective cohort s...

  8. Delayed emergence after anesthesia.

    Science.gov (United States)

    Tzabazis, Alexander; Miller, Christopher; Dobrow, Marc F; Zheng, Karl; Brock-Utne, John G

    2015-06-01

    In most instances, delayed emergence from anesthesia is attributed to residual anesthetic or analgesic medications. However, delayed emergence can be secondary to unusual causes and present diagnostic dilemmas. Data from clinical studies is scarce and most available published material is comprised of case reports. In this review, we summarize and discuss less common and difficult to diagnose reasons for delayed emergence and present cases from our own experience or reference published case reports/case series. The goal is to draw attention to less common reasons for delayed emergence, identify patient populations that are potentially at risk and to help anesthesiologists identifying a possible cause why their patient is slow to wake up.

  9. American Dream Delayed

    DEFF Research Database (Denmark)

    Khorunzhina, Natalia; Miller, Robert A.

    This paper investigates the delay in homeownership and a subsequent reduction in homeownership rate observed over the past decades. We focus on the delay in giving birth to children and increased labor market participation as contributing factors to homeownership dynamics for prime-age female hou...

  10. Production of outer surface protein A by Borrelia burgdorferi during transmission from infected mammals to feeding ticks is insufficient to trigger OspA seroconversion.

    Science.gov (United States)

    Woodman, Michael E; Cooley, Anne E; Stevenson, Brian

    2008-11-01

    The Lyme disease spirochete, Borrelia burgdorferi, produces two outer surface lipoproteins, OspA and OspB, that are essential for colonization of tick vectors. Both proteins are highly expressed during transmission from infected mammals to feeding ticks and during colonization of tick midguts, but are repressed when bacteria are transmitted from ticks to mammals. Humans and other infected mammals generally do not produce antibodies against either protein, although some Lyme disease patients do seroconvert and produce antibodies against OspA for unknown reasons. We hypothesized that, if such patients had been fed upon by additional ticks, bacteria moving from the patients' bodies to the feeding ticks would have produced OspA and OspB proteins, which then led to immune system recognition and antibody production. This hypothesis was tested by analyzing immune responses of infected mice following feedings by additional Ixodes scapularis ticks. However, results of the present studies demonstrate that expression of OspA and OspB by B. burgdorferi during transmission from infected mammals to feeding ticks does not trigger seroconversion.

  11. Characteristics of seroconversion and implications for diagnosis of post-treatment Lyme disease syndrome: acute and convalescent serology among a prospective cohort of early Lyme disease patients.

    Science.gov (United States)

    Rebman, Alison W; Crowder, Lauren A; Kirkpatrick, Allison; Aucott, John N

    2015-03-01

    Two-tier serology is often used to confirm a diagnosis of Lyme disease. One hundred and four patients with physician diagnosed erythema migrans rashes had blood samples taken before and after 3 weeks of doxycycline treatment for early Lyme disease. Acute and convalescent serologies for Borrelia burgdorferi were interpreted according to the 2-tier antibody testing criteria proposed by the Centers for Disease Control and Prevention. Serostatus was compared across several clinical and demographic variables both pre- and post-treatment. Forty-one patients (39.4%) were seronegative both before and after treatment. The majority of seropositive individuals on both acute and convalescent serology had a positive IgM western blot and a negative IgG western blot. IgG seroconversion on western blot was infrequent. Among the baseline variables included in the analysis, disseminated lesions (p Lyme disease. Furthermore, these findings underline the difficulty for rheumatologists in identifying a prior exposure to Lyme disease in caring for patients with medically unexplained symptoms or fibromyalgia-like syndromes.

  12. commensurate point delays

    Directory of Open Access Journals (Sweden)

    M. de la Sen

    2005-01-01

    nominal controller is maintained. In the current approach, the finite spectrum assignment is only considered as a particular case of the designer's choice of a (delay-dependent arbitrary spectrum assignment objective.

  13. Time Delay Cosmography

    OpenAIRE

    Treu, Tommaso; Marshall, Philip J.

    2016-01-01

    Gravitational time delays, observed in strong lens systems where the variable background source is multiply-imaged by a massive galaxy in the foreground, provide direct measurements of cosmological distance that are very complementary to other cosmographic probes. The success of the technique depends on the availability and size of a suitable sample of lensed quasars or supernovae, precise measurements of the time delays, accurate modeling of the gravitational potential of the main deflector,...

  14. Imputación del instante de seroconversión al VIH en cohortes de hemofílicos Imputation of the date of HIV seroconversion in cohorts of haemophiliacs

    Directory of Open Access Journals (Sweden)

    S. Pérez-Hoyos

    2003-12-01

    de seroconversión frente al VIH que puede ser utilizada para estimar el tiempo libre de sida y la supervivencia en una cohorte de hemofílicos para los que se desconoce la fecha de seroconversiónObjectives: To describe the methods used to impute HIV seroconversion date in the haemophiliac cohorts from GEMES project and to validate its use. Method: 632 haemophiliacs coming from three hemophilia units identified as HIV+ and 1.092 individuals coming from 5 project GEMES cohorts with a seroconversion window (time among test HIV- and HIV+ less than 3 years where mid point (PM was assumed as seroconversion date. For both groups, seroconversion date was imputed after estimating the probability distribution of seroconversion by means of the EM algorithm. Two imputation methods are used: one obtained from the expected value and the other from the geometric mean of 5 random samples. from the estimated distribution. Imputations have been validated in the non haemophiliacs cohorts comparing with the PM seroconversion date. Also AIDS free time and survival from the different seroconversion imputed dates were compared. Results: Median seroconversion date is located in May of 1993 for the non haemophiliacs and in 1982 for the haemophiliacs. Not big differences are observed among the imputed seroconversion dates and the mid-point seroconversion date in the non-haemophiliac cohorts. Similar results are found for the haemophiliac cohorts. Also no differences are observed in the estimated AIDS-free time for both groups of cohorts. Conclusions: Geometric mean imputation from several random samples provides a good estimate of the HIV seroconversion date that can be used to estimate AIDS-free time and survival in haemophiliac cohorts where seroconversion date is ignored.

  15. Hepatitis B virus genotype distribution and genotype-specific BCP/preCore substitutions in acute and chronic infections in Argentina.

    Directory of Open Access Journals (Sweden)

    María Mora González López Ledesma

    Full Text Available In order to assess Hepatitis B Virus genotype (g and subgenotype (sg implications in the course of infection, 234 HBsAg positive patients in different infection stages were characterized (66 acute infections, 63 HBeAg positive chronic infections and 105 anti-HBe positive chronic infections.Overall, sgA2 (17.9%, gD (20.9%, sgF1b (34.2% and sgF4 (19.7% were the most prevalent. Subgenotype F1b was overrepresented in acute and chronic HBeAg infections (56.1%, whereas gD was the most frequent (40.0% in anti-HBe positive chronic infections. Among chronic infections, HBeAg positivity rates were 50.0, 12.5, 62.8 and 35.3% for sgA2, gD, sgF1b and sgF4, respectively (p <0.05. A bias toward BCP/preCore mutations was observed among genotypes. In anti-HBe positive chronic infections, sgF1b was more prone to have A1762T/G1764A mutation than sgA2, sgF4 and gD (75.0, 40.0, 33.3 and 31.8%, p<0.005, whereas in the pC region, gD and sgF4 were more likely to have G1896A than sgA2 and sgF1b (81.0, 72.7, 0.0 and 31.3%, p <0.001. The unexpected low frequency of the G1896A mutation in the sgF1b (despite carrying 1858T prompted us to perform a further analysis in order to identify genotype-specific features that could justify the pattern mutations observed. A region encompassing nucleotides 1720 to 1920 showed the higher dissimilarity between sgF1b and sgF4. Genotypes and subgenotypes carrying the 1727G, 1740C and 1773T polymorphisms were prevented to mutate position 1896.HBeAg seroconversion is a critical event in the natural history of HBV infection. Differences in the HBeAg positivity rate might be relevant since different studies have observed that delayed HBeAg seroconversion is associated with a more severe clinical course of infection, highlighting the critical role that genotypes/subgenotypes might play in the progression of HBV infection. Polymorphisms in the regions 1720 to 1920 could be involved in the molecular mechanisms underlying seroconversion of each

  16. HBeAg negative serological status and low viral replication levels characterize chronic hepatitis B virus-infected women at reproductive age in Greece: A one-year prospective single center study

    Institute of Scientific and Technical Information of China (English)

    Ioannis S. Elefsiniotis; Irene Glynou; Ioanna Magaziotou; Konstantinos D. Pantazis; Nikolaos V. Fotos; Hero Brokalaki; Helen Kada; George Saroglou

    2005-01-01

    AIM: To evaluate the seroprevalence of hepatitis B surface antigen (HBsAg) in 13 581 women at reproductive age and the hepatitis B e antigen (HBeAg)/anti-HBe status as well as serum hepatitis B virus (HBV)-DNA levels in a subgroup of HBsAg(+) pregnant women at labor in Greece.METHODS: Serological markers were detected using enzyme immunoassays. Serum HBV-DNA was determined by a sensitive quantitative PCR assay. Statistical analysis of data was based on parametric methodology.RESULTS: Overall, 1.156% of women were HBsAg(+)and the majority of them (71.3%) were Albanian. The prevalence of HBsAg was 5.1% in Albanian women, 4.2%in Asian women and 1.14% in women from Eastem European countries. The prevalence of HBsAg in African (0.36%) and Greek women (0.29%) was very low. Only 4.45% of HBsAg (+) women were also HBeAg(+) whereas the vast majority of them were HBeAg(-)/anti-HBe(+). Undetectable levels of viremia (<200 copies/mL) were observed in 32.26% of pregnant women at labor and 29.03% exhibited extremely low levels of viral replication (<400 copies/mL). Only two pregnant women exhibited extremely high serum HBVDNA levels (>10 000 000 copies/mL), whereas 32.26%exhibited HBV-DNA levels between 1 500 and 40 000copies/mL.CONCLUSION: The overall prevalence of HBsAg is relatively low among women at reproductive age in Greece but is higher enough among specific populations. The HBeAg(-)/anti-HBe(+) serological status and the extremely low or even undetectable viral replicative status in the majority of HBsAg(+) women of our study population, suggest that only a small proportion of HBsAg(+) women in Greece exhibit a high risk for vertical transmission of the infection.

  17. Time Delay Cosmography

    CERN Document Server

    Treu, Tommaso

    2016-01-01

    Gravitational time delays, observed in strong lens systems where the variable background source is multiply-imaged by a massive galaxy in the foreground, provide direct measurements of cosmological distance that are very complementary to other cosmographic probes. The success of the technique depends on the availability and size of a suitable sample of lensed quasars or supernovae, precise measurements of the time delays, accurate modeling of the gravitational potential of the main deflector, and our ability to characterize the distribution of mass along the line of sight to the source. We review the progress made during the last 15 years, during which the first competitive cosmological inferences with time delays were made, and look ahead to the potential of significantly larger lens samples in the near future.

  18. Prediction of delayed subsidence

    Science.gov (United States)

    Burns, K.

    A predictive model of delayed subsidence is discussed. A numerical implementation is tested on one of the best-described study areas, Allegheny County in Pennsylvania. In planning insurance of restitution measures, a predictive model is of value in estimating the magnitude of the problem and the size of long-term budgetary commitments. Contrary to active subsidence, which occurs concurrently with mining operations, or is completed within a few days following coal extraction, delayed subsidence may take many years to appear at the surface after coal mines are abandoned. There are two principal morphological types of delayed subsidence: troughs, which are shallow depressions, and sinks, which are steep-sided crown pits. Both types are damaging to surface structures, and a variety of methods were introduced to deal with the problem, ranging from subsidence insurance to site restitution.

  19. Time delay cosmography

    Science.gov (United States)

    Treu, Tommaso; Marshall, Philip J.

    2016-07-01

    Gravitational time delays, observed in strong lens systems where the variable background source is multiply imaged by a massive galaxy in the foreground, provide direct measurements of cosmological distance that are very complementary to other cosmographic probes. The success of the technique depends on the availability and size of a suitable sample of lensed quasars or supernovae, precise measurements of the time delays, accurate modeling of the gravitational potential of the main deflector, and our ability to characterize the distribution of mass along the line of sight to the source. We review the progress made during the last 15 years, during which the first competitive cosmological inferences with time delays were made, and look ahead to the potential of significantly larger lens samples in the near future.

  20. Establishment of the serologic testing algorithm for recent human immunodeficiency virus (HIV seroconversion (STARHS strategy in the city of São Paulo, Brazil

    Directory of Open Access Journals (Sweden)

    Esper Georges Kallas

    2004-12-01

    Full Text Available Several strategies aim at characterizing the AIDS epidemic in different parts of the world. Among these, the identification of recent HIV-1 infections using the recently described serologic testing algorithm for recent human immunodeficiency virus (HIV seroconversion (STARHS strategy was employed in four testing sites of the City of São Paulo Public Health Department (CSPPHD. Those identified as recently infected were invited to participate in a prospective clinical and laboratory evaluation study. We describe the establishment of the patient identification network and the success in enrolling the participants, as well as their clinical and laboratory characteristics. From May to December 2002, 6,443 persons were tested for HIV in the four participating sites, of whom 384 (5.96% tested HIV-1 positive; 43 (11.2% of them were identified as recently infected. Twenty-two were successfully enrolled in the follow-up study, but three of them did not meet clinical and/or laboratory criteria for recent HIV-1 infection. After these exclusions, the laboratory findings revealed a median CD4+ T lymphocyte count of 585 cells/muL (inter-quartile range 25-75% [IQR], 372-754, a CD8+ T lymphocyte count of 886 cells/muL (IQR, 553-1098, a viral load of 11,000 HIV-RNA copies/mL (IQR, 3,650-78,150, log10 of 4.04 (IQR 3.56-4.88. The identification of recent HIV infections is an extremely valuable way to evaluate the spread of the virus in a given population, especially when cohort studies, considered the gold standard method to evaluate incidence, are not available. This work demonstrated that establishing a network to identify such patients is a feasible task, even considering the difficulties in a large, resource-limited country or city.

  1. Gender differences in progression to AIDS and death from HIV seroconversion in a cohort of injecting dug users from 1986 to 2001

    Science.gov (United States)

    de la Hera, M. G; Ferreros, I.; del Amo, J.; de Olalla, P. G.; Hoyos, S. P.; Muga, R.; del Romero, J.; Guerrero, R.; Hernandez-Aguado, I.; and, G

    2004-01-01

    Background: Although the consensus is that gender does not influence HIV progression, its relevance may depend on the setting. Aim: To study gender differences in HIV progression to AIDS and death from 1986 to 2001 in a cohort of injecting drug user (IDU) seroconverters in Spain. Methods: Risk of AIDS and death in persons infected for the same length of time were compared through Kaplan-Meier, allowing for late entry, and Cox regression adjusting for gender, age, and calendar period (before 1992, 1992–1995, 1996–1998, 1999–2001) fitted as time dependent covariates. Results: Of 929 IDU, 24.7% were women. Median seroconversion year was 1993.3 for men and women. 44% of women and 34% of men received antiretroviral therapy. Risk of AIDS was lower in women in univariate (hazard ratio (HR) 0.72; 95%CI:0.51 to 1.01) and multivariate analyses (HR 0.73 95%CI:0.52 to 1.03). A 46% reduction in risk of AIDS for period 1999–2001 compared with 1992–1995 was seen in both men and women (HR: 0.56 (95%CI:0.36 to 0.87). As for mortality, women's risk of death was lower univariately (HR 0.67 95%CI:0.45 to 0.99) although compared with 1992–95, men experienced a 34% reduction in mortality during 1999–2001 (HR 0.66 95%CI:0.40 to 1.01), which was not statistically significant in women. Conclusions: HIV progression was lower in female IDU before and after 1997 and their uptake of antiretroviral therapy was higher than male IDU. The inability to detect a reduction in mortality for women during 1999–2001 is probably attributable to lack of power. Differences in severity of addiction, drug using patterns, and competing causes of death may explain these findings. PMID:15483312

  2. Establishment of the serologic testing algorithm for recent human immunodeficiency virus (HIV seroconversion (STARHS strategy in the city of São Paulo, Brazil

    Directory of Open Access Journals (Sweden)

    Esper Georges Kallas

    Full Text Available Several strategies aim at characterizing the AIDS epidemic in different parts of the world. Among these, the identification of recent HIV-1 infections using the recently described serologic testing algorithm for recent human immunodeficiency virus (HIV seroconversion (STARHS strategy was employed in four testing sites of the City of São Paulo Public Health Department (CSPPHD. Those identified as recently infected were invited to participate in a prospective clinical and laboratory evaluation study. We describe the establishment of the patient identification network and the success in enrolling the participants, as well as their clinical and laboratory characteristics. From May to December 2002, 6,443 persons were tested for HIV in the four participating sites, of whom 384 (5.96% tested HIV-1 positive; 43 (11.2% of them were identified as recently infected. Twenty-two were successfully enrolled in the follow-up study, but three of them did not meet clinical and/or laboratory criteria for recent HIV-1 infection. After these exclusions, the laboratory findings revealed a median CD4+ T lymphocyte count of 585 cells/muL (inter-quartile range 25-75% [IQR], 372-754, a CD8+ T lymphocyte count of 886 cells/muL (IQR, 553-1098, a viral load of 11,000 HIV-RNA copies/mL (IQR, 3,650-78,150, log10 of 4.04 (IQR 3.56-4.88. The identification of recent HIV infections is an extremely valuable way to evaluate the spread of the virus in a given population, especially when cohort studies, considered the gold standard method to evaluate incidence, are not available. This work demonstrated that establishing a network to identify such patients is a feasible task, even considering the difficulties in a large, resource-limited country or city.

  3. Delayed Random Relays

    CERN Document Server

    Ohira, Toru

    2016-01-01

    We present here a system with collection of random walks relaying a signal in one dimension with a presence of a delay. We are interested in the time for a signal to travel from one end (start) to the other end (finish) of the lined group of random walkers. It is found that there is an optimal number of walkers for the signal to travel fastest if the delay is present. We discuss implications of this model and associated behaviors to physical and biological systems.

  4. Approximation of distributed delays

    CERN Document Server

    Lu, Hao; Eberard, Damien; Simon, Jean-Pierre

    2010-01-01

    We address in this paper the approximation problem of distributed delays. Such elements are convolution operators with kernel having bounded support, and appear in the control of time-delay systems. From the rich literature on this topic, we propose a general methodology to achieve such an approximation. For this, we enclose the approximation problem in the graph topology, and work with the norm defined over the convolution Banach algebra. The class of rational approximates is described, and a constructive approximation is proposed. Analysis in time and frequency domains is provided. This methodology is illustrated on the stabilization control problem, for which simulations results show the effectiveness of the proposed methodology.

  5. Delay Bounds for Multiclass FIFO

    OpenAIRE

    Jiang, Yuming; Misra, Vishal

    2016-01-01

    FIFO is perhaps the simplest scheduling discipline. For single-class FIFO, its delay guarantee performance has been extensively studied: The well-known results include a stochastic delay bound for $GI/GI/1$ by Kingman and a deterministic delay bound for $D/D/1$ by Cruz. However, for multiclass FIFO, few such results are available. To fill the gap, we prove delay bounds for multiclass FIFO in this work, considering both deterministic and stochastic cases. Specifically, delay bounds are present...

  6. Delayed breast implant reconstruction

    DEFF Research Database (Denmark)

    Hvilsom, Gitte B.; Hölmich, Lisbet R.; Steding-Jessen, Marianne;

    2012-01-01

    We evaluated the association between radiation therapy and severe capsular contracture or reoperation after 717 delayed breast implant reconstruction procedures (288 1- and 429 2-stage procedures) identified in the prospective database of the Danish Registry for Plastic Surgery of the Breast during...... reconstruction approaches other than implants should be seriously considered among women who have received radiation therapy....

  7. Delayed traumatic diaphragmatic hernia

    Science.gov (United States)

    Lu, Jing; Wang, Bo; Che, Xiangming; Li, Xuqi; Qiu, Guanglin; He, Shicai; Fan, Lin

    2016-01-01

    Abstract Background: Traumatic diaphragmatic hernias (TDHs) are sometimes difficult to identify at an early stage and can consequently result in diagnostic delays with life-threatening outcomes. It is the aim of this case study to highlight the difficulties encountered with the earlier detection of traumatic diaphragmatic hernias. Methods: Clinical data of patients who received treatment for delayed traumatic diaphragmatic hernias in registers of the First Affiliated Hospital of Xi’an Jiaotong University from 1998 to 2014 were analyzed retrospectively. Results: Six patients were included in this study. Left hemidiaphragm was affected in all of them. Most of the patients had a history of traffic accident and 1 a stab-penetrating injury. The interval from injury to developing symptoms ranged from 2 to 11 years (median 5 years). The hernial contents included the stomach, omentum, small intestine, and colon. Diaphragmatic injury was missed in all of them during the initial managements. All patients received operations once the diagnosis of delayed TDH was confirmed, and no postoperative mortality was detected. Conclusions: Delayed TDHs are not common, but can lead to serious consequences once occurred. Early detection of diaphragmatic injuries is crucial. Surgeons should maintain a high suspicion for injuries of the diaphragm in cases with abdominal or lower chest traumas, especially in the initial surgical explorations. We emphasize the need for radiographical follow-up to detect diaphragmatic injuries at an earlier stage. PMID:27512848

  8. 'No delays achiever'.

    Science.gov (United States)

    2007-05-01

    The latest version of the NHS Institute for Innovation and Improvement's 'no delays achiever', a web based tool created to help NHS organisations achieve the 18-week target for GP referrals to first treatment, is available at www.nodelaysachiever.nhs.uk.

  9. Permissible Delay in Payments

    Directory of Open Access Journals (Sweden)

    Yung-Fu Huang

    2007-01-01

    Full Text Available The main purpose of this paper wants to investigate the optimal retailer's lot-sizing policy with two warehouses under partially permissible delay in payments within the economic order quantity (EOQ framework. In this paper, we want to extend that fully permissible delay in payments to the supplier would offer the retailer partially permissible delay in payments. That is, the retailer must make a partial payment to the supplier when the order is received. Then the retailer must pay off the remaining balance at the end of the permissible delay period. In addition, we want to add the assumption that the retailer's storage space is limited. That is, the retailer will rent the warehouse to store these exceeding items when the order quantity is larger than retailer's storage space. Under these conditions, we model the retailer's inventory system as a cost minimization problem to determine the retailer's optimal cycle time and optimal order quantity. Three theorems are developed to efficiently determine the optimal replenishment policy for the retailer. Finally, numerical examples are given to illustrate these theorems and obtained a lot of managerial insights.

  10. Delayed fluorescence in photosynthesis.

    Science.gov (United States)

    Goltsev, Vasilij; Zaharieva, Ivelina; Chernev, Petko; Strasser, Reto J

    2009-01-01

    Photosynthesis is a very efficient photochemical process. Nevertheless, plants emit some of the absorbed energy as light quanta. This luminescence is emitted, predominantly, by excited chlorophyll a molecules in the light-harvesting antenna, associated with Photosystem II (PS II) reaction centers. The emission that occurs before the utilization of the excitation energy in the primary photochemical reaction is called prompt fluorescence. Light emission can also be observed from repopulated excited chlorophylls as a result of recombination of the charge pairs. In this case, some time-dependent redox reactions occur before the excitation of the chlorophyll. This delays the light emission and provides the name for this phenomenon-delayed fluorescence (DF), or delayed light emission (DLE). The DF intensity is a decreasing polyphasic function of the time after illumination, which reflects the kinetics of electron transport reactions both on the (electron) donor and the (electron) acceptor sides of PS II. Two main experimental approaches are used for DF measurements: (a) recording of the DF decay in the dark after a single turnover flash or after continuous light excitation and (b) recording of the DF intensity during light adaptation of the photosynthesizing samples (induction curves), following a period of darkness. In this paper we review historical data on DF research and recent advances in the understanding of the relation between the delayed fluorescence and specific reactions in PS II. An experimental method for simultaneous recording of the induction transients of prompt and delayed chlorophyll fluorescence and decay curves of DF in the millisecond time domain is discussed.

  11. Delay-independent stabilization for teleoperation with time varying delay

    OpenAIRE

    Fujita, Hiroyuki; Namerikawa, Toru

    2009-01-01

    This paper deals with the stability for nonlinear teleoperation with time varying communication delays. The proposed method is passivity-based controllers with time varying gains which depend on the rate of change of time varying delay. In our proposed method, stability condition is independent of the magnitude of the communication delay and the damping of the system. The delay-independent stability is shown via Lyapunov stability methods. Several experimental results show the effectiveness o...

  12. [Striated and delayed nephrography].

    Science.gov (United States)

    Marlois, O; Padovani, J; Faure, F; Devred, P; Grangier, M L; Panuel, M

    1985-10-01

    About a case of striated and delayed nephrogram seen on a diabetic child, authors come back to the different etiologies. Among them, the tubular precipitation of Tamm-Horsfall protein seems to be given like on the right possibilities. Whatever is its etiology, the mechanism of striated appearance is always the same, being founded on the radiated disposal of the collecting ducts and on a tubular stasis beeing with iodine concentration.

  13. Theoretical Delay Time Distributions

    CERN Document Server

    Nelemans, Gijs; Bours, Madelon

    2012-01-01

    We briefly discuss the method of population synthesis to calculate theoretical delay time distributions of type Ia supernova progenitors. We also compare the results of the different research groups and conclude that although one of the main differences in the results for single degenerate progenitors is the retention efficiency with which accreted hydrogen is added to the white dwarf core, this cannot explain all the differences.

  14. Theoretical Delay Time Distributions

    Science.gov (United States)

    Nelemans, Gijs; Toonen, Silvia; Bours, Madelon

    2013-01-01

    We briefly discuss the method of population synthesis to calculate theoretical delay time distributions of Type Ia supernova progenitors. We also compare the results of different research groups and conclude that, although one of the main differences in the results for single degenerate progenitors is the retention efficiency with which accreted hydrogen is added to the white dwarf core, this alone cannot explain all the differences.

  15. Geometric Time Delay Interferometry

    OpenAIRE

    Vallisneri, Michele

    2005-01-01

    The space-based gravitational-wave observatory LISA, a NASA-ESA mission to be launched after 2012, will achieve its optimal sensitivity using Time Delay Interferometry (TDI), a LISA-specific technique needed to cancel the otherwise overwhelming laser noise in the inter-spacecraft phase measurements. The TDI observables of the Michelson and Sagnac types have been interpreted physically as the virtual measurements of a synthesized interferometer. In this paper, I present Geometric TDI, a new an...

  16. Time-Delay Interferometry

    OpenAIRE

    Dhurandhar Sanjeev V.; Tinto Massimo

    2005-01-01

    Equal-arm interferometric detectors of gravitational radiation allow phase measurements many orders of magnitude below the intrinsic phase stability of the laser injecting light into their arms. This is because the noise in the laser light is common to both arms, experiencing exactly the same delay, and thus cancels when it is differenced at the photo detector. In this situation, much lower level secondary noises then set overall performance. If, however, the two arms have different lengths (...

  17. Delay in atomic photoionization

    CERN Document Server

    Kheifets, A S

    2010-01-01

    We analyze the time delay between emission of photoelectrons from the outer valence $ns$ and $np$ sub-shells in noble gas atoms following absorption of an attosecond XUV pulse. By solving the time dependent Schr\\"odinger equation and carefully examining the time evolution of the photoelectron wave packet, we establish the apparent "time zero" when the photoelectron leaves the atom. Various processes such as elastic scattering of the photoelectron on the parent ion and many-electron correlation affect the quantum phase of the dipole transition matrix element, the energy dependence of which defines the emission timing. This qualitatively explains the time delay between photoemission from the $2s$ and $2p$ sub-shells of Ne as determined experimentally by attosecond streaking [{\\em Science} {\\bf 328}, 1658 (2010)]. However, with our extensive numerical modeling, we were only able to account for less than a half of the measured time delay of $21\\pm5$~as. We argue that the XUV pulse alone cannot produce such a larg...

  18. Time-Delay Interferometry

    Directory of Open Access Journals (Sweden)

    Massimo Tinto

    2014-08-01

    Full Text Available Equal-arm detectors of gravitational radiation allow phase measurements many orders of magnitude below the intrinsic phase stability of the laser injecting light into their arms. This is because the noise in the laser light is common to both arms, experiencing exactly the same delay, and thus cancels when it is differenced at the photo detector. In this situation, much lower level secondary noises then set the overall performance. If, however, the two arms have different lengths (as will necessarily be the case with space-borne interferometers, the laser noise experiences different delays in the two arms and will hence not directly cancel at the detector. In order to solve this problem, a technique involving heterodyne interferometry with unequal arm lengths and independent phase-difference readouts has been proposed. It relies on properly time-shifting and linearly combining independent Doppler measurements, and for this reason it has been called time-delay interferometry (TDI. This article provides an overview of the theory, mathematical foundations, and experimental aspects associated with the implementation of TDI. Although emphasis on the application of TDI to the Laser Interferometer Space Antenna (LISA mission appears throughout this article, TDI can be incorporated into the design of any future space-based mission aiming to search for gravitational waves via interferometric measurements. We have purposely left out all theoretical aspects that data analysts will need to account for when analyzing the TDI data combinations.

  19. Delayed Speech or Language Development

    Science.gov (United States)

    ... to 2-Year-Old Delayed Speech or Language Development KidsHealth > For Parents > Delayed Speech or Language Development ... child is right on schedule. Normal Speech & Language Development It's important to discuss early speech and language ...

  20. Efficacy of Real-world Entecavir Therapy in Treatment-naïve Chronic Hepatitis B Patients

    Directory of Open Access Journals (Sweden)

    Yan-Di Xie

    2017-01-01

    Conclusions: ETV treatment was effective for HBV DNA suppression in this study, but HBsAg loss and HBeAg clearance/seroconversion rates were lower compared with previous clinical trials. PVR was associated with HBeAg clearance and cirrhosis.

  1. Delay Choice vs. Delay Maintenance: Different Measures of Delayed Gratification in Capuchin Monkeys (Cebus apella)

    Science.gov (United States)

    Addessi, Elsa; Paglieri, Fabio; Beran, Michael J.; Evans, Theodore A.; Macchitella, Luigi; De Petrillo, Francesca; Focaroli, Valentina

    2013-01-01

    Delaying gratification involves two components: (i) delay choice (selecting a delayed reward over an immediate one), and (ii) delay maintenance (sustaining the decision to delay gratification even if the immediate reward is available during the delay). In primates, two tasks most commonly have explored these components, the Intertemporal choice task and the Accumulation task. It is unclear whether these tasks provide equivalent measures of delay of gratification. Here, we compared the performance of the same capuchin monkeys, belonging to two study populations, between these tasks. We found only limited evidence of a significant correlation in performance. Consequently, in contrast to what is often assumed, our data provide only partial support to the hypothesis that these tasks provide equivalent measures of delay of gratification. PMID:23544770

  2. Delaying information search

    Directory of Open Access Journals (Sweden)

    Yaniv Shani

    2012-11-01

    Full Text Available In three studies, we examined factors that may temporarily attenuate information search. People are generally curious and dislike uncertainty, which typically encourages them to look for relevant information. Despite these strong forces that promote information search, people sometimes deliberately delay obtaining valuable information. We find they may do so when they are concerned that the information might interfere with future pleasurable activities. Interestingly, the decision to search or to postpone searching for information is influenced not only by the value and importance of the information itself but also by well-being maintenance goals related to possible detrimental effects that negative knowledge may have on unrelated future plans.

  3. Pseudotumoral delayed cerebral radionecrosis

    Energy Technology Data Exchange (ETDEWEB)

    Ciaudo-Lacroix, C.; Lapresle, J. (Centre Hospitalier de Bicetre, 94 - Le Kremlin-Bicetre (France))

    1985-01-01

    A 60 year-old woman with a scalp epithelioma underwent radiotherapy, the dose being 57 Gray. A first epileptic seizure occurred twenty months later. Neurological examination revealed signs of left hemisphere involvement. ..gamma..EG, angiography, CT scans, demonstrated a pseudotumoral avascular process. On account of the localisation, the patient being right-handed, no surgical procedure was performed. In spite of corticotherapy and anticonvulsive treatment, seizures recurred and neurological signs slowly progressed. The patient died, 22 months after the first seizure, of an associated disseminated carcinoma with cachexia. Neuropathological examination showed a massive lesion presenting all the features of delayed radionecrosis in the left hemisphere: situated mainly in the white matter; numerous vascular abnormalities; wide-spread demyelination; disappearance of oligoglial cells. The Authors recall the clinical and anatomical aspects of this condition for which the only successful treatment is surgical removal when location and size of the lesion permit. Finally, the mechanisms which have been proposed to explain this delayed cerebral radionecrosis are discussed.

  4. Epidemiology of delayed ejaculation.

    Science.gov (United States)

    Di Sante, Stefania; Mollaioli, Daniele; Gravina, Giovanni Luca; Ciocca, Giacomo; Limoncin, Erika; Carosa, Eleonora; Lenzi, Andrea; Jannini, Emmanuele A

    2016-08-01

    A large body of literature on diminished ejaculatory disorders has been generated without the use of a clear diagnostic definition. Many studies have not distinguished between the orgasm and ejaculation disorders leading to doubtful results. Delayed ejaculation (DE) is one of the diminished ejaculatory disorders, which range from varying delays in ejaculatory latency to a complete inability to ejaculate. The present review is aimed at providing a comprehensive overview of the current knowledge on the definition and epidemiology of diminished ejaculatory disorders. We focus on the acquired diseases, such as benign prostatic hyperplasia (BPH) and specific drug regimens that may cause an iatrogenic form of ejaculatory disorder. In addition, the impact of aging is discussed since the prevalence of DE appears to be moderately but positively related to age. Finally, we also focus on the importance of the hormonal milieu on male ejaculation. To date, evidence on the endocrine control of ejaculation is derived from small clinical trials, but the evidence suggests that hormones modulate the ejaculatory process by altering its overall latency.

  5. Stability and delay sensitivity of neutral fractional-delay systems

    Science.gov (United States)

    Xu, Qi; Shi, Min; Wang, Zaihua

    2016-08-01

    This paper generalizes the stability test method via integral estimation for integer-order neutral time-delay systems to neutral fractional-delay systems. The key step in stability test is the calculation of the number of unstable characteristic roots that is described by a definite integral over an interval from zero to a sufficient large upper limit. Algorithms for correctly estimating the upper limits of the integral are given in two concise ways, parameter dependent or independent. A special feature of the proposed method is that it judges the stability of fractional-delay systems simply by using rough integral estimation. Meanwhile, the paper shows that for some neutral fractional-delay systems, the stability is extremely sensitive to the change of time delays. Examples are given for demonstrating the proposed method as well as the delay sensitivity.

  6. Synchronizing time delay systems using variable delay in coupling

    Energy Technology Data Exchange (ETDEWEB)

    Ambika, G., E-mail: g.ambika@iiserpune.ac.in [Indian Institute of Science Education and Research, Pune 411 021 (India); Amritkar, R.E., E-mail: amritkar@prl.res.in [Physical Research Laboratory, Ahmedabad 380 009 (India)

    2011-11-15

    Highlights: > Delay and anticipation in coupling function varies with system dynamics. > Delay or anticipation of the synchronized state is independent of system delay. > Stability analysis developed is quite general. > We demonstrate enhanced security in communication. > Generalized synchronization possible over a wide range of parameter mismatch. - Abstract: We present a mechanism for synchronizing time delay systems using one way coupling with a variable delay in coupling that is reset at finite intervals. We present the analysis of the error dynamics that helps to isolate regions of stability of the synchronized state in the parameter space of interest for single and multiple delays. We supplement this by numerical simulations in a standard time delay system like Mackey Glass system. This method has the advantage that it can be adjusted to be delay or anticipatory in synchronization with a time which is independent of the system delay. We demonstrate the use of this method in communication using the bi channel scheme. We show that since the synchronizing channel carries information from transmitter only at intervals of reset time, it is not susceptible to an easy reconstruction.

  7. Small delay approximation of stochastic delay differential equations

    Science.gov (United States)

    Guillouzic, Steve; L'heureux, Ivan; Longtin, André

    1999-04-01

    Delay differential equations evolve in an infinite-dimensional phase space. In this paper, we consider the effect of external fluctuations (noise) on delay differential equations involving one variable, thus leading to univariate stochastic delay differential equations (SDDE's). For small delays, a univariate nondelayed stochastic differential equation approximating such a SDDE is presented. Another approximation, complementary to the first, is also obtained using an average of the SDDE's drift term over the delayed dynamical variable, which defines a conditional average drift. This second approximation is characterized by the fact that the diffusion term is identical to that of the original SDDE. For small delays, our approach yields a steady-state probability density and a conditional average drift which are in close agreement with numerical simulations of the original SDDE. We illustrate this scheme with the delayed linear Langevin equation and a stochastic version of the delayed logistic equation. The technique can be used with any type of noise, and is easily generalized to multiple delays.

  8. Delay tolerant networks

    CERN Document Server

    Gao, Longxiang; Luan, Tom H

    2015-01-01

    This brief presents emerging and promising communication methods for network reliability via delay tolerant networks (DTNs). Different from traditional networks, DTNs possess unique features, such as long latency and unstable network topology. As a result, DTNs can be widely applied to critical applications, such as space communications, disaster rescue, and battlefield communications. The brief provides a complete investigation of DTNs and their current applications, from an overview to the latest development in the area. The core issue of data forward in DTNs is tackled, including the importance of social characteristics, which is an essential feature if the mobile devices are used for human communication. Security and privacy issues in DTNs are discussed, and future work is also discussed.

  9. On the Gravitomagnetic Time Delay

    OpenAIRE

    Ciufolini, I.; Kopeikin, S.; Mashhoon, B.; Ricci, F

    2002-01-01

    We study the gravitational time delay in ray propagation due to rotating masses in the linear approximation of general relativity. Simple expressions are given for the gravitomagnetic time delay that occurs when rays of radiation cross a slowly rotating shell and propagate in the field of a distant rotating source. Moreover, we calculate the local gravitational time delay in the Goedel universe. The observational consequences of these results in the case of weak gravitational lensing are disc...

  10. Demographic determinants of delayed divorce.

    Science.gov (United States)

    Chan, L Y; Heaton, T B

    1989-01-01

    This study identifies factors that predict delayed divorce in the US. The findings show that factors which influence marital stability in general also correlate with delayed divorce in the same direction. Wife's age at marriage, age of the youngest child, wife's religion, region of residence, and metropolitan residence have substantial effects of delayed divorce, but the effects of race, parental divorce, premarital pregnancy, and socioeconomic status are small.

  11. Location Estimation using Delayed Measurements

    DEFF Research Database (Denmark)

    Bak, Martin; Larsen, Thomas Dall; Nørgård, Peter Magnus

    1998-01-01

    When combining data from various sensors it is vital to acknowledge possible measurement delays. Furthermore, the sensor fusion algorithm, often a Kalman filter, should be modified in order to handle the delay. The paper examines different possibilities for handling delays and applies a new techn...... technique to a sensor fusion system for estimating the location of an autonomous guided vehicle. The system fuses encoder and vision measurements in an extended Kalman filter. Results from experiments in a real environment are reported...

  12. Concurrent Delay in Construction Disputes

    DEFF Research Database (Denmark)

    Cavaleri, Sylvie Cécile

    period of delay can potentially be attributed to several events falling within both parties' spheres of responsibility, commonly termed concurrent delay, is rarely regulated in construction contracts in spite of its common occurrence. This book analyses both the theoretical foundations and the practical......Delay is one of the issues most frequently encountered in today’s construction industry; it causes significant economic damage to all parties involved. Construction contracts, standard and bespoke, almost invariably consider delay from a perspective of single liability. If the event causing...

  13. Time Delay of CGM Sensors

    Science.gov (United States)

    Schmelzeisen-Redeker, Günther; Schoemaker, Michael; Kirchsteiger, Harald; Freckmann, Guido; Heinemann, Lutz; del Re, Luigi

    2015-01-01

    Background: Continuous glucose monitoring (CGM) is a powerful tool to support the optimization of glucose control of patients with diabetes. However, CGM systems measure glucose in interstitial fluid but not in blood. Rapid changes in one compartment are not accompanied by similar changes in the other, but follow with some delay. Such time delays hamper detection of, for example, hypoglycemic events. Our aim is to discuss the causes and extent of time delays and approaches to compensate for these. Methods: CGM data were obtained in a clinical study with 37 patients with a prototype glucose sensor. The study was divided into 5 phases over 2 years. In all, 8 patients participated in 2 phases separated by 8 months. A total number of 108 CGM data sets including raw signals were used for data analysis and were processed by statistical methods to obtain estimates of the time delay. Results: Overall mean (SD) time delay of the raw signals with respect to blood glucose was 9.5 (3.7) min, median was 9 min (interquartile range 4 min). Analysis of time delays observed in the same patients separated by 8 months suggests a patient dependent delay. No significant correlation was observed between delay and anamnestic or anthropometric data. The use of a prediction algorithm reduced the delay by 4 minutes on average. Conclusions: Prediction algorithms should be used to provide real-time CGM readings more consistent with simultaneous measurements by SMBG. Patient specificity may play an important role in improving prediction quality. PMID:26243773

  14. Concurrent Delay in Construction Disputes

    DEFF Research Database (Denmark)

    Cavaleri, Sylvie Cécile

    Delay is one of the issues most frequently encountered in today’s construction industry; it causes significant economic damage to all parties involved. Construction contracts, standard and bespoke, almost invariably consider delay from a perspective of single liability. If the event causing...... period of delay can potentially be attributed to several events falling within both parties' spheres of responsibility, commonly termed concurrent delay, is rarely regulated in construction contracts in spite of its common occurrence. This book analyses both the theoretical foundations and the practical...

  15. Registration Delay and Student Performance

    Science.gov (United States)

    Siefken, Jason

    2017-01-01

    Tracking the difference between the time a first-year student is allowed to register for a course and the time he or she does register for a course (a student's registration delay), we notice a negative correlation between registration delay and final grade in a course. The difference between a student who registers within the first two minutes…

  16. 78 FR 59422 - Delayed Applications

    Science.gov (United States)

    2013-09-26

    ... Pipeline and Hazardous Materials Safety Administration Delayed Applications AGENCY: Office of Hazardous... applications delayed more than 180 days. SUMMARY: In accordance with the requirements of 49 U.S.C. 5117(c), PHMSA is publishing the following list of special permit applications that have been in process for 180...

  17. High resolution digital delay timer

    Science.gov (United States)

    Martin, Albert D.

    1988-01-01

    Method and apparatus are provided for generating an output pulse following a trigger pulse at a time delay interval preset with a resolution which is high relative to a low resolution available from supplied clock pulses. A first lumped constant delay (20) provides a first output signal (24) at predetermined interpolation intervals corresponding to the desired high resolution time interval. Latching circuits (26, 28) latch the high resolution data (24) to form a first synchronizing data set (60). A selected time interval has been preset to internal counters (142, 146, 154) and corrected for circuit propagation delay times having the same order of magnitude as the desired high resolution. Internal system clock pulses (32, 34) count down the counters to generate an internal pulse delayed by an interval which is functionally related to the preset time interval. A second LCD (184) corrects the internal signal with the high resolution time delay. A second internal pulse is then applied to a third LCD (74) to generate a second set of synchronizing data (76) which is complementary with the first set of synchronizing data (60) for presentation to logic circuits (64). The logic circuits (64) further delay the internal output signal (72) to obtain a proper phase relationship of an output signal (80) with the internal pulses (32, 34). The final delayed output signal (80) thereafter enables the output pulse generator (82) to produce the desired output pulse (84) at the preset time delay interval following input of the trigger pulse (10, 12).

  18. Calibrating for Ionospheric Phase Delays

    Science.gov (United States)

    Macdoran, P. F.

    1985-01-01

    Technique determines ionospheric phase delay on real-time universally applicable basis in terms of electrons per meter squared by coherently modulating two L-band carrier frequencies received from two Global Positioning System satelites. Two pseudorandom number sequences cross-correlated to derive delay time.

  19. #FakeNobelDelayReasons

    CERN Multimedia

    2013-01-01

    Tuesday’s hour-long delay of the Nobel Prize in Physics announcement was (and still is) quite the cause for speculation. But on the Twittersphere, it was simply the catalyst for some fantastic puns, so-bad-they're-good physics jokes and other shenanigans. Here are some of our favourite #FakeNobelDelayReasons.    

  20. Imitation dynamics with time delay.

    Science.gov (United States)

    Wang, Shi-Chang; Yu, Jie-Ru; Kurokawa, Shun; Tao, Yi

    2017-05-07

    Based on the classic imitation dynamics (Hofbauer and Sigmund, 1998, Evolutionary Games and Population Dynamics, Cambridge University Press), the imitation dynamics with time delay is investigated, where the probability that an individual will imitate its opponent's own strategy is assumed to depend on the comparison between the past expected payoff of this individual's own strategy and the past expected payoff of its opponent's own strategy, i.e. there is a time delay effect. For the two-phenotype model, we show that if the system has an interior equilibrium and this interior equilibrium is stable when there is no time delay, then there must be a critical value of time delay such that the system tends to a stable periodic solution when the time delay is larger than the critical value. On the other hand, for three-phenotype (rock-scissors-paper) model, the numerical analysis shows that for the stable periodic solution induced by the time delay, the amplitude and the period will increase with the increase of the time delay. These results should help to understand the evolution of behavior based on the imitation dynamics with time delay. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Magnetic bearing optical delay line

    NARCIS (Netherlands)

    Dool, T.C. van den; Kamphues, F.G.; Fouss, B.; Henrioulle, K.; Hogenhuis, H.

    2004-01-01

    TNO TPD, in close cooperation with Micromega-Dynamics and Dutch Space, has developed an advanced Optical Delay Line (ODL) for use in PRIMA, GENIE and other ground based interferometers. The delay line design is modular and flexible, which makes scaling for other applications a relatively easy task.

  2. Time-delay damping theory

    Institute of Scientific and Technical Information of China (English)

    洪峰

    2002-01-01

    In this paper, existing damping theories are briefly reviewed. On the basis of the existing damping theories, a new kind of damping theory, i.e., the time-delay damping theory, is developed. In the time-delay damping theory, the damping force is considered to be directly proportional to the increment of displacement. The response analysis of an SDOF time-delay damping system is carried out, and the methods for obtaining the solution for a time-delay damping system in the time domain as well as the frequency domain are given. The comparison between results from different damping theories shows that the time-delay damping theory is both reasonable and convenient.

  3. Asynchronous Bounded Expected Delay Networks

    CERN Document Server

    Bakhshi, Rena; Fokkink, Wan; Pang, Jun

    2010-01-01

    The commonly used asynchronous bounded delay (ABD) network models assume a fixed bound on message delay. We propose a probabilistic network model, called asynchronous bounded expected delay (ABE) model. Instead of a strict bound, the ABE model requires only a bound on the expected message delay. While the conditions of ABD networks restrict the set of possible executions, in ABE networks all asynchronous executions are possible, but executions with extremely long delays are less probable. In contrast to ABD networks, ABE networks cannot be synchronised efficiently. At the example of an election algorithm, we show that the minimal assumptions of ABE networks are sufficient for the development of efficient algorithms. For anonymous, unidirectional ABE rings of known size N we devise a probabilistic leader election algorithm having average message and time complexity O(N).

  4. Clinical significance of hepatitis B e antigen level measurement during long-term lamivudine therapy in chronic hepatitis B patients with e antigen positive

    Institute of Scientific and Technical Information of China (English)

    Jung Woo Shin; Neung Hwa Park; Seok Won Jung; Byung Chul Kim; Sung Ho Kwon; Jae Serk Park; In Du Jeong; Sung-Jo Bang; Do Ha Kim

    2006-01-01

    AIM: To determine the changes of quantitative hepatitis B e antigen (HBeAg) that predicts early detection of nonresponse or breakthrough to long-term lamivudine (LAM)therapy.METHODS: Among HBeAg positive chronic hepatitis B patients who failed to achieve HBeAg seroconversion within 12 mo, we retrospectively analyzed 220 patients who had received LAM more than 24 mo.RESULTS: The mean duration of LAM therapy was 36(range, 24-72) mo. HBeAg seroconversion after the first 12 mo of LAM therapy was achieved in 53 (24.1%)patients. Viral breakthrough was observed in 105 (47.7%)patients. To find out whether the changing patterns of HBeAg levels can predict the outcome of LAM therapy,we analyzed the reduction rates of HBeAg levels during LAM therapy. Using the decrease more than 90% of pretreatment HBeAg levels, the sensitivity and specificity of response were 96.2% and 70.1%, respectively.Patients were divided into 3 groups according to the reduction patterns of the decrease of quantitative HBeAg: decrescendo, decrescendo-crescendo, no change or fluctuating groups. The optimal time to predict nonresponse or breakthrough was the first 9 mo of therapy.At 9 mo of therapy, 49 (92.5%) of 53 patients who had achieved HBeAg seroconversion were included in the decrescendo group. On the contrary, in the no change or fluctuating group, only four (7.5%) had achieved HBeAg seroconversion. Among patients who did not show the continuous decrease of HBeAg levels at 9 mo, 95.2%(negative predictive value) failed to achieve HBeAg seroconversion.CONCLUSION: Almost all patients who failed to show a continuous decrease of HBeAg levels at 9 mo of LAM therapy were non-response or breakthrough. Therefore,monitoring changes of HBeAg levels during LAM therapy in HBeAg positive chronic hepatitis B may be valuable for identifying patients who are at high risk of non-response or breakthrough.

  5. Estudo de soroconversão com formulações da vacina Biken CAM-70 contra sarampo Comparison of seroconversion rates with CAM-70 measles vaccine at different dosages

    Directory of Open Access Journals (Sweden)

    Luiz Antonio B Camacho

    2000-08-01

    Full Text Available OBJETIVO: Comparar a resposta sorológica induzida por formulações com diferentes concentrações de vírus da vacina contra sarampo da cepa Biken CAM-70. MÉTODOS: Crianças sadias de 9 a 18 meses de um centro de saúde do Rio de Janeiro, RJ, cujos responsáveis concordaram em participar, foram randomizadas em três grupos vacinados com concentrações de 5.000, 1.000 ou 200 CCID50 (50% Tissue Culture Infective Dose. Os participantes e o pessoal da pesquisa ignoravam o tipo de vacina administrado. A avaliação sorológica foi realizada pelo teste de redução em plaque de lise. Duas análises intermediárias dos dados foram programadas. RESULTADOS: Das 223 crianças recrutadas, 84% completaram todos os procedimentos; 79% tinham idade menor que 10 meses; e 93% não tinham anticorpos contra sarampo no soro pré-vacinal. As proporções de soroconversão (quadruplicação das concentrações pré-vacinais foram 82%, 55% e 37% (pOBJECTIVES: To compare seroconversion rates induced by Biken CAM-70 measles vaccines at different viral concentrations. METHODS: Healthy children aged 9 to 18 months from a primary health care unit in Rio de Janeiro, Brazil, and whose guardians agreed with their participation, were randomly assigned to receive one of the following vaccine formulations: 5,000, 1,000 or 200 CCID50 (50% Tissue Culture Infective Dose. The research team, participants, and data analysts were blinded to the type of vaccine administered. Pre- and post-vaccination antibody levels were assessed through Plaque Reduction Neutralization Test. Two interim data analyses were planned to assess unequivocal evidence of the superiority of one of the vaccine types. RESULTS: From 223 recruited children, 84% completed the whole course. Of them, 79% were less than 10 months of age, and 93% did not show detectable measles antibodies in pre-vaccination serum. Seroconversion (four-fold increase in antibody levels in groups vaccinated with 5,000, 1,000 or 200 CCID

  6. Delayed radiation neuropathy

    Energy Technology Data Exchange (ETDEWEB)

    Nagashima, T.; Miyamoto, K.; Beppu, H.; Hirose, K.; Yamada, K. (Tokyo Metropolitan Neurological Hospital (Japan))

    1981-07-01

    A case of cervical plexus neuropathy was reported in association with chronic radio-dermatitis, myxedema with thyroid adenoma and epiglottic tumor. A 38-year-old man has noticed muscle weakness and wasting of the right shoulder girdle since age 33. A detailed history taking revealed a previous irradiation to the neck because of the cervical lymphadenopathy at age 10 (X-ray 3,000 rads), keroid skin change at age 19, obesity and edema since 26, and hoarseness at 34. Laryngoscopic examination revealed a tumor on the right vocal cord, diagnosed as benign papilloma by histological study. In addition, there were chronic radio-dermatitis around the neck, primary hypothyroidism with a benign functioning adenoma on the right lobe of the thyroid, the right phrenic nerve palsy and the right recurrent nerve palsy. All these lesions were considered to be the late sequellae of radiation to the neck in childhood. Other neurological signs were weakness and amyotrophy of the right shoulder girdle with patchy sensory loss, and areflexia of the right arm. Gross power was fairly well preserved in the right hand. EMG showed neurogenic changes in the tested muscles, suggesting a peripheral nerve lesion. Nerve conduction velocities were normal. No abnormal findings were revealed by myelography and spinal CT. The neurological findings of the patient were compatible with the diagnosis of middle cervical plexus palsy apparently due to late radiation effect. In the literature eight cases of post-radiation neuropathy with a long latency have been reported. The present case with the longest latency after the radiation should be included in the series of the reported cases of ''delayed radiation neuropathy.'' (author).

  7. Seroconversion and seroreactivity patterns of dairy goats naturally exposed to caprine arthritis-encephalitis virus in Brazil Soroconversão e sororeatividade de cabras leiteiras naturalmente expostas ao virus da artrite-encefalite caprina no Brasil

    Directory of Open Access Journals (Sweden)

    Roberto Soares Castro

    2002-08-01

    Full Text Available A labelled avidin-biotin ELISA (lab-ELISA using repeated serum samples of goats showed a progressive seroconversion with higher seroconversion rate at the period going from the beginning of the breeding up to the last half of lactation (35.0%, compared to that recorded at the beginning of breeding (17.8%(pForam realizados exames sorológicos em cabras leiteiras, utilizando-se ELISA marcado com avidina-biotina (LAB-ELISA. Esses exames mostraram soroconversão progressiva, com uma taxa maior entre os animais a partir do início da reprodução até a última metade da lactação (35% comparada à observada nos animais até o início da reprodução (17,8%(p<0,05. Além disso, o padrão de sororeatividade das amostras colhidas a cada 30-40 dias, durante 12 meses, avaliado pelo LAB-ELISA, foi caracterizado por alta variabilidade individual. Não foi observada sororeversão, e títulos mais altos foram obtidos mais no grupo constituído por animais que entraram em lactação (n=6, média de títulos=913,4 do que no grupo constituído por animais que cruzaram, mas não conceberam (n=4, média de títulos=261,2(p<0,01.

  8. Time Delay in Molecular Photoionization

    CERN Document Server

    Hockett, P; Villeneuve, D M; Corkum, P B

    2015-01-01

    Time-delays in the photoionization of molecules are investigated. As compared to atomic ionization, the time-delays expected from molecular ionization present a much richer phenomenon, with a strong spatial dependence due to the anisotropic nature of the molecular scattering potential. We investigate this from a scattering theory perspective, and make use of molecular photoionization calculations to examine this effect in representative homonuclear and hetronuclear diatomic molecules, nitrogen and carbon monoxide. We present energy and angle-resolved maps of the Wigner delay time for single-photon valence ionization, and discuss the possibilities for experimental measurements.

  9. Leibniz Dynamics with Time Delay

    OpenAIRE

    Albu, I. D.; Opris, D.

    2005-01-01

    In this paper we show that several dynamical systems with time delay can be described as vector fields associated to smooth functions via a bracket of Leibniz structure. Some examples illustrate the theoretical considerations.

  10. Delays and networked control systems

    CERN Document Server

    Hetel, Laurentiu; Daafouz, Jamal; Johansson, Karl

    2016-01-01

    This edited monograph includes state-of-the-art contributions on continuous time dynamical networks with delays. The book is divided into four parts. The first part presents tools and methods for the analysis of time-delay systems with a particular attention on control problems of large scale or infinite-dimensional systems with delays. The second part of the book is dedicated to the use of time-delay models for the analysis and design of Networked Control Systems. The third part of the book focuses on the analysis and design of systems with asynchronous sampling intervals which occur in Networked Control Systems. The last part of the book exposes several contributions dealing with the design of cooperative control and observation laws for networked control systems. The target audience primarily comprises researchers and experts in the field of control theory, but the book may also be beneficial for graduate students. .

  11. A Kac CROW Delay Line

    CERN Document Server

    Sumetsky, M

    2013-01-01

    A low-loss CROW delay line with a weak inter-resonator coupling determined by the Kac matrix is dispersionless and can be easily impedance-matched by adjusting the coupling to the input/output waveguide.

  12. Systematics in delayed neutron yields

    Energy Technology Data Exchange (ETDEWEB)

    Ohsawa, Takaaki [Kinki Univ., Higashi-Osaka, Osaka (Japan). Atomic Energy Research Inst.

    1998-03-01

    An attempt was made to reproduce the systematic trend observed in the delayed neutron yields for actinides on the basis of the five-Gaussian representation of the fission yield together with available data sets for delayed neutron emission probability. It was found that systematic decrease in DNY for heavier actinides is mainly due to decrease of fission yields of precursors in the lighter side of the light fragment region. (author)

  13. Time Delay in Molecular Photoionization

    OpenAIRE

    Hockett, P.; Frumker, E.; Villeneuve, D M; Corkum, P. B.

    2015-01-01

    Time-delays in the photoionization of molecules are investigated. As compared to atomic ionization, the time-delays expected from molecular ionization present a much richer phenomenon, with a strong spatial dependence due to the anisotropic nature of the molecular scattering potential. We investigate this from a scattering theory perspective, and make use of molecular photoionization calculations to examine this effect in representative homonuclear and hetronuclear diatomic molecules, nitroge...

  14. Measuring information-transfer delays.

    Directory of Open Access Journals (Sweden)

    Michael Wibral

    Full Text Available In complex networks such as gene networks, traffic systems or brain circuits it is important to understand how long it takes for the different parts of the network to effectively influence one another. In the brain, for example, axonal delays between brain areas can amount to several tens of milliseconds, adding an intrinsic component to any timing-based processing of information. Inferring neural interaction delays is thus needed to interpret the information transfer revealed by any analysis of directed interactions across brain structures. However, a robust estimation of interaction delays from neural activity faces several challenges if modeling assumptions on interaction mechanisms are wrong or cannot be made. Here, we propose a robust estimator for neuronal interaction delays rooted in an information-theoretic framework, which allows a model-free exploration of interactions. In particular, we extend transfer entropy to account for delayed source-target interactions, while crucially retaining the conditioning on the embedded target state at the immediately previous time step. We prove that this particular extension is indeed guaranteed to identify interaction delays between two coupled systems and is the only relevant option in keeping with Wiener's principle of causality. We demonstrate the performance of our approach in detecting interaction delays on finite data by numerical simulations of stochastic and deterministic processes, as well as on local field potential recordings. We also show the ability of the extended transfer entropy to detect the presence of multiple delays, as well as feedback loops. While evaluated on neuroscience data, we expect the estimator to be useful in other fields dealing with network dynamics.

  15. Basin stability in delayed dynamics

    Science.gov (United States)

    Leng, Siyang; Lin, Wei; Kurths, Jürgen

    2016-02-01

    Basin stability (BS) is a universal concept for complex systems studies, which focuses on the volume of the basin of attraction instead of the traditional linearization-based approach. It has a lot of applications in real-world systems especially in dynamical systems with a phenomenon of multi-stability, which is even more ubiquitous in delayed dynamics such as the firing neurons, the climatological processes, and the power grids. Due to the infinite dimensional property of the space for the initial values, how to properly define the basin’s volume for delayed dynamics remains a fundamental problem. We propose here a technique which projects the infinite dimensional initial state space to a finite-dimensional Euclidean space by expanding the initial function along with different orthogonal or nonorthogonal basis. A generalized concept of basin’s volume in delayed dynamics and a highly practicable calculating algorithm with a cross-validation procedure are provided to numerically estimate the basin of attraction in delayed dynamics. We show potential applicabilities of this approach by applying it to study several representative systems of biological or/and physical significance, including the delayed Hopfield neuronal model with multistability and delayed complex networks with synchronization dynamics.

  16. Delay Independent Criterion for Multiple Time-delay Systems

    Science.gov (United States)

    Chang, C. J.; Liu, K. F. R.; Yeh, K.; Chen, C. W.; Chung, P. Y.

    Based on the fuzzy Lyapunov method, this work addresses the stability conditions for nonlinear systems with multiple time delays to ensure the stability of building structure control systems. The delay independent conditions are derived via the traditional Lyapunov and fuzzy Lyapunov methods for multiple time-delay systems as approximated by the Tagagi-Sugeno (T-S) fuzzy model. The fuzzy Lyapunov function is defined as a fuzzy blending of quadratic Lyapunov functions. A parallel distributed compensation (PDC) scheme is utilized to construct a global fuzzy logic control (FLC) by blending all linear local state feedback controllers in the controller design procedure. Furthermore, the H infinity performance and robustness of the design for modeling errors also need to be considered in the stability conditions.

  17. Impact of Maternal HIV Seroconversion during Pregnancy on Early Mother to Child Transmission of HIV (MTCT Measured at 4-8 Weeks Postpartum in South Africa 2011-2012: A National Population-Based Evaluation.

    Directory of Open Access Journals (Sweden)

    Thu-Ha Dinh

    Full Text Available Mother-to-child transmission of HIV (MTCT depends on the timing of HIV infection. We estimated HIV-seroconversion during pregnancy (HSP after having a HIV-negative result antenatally, and its contribution to early MTCT in South Africa (SA.Between August 2011 and March 2012, we recruited a nationally representative sample of mother-infant pairs with infants aged 4-to-8 weeks from 578 health facilities. Data collection included mother interviews, child health-card reviews, and infant dried-blood-spots sample (iDBS. iDBS were tested for HIV antibodies and HIV-deoxyribonucleic-acid (HIV-DNA. HSP was defined as maternal self-report of an HIV-negative test during this pregnancy, no documented use of antiretroviral drugs and a matched HIV sero-positive iDBS. We used 20 imputations from a uniform distribution for time from reported antenatal HIV-negative result to delivery to estimate time of HSP. Early MTCT was defined based on detection of HIV-DNA in iDBS. Estimates were adjusted for clustering, nonresponse, and weighted by SA's 2011 live-births.Of 9802 mother-infant pairs, 2738 iDBS were HIV sero-positive, including 212 HSP, resulting in a nationally weighted estimate of 3.3% HSP (95% Confidence Interval: 2.8%-3.8%. Median time of HIV-seroconversion was 32.8weeks gestation;28.3% (19.7%- 36.9% estimated to be >36 weeks. Early MTCT was 10.7% for HSP (6.2%-16.8% vs. 2.2% (1.7%-2.8% for mothers with known HIV-positive status. Although they represent 2.2% of all mothers and 6.7% of HIV-infected mothers, HSP accounted for 26% of early MTCT. Multivariable analysis indicated the highest risk for HSP was among women who knew the baby's father was HIV-infected (adjusted-hazard ratio (aHR 4.71; 1.49-14.99, or who had been screened for tuberculosis (aHR 1.82; 1.43-2.32.HSP risk is high and contributes significantly to early MTCT. Identification of HSP by repeat-testing at 32 weeks gestation, during labor, 6 weeks postpartum, in tuberculosis-exposed women, and in

  18. Incidence of hepatitis C virus (HCV in a multicenter cohort of HIV-positive patients in Spain 2004-2011: increasing rates of HCV diagnosis but not of HCV seroconversions.

    Directory of Open Access Journals (Sweden)

    Paz Sobrino-Vegas

    Full Text Available OBJECTIVES: We aim to describe rates and risk factors of Hepatitis C Virus (HCV diagnoses, follow-up HCV testing and HCV seroconversion from 2004-2011 in a cohort of HIV-positive persons in Spain. METHODS: CoRIS is a multicentre, open and prospective cohort recruiting adult HIV-positive patients naïve to antiretroviral therapy. We analysed patients with at least one negative and one follow-up HCV serology. Incidence Rates (IR were calculated and multivariate Poisson regression was used to estimate adjusted Rates Ratios (aIRR. RESULTS: Of 2112 subjects, 53 HCV diagnoses were observed, IR = 0.93/100 py (95%CI: 0.7-1.2. IR increased from 0.88 in 2004-05 to 1.36 in 2010-11 (aIRR = 1.55; 95%CI: 0.37-6.55. In men who have sex with men (MSM from 0.76 to 1.10 (aIRR = 1.45; 95%CI: 0.31-6.82; in heterosexual (HTX subjects from 1.19 to 1.28 (aIRR = 1.08; 95%CI: 0.11-10.24. HCV seroconversion rates decreased from 1.77 to 0.65 (aIRR = 0.37; 95%CI: 0.12-1.11; in MSM from 1.06 to 0.49 (aIRR = 0.46; 95%CI: 0.09-2.31; in HTX from 2.55 to 0.59 (aIRR = 0.23; 95%CI: 0.06-0.98. HCV infection risk was higher for injecting drug users (IDU compared to HTX (aIRR = 9.63;95%CI: 2.9-32.2; among MSM, for subjects aged 40-50 compared to 30 or less (IRR = 3.21; 95%CI: 1.7-6.2; and among HTX, for female sex (aIRR = 2.35; 95%CI: 1.03-5.34 and <200 CD4-count (aIRR = 2.39; 95%CI: 0.83-6.89. CONCLUSION: We report increases in HCV diagnoses rates which seem secondary to intensification of HCV follow-up testing but not to rises in HCV infection rates. HCV IR is higher in IDU. In MSM, HCV IR increases with age. Among HTX, HCV IR is higher in women and in subjects with impaired immunological situation.

  19. 49 CFR 236.563 - Delay time.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Delay time. 236.563 Section 236.563 Transportation... Cab Signal Systems Rules and Instructions; Locomotives § 236.563 Delay time. Delay time of automatic... requirements of § 236.24 shall take into consideration the delay time....

  20. Stochastic modelling of train delays and delay propagation in stations

    NARCIS (Netherlands)

    Yuan, J.

    2006-01-01

    A trade-off exists between efficiently utilizing the capacity of railway networks and improving the reliability and punctuality of train operations. This dissertation presents a new analytical probability model based on blocking time theory which estimates the knock-on delays of trains caused by

  1. Delaying vortex breakdown by waves

    Science.gov (United States)

    Yao, M. F.; Jiang, L. B.; Wu, J. Z.; Ma, H. Y.; Pan, J. Y.

    1989-03-01

    The effect of spiral waves on delaying vortex breakdown in a tube is studied experimentally and theoretically. When a harmonic oscillation was imposed on one of guiding vanes in the tube, the breakdown was observed to be postponed appreciately. According to the generalized Lagrangian mean theory, proper forcing spiral waves may produce an additional streaming momentum, of which the effect is favorable and similar to an axial suction at downstream end. The delayed breakdown position is further predicted by using nonlinear wave theory. Qualitative agreement between theory and experiment is obtained, and experimental comparison of the effects due to forcing spiral wave and axial suction is made.

  2. Delay equations and radiation damping

    Science.gov (United States)

    Chicone, C.; Kopeikin, S. M.; Mashhoon, B.; Retzloff, D. G.

    2001-06-01

    Starting from delay equations that model field retardation effects, we study the origin of runaway modes that appear in the solutions of the classical equations of motion involving the radiation reaction force. When retardation effects are small, we argue that the physically significant solutions belong to the so-called slow manifold of the system and we identify this invariant manifold with the attractor in the state space of the delay equation. We demonstrate via an example that when retardation effects are no longer small, the motion could exhibit bifurcation phenomena that are not contained in the local equations of motion.

  3. Time-domain nature of group delay

    Institute of Scientific and Technical Information of China (English)

    王建武; 冯正和

    2015-01-01

    The characteristic of group delay is analyzed based on an electronic circuit, and its time-domain nature is studied with time-domain simulation and experiment. The time-domain simulations and experimental results show that group delay is the delay of the energy center of the amplitude-modulated pulse, rather than the propagation delay of the electromagnetic field. As group velocity originates from the definition of group delay and group delay is different from the propagation delay, the superluminality or negativity of group velocity does not mean the superluminal or negative propagation of the electromagnetic field.

  4. Diagnostic Delay in Rheumatoid Arthritis

    DEFF Research Database (Denmark)

    Mølbaek, Karen; Hørslev-Petersen, Kim; Primdahl, Jette

    2016-01-01

    BACKGROUND: To prevent joint damage among patients with rheumatoid arthritis (RA), there is a need to minimize delays from the onset of symptoms until the initiation of appropriate therapy. The present study explored the factors that have an impact on the time it takes for Danish patients with RA...

  5. Livermore blasted for project delay

    CERN Multimedia

    1999-01-01

    In a 12 page report issued last week, a review committee set up by the University of California has concluded that mismanagement and poor planning are to blame for significant cost overruns and delays in the construction of NIF, the worlds largest laser (1 page).

  6. Providing delay guarantees in Bluetooth

    NARCIS (Netherlands)

    Ait Yaiz, R.; Heijenk, Gerhard J.; Titsworth, F.

    2003-01-01

    Bluetooth polling, also referred to as Bluetooth MAC scheduling or intra-piconet scheduling, is the mechanism that schedules the traffic between the participants in a Bluetooth network. Hence, this mechanism is highly determining with respect to the delay packets experience in a Bluetooth network.

  7. Deconstructing delayed posttraumatic stress disorder

    NARCIS (Netherlands)

    Smid, G.E.

    2011-01-01

    According to the Diagnostic and Statistical Manual of Mental Disorders, delayed posttraumatic stress disorder (PTSD) must be diagnosed in individuals fulfilling criteria for PTSD if the onset of symptoms is at least six months after the trauma. The purpose of this thesis was to establish the prevale

  8. Advanced optical delay line demonstrator

    NARCIS (Netherlands)

    Dool, T.C. van den; Kamphues, F.G.; Fouss, B.; Henrioulle, K.; Hogenhuis, H.

    2004-01-01

    TNO TPD, in cooperation with Micromega-Dynamics and Dutch Space, has designed an advanced Optical Delay Line (ODL) for use in future ground based and space interferometry missions. The work is performed under NIVR contract in preparation for GENIE and DARWIN. Using the ESO PRIMA DDL requirements as

  9. Providing Delay Guarantees in Bluetooth

    NARCIS (Netherlands)

    Ait Yaiz, Rachid; Heijenk, Geert; Titsworth, F.

    2003-01-01

    Bluetooth polling, also referred to as Bluetooth MAC scheduling or intra-piconet scheduling, is the mechanism that schedules the traffic between the participants in a Bluetooth network. Hence, this mechanism is highly determining with respect to the delay packets experience in a Bluetooth network. I

  10. Analytical model for calculating indeterminate results interval of screening tests, the effect on seroconversion window period: a brief evaluation of the impact of uncertain results on the blood establishment budget.

    Science.gov (United States)

    Pereira, Paulo; Westgard, James O; Encarnação, Pedro; Seghatchian, Jerard

    2014-10-01

    The evaluation of measurement uncertainty is not required by the European Union regulation or blood establishments’ laboratory tests. However, it is required for tests accredited by ISO 15189. Also, the forthcoming ISO 9001 edition requires “risk based thinking” with risk described as “the effect of uncertainty on an expected result”. ISO recommends GUM models for determination of measurement uncertainty, but their application is not intended for ordinal value measurements, such as what happens with screening test binary results. This article reviews, discusses and proposes concepts intended for measurement uncertainty of screening test results. The precision model focuses on cutoff level allowing the evaluation of the indeterminate interval using analytical sources of variance. The intervalis considered in the estimation of the seroconversion window period. The delta-value of patients and healthy subjects’ samples allows ranking two tests according to the probability of the two classes of indeterminate results: chance of false negative results and chance of false positive results (waste on budget).

  11. Time Delay Circuits: A Quality Criterion for Delay Variations versus Frequency

    NARCIS (Netherlands)

    Garakoui, Seyed Kasra; Klumperink, Eric A.M.; Nauta, Bram; Vliet, van Frank E.

    2010-01-01

    This paper shows that the group delay of a delay circuit does not give sufficient information to predict the delay vs. frequency. A new criterion (fϕ=0) is proposed that characterizes the delay variations over a specified frequency range. The mathematical derivation of fϕ=0 for a single delay block

  12. THE ALL-DELAY STABILITY OF DEGENERATE DIFFERENTIAL SYSTEMS WITH DELAY

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In this paper,the all-delay stability of degenerate differential systems with delay is discussed.We come up with some new criteria for evaluating the all-delay stability of degenerate differential systems with delay and degenerate neutral differential systems with delay.Also,we give an example to illustrate the main results.

  13. Delay of Vehicle Motion in Traffic Dynamics

    CERN Document Server

    Bando, M; Nakanishi, K; Nakayama, A; Bando, Masako; Hasebe, Katsuya; Nakanishi, Ken; Nakayama, Akihiro

    1996-01-01

    We demonstrate that in Optimal Velocity Model (OVM) delay times of vehicles coming from the dynamical equation of motion of OVM almost explain the order of delay times observed in actual traffic flows without introducing explicit delay times. Delay times in various cases are estimated: the case of a leader vehicle and its follower, a queue of vehicles controlled by traffic lights and many-vehicle case of highway traffic flow. The remarkable result is that in most of the situation for which we can make a reasonable definition of a delay time, the obtained delay time is of order 1 second.

  14. Delay locked loop integrated circuit.

    Energy Technology Data Exchange (ETDEWEB)

    Brocato, Robert Wesley

    2007-10-01

    This report gives a description of the development of a Delay Locked Loop (DLL) integrated circuit (IC). The DLL was developed and tested as a stand-alone IC test chip to be integrated into a larger application specific integrated circuit (ASIC), the Quadrature Digital Waveform Synthesizer (QDWS). The purpose of the DLL is to provide a digitally programmable delay to enable synchronization between an internal system clock and external peripherals with unknown clock skew. The DLL was designed and fabricated in the IBM 8RF process, a 0.13 {micro}m CMOS process. It was designed to operate with a 300MHz clock and has been tested up to 500MHz.

  15. Minimum Delay Moving Object Detection

    KAUST Repository

    Lao, Dong

    2017-01-08

    We present a general framework and method for detection of an object in a video based on apparent motion. The object moves relative to background motion at some unknown time in the video, and the goal is to detect and segment the object as soon it moves in an online manner. Due to unreliability of motion between frames, more than two frames are needed to reliably detect the object. Our method is designed to detect the object(s) with minimum delay, i.e., frames after the object moves, constraining the false alarms. Experiments on a new extensive dataset for moving object detection show that our method achieves less delay for all false alarm constraints than existing state-of-the-art.

  16. Time delay and distance measurement

    Science.gov (United States)

    Abshire, James B. (Inventor); Sun, Xiaoli (Inventor)

    2011-01-01

    A method for measuring time delay and distance may include providing an electromagnetic radiation carrier frequency and modulating one or more of amplitude, phase, frequency, polarization, and pointing angle of the carrier frequency with a return to zero (RZ) pseudo random noise (PN) code. The RZ PN code may have a constant bit period and a pulse duration that is less than the bit period. A receiver may detect the electromagnetic radiation and calculate the scattering profile versus time (or range) by computing a cross correlation function between the recorded received signal and a three-state RZ PN code kernel in the receiver. The method also may be used for pulse delay time (i.e., PPM) communications.

  17. Air congestion delay: a review

    Directory of Open Access Journals (Sweden)

    Daniel Alberto Pamplona

    2016-04-01

    Full Text Available This article is a literature review of the air congestion delay and its costs. Air congestion is a worldwide problem. Its existence brings costs for airlines and discomfort for passengers. With the increasing demand for air transport, the study of air congestion has attracted the attention of many researchers around the world. The cause for the delays is erroneously attributed only to the lack of infrastructure investments. The literature review shows that other factors such as population growth, increasing standards of living, lack of operational planning and environmental issues exercise decisive influence. Several studies have been conducted in order to analyze and propose solutions to this problem that affects society as a whole.

  18. Teriparatide Induced Delayed Persistent Hypercalcemia

    Directory of Open Access Journals (Sweden)

    Nirosshan Thiruchelvam

    2014-01-01

    Full Text Available Teriparatide, a recombinant PTH, is an anabolic treatment for osteoporosis that increases bone density. Transient hypercalcemia is a reported side effect of teriparatide that is seen few hours following administration of teriparatide and resolves usually within 16 hours of drug administration. Persistent hypercalcemia, although not observed in clinical trials, is rarely reported. The current case describes a rare complication of teriparatide induced delayed persistent hypercalcemia.

  19. Six Channel Digital Delay Generator

    Science.gov (United States)

    1980-01-01

    Historically, delays were generated by R-C networks that fired thyratrons to provide the re- quired output pulses. Because of severe electrical interference...instruction manual. The system clock was an M. F. electronics model 5401-1 in a printed circuit mounting package. This particular model has a 10 MHz...constructed in-house to provide the high voltages required to trip flash x-ray systems and thyratron controlled firing units. Details of this circuit are

  20. Assembly delay line pulse generators

    CERN Document Server

    1971-01-01

    Assembly of six of the ten delay line pulse generators that will power the ten kicker magnet modules. One modulator part contains two pulse generators. Capacitors, inductances, and voltage dividers are in the oil tank on the left. Triggered high-pressure spark gap switches are on the platforms on the right. High voltage pulse cables to the kicker magnet emerge under the spark gaps. In the centre background are the assembled master gaps.

  1. A quantum delayed choice experiment

    CERN Document Server

    Peruzzo, Alberto; Brunner, Nicolas; Popescu, Sandu; O'Brien, Jeremy L

    2012-01-01

    Quantum systems exhibit particle-like or wave-like behaviour depending on the experimental apparatus they are confronted by. This wave-particle duality is at the heart of quantum mechanics, and is fully captured in Wheeler's famous delayed choice gedanken experiment. In this variant of the double slit experiment, the observer chooses to test either the particle or wave nature of a photon after it has passed through the slits. Here we report on a quantum delayed choice experiment, based on a quantum controlled beam-splitter, in which both particle and wave behaviours can be investigated simultaneously. The genuinely quantum nature of the photon's behaviour is tested via a Bell inequality, which here replaces the delayed choice of the observer. We observe strong Bell inequality violations, thus showing that no model in which the photon knows in advance what type of experiment it will be confronted by, hence behaving either as a particle or as wave, can account for the experimental data.

  2. Minimum Delay Moving Object Detection

    KAUST Repository

    Lao, Dong

    2017-05-14

    This thesis presents a general framework and method for detection of an object in a video based on apparent motion. The object moves, at some unknown time, differently than the “background” motion, which can be induced from camera motion. The goal of proposed method is to detect and segment the object as soon it moves in an online manner. Since motion estimation can be unreliable between frames, more than two frames are needed to reliably detect the object. Observing more frames before declaring a detection may lead to a more accurate detection and segmentation, since more motion may be observed leading to a stronger motion cue. However, this leads to greater delay. The proposed method is designed to detect the object(s) with minimum delay, i.e., frames after the object moves, constraining the false alarms, defined as declarations of detection before the object moves or incorrect or inaccurate segmentation at the detection time. Experiments on a new extensive dataset for moving object detection show that our method achieves less delay for all false alarm constraints than existing state-of-the-art.

  3. Gender disparity in distribution of the major hydrophilic region variants of hepatitis B virus genotype C according to hepatitis B e antigen serostatus.

    Science.gov (United States)

    Lee, Seoung-Ae; Cho, Yoo-Kyung; Lee, Keun-Hwa; Hwang, Eung-Soo; Kook, Yoon-Hoh; Kim, Bum-Joon

    2011-03-01

    Hepatitis B virus (HBV) e antigen (HBeAg) seroconversion during chronic HBV infection is known to play an important role in disease progression and patient response to antiviral agents. The aim of the present study was to analyze gender disparity in distribution of major hydrophilic region (MHR) variants according to HBeAg serostatus. Prevalence of MHR variants from 68 Korean patients with chronic hepatitis (31 HBeAg-positive and 37 HBeAg-negative) was examined in terms of HBeAg serostatus and sex by direct sequencing analysis of the MHR. Gender disparity was observed in the distribution of MHR variants according to HBeAg serostatus. In male patients, the prevalence of MHR variants was significantly higher in HBeAg negative patients than in HBeAg positive patients [58.8% (10/17 patients) vs. 14.3% (3/21 patients), P=0.004]. However, the same was not true in female patients [55.0% (11/20 patients) vs. 60.0% (6/10 patients), P=1.000)]. In addition, 2 mutation types (L110I and G145A) related to HBeAg serostatus were found. In conclusion, HBeAg seroconversion in male chronic patients infected with genotype C could lead to mutations of MHR, major target to host immune response, which might in turn contribute to HBV persistence and immune evasion. Copyright © 2011 Wiley-Liss, Inc.

  4. On Hamlet's Delay in the Revenge

    Institute of Scientific and Technical Information of China (English)

    刘莎

    2009-01-01

    Hamlet is a representative tragedy written by Shakespeare. Question on Hemlet's delay has been drawing the interest of many literature critics. It is still under discussion today. This thesis focuses on analyzing the reasons for Hamlet's delay in the revenge.

  5. Dynamic Cournot Duopoly Game with Delay

    Directory of Open Access Journals (Sweden)

    A. A. Elsadany

    2014-01-01

    Full Text Available The delay Cournot duopoly game is studied. Dynamical behaviors of the game are studied. Equilibrium points and their stability are studied. The results show that the delayed system has the same Nash equilibrium point and the delay can increase the local stability region.

  6. Modelling delay propagation within an airport network

    NARCIS (Netherlands)

    Pyrgiotis, N.; Malone, K.M.; Odoni, A.

    2013-01-01

    We describe an analytical queuing and network decomposition model developed to study the complex phenomenon of the propagation of delays within a large network of major airports. The Approximate Network Delays (AND) model computes the delays due to local congestion at individual airports and capture

  7. Delayed umbilical cord separation in alloimmune neutropenia.

    OpenAIRE

    Kemp, A S; Lubitz, L

    1993-01-01

    Delayed umbilical cord separation in association with neonatal alloimmune neutropenia is reported. Delayed umbilical cord separation has been described in association with defects in neutrophil function. The present case indicates that deficiency in neutrophil number should also be considered as a cause of delayed cord separation.

  8. Modelling delay propagation within an airport network

    NARCIS (Netherlands)

    Pyrgiotis, N.; Malone, K.M.; Odoni, A.

    2013-01-01

    We describe an analytical queuing and network decomposition model developed to study the complex phenomenon of the propagation of delays within a large network of major airports. The Approximate Network Delays (AND) model computes the delays due to local congestion at individual airports and

  9. BOLD delay times using group delay in sickle cell disease

    Science.gov (United States)

    Coloigner, Julie; Vu, Chau; Bush, Adam; Borzage, Matt; Rajagopalan, Vidya; Lepore, Natasha; Wood, John

    2016-03-01

    Sickle cell disease (SCD) is an inherited blood disorder that effects red blood cells, which can lead to vasoocclusion, ischemia and infarct. This disease often results in neurological damage and strokes, leading to morbidity and mortality. Functional Magnetic Resonance Imaging (fMRI) is a non-invasive technique for measuring and mapping the brain activity. Blood Oxygenation Level-Dependent (BOLD) signals contain also information about the neurovascular coupling, vascular reactivity, oxygenation and blood propagation. Temporal relationship between BOLD fluctuations in different parts of the brain provides also a mean to investigate the blood delay information. We used the induced desaturation as a label to profile transit times through different brain areas, reflecting oxygen utilization of tissue. In this study, we aimed to compare blood flow propagation delay times between these patients and healthy subjects in areas vascularized by anterior, middle and posterior cerebral arteries. In a group comparison analysis with control subjects, BOLD changes in these areas were found to be almost simultaneous and shorter in the SCD patients, because of their increased brain blood flow. Secondly, the analysis of a patient with a stenosis on the anterior cerebral artery indicated that signal of the area vascularized by this artery lagged the MCA signal. These findings suggest that sickle cell disease causes blood propagation modifications, and that these changes could be used as a biomarker of vascular damage.

  10. Prednisolon-forbehandling øger effekten af humant lymfoblastinterferon ved kronisk hepatitis B. INTERPRED Trial Group

    DEFF Research Database (Denmark)

    Krogsgaard, K; Marcellin, P; Trepo, C

    1998-01-01

    thrice weekly for 11 weeks. There were statistically significant effects of prednisolone pre-treatment on both HBeAg disappearance and HBeAg to anti-HBe seroconversion (log rank test statistics 5.43; p = 0.02 and 4.75; p = 0.03). HBeAg disappearance and HBeAg to anti-HBe seroconversion rates were 28 vs....... 44% and 23 vs. 38% (placebo vs. prednisolone). Fifteen patients (7.5%) lost HBsAg. Three out of 22 cirrhotic patients (14%), one of whom received prednisolone pre-treatment, developed hepatic decompensation with a fatal outcome. Prednisolone pre-treatment, enhances the effect of lymphoblastoid...

  11. Reactor shutdown delays medical procedures

    Science.gov (United States)

    Gwynne, Peter

    2008-01-01

    A longer-than-expected maintenance shutdown of the Canadian nuclear reactor that produces North America's entire supply of molybdenum-99 - from which the radioactive isotopes technetium-99 and iodine-131 are made - caused delays to the diagnosis and treatment of thousands of seriously ill patients last month. Technetium-99 is a key component of nuclear-medicine scans, while iodine-131 is used to treat cancer and other diseases of the thyroid. Production eventually resumed, but only after the Canadian government had overruled the Canadian Nuclear Safety Commission (CNSC), which was still concerned about the reactor's safety.

  12. Delay modeling in logic simulation

    Energy Technology Data Exchange (ETDEWEB)

    Acken, J. M.; Goldstein, L. H.

    1980-01-01

    As digital integrated circuit size and complexity increases, the need for accurate and efficient computer simulation increases. Logic simulators such as SALOGS (SAndia LOGic Simulator), which utilize transition states in addition to the normal stable states, provide more accurate analysis than is possible with traditional logic simulators. Furthermore, the computational complexity of this analysis is far lower than that of circuit simulation such as SPICE. An eight-value logic simulation environment allows the use of accurate delay models that incorporate both element response and transition times. Thus, timing simulation with an accuracy approaching that of circuit simulation can be accomplished with an efficiency comparable to that of logic simulation. 4 figures.

  13. Delay Variation Model with Two Service Queues

    Directory of Open Access Journals (Sweden)

    Filip Rezac

    2010-01-01

    Full Text Available Delay in VoIP technology is very unpleasant issue and therefore a voice packets prioritization must be ensured. To maintain the high call quality a maximum information delivery time from the sender to the recipient is set to 150 ms. This paper focuses on the design of a mathematical model of end-to-end delay of a VoIP connection, in particular on a delay variation. It describes all partial delay components and mechanisms, their generation, facilities and mathematical formulations. A new approach to the delay variation model is presented and its validation has been done by experimention.

  14. H∞ State Feedback Delay-dependent Control for Discrete Systems with Multi-time-delay

    Institute of Scientific and Technical Information of China (English)

    Bai-Da Qu

    2005-01-01

    In this paper,H∞ state feedback control with delay information for discrete systems with multi-time-delay is discussed. Making use of linear matrix inequality (LMI) approach, a time-delay-dependent criterion for a discrete system with multi-time-delay to satisfy H∞ performance indices is induced, and then a strategy for H∞ state feedback control with delay values for plant with multi-time-delay is obtained. By solving corresponding LMI, a delay-dependent state feedback controller satisfying H∞ performance indices is designed. Finally, a simulation example demonstrates the validity of the proposed approach.

  15. Asymptotic Delay Analysis for Cross-Layer Delay-Based Routing in Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Philippe Jacquet

    2007-01-01

    Full Text Available This paper addresses the problem of the evaluation of the delay distribution via analytical means in IEEE 802.11 wireless ad hoc networks. We show that the asymptotic delay distribution can be expressed as a power law. Based on the latter result, we present a cross-layer delay estimation protocol and we derive new delay-distribution-based routing algorithms, which are well adapted to the QoS requirements of real-time multimedia applications. In fact, multimedia services are not sensitive to average delays, but rather to the asymptotic delay distributions. Indeed, video streaming applications drop frames when they are received beyond a delay threshold, determined by the buffer size. Although delay-distribution-based routing is an NP-hard problem, we show that it can be solved in polynomial time when the delay threshold is large, because of the asymptotic power law distribution of the link delays.

  16. Delay-Dependent Observers for Uncertain Nonlinear Time-Delay Systems

    Directory of Open Access Journals (Sweden)

    Dongmei Yan

    2013-05-01

    Full Text Available This paper is concerned with the observer design problem for a class of discrete-time uncertain nonlinear systems with time-varying delay. The nonlinearities are assumed to satisfy global Lipschitz conditions which appear in both the state and measurement equations. The uncertainties are assumed to be time-varying but norm-bounded. Two Luenberger-like observers are proposed. One is delay observer and the other is delay-free observer. The delay observer which has an internal time delay is applicable when the time delay is known. The delay-free observer which does not use delayed information is especially applicable when the time delay is not known explicitly. Delay-dependent conditions for the existences of these two observers are derived based on Lyapunpv functional approach. Based on these conditions, the observer gains are obtained using the cone complementarity linearization algorithm. Finally, a numerical example is given to illustrate the effectiveness of the proposed method.

  17. Precise delay measurement through combinatorial logic

    Science.gov (United States)

    Burke, Gary R. (Inventor); Chen, Yuan (Inventor); Sheldon, Douglas J. (Inventor)

    2010-01-01

    A high resolution circuit and method for facilitating precise measurement of on-chip delays for FPGAs for reliability studies. The circuit embeds a pulse generator on an FPGA chip having one or more groups of LUTS (the "LUT delay chain"), also on-chip. The circuit also embeds a pulse width measurement circuit on-chip, and measures the duration of the generated pulse through the delay chain. The pulse width of the output pulse represents the delay through the delay chain without any I/O delay. The pulse width measurement circuit uses an additional asynchronous clock autonomous from the main clock and the FPGA propagation delay can be displayed on a hex display continuously for testing purposes.

  18. Estimation of time delay by coherence analysis

    CERN Document Server

    Govindan, R B; Kopper, F; Claussen, J C; Deuschl, G

    2004-01-01

    Using coherence analysis (which is an extensively used method to study the correlations in frequency domain, between two simultaneously measured signals) we estimate the time delay between two signals. This method is suitable for time delay estimation of narrow band coherence signals for which the conventional methods cannot be reliably applied. We show by analysing coupled R\\"ossler attractors with a known delay, that the method yields satisfactory results. Then, we apply this method to human pathologic tremor. The delay between simultaneously measured traces of Electroencephalogram (EEG) and Electromyogram (EMG) data of subjects with essential hand tremor is calculated. We find that there is a delay of 11-27 milli-seconds ($ms$) between the tremor correlated parts (cortex) of the brain (EEG) and the trembling hand (EMG) which is in agreement with the experimentally observed delay value of 15 $ms$ for the cortico-muscular conduction time. By surrogate analysis we calculate error-bars of the estimated delay.

  19. Synchronization of time-delay chaotic systems on small-world networks with delayed coupling

    Institute of Scientific and Technical Information of China (English)

    Qi Wei; Wang Ying-Hai

    2009-01-01

    By using the well-known Ikeda model as the node dynamics,this paper studies synchronization of time-delay systems on small-world networks where the connections between units involve time delays.It shows that,in contrast with the undelayed case,networks with delays can actually synchronize more easily.Specifically,for randomly distributed delays,time-delayed mutual coupling suppresses the chaotic behaviour by stabilizing a fixed point that is unstable for the uncoupled dynamical system.

  20. Time-delay feedback control in a delayed dynamical chaos system and its applications

    Institute of Scientific and Technical Information of China (English)

    Ye Zhi-Yong; Yang Guang; Deng Cun-Bing

    2011-01-01

    The feedback control of a delayed dynamical system, which also includes various chaotic systems with time delays, is investigated. On the basis of stability analysis of a nonautonomons system with delays, some simple yet less conservative criteria are obtained for feedback control in a delayed dynamical system. Finally, the theoretical result is applied to a typical class of chaotic Lorenz system and Chua circuit with delays. Numerical simulations are also given to verify the theoretical results.

  1. [Delayed post effort muscle soreness].

    Science.gov (United States)

    Coudreuse, J M; Dupont, P; Nicol, C

    2004-08-01

    Muscle intolerance to exercise may result from different processes. Diagnosis involves confirming first the source of pain, then potential pathological myalgia. Delayed-onset muscle soreness (DOMS), commonly referred as tiredness, occurs frequently in sport. DOMS usually develops 12-48 h after intensive and/or unusual eccentric muscle action. Symptoms usually involve the quadriceps muscle group but may also affect the hamstring and triceps surae groups. The muscles are sensitive to palpation, contraction and passive stretch. Acidosis, muscle spasm and microlesions in both connective and muscle tissues may explain the symptoms. However, inflammation appears to be the most common explanation. Interestingly, there is strong evidence that the progression of the exercise-induced muscle injury proceeds no further in the absence of inflammation. Even though unpleasant, DOMS should not be considered as an indicator of muscle damage but, rather, a sign of the regenerative process, which is well known to contribute to the increased muscle mass. DOMS can be associated with decreased proprioception and range of motion, as well as maximal force and activation. DOMS disappears 2-10 days before complete functional recovery. This painless period is ripe for additional joint injuries. Similarly, if some treatments are well known to attenuate DOMS, none has been demonstrated to accelerate either structural or functional recovery. In terms of the role of the inflammatory process, these treatments might even delay overall recovery.

  2. Elite athletes and pubertal delay.

    Science.gov (United States)

    Kapczuk, Karina

    2017-10-01

    Intensive physical training and participation in competitive sports during childhood and early adolescence may affect athletes' pubertal development. On the other hand, pubertal timing, early or late, may impact on an athlete selection for a particular sport. Genetic predisposition, training load, nutritional status and psychological stress determine athletes' pubertal timing. Athletes that practice esthetic sports, especially gymnasts, are predisposed to a delay in pubertal development. The growing evidence indicates that energy deficiency, not a systemic training per se, plays a crucial role in the pathogenesis of functional hypothalamic hypogonadism in female athletes. Metabolic and psychologic stress activate hypothalamic-pituitary-adrenal axis and suppress hypothalamic-pituitary-ovarian axis. Female athletes who do not begin secondary sexual development by the age of 14 or menstruation by the age of 16 warrant a comprehensive evaluation and a targeted treatment. Somatic growth and sexual maturation of elite female athletes are largely sport-specific since each sport favors a particular somatotype and requires a specific training. Chronic negative energy balance resulting from a systemic physical training and inadequate energy intake may delay pubertal development in elite athletes. Youth athletes, especially those engaged in competitive sports that emphasize prepubertal or lean appearance, are at risk of developing relative energy deficiency in sport associated with disordered eating or eating disorders. Management strategies should address the complex conditions underlying functional hypothalamic hypogonadism.

  3. Human Immunodeficiency Virus Seroconversion and Associated ...

    African Journals Online (AJOL)

    posing therapeutic and prevention challenges, especially in developing countries ... countries where over 70% of the 35 million people living with. HIV reside.[1-4] In .... in Tanzania is based on the Venereal Disease Research. Laboratory test ...

  4. Conversion of linear time-invariant time-delay feedback systems into delay-differential equations with commensurate delays

    Science.gov (United States)

    Yamazaki, Tatsuya; Hagiwara, Tomomichi

    2014-08-01

    A new stability analysis method of time-delay systems (TDSs) called the monodromy operator approach has been studied under the assumption that a TDS is represented as a time-delay feedback system consisting of a finite-dimensional linear time-invariant (LTI) system and a pure delay. For applying this approach to TDSs described by delay-differential equations (DDEs), the problem of converting DDEs into representation as time-delay feedback systems has been studied. With regard to such a problem, it was shown that, under discontinuous initial functions, it is natural to define the solutions of DDEs in two different ways, and the above conversion problem was solved for each of these two definitions. More precisely, the solution of a DDE was represented as either the state of the finite-dimensional part of a time-delay feedback system or a part of the output of another time-delay feedback system, depending on which definition of the DDE solution one is talking about. Motivated by the importance in establishing a thorough relationship between time-delay feedback systems and DDEs, this paper discusses the opposite problem of converting time-delay feedback systems into representation as DDEs, including the discussions about the conversion of the initial conditions. We show that the state of (the finite-dimensional part of) a time-delay feedback system can be represented as the solution of a DDE in the sense of one of the two definitions, while its 'essential' output can be represented as that of another DDE in the sense of the other type of definition. Rigorously speaking, however, it is also shown that the latter representation is possible regardless of the initial conditions, while some initial condition could prevent the conversion into the former representation. This study hence establishes that the representation of TDSs as time-delay feedback systems possesses higher ability than that with DDEs, as description methods for LTI TDSs with commensurate delays.

  5. Mixed delay-independent/delay-dependent stability of uncertain linear time-delayed systems

    Institute of Scientific and Technical Information of China (English)

    LI Wenlin; DONG Rui

    2004-01-01

    @@ Consider uncertain linear time delay systems described by the following state equation: x(t)=[A0+Δ A0(t)]x(t)+∑ri=1[Ai+ΔAi(t)]x(t-τi).(1) x(t)=(t)t∈[-,0];=maxri=1{τi}(2) where Δ A0(*) and Δ Ai(*)(i=1,…,r) are real matrix functions.Δ Ai(t)=LiFi(t)Ei,ΔA0(t)=L0F0(t)E0, where Li,Ei are known real constant matrices and Fi(t) are unknown real time-varying matrices with Lebesgue measurable elements satisfying ‖Fi(t)‖I,t(i=0,1,…,r). In this note, we develop the methods of robust stability which is dependent on the size of some delays but independent on the size of the others and is based on the solution of linear matrix inequalities.

  6. Virtual unit delay for digital frequency adaptive T/4 delay phase-locked loop system

    DEFF Research Database (Denmark)

    Yang, Yongheng; Zhou, Keliang; Blaabjerg, Frede

    2016-01-01

    -controller/processor with a fixed sampling rate considering the cost and complexity, where the number of unit delays that have been adopted should be an integer. For instance, in conventional digital control systems, a single-phase T/4 Delay Phase-Locked Loop (PLL) system takes 50 unit delays (i.e., in a 50-Hz system...... Delay PLL system should be done in its implementation. This process will result in performance degradation in the digital control system, as the exactly required number of delays is not realized. Hence, in this paper, a Virtual Unit Delay (VUD) has been proposed to address such challenges to the digital...... T/4 Delay PLL system. The proposed VUD adopts linear interpolation polynomial to approximate the fractional delay induced by the varying grid frequency in such a way that the control performance is enhanced. The proposed VUD has been demonstrated on a digitally controlled T/4 Delay PLL system...

  7. Variable-delay feedback control of unstable steady states in retarded time-delayed systems

    CERN Document Server

    Gjurchinovski, Aleksandar; 10.1103/PhysRevE.81.016209

    2010-01-01

    We study the stability of unstable steady states in scalar retarded time-delayed systems subjected to a variable-delay feedback control. The important aspect of such a control problem is that time-delayed systems are already infinite-dimensional before the delayed feedback control is turned on. When the frequency of the modulation is large compared to the system's dynamics, the analytic approach consists of relating the stability properties of the resulting variable-delay system with those of an analogous distributed delay system. Otherwise, the stability domains are obtained by a numerical integration of the linearized variable-delay system. The analysis shows that the control domains are significantly larger than those in the usual time-delayed feedback control, and that the complexity of the domain structure depends on the form and the frequency of the delay modulation.

  8. Post-CTS Delay Insertion

    Directory of Open Access Journals (Sweden)

    Jianchao Lu

    2010-01-01

    clock skew operation is performed only at the clock sinks in order to preserve the structure and the optimizations implemented in the clock tree synthesis stage. The methodology is implemented as a linear programming model amenable to two design objectives: fixing timing violations or optimizing the clock period. Experimental results show that the clock networks of the largest ISCAS'89 circuits can be corrected post-CTS to resolve the timing conflicts in approximately 90% of the circuits with minimal delay insertion (0.159  ×  clock period per clock path on average. It is also shown that the majority of the clock period improvement achievable through unrestricted clock skew scheduling are obtained through very limited insertion (≈43% average improvement through 10% of max insertion.

  9. Transition delay using control theory.

    Science.gov (United States)

    Bagheri, S; Henningson, D S

    2011-04-13

    This review gives an account of recent research efforts to use feedback control for the delay of laminar-turbulent transition in wall-bounded shear flows. The emphasis is on reducing the growth of small-amplitude disturbances in the boundary layer using numerical simulations and a linear control approach. Starting with the application of classical control theory to two-dimensional perturbations developing in spatially invariant flows, flow control based on control theory has progressed towards more realistic three-dimensional, spatially inhomogeneous flow configurations with localized sensing/actuation. The development of low-dimensional models of the Navier-Stokes equations has played a key role in this progress. Moreover, shortcomings and future challenges, as well as recent experimental advances in this multi-disciplinary field, are discussed.

  10. Fuzzy delay model based fault simulator for crosstalk delay fault test generation in asynchronous sequential circuits

    Indian Academy of Sciences (India)

    S Jayanthy; M C Bhuvaneswari

    2015-02-01

    In this paper, a fuzzy delay model based crosstalk delay fault simulator is proposed. As design trends move towards nanometer technologies, more number of new parameters affects the delay of the component. Fuzzy delay models are ideal for modelling the uncertainty found in the design and manufacturing steps. The fault simulator based on fuzzy delay detects unstable states, oscillations and non-confluence of settling states in asynchronous sequential circuits. The fuzzy delay model based fault simulator is used to validate the test patterns produced by Elitist Non-dominated sorting Genetic Algorithm (ENGA) based test generator, for detecting crosstalk delay faults in asynchronous sequential circuits. The multi-objective genetic algorithm, ENGA targets two objectives of maximizing fault coverage and minimizing number of transitions. Experimental results are tabulated for SIS benchmark circuits for three gate delay models, namely unit delay model, rise/fall delay model and fuzzy delay model. Experimental results indicate that test validation using fuzzy delay model is more accurate than unit delay model and rise/fall delay model.

  11. Vitamin E treatment for children with chronic hepatitis B: A randomized placebo controlled trial

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    AIM: To evaluate the safety and efficacy of vitamin E in children with chronic hepatitis B. METHODS: We randomly assigned patients with chronic hepatitis B, positive for hepatitis B e antigen (HBeAg), to receive either vitamin E or placebo once daily for 6 mo in a 3:1 ratio and double-blind manner. The primary end point was HBeAg seroconversion, defined as the loss of HBeAg, undetectable levels of serum hepatitis B virus DNA, and the appearance of antibodies against HBeAg 12 rno after therapy. RESULTS: At baseline visit, 49 patients had normal and 43 had increased serum aminotransferase levels. Twenty-nine patients did not respond to previous treatment with interferon-α or lamivudine. Seventy-six children completed the study; 16 were non-compliant (n = 7), lost to follow-up (n = 7), or started another antiviral treatment (n = 3). Intention-to-treat analysis showed HBeAg seroconversion in 16 children (23.2%) treated with vitamin E and two (8.7%) in the placebo group (P = 0.13). Vitamin E was well tolerated. CONCLUSION: There is only a tendency that vitamin E may promote HBeAg seroconversion. Erefore larger studies are needed to clarify the role of antioxidants in the therapy of chronic hepatitis B.

  12. Dynamics of Nonlinear Time-Delay Systems

    CERN Document Server

    Lakshmanan, Muthusamy

    2010-01-01

    Synchronization of chaotic systems, a patently nonlinear phenomenon, has emerged as a highly active interdisciplinary research topic at the interface of physics, biology, applied mathematics and engineering sciences. In this connection, time-delay systems described by delay differential equations have developed as particularly suitable tools for modeling specific dynamical systems. Indeed, time-delay is ubiquitous in many physical systems, for example due to finite switching speeds of amplifiers in electronic circuits, finite lengths of vehicles in traffic flows, finite signal propagation times in biological networks and circuits, and quite generally whenever memory effects are relevant. This monograph presents the basics of chaotic time-delay systems and their synchronization with an emphasis on the effects of time-delay feedback which give rise to new collective dynamics. Special attention is devoted to scalar chaotic/hyperchaotic time-delay systems, and some higher order models, occurring in different bran...

  13. Modeling delayed processes in biological systems

    Science.gov (United States)

    Feng, Jingchen; Sevier, Stuart A.; Huang, Bin; Jia, Dongya; Levine, Herbert

    2016-09-01

    Delayed processes are ubiquitous in biological systems and are often characterized by delay differential equations (DDEs) and their extension to include stochastic effects. DDEs do not explicitly incorporate intermediate states associated with a delayed process but instead use an estimated average delay time. In an effort to examine the validity of this approach, we study systems with significant delays by explicitly incorporating intermediate steps. We show that such explicit models often yield significantly different equilibrium distributions and transition times as compared to DDEs with deterministic delay values. Additionally, different explicit models with qualitatively different dynamics can give rise to the same DDEs revealing important ambiguities. We also show that DDE-based predictions of oscillatory behavior may fail for the corresponding explicit model.

  14. Memorized discrete systems and time-delay

    CERN Document Server

    Luo, Albert C J

    2017-01-01

    This book examines discrete dynamical systems with memory—nonlinear systems that exist extensively in biological organisms and financial and economic organizations, and time-delay systems that can be discretized into the memorized, discrete dynamical systems. It book further discusses stability and bifurcations of time-delay dynamical systems that can be investigated through memorized dynamical systems as well as bifurcations of memorized nonlinear dynamical systems, discretization methods of time-delay systems, and periodic motions to chaos in nonlinear time-delay systems. The book helps readers find analytical solutions of MDS, change traditional perturbation analysis in time-delay systems, detect motion complexity and singularity in MDS; and determine stability, bifurcation, and chaos in any time-delay system.

  15. Delays in the management of retroperitoneal sarcomas

    DEFF Research Database (Denmark)

    Seinen, Jojanneke; Almquist, Martin; Styring, Emelie

    2010-01-01

    at the general practitioner, 36 days at local hospitals, and 55 days at the sarcoma centre. Conclusion. Centralization per se is not sufficient for optimized and efficient management. Our findings suggest that delays can be minimized by direct referral of patients from primary health care to sarcoma centers...... sarcoma in the southern Sweden health care region 2003-2009 were eligible for the study. Data on referrals and diagnostic investigations were collected from clinical files from primary health care, local hospitals, and from the sarcoma centre. Lead times were divided into patient delays and health care...... delays caused by primary health care, local hospitals, or procedures at the sarcoma centre. Results. Complete data were available from 33 patients and demonstrated a median patient delay of 23 days (0-17 months) and median health care delay of 94 days (1-40 months) with delays of median 15 days...

  16. Delays in the management of retroperitoneal sarcomas

    DEFF Research Database (Denmark)

    Seinen, Jojanneke; Almquist, Martin; Styring, Emelie

    2010-01-01

    at the general practitioner, 36¿days at local hospitals, and 55¿days at the sarcoma centre. Conclusion. Centralization per se is not sufficient for optimized and efficient management. Our findings suggest that delays can be minimized by direct referral of patients from primary health care to sarcoma centers...... sarcoma in the southern Sweden health care region 2003-2009 were eligible for the study. Data on referrals and diagnostic investigations were collected from clinical files from primary health care, local hospitals, and from the sarcoma centre. Lead times were divided into patient delays and health care...... delays caused by primary health care, local hospitals, or procedures at the sarcoma centre. Results. Complete data were available from 33 patients and demonstrated a median patient delay of 23¿days (0-17¿months) and median health care delay of 94¿days (1-40¿months) with delays of median 15¿days...

  17. Delay banking for air traffic management

    Science.gov (United States)

    Green, Steven M. (Inventor)

    2007-01-01

    A method and associated system for time delay banking for aircraft arrival time, aircraft departure time and/or en route flight position. The delay credit value for a given flight may decrease with passage of time and may be transferred to or traded with other flights having the same or a different user (airline owner or operator). The delay credit value for a given aircraft flight depends upon an initial delay credit value, which is determined by a central system and depends upon one or more other flight characteristics. Optionally, the delay credit value decreases with passage of time. Optionally, a transaction cost is assessed against a delay credit value that is used on behalf of another flight with the same user or is traded with a different user.

  18. Time Delay Estimation Algoritms for Echo Cancellation

    Directory of Open Access Journals (Sweden)

    Kirill Sakhnov

    2011-01-01

    Full Text Available The following case study describes how to eliminate echo in a VoIP network using delay estimation algorithms. It is known that echo with long transmission delays becomes more noticeable to users. Thus, time delay estimation, as a part of echo cancellation, is an important topic during transmission of voice signals over packetswitching telecommunication systems. An echo delay problem associated with IP-based transport networks is discussed in the following text. The paper introduces the comparative study of time delay estimation algorithm, used for estimation of the true time delay between two speech signals. Experimental results of MATLab simulations that describe the performance of several methods based on cross-correlation, normalized crosscorrelation and generalized cross-correlation are also presented in the paper.

  19. Phase changes in delay propagation networks

    CERN Document Server

    Belkoura, Seddik

    2016-01-01

    The analysis of the dynamics of delays propagation is one of the major topics inside Air Transport Management research. Delays are generated by the elements of the system, but their propagation is a global process fostered by relationships inside the network. If the topology of such propagation process has been extensively studied in the literature, little attention has been devoted to the fact that such topology may have a dynamical nature. Here we differentiate between two phases of the system by applying two causality metrics, respectively describing the standard phase (i.e. propagation of normal delays) and a disrupted one (corresponding to abnormal and unexpected delays). We identify the critical point triggering the change of the topology of the system, in terms of delays magnitude, using a historical data set of flights crossing Europe in 2011. We anticipate that the proposed results will open new doors towards the understanding of the delay propagation dynamics and the mitigation of extreme events.

  20. Study of hepatic histomorphology in HBeAg+ and HBeAg- patients with CHB:Experience from Bangladesh

    Institute of Scientific and Technical Information of China (English)

    Ayub Al Mamun; Mamun-Al-Mahtab; S M Fazle Akbar; Kutub Uddin Mollick; Arun Jyoti Tarafdar; Faiz Ahmad Khondokar; Ahmed Lutful Mubin; Md Helal Uddin; Salimur Rahman

    2013-01-01

    Objective:To compareKnodell andHAI scores in patients with wild type and pre-core/core promoter mutantCHB to see if there is any difference in severity of liver injury between these two types ofHBV.Methods:We did percutaneous liver biopsies of155CHB patients.Of them 102(65.8%) were infected wild typeHBV and the rest53(34.2%) were infected with pre-core/core promoter mutantCHB.Results:11/53(20.8%) patients with pre-core/core promoter mutant CHB had moderate to severeCH(HAI score8-18).In contrast, moderate to severeCH was seen in 19/102(18.6%) patients with wild typeCHB.Fibrosis score was >2 in15/53(28.3%) pre-core/core promoter mutantCHB as opposed to20/102(19.6%) patients with wild typeCHB.Conclusions:The study shows that pre-core/core promoter mutantHBV produces more severe histological liver disease compared to wild typeHBV.

  1. Prehospital delay in acute coronary syndrome--an analysis of the components of delay

    DEFF Research Database (Denmark)

    Ottesen, Michael Mundt; Dixen, Ulrik; Torp-Pedersen, Christian;

    2004-01-01

    more frequently atypical symptoms and increased prehospital delay caused by prolonged physician and transportation delay. Physician delay among women and men were 69 and 16 min, respectively. Patients with prior myocardial infarction had reduced prehospital delay, which was caused by shorter decision...... admitted with acute coronary syndrome is warranted. METHODS: A structured interview was conducted on 250 consecutive patients admitted alive with acute coronary syndrome. RESULTS: Median prehospital, decision, physician and transportation delays were 107, 74, 25 and 22 min, respectively. Women (n=77) had...... of acute coronary syndrome among women, and thereby contributes to unnecessary long delay to treatment. The patient's prior experience and interpretation has a significant influence on behaviour....

  2. Syphilis seroconversion among drug addicts during methadone maintenance treatment in Maanshan city,Anhui province: incidence and risk factors%马鞍山市吸毒者美沙酮维持期间梅毒血清阳转及危险因素的研究

    Institute of Scientific and Technical Information of China (English)

    徐建荣; 季必华; 秦其荣; 丁以星; 夏福林

    2014-01-01

    目的 了解美沙酮维持治疗期间吸毒者梅毒血清阳转的具体情况、特征,探讨与阳转相关的危险因素.方法 对马鞍山美沙酮门诊成立以来,治疗前梅毒血清阴性,保持治疗且随访梅毒血清2年以上的全部吸毒者,回顾梅毒血清阳转情况、特征,并对相关危险因素进行分析.结果 161例研究对象中,2年美沙酮维持治疗期间15例梅毒血清阳转,平均阳转率为4.66/100人年;梅毒血清阳转率呈前期高,后期低的特征;单因素x2分析和多因素Logistic回归分析结果显示,梅毒血清阳转与“治疗前最近一次性生活没有使用安全套”相关,差异有统计学意义.结论 美沙酮门诊应尽早对吸毒者进行安全性行为干预,早期推广安全套使用尤为重要,以更好阻断性传播途径.%Objective To evaluate the incidence of and risk factors for syphilis seroconversion amomg drug addicts during methadone maintenance treatment (MMT).Methods A retrospective study was performed on drug addicts receiving MMT at MMT clinics in Maanshan,who were seronegative for syphilis before the treatment and followed up by serological tests for syphilis for more than two years.The incidence of and risk factors for syphilis seroconversion during the two years of follow up were analyzed in all the subjects.Results A total of 161 drug addicts were included in this study,of whom,15 experienced seroconversion for syphilis with the average seroconversion rate being 4.66 per 100 person-years.The seroconversion tended to occurr in the early stage of MMT.Both Chi-square analysis and multivariate logistic regression analysis showed that syphilis seroconversion was independently associated with nonuse of condoms during the last sexual behavior before receiving MMT.Conclusions Interventions should be undertaken as early as possible to promote safe sexual behaviors among drug addicts at methadone clinics,and to promote condom use is especially important for blocking

  3. Time-delay and fractional derivatives

    OpenAIRE

    Tenreiro Machado JA

    2011-01-01

    This paper proposes the calculation of fractional algorithms based on time-delay systems. The study starts by analyzing the memory properties of fractional operators and their relation with time delay. Based on the Fourier analysis an approximation of fractional derivatives through time-delayed samples is developed. Furthermore, the parameters of the proposed approximation are estimated by means of genetic algorithms. The results demonstrate the feasibility of the new perspective.

  4. Treatment of bronchial ruptures by delayed surgery

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Objective:To study the causes that resulted in delayed surgery for bronchial ruptures and the results.Methods:The cases with the bronchial ruptures by the delayed surgery last decade were retrospectively reviewed.The causes and unsatisfactory results were analysed.Results:The severe complications usually occurred after the delayed surgery and the results were not as satisfactory as those by early surgery.Conclusion:The bronchial ruptures ought to be operated in the early stage after being wounded.

  5. Temperature Dependent Wire Delay Estimation in Floorplanning

    DEFF Research Database (Denmark)

    Winther, Andreas Thor; Liu, Wei; Nannarelli, Alberto;

    2011-01-01

    Due to large variations in temperature in VLSI circuits and the linear relationship between metal resistance and temperature, the delay through wires of the same length can be different. Traditional thermal aware floorplanning algorithms use wirelength to estimate delay and routability. In this w......Due to large variations in temperature in VLSI circuits and the linear relationship between metal resistance and temperature, the delay through wires of the same length can be different. Traditional thermal aware floorplanning algorithms use wirelength to estimate delay and routability...

  6. Angle-resolved time delay in photoemission

    CERN Document Server

    Wätzel, Jonas; Pavlyukh, Yaroslav; Berakdar, Jamal

    2014-01-01

    We investigate theoretically the relative time delay of photoelectrons originating from different atomic subshells of noble gases. This quantity was measured via attosecond streaking and studied theoretically by Schultze et al. [Science 328, 1658 (2010)] for neon. A substantial discrepancy was found between the measured and the calculated values of the relative time delay. Several theoretical studies were put forward to resolve this issue, e.g., by including correlation effects. In the present paper we explore a further aspect, namely the directional dependence of time delay. In contrast to neon, for argon target a strong angular dependence of time delay is found near a Cooper minimum.

  7. Dimensional reduction of nonlinear time delay systems

    Directory of Open Access Journals (Sweden)

    M. S. Fofana

    2005-01-01

    infinite-dimensional problem without the assumption of small time delay. This dimensional reduction is illustrated in this paper with the delay versions of the Duffing and van der Pol equations. For both nonlinear delay equations, transcendental characteristic equations of linearized stability are examined through Hopf bifurcation. The infinite-dimensional nonlinear solutions of the delay equations are decomposed into stable and centre subspaces, whose respective dimensions are determined by the linearized stability of the transcendental equations. Linear semigroups, infinitesimal generators, and their adjoint forms with bilinear pairings are the additional candidates for the infinite-dimensional reduction.

  8. Group Delay of High Q Antennas

    DEFF Research Database (Denmark)

    Bahramzy, Pevand; Pedersen, Gert Frølund

    2013-01-01

    become an issue, when working with high Q antennas, because of the steep phase shift over the frequency. In this paper, it is measured how large group delay variations can become, when going from a low Q antenna to a high Q antenna. The group delay of a low Q antenna is shown to be around 1.3 ns, whereas...... a high Q antenna has group delay of around 22 ns. It is due to this huge group delay variation characteristics of high Q antennas, that signal distortion might occur in the radio system with high Q antennas....

  9. Reducing Transmitted Vibration Using Delayed Hysteretic Suspension

    Directory of Open Access Journals (Sweden)

    Lahcen Mokni

    2011-01-01

    Full Text Available Previous numerical and experimental works show that time delay technique is efficient to reduce transmissibility of vibration in a single pneumatic chamber by controlling the pressure in the chamber. The present work develops an analytical study to demonstrate the effectiveness of such a technique in reducing transmitted vibrations. A quarter-car model is considered and delayed hysteretic suspension is introduced in the system. Analytical predictions based on perturbation analysis show that a delayed hysteretic suspension enhances vibration isolation comparing to the case where the nonlinear damping is delay-independent.

  10. Delay Computation Using Fuzzy Logic Approach

    Directory of Open Access Journals (Sweden)

    Ramasesh G. R.

    2012-10-01

    Full Text Available The paper presents practical application of fuzzy sets and system theory in predicting delay, with reasonable accuracy, a wide range of factors pertaining to construction projects. In this paper we shall use fuzzy logic to predict delays on account of Delayed supplies and Labor shortage. It is observed that the project scheduling software use either deterministic method or probabilistic method for computation of schedule durations, delays, lags and other parameters. In other words, these methods use only quantitative inputs leaving-out the qualitative aspects associated with individual activity of work. The qualitative aspect viz., the expertise of the mason or the lack of experience can have a significant impact on the assessed duration. Such qualitative aspects do not find adequate representation in the Project Scheduling software. A realistic project is considered for which a PERT chart has been prepared using showing all the major activities in reasonable detail. This project has been periodically updated until its completion. It is observed that some of the activities are delayed due to extraneous factors resulting in the overall delay of the project. The software has the capability to calculate the overall delay through CPM (Critical Path Method when each of the activity-delays is reported. We shall now demonstrate that by using fuzzy logic, these delays could have been predicted well in advance.

  11. Delay-range-dependent chaos synchronization approach under varying time-lags and delayed nonlinear coupling.

    Science.gov (United States)

    Zaheer, Muhammad Hamad; Rehan, Muhammad; Mustafa, Ghulam; Ashraf, Muhammad

    2014-11-01

    This paper proposes a novel state feedback delay-range-dependent control approach for chaos synchronization in coupled nonlinear time-delay systems. The coupling between two systems is esteemed to be nonlinear subject to time-lags. Time-varying nature of both the intrinsic and the coupling delays is incorporated to broad scope of the present study for a better-quality synchronization controller synthesis. Lyapunov-Krasovskii (LK) functional is employed to derive delay-range-dependent conditions that can be solved by means of the conventional linear matrix inequality (LMI)-tools. The resultant control approach for chaos synchronization of the master-slave time-delay systems considers non-zero lower bound of the intrinsic as well as the coupling time-delays. Further, the delay-dependent synchronization condition has been established as a special case of the proposed LK functional treatment. Furthermore, a delay-range-dependent condition, independent of the delay-rate, has been provided to address the situation when upper bound of the delay-derivative is unknown. A robust state feedback control methodology is formulated for synchronization of the time-delay chaotic networks against the L2 norm bounded perturbations by minimizing the L2 gain from the disturbance to the synchronization error. Numerical simulation results are provided for the time-delay chaotic networks to show effectiveness of the proposed delay-range-dependent chaos synchronization methodologies. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

  12. 北京市男男性行为者HIV和梅毒螺旋体血清抗体阳转率及影响因素%Incidence and risk factors of HIV and syphilis seroconversion among men who have sex with men in Beijing

    Institute of Scientific and Technical Information of China (English)

    李书明; 邵一鸣; 周振海; 姜树林; 刘英杰; 李东亮; 张政; 张晓曦; 罗凤基; 阮玉华

    2011-01-01

    目的 了解北京市男男性行为者(MSM)的HIV和梅毒螺旋体血清抗体阳转情况及其影响因素. 方法 在北京市以社区为基础招募HIV阴性的MSM共525名,以一对一的方式进行问卷调查,收集人口学和行为学情况资料,在第6、12个月进行随访,并采集血样进行HIV和梅毒螺旋体抗体检测,初筛均采用ELISA法,确证分别采用蛋白印迹(WB)和凝集法. 结果 基线共调查550名,HIV和梅毒螺旋体血清抗体阳性率分别为4.5%(25/550)和29.3%(161/550),HIV血清抗体阴性队列525名,随访12个月,队列保持率为87.0%(457/525),HIV和梅毒螺旋体血清抗体阳转率分别为3.37/100人年和9.32/100人年.近3个月同性性行为后冲洗直肠者阳转率为7.11/100人年,未冲洗者为0.76/100人年,冲洗与HIV血清抗体阳转相关(HR=9.23,95%CI=2.08~40.88).近3个月在公园、公厕或浴池寻找男性性伴者阳转率为41.77/100人年,无该行为者阳转率为7.97/100人年;近3个月同性性行为后冲洗直肠者阳转率为16.17/100人年,无该行为者阳转率为4.92/100人年;近3个月在公园、公厕或浴池寻找男性性伴(HR=4.67,95%CI=1.77~12.34)和近3个月同性性行为后冲洗直肠(HR=3.09,95%CI=1.40~6.83)与梅毒螺旋体血清抗体阳转相关. 结论 北京市MSM的HIV和梅毒螺旋体血清抗体阳转情况十分严重,主要影响因素为同性性行为后冲洗直肠、到公园等场所寻找男性性伴.%Objective To study the incidence and risk factors of HIV and syphilis seroconversion among men who have sex with men(MSM) in Beijing. Methods A total of 550 MSM were recruited on the basis of community and followed up after 6 and 12 months in Beijing.Each subject was investigated by only one investigator at one time to collect information on demographics and behaviors.Blood samples were collected to test HIV and syphilis seroconversion.ELISA was used for screening test,west blotting(WB) and Particle agglutination were used

  13. 深圳市男男性行为人群HIV梅毒及HCV新发感染的队列研究%A prospective cohort study on HIV, syphilis and HCV seroconversion among men who have sex with men in Shenzhen

    Institute of Scientific and Technical Information of China (English)

    赵锦; 蔡文德; 陈珠蝶; 刘少础; 张燕; 甘永霞; 陈琳; 程锦泉

    2011-01-01

    目的 了解深圳市男男性行为人群(MSM)艾滋病病毒(HIV)、梅毒及丙型肝炎病毒(HCV)抗体阳转情况.方法 依托深圳市每年开展的时间场所抽样结合同伴推动抽样方法,于2009年5月招募325名MSM为前瞻性研究队列,在基线和一年随访时调查其高危行为情况,并采集血样检测HIV、梅毒和HCV抗体.结果 队列随访一年,MSM队列保持率仅为56.2%,HIV血清抗体阳转率为4.44/100人年,梅毒阳转率为7.00/100人年,HCV血清抗体阳转率为1.61/100人年.结论 深圳市MSM人群HIV、梅毒以及HCV的新发感染率均比较高,应考虑在现有干预方案基础上增加针对性的有效干预措施.%Objective To study the incidence rate of human immunodeficiency virus (HIV) , syphilis and hepatitis C virus (HCV) seroconversion among men who have sex with men (MSM) in Shenzhen. Methods MSM were enrolled by methods of time-location sampling and respondent-driven sampling , and 325 MSM were recruited as baseline samples for a prospective cohort study. Annual follow-up visits were carried out to identify the high risk behaviors and blood samples were taken for testing the antibodies against HIV, syphilis and HCV. Results During one year follow-up , cohort retention rate was 56. 2%. The incidence rate of HIV seroconversion was 4. 44/100 person-years, syphilis - 7. 00/100 person-years, and HCV seroconversion - 1. 61/100 person-years. Conclusion The incidences of both HIV and syphilis as well as HCV seroconversion are comparatively high among MSM in Shenzhen. More effective measures should be implemented to reduce the infection rate in this population group.

  14. Delayed umbilical cord clamping in premature neonates.

    Science.gov (United States)

    Kaempf, Joseph W; Tomlinson, Mark W; Kaempf, Andrew J; Wu, YingXing; Wang, Lian; Tipping, Nicole; Grunkemeier, Gary

    2012-08-01

    Delayed umbilical cord clamping is reported to increase neonatal blood volume. We estimated the clinical outcomes in premature neonates who had delayed umbilical cord clamping compared with a similar group who had early umbilical cord clamping. This was a before-after investigation comparing early umbilical cord clamping with delayed umbilical cord clamping (45 seconds) in two groups of singleton neonates, very low birth weight (VLBW) (401-1,500 g) and low birth weight (LBW) (greater than 1,500 g but less than 35 weeks gestation). Neonates were excluded from delayed umbilical cord clamping if they needed immediate major resuscitation. Primary outcomes were provision of delivery room resuscitation, hematocrit, red cell transfusions, and the principle Vermont Oxford Network outcomes. In VLBW neonates (77 delayed umbilical cord clamping, birth weight [mean±standard deviation] 1,099±266 g; 77 early umbilical cord clamping 1,058±289 g), delayed umbilical cord clamping was associated with less delivery room resuscitation, higher Apgar scores at 1 minute, and higher hematocrit. Delayed umbilical cord clamping was not associated with significant differences in the overall transfusion rate, peak bilirubin, any of the principle Vermont Oxford Network outcomes, or mortality. In LBW neonates (172 delayed umbilical cord clamping, birth weight [mean±standard deviation] 2,159±384 g; 172 early umbilical cord clamping 2,203±447 g), delayed umbilical cord clamping was associated with higher hematocrit and was not associated with a change in delivery room resuscitation or Apgar scores or with changes in the transfusion rate or peak bilirubin. Regression analysis showed increasing gestational age and birth weight and delayed umbilical cord clamping were the best predictors of higher hematocrit and less delivery room resuscitation. Delayed umbilical cord clamping can safely be performed in singleton premature neonates and is associated with a higher hematocrit, less delivery room

  15. Delay Banking for Managing Air Traffic

    Science.gov (United States)

    Green, Steve

    2008-01-01

    Delay banking has been invented to enhance air-traffic management in a way that would increase the degree of fairness in assigning arrival, departure, and en-route delays and trajectory deviations to aircraft impacted by congestion in the national airspace system. In delay banking, an aircraft operator (airline, military, general aviation, etc.) would be assigned a numerical credit when any of their flights are delayed because of an air-traffic flow restriction. The operator could subsequently bid against other operators competing for access to congested airspace to utilize part or all of its accumulated credit. Operators utilize credits to obtain higher priority for the same flight, or other flights operating at the same time, or later, in the same airspace, or elsewhere. Operators could also trade delay credits, according to market rules that would be determined by stakeholders in the national airspace system. Delay banking would be administered by an independent third party who would use delay banking automation to continually monitor flights, allocate delay credits, maintain accounts of delay credits for participating airlines, mediate bidding and the consumption of credits of winning bidders, analyze potential transfers of credits within and between operators, implement accepted transfers, and ensure fair treatment of all participating operators. A flow restriction can manifest itself in the form of a delay in assigned takeoff time, a reduction in assigned airspeed, a change in the position for the aircraft in a queue of all aircraft in a common stream of traffic (e.g., similar route), a change in the planned altitude profile for an aircraft, or change in the planned route for the aircraft. Flow restrictions are typically imposed to mitigate traffic congestion at an airport or in a region of airspace, particularly congestion due to inclement weather, or the unavailability of a runway or region of airspace. A delay credit would be allocated to an operator of a

  16. Delay-dependent robust passivity control for uncertain time-delay systems

    Institute of Scientific and Technical Information of China (English)

    Li Guifang; Li Huiying; Yang Chengwu

    2007-01-01

    The robust passivity control problem is addressed for a class of uncertain delayed systems with timevarying delay. The parameter uncertainties are norm-bounded. First, the delay-dependent stability sufficient condition is obtained for the nominal system, and then, based-on the former, the delay-dependent robust passivity criteria is provided and the corresponding controller is designed in terms of linear matrix inequalities. Finally, a numerical example is given to demonstrate the validity of the proposed approach.

  17. Delay-dependent state feedback robust stabilization for uncertain singular time-delay systems

    Institute of Scientific and Technical Information of China (English)

    Gao Huanli; Xu Bugong

    2008-01-01

    The problem of robust stabilization for uncertain singular time-delay systems is studied.First,a new delay-dependent asymptotic stability criteria for normal singular time-delay systems is given,which is less conservative.Using this result,the problem of state feedback robust stabilization for uncertain singular time-delay systems is discussed.Finally,two examples are given to illustrate the effectiveness of the results.

  18. Factors in delayed muscle soreness.

    Science.gov (United States)

    Abraham, W M

    1977-01-01

    The possible causes of delayed muscle soreness which occur 24 to 48 hr after exercise were examined from three different approaches, each designed to test an existing hypothesis. Surface electromyograms were used to evaluate the muscle spasm theory; the possibility of actual muscle cell damage was monitored by the presence of myoglobinuria, while the ratio of hydroxyproline/creatinine (OHP/Cr) in 24 hr urine collection was used as a marker for connective tissue involvement. In the first study, although all volunteers developed muscle soreness 24 and 48 hr after exercise, no change in the EMG activity of the sore muscles was observed. Myoglobin excretion was found in 88% of the subjects who developed soreness. However, in a second study, 92% of the subject who performed both moderate and heavy exercise but did not develop muscle soreness had myoglobinuria. In contrast, during a third experiment subjects on gelatin-free diets showed an increase (P less than .1) in the OHP/Cr between control (.020+/-.001) and 48 hr post-exercise (.002+/-.001, X+/-SE). Soreness resulted in all cases. When the OHP/Cr value is taken for the day of maximal soreness, the post-exercise mean increases to .024+/-.001 and the level of significance rises (P less than .005). These observations support the concept that exercise induced soreness may be related to disruption of the connective tissue elements in the muscle and/or their attachments.

  19. Space object tracking with delayed measurements

    Science.gov (United States)

    Chen, Huimin; Shen, Dan; Chen, Genshe; Blasch, Erik; Pham, Khanh

    2010-04-01

    This paper is concerned with the nonlinear filtering problem for tracking a space object with possibly delayed measurements. In a distributed dynamic sensing environment, due to limited communication bandwidth and long distances between the earth and the satellites, it is possible for sensor reports to be delayed when the tracking filter receives them. Such delays can be complete (the full observation vector is delayed) or partial (part of the observation vector is delayed), and with deterministic or random time lag. We propose an approximate approach to incorporate delayed measurements without reprocessing the old measurements at the tracking filter. We describe the optimal and suboptimal algorithms for filter update with delayed measurements in an orbital trajectory estimation problem without clutter. Then we extend the work to a single object tracking under clutter where probabilistic data association filter (PDAF) is used to replace the recursive linear minimum means square error (LMMSE) filter and delayed measurements with arbitrary lags are be handled without reprocessing the old measurements. Finally, we demonstrate the proposed algorithms in realistic space object tracking scenarios using the NASA General Mission Analysis Tool (GMAT).

  20. ANALYSING SURFACE MOVEMENT DELAYS IN AN AIRPORT

    Directory of Open Access Journals (Sweden)

    Volodymyr Kharchenko

    2014-07-01

    Full Text Available Queuing effect can be in the different components of ground operations. Causes of surface – movement delays are long taxi – in and taxi – out operations during departure and arrival of aircraft. Surface movement delays in an airport are analyzed

  1. Minimizing the Delay at Traffic Lights

    Science.gov (United States)

    Van Hecke, Tanja

    2009-01-01

    Vehicles holding at traffic lights is a typical queuing problem. At crossings the vehicles experience delay in both directions. Longer periods with green lights in one direction are disadvantageous for the vehicles coming from the other direction. The total delay for getting through the traffic point is what counts. This article presents an…

  2. Delay synchronization of temporal Boolean networks

    Science.gov (United States)

    Wei, Qiang; Xie, Cheng-jun; Liang, Yi; Niu, Yu-jun; Lin, Da

    2016-01-01

    This paper investigates the delay synchronization between two temporal Boolean networks base on semi-tensor product method, which improve complete synchronization. Necessary and sufficient conditions for delay synchronization are drawn base on algebraic expression of temporal Boolean networks. A example is presented to show the effectiveness of theoretical analysis.

  3. Estimating Time Delays With Antenna Array

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This paper discusses the problem of estimating the time delays of multipath signals in wireless communications. The new multipath channel model is presented. And based on this new channel model, we generalize the classical MUSIC algorithm to estimate the time delays of multipath signals. Simulation examples are included to illustrate the algorithm performance.

  4. Comment on "Time delays in molecular photoionization"

    CERN Document Server

    Baykusheva, D

    2016-01-01

    In a recent article by P. Hockett \\textit{et al.}, time delays arising in the context of molecular single-photon ionization are investigated from a theoretical point of view. We argue that one of the central equations derived in the paper is incorrect and present a reformulation that is consistent with the established treatment of angle-dependent scattering delays.

  5. Broadband hyperchaotic oscillator with delay line

    DEFF Research Database (Denmark)

    Cenys, Antanas; Lindberg, Erik; Anagnostopoulos, A. N.;

    2002-01-01

    Dynamical systems with time delay can be employed as high dimensional hyperchaotic oscillators with multiple positive Lyapunov exponents. We describe an electronic circuit composed of a 3-stage amplifier and a delay line in the feedback loop. The 1st stage of the amplifier is a nonlinear one while...

  6. Controllability of delay systems with restrained controls

    Science.gov (United States)

    Chukwu, E. N.

    1979-01-01

    Using a geometric growth condition, both the function space and Euclidean controllability of a nonlinear delay system which has a compact and convex control set are characterized. This extends analogous results for ordinary differential systems, and it yields conditions under which perturbed nonlinear delay controllable systems are controllable.

  7. Diagnostic Delay in Women with Endometriosis

    Institute of Scientific and Technical Information of China (English)

    Xiao-man Ding; Jing-he Lang

    2005-01-01

    @@ Women affected by endometriosis claim that delayed diagnosis of endometriosis is a great problem. Studies have shown a delay from 3 to 11 years between the onset of pain symptom and the final diagnosis of endometriosis. But the diagnostic time of Chinese patients has not been reported.

  8. Test Anxiety and Academic Delay of Gratification

    Science.gov (United States)

    Bembenutty, Hefer

    2009-01-01

    The present study examined the relationship between college students' willingness to delay gratification, motivation, self-regulation of learning, and their level of test anxiety (N = 364). Academic delay of gratification refers to students' postponement of immediately available opportunities to satisfy impulses in favor of pursuing academic…

  9. [Delayed asthma bronchiale due to epoxy resin].

    Science.gov (United States)

    Authried, Georg; Al-Asadi, Haifaa; Møller, Ulla; Sherson, David Lee

    2013-10-28

    Epoxy resin is a low molecular weight agent, which can cause both acute and delayed allergic reactions. However, it is known causing skin reactions with direct or airborne contact. Rarely it can cause airway reactions like asthma bronchiale. We describe a case of a windmill worker who developed delayed asthma bronchiale due to airborne contact with epoxy resin.

  10. Analyzing delay causes in Egyptian construction projects

    Directory of Open Access Journals (Sweden)

    Mohamed M. Marzouk

    2014-01-01

    Full Text Available Construction delays are common problems in civil engineering projects in Egypt. These problems occur frequently during project life-time leading to disputes and litigation. Therefore, it is essential to study and analyze causes of construction delays. This research presents a list of construction delay causes retrieved from literature. The feedback of construction experts was obtained through interviews. Subsequently, a questionnaire survey was prepared. The questionnaire survey was distributed to thirty-three construction experts who represent owners, consultants, and contractor’s organizations. Frequency Index, Severity Index, and Importance Index are calculated and according to the highest values of them the top ten delay causes of construction projects in Egypt are determined. A case study is analyzed and compared to the most important delay causes in the research. Statistical analysis is carried out using analysis of variance ANOVA method to test delay causes, obtained from the survey. The test results reveal good correlation between groups while there is significant difference between them for some delay causes and finally roadmap for prioritizing delay causes groups is presented.

  11. Analyzing delay causes in Egyptian construction projects.

    Science.gov (United States)

    Marzouk, Mohamed M; El-Rasas, Tarek I

    2014-01-01

    Construction delays are common problems in civil engineering projects in Egypt. These problems occur frequently during project life-time leading to disputes and litigation. Therefore, it is essential to study and analyze causes of construction delays. This research presents a list of construction delay causes retrieved from literature. The feedback of construction experts was obtained through interviews. Subsequently, a questionnaire survey was prepared. The questionnaire survey was distributed to thirty-three construction experts who represent owners, consultants, and contractor's organizations. Frequency Index, Severity Index, and Importance Index are calculated and according to the highest values of them the top ten delay causes of construction projects in Egypt are determined. A case study is analyzed and compared to the most important delay causes in the research. Statistical analysis is carried out using analysis of variance ANOVA method to test delay causes, obtained from the survey. The test results reveal good correlation between groups while there is significant difference between them for some delay causes and finally roadmap for prioritizing delay causes groups is presented.

  12. Stabilization of a Nonlinear Delay System

    Directory of Open Access Journals (Sweden)

    Walid Arouri

    2012-01-01

    Full Text Available Problem statement: The analysis and control of delayed systems are becoming more and more research topics in progress. This is mainly due to the fact that the delay is frequently encountered in technological systems. This can affect their significantly operations. Most control command laws are based on current digital computers and delays are intrinsic to the process or in the control loop caused by the transmission time control sequences, or computing time. The delay may affect one or more states of the considered system. It may also affect the establishment of the command. Several studies have investigated the stability of delay systems under the assumption that the delay is a variable phenomenon; such variation is considered to be bounded or limited to facilitate analysis of the system. In this study we propose a modelling of delayed system by using the multimodels and switched system theory. The analysis of stability is based on the use of second Lyapunov method. The issued stability conditions are expressed as Bilinear Matrix Inequalities impossible to resolve. That’s why we propose the same original relaxations to come over this difficulty, an example of induction machine is given to illustrate over approach. Approach: We propose to use the control theory developed for switched systems to synthesis a control laws for the stabilisation of delays system. Results: We stabilize the induction machine around many operating points despite the non linearities. Conclusion: The developed method is less conservative and less pessimistic than the used classical methods.

  13. Delayed biodiversity change: no time to waste.

    Science.gov (United States)

    Essl, Franz; Dullinger, Stefan; Rabitsch, Wolfgang; Hulme, Philip E; Pyšek, Petr; Wilson, John R U; Richardson, David M

    2015-07-01

    Delayed biodiversity responses to environmental forcing mean that rates of contemporary biodiversity changes are underestimated, yet these delays are rarely addressed in conservation policies. Here, we identify mechanisms that lead to such time lags, discuss shifting human perceptions, and propose how these phenomena should be addressed in biodiversity management and science.

  14. Congenital rubella syndrome and delayed manifestations

    DEFF Research Database (Denmark)

    Dammeyer, Jesper Herup

    2010-01-01

    Objective: Several hypotheses of different medical and psychological delayed manifestations among people who have congenital rubella syndrome (CRS) have been discussed. This study tests some of these hypotheses of delayed manifestations. Methods: Gathering information about 35 individuals who hav...... which people with CRS face must primarily be understood in relation to congenital deafblindness and dual sensory and communicative deprivation....

  15. Discounting of Delayed Rewards Is Not Hyperbolic

    Science.gov (United States)

    Luhmann, Christian C.

    2013-01-01

    Delay discounting refers to decision-makers' tendency to value immediately available goods more than identical goods available only after some delay. In violation of standard economic theory, decision-makers frequently exhibit dynamic inconsistency; their preferences change simply due to the passage of time. The standard explanation for this…

  16. On Delay and Security in Network Coding

    Science.gov (United States)

    Dikaliotis, Theodoros K.

    2013-01-01

    In this thesis, delay and security issues in network coding are considered. First, we study the delay incurred in the transmission of a fixed number of packets through acyclic networks comprised of erasure links. The two transmission schemes studied are routing with hop-by-hop retransmissions, where every node in the network simply stores and…

  17. Improved delay-dependent exponential stability for uncertain stochastic neural networks with time-varying delays

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, O.M., E-mail: madwind@chungbuk.ac.k [School of Electrical Engineering, Chungbuk National University, Cheongju (Korea, Republic of); Lee, S.M., E-mail: moony@daegu.ac.k [School of Electronics Engineering, Daegu University, Kyongsan (Korea, Republic of); Park, Ju H., E-mail: jessie@ynu.ac.k [Department of Electrical Engineering, Yeungnam University, Kyongsan (Korea, Republic of)

    2010-02-22

    This Letter investigates the problem of delay-dependent exponential stability analysis for uncertain stochastic neural networks with time-varying delay. Based on the Lyapunov stability theory, improved delay-dependent exponential stability criteria for the networks are established in terms of linear matrix inequalities (LMIs).

  18. Delay in the diagnosis of cancer

    DEFF Research Database (Denmark)

    Hansen, Rikke Pilegaard

    of delay is described and an operational definition and a review of the literature of delay are presented. Then follows a description of the methods for assessing delay and the results of a descriptive study of delay (Article 1) and three studies of the associations between delay and patients...... for a detailed description of the patients' diagnostic pathways, allowing the researchers to draw the time line from symptom onset to treatment start, and to describe the characteristics of the patients and the GPs. Existing scales were used whenever possible; otherwise, ad hoc questions were constructed...... in the study. The chapter addresses issues of data and study validity, and the precision of the study. Data validity is discussed in relation to study design, data collection, data quality and statistical analyses. Study validity is discussed in terms of precision, and internal and external validity...

  19. Photonic Quantum Circuits with Time Delays

    CERN Document Server

    Pichler, Hannes

    2015-01-01

    We study the dynamics of photonic quantum circuits consisting of nodes coupled by quantum channels. We are interested in the regime where time delay in communication between the nodes is significant. This includes the problem of quantum feedback, where a quantum signal is fed back on a system with a time delay. We develop a matrix product state approach to solve the Quantum Stochastic Schr\\"odinger Equation with time delays, which accounts in an efficient way for the entanglement of nodes with the stream of emitted photons in the waveguide, and thus the non-Markovian character of the dynamics. We illustrate this approach with two paradigmatic quantum optical examples: two coherently driven distant atoms coupled to a photonic waveguide with a time delay, and a driven atom coupled to its own output field with a time delay as an instance of a quantum feedback problem.

  20. Stochastic thermodynamics for delayed Langevin systems.

    Science.gov (United States)

    Jiang, Huijun; Xiao, Tiejun; Hou, Zhonghuai

    2011-06-01

    We discuss stochastic thermodynamics (ST) for delayed Langevin systems in this paper. By using the general principles of ST, the first-law-like energy balance and trajectory-dependent entropy s(t) can be well defined in a way that is similar to that in a system without delay. Because the presence of time delay brings an additional entropy flux into the system, the conventional second law (Δs(tot))≥0 no longer holds true, where Δs(tot) denotes the total entropy change along a stochastic path and (·) stands for the average over the path ensemble. With the help of a Fokker-Planck description, we introduce a delay-averaged trajectory-dependent dissipation functional η[χ(t)] which involves the work done by a delay-averaged force F(x,t) along the path χ(t) and equals the medium entropy change Δs(m)[x(t)] in the absence of delay. We show that the total dissipation functional R=Δs+η, where Δs denotes the system entropy change along a path, obeys (R)≥0, which could be viewed as the second law in the delayed system. In addition, the integral fluctuation theorem (e(-R))=1 also holds true. We apply these concepts to a linear Langevin system with time delay and periodic external force. Numerical results demonstrate that the total entropy change (Δs(tot)) could indeed be negative when the delay feedback is positive. By using an inversing-mapping approach, we are able to obtain the delay-averaged force F(x,t) from the stationary distribution and then calculate the functional R as well as its distribution. The second law (R)≥0 and the fluctuation theorem are successfully validated.

  1. Delay-dependent observer-based stabilizing controller design for linear multiple state-delayed systems

    Institute of Scientific and Technical Information of China (English)

    Dejin WANG

    2003-01-01

    This article concerns a coupled LMIs approach to delay-dependent observer-based output feedback stabilizing controller design for linear continuous-time systems with multiple state delays. The advantage of our proposed delay-dependent coupled LMIs criterion lies in that: (1) it can optimize one of multiple time delays with others selected properly, and at the same time, the feedback-gain and observer-gain can be obtained, respectively. (2) it is less conservative than the existing delay-independent ones in the literature. Algorithm to solve the coupled LMIs is also given. Numerical examples illustrate the effectiveness of our method.

  2. Isochronal synchronization of time delay and delay-coupled chaotic systems

    Energy Technology Data Exchange (ETDEWEB)

    Grzybowski, J M V; Yoneyama, T [Instituto Tecnologico de Aeronautica, ITA, Praca Marechal Eduardo Gomes, 50, Vila das Acacias, Sao Jose dos Campos, SP, Brazil, CEP 12.228-900 (Brazil); Macau, E E N, E-mail: zzmariovic@yahoo.com.br, E-mail: elbert@lac.inpe.br, E-mail: takashi@ita.br [Instituto Nacional de Pesquisas Espaciais, INPE, PO Box 515, Sao Jose dos Campos, SP, Brazil, CEP 12.227-010 (Brazil)

    2011-04-29

    This paper studies the problem of isochronal synchronization of time-delay chaotic systems featuring also coupling delay. Based on the Lyapunov-Krasovskii stability theory, sufficient conditions are derived for the stability of isochronal synchronization between a pair of identical chaotic systems. Such criteria permit the proper design of stable proportional linear feedback controller, more specifically, the design of adequate proportional feedback gain matrices. The proposed criteria are suited to systems with (i) intrinsic delay, (ii) coupling delay or (iii) both. Numerical simulations of the synchronization of delay-coupled systems are presented as examples of the application of the criteria.

  3. A novel approach to delay-fractional-dependent stability criterion for linear systems with interval delay.

    Science.gov (United States)

    An, Jiyao; Li, Zhiyong; Wang, Xiaomei

    2014-03-01

    This paper considers the problem of delay-fractional-dependent stability analysis of linear systems with interval time-varying state delay. By developing a delay variable decomposition approach, both the information of the variable dividing subinterval delay, and the information of the lower and upper bound of delay can be taken into full consideration. Then a new delay-fractional-dependent stability criterion is derived without involving any direct approximation in the time-derivative of the Lyapunov-Krasovskii (LK) functional via some suitable Jensen integral inequalities and convex combination technique. The merits of the proposed result lie in less conservatism, which are realized by choosing different Lyapunov matrices in the variable delay subintervals and estimating the upper bound of some cross term in LK functional more exactly. At last, two well-known numerical examples are employed to show the effectiveness and less conservatism of the proposed method.

  4. Delayed diagnosis of narcolepsy: characterization and impact.

    Science.gov (United States)

    Thorpy, Michael J; Krieger, Ana C

    2014-05-01

    Narcolepsy, a chronic neurologic condition resulting from dysregulation of the sleep-wake cycle, usually has an onset at an early age. However, a long delay until diagnosis has been consistently reported in the literature across countries and several publications have focused on characterizing this delay. Most studies report a mean delay to diagnosis of up to 15 years, with individual cases of >60 years, although a trend over time toward a shorter diagnostic delay has been suggested. While variables associated with this delay have been identified, a lack of symptom recognition resulting in misdiagnosis prior to reaching the narcolepsy diagnosis is the likely underlying reason. This lack of symptom recognition is especially relevant considering the high comorbidity burden that has been shown in patients with narcolepsy as some disorders manifest with symptoms that overlap with narcolepsy. A consequence of delayed diagnosis is delayed treatment, which affects the burden of disease. Substantial detrimental effects on health-care resource utilization, employment, and quality of life have been described after narcolepsy onset and prior to the diagnosis of narcolepsy. This review highlights the importance of closing the diagnostic gap by expanding awareness of narcolepsy and its symptoms.

  5. Spin-orbit delays in photoemission

    Science.gov (United States)

    Jordan, I.; Huppert, M.; Pabst, S.; Kheifets, A. S.; Baykusheva, D.; Wörner, H. J.

    2017-01-01

    Attosecond delays between photoelectron wave packets emitted from different electronic shells are now well established. Is there any delay between electrons originating from the same electronic shell but leaving the cation in different fine-structure states? This question is relevant for all attosecond photoemission studies involving heavy elements, be it atoms, molecules or solids. We answer this fundamental question by measuring energy-dependent delays between photoelectron wave packets associated with the 3/2 2P and 1/2 2P components of the electronic ground states of Xe+ and Kr+. We observe delays reaching up to 33 ±6 as in the case of Xe. Our results are compared with two state-of-the-art theories. Whereas both theories quantitatively agree with the results obtained for Kr, neither of them fully reproduces the experimental results in Xe. Performing delay measurements very close to the ionization thresholds, we compare the agreement of several analytical formulas for the continuum-continuum delays with experimental data. Our results show an important influence of spin-orbit coupling on attosecond photoionization delays, highlight the requirement for additional theory development, and offer a precision benchmark for such work.

  6. Delays in Building Construction Projects in Ghana

    Directory of Open Access Journals (Sweden)

    Adwoa B Agyakwah-Baah

    2010-07-01

    Full Text Available This study investigates the causes of delay of building construction projects in Ghana to determine the most important according to the key project participants; clients, consultants, and contractors. Thirty-two possible causes of delay were identified from the literature and semi-structured interviews of 15 key players in the implementation process. These delay factors were further categorised into nine major groups. The list of delay causes was subjected to a questionnaire survey for the identification of the most important causes of delay. The field survey included 130 respondents made up of 39 contractors, 37 clients and 54 consultants. The relative importance of the individual causes and the groups were calculated and ranked by their relative importance index. The overall results of the study indicate that the respondents generally agree that financial group factors ranked highest among the major factors causing delay in construction projects in Ghana. The financial group factors were delay in honouring payment certificates, difficulty in accessing credit and fluctuation in prices. Materials group factors are second followed by scheduling and controlling factors.

  7. Analysis on sero-conversion status of HIV-discordant spouse from 2006-2010 in Henan province%河南省2006-2010年艾滋病单方阳性配偶阳转状况分析

    Institute of Scientific and Technical Information of China (English)

    李洁; 马彦民; 孙定勇; 朱谦; 王哲

    2012-01-01

    Objective To study the management status of HIV-discordant family in Henan province from 2006 to 2010.Methods Data on AIDS infected family from “AIDS Infected Family Follow-up Management and Analysis System” was collected and analized to uderstand the management status of HIV-discordant situation.Results The sero-conversion rates of HIV-discordant spouse were 1.94/100 person-years in 2006,1.79/100 person-years in 2007,0.59/100 person- years in 2008 and 0.41/100 person-years in 2009,showing the yearly decrease.Regarding the number of sero-conversion in the same year,male was significantly higher than female in 2007,but not in the other years.The ratio on the course of sero-conversion which was >2.5 years was increasing.Frequency of most HIV-discordant couples' sexual activities was 1-4 times/month with consistent use of condoms.Conclusion The population of HIV-discordant spouse in Henan province was stable.Regarding management of those HIV-discordant spouse,the acceptance on the rate of test rate was increasing.The course of sero-conversion was also increasing,with most HIV-discordant couples insist on condom use while the sero-conversion rate of HIV-discordant spouse appeared to be low.%目的 了解2006-2010年河南省艾滋病单方阳性配偶管理状况及阳转情况.方法 通过“河南省艾滋病感染家庭随访管理分析系统”收集2006-2010年全省艾滋病单方感染家庭相关资料,对单方阳性配偶管理状况及阳转情况进行分析.结果 河南省艾滋病单方阳性配偶2006-2009年HIV抗体的阳转率分别为1.94/100人年、1.79/100人年、0.59/100人年和0.41/100人年,并呈现逐年下降趋势.同年阳转病例中,除2007年男性明显多于女性外,其他年度男女性别阳转率差异无统计学意义.阳转时间>2.5年病例所占比例有所增加.绝大多数单方阳性夫妻间的性生活频率在1~4次/月,并能坚持使用安全套.结论 河南省单方阳性配偶人群规模稳定,

  8. 重庆市男男性行为者HIV抗体阳转率及其影响因素研究%Study on HIV-1 seroconversion rate and its associated factors among men who have sex with men in Chongqing City

    Institute of Scientific and Technical Information of China (English)

    冯连贵; 徐世明; 丁贤彬; 卢戎戎; 欧阳琳; 郑建琼; 徐静; 韩梅; 郭晓嘉; 杨明芳

    2011-01-01

    Objective To understand HIV seroconversion rate and its associated factors among men who have sex with men, so as to provide the evidence for evaluating the effect and developing the comprehensive strategy for AIDS prevention and control among men who have sex with men. Methods MSM with HIV and Syphilis negative recruited were interviewed with the structured questionnaire and blood sample test for HIV and Syphilis antibody were taken after six months. HIV seroconversion rate and its influencing factors were analyzed by multivariate Logistic regression. Results A total of 214 MSM participated in the follow-up study. The average age was 25.6 ± 6.3. 88.3% of them had anal sex with men. The number of partners was 2 (median). The rate of condom use in the last time and in recent six months was 76.2% and 52.4% respectively. HIV seroconversion rate was 12.5(9.1 ~ 15.7)/100 person-year. Syphilis incidence was 17.8 ( 13.1 ~ 23.5)/100 person-year. The result of multivariate analysis indicated that education level ( OR = 0. 27,95 % CI: 0.13~ 0.59) and Syphilis positive ( OR = 9.23,95 % CI: 2.42~ 35.18) were independent factors of HIV seroconversion rate. Conclusions HIV seroconversion rate is high and the rate of condomn use is low among men who have sex with men. AIDS epidemic among men who have sex with men is serious.%目的 了解男男性行为者(men who have sex with men,MSM)人群HIV抗体阳转率及其影响因素,为评估MSM人群艾滋病防治效果与开展针对性防治工作提供依据.方法 对招募自愿参加随访研究的HIV与梅毒均阴性的MSM进行随访,6个月后再次进行问卷调查与采集血样检测HIV与梅毒,以HIV抗体阳转率为应变量,人口学特征、性行为情况等为自变量进行Logistic回归,分析鉴别HIV抗体阳转率的影响因素.结果 214例MSM参加随访,平均年龄(25.6±6.3)岁,88.3%的人最近6个月与男性有肛交史,最近6个月平均性伴数为2个,最近一次与男

  9. Delay-dependent robust H∞ controller design for a class of nonlinear uncertainty time-delay systems with input delay

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Based on an appropriate Lyapunov function,this paper analyzes the design of a delay-dependent robust H∞ state feedback control,with a focus on a class of non linear uncertainty linear time-delay systems with input delay using linear matrix inequalities.Under the condition that the nonlinear uncertain functions are gain bounded,a sufficient condition dependent on the delays of the state and input is presented for the existence of H∞ controller.The proposed controller not only stabilized closed-loop uncertain systems but also guaranteed a prescribed H∞ norm bound of closed-loop transfer matrix from the disturbance to controlled output.By solving a linear matrix inequation,we can obtain the robust H∞ controller.An example is given to show the effectiveness of the proposed method.

  10. Efficacy of telbivudine combined with adefovir dipivoxil and pegylated interferon combined with entecavir as antiviral therapy for chronic hepatitis B: a comparative analysis

    Directory of Open Access Journals (Sweden)

    LI Na

    2016-09-01

    Full Text Available Objective To investigate the efficacy of telbivudine combined with adefovir dipivoxil and PEG-IFN-α-2a combined with entecavir as the antiviral therapy for HBeAg-positive patients with chronic hepatitis B (CHB and a high viral load. Methods A total of 80 previously untreated HBeAg-positive CHB patients with a high viral load who were treated in The Sixth People′s Hospital of Qingdao from November 2012 to November 2015 were enrolled and randomly divided into two groups. The patients in group A were treated with telbivudine combined with adefovir dipivoxil, and those in group B were treated with PEG-IFN-α-2a combined with entecavir. Biochemical and virologic response rates and seroconversion rate were observed at weeks 12, 24, and 48 of administration. The drug resistance rate and incidence rates of adverse events were observed in both groups. The Chi-square test was applied for comparision of categorical data between the two groups, and the t-test was applied for comparision of continuous data between the two groups. Results Biochemical and virologic response rates at weeks 12, 24, and 48 of administration showed no significant differences between the two groups. The seroconversion rates at weeks 12 and 24 of administration showed no significant differences between the two groups, while at week 48 of administration, group B had significantly higher HBeAg clearance rate and seroconversion rate than group A (45.0% vs 67.5%, 22.5% vs 45.0%,χ2=4.114 3 and 4.528 3, both P<0.05. Group B had significantly higher incidence rates of adverse events than group A. Conclusion Telbivudine combined with adefovir dipivoxil and PEG-IFN-α-2a combined with entecavir can effectively inhibit the replication of high-load HBV DNA, delay disease progression, and realize HBeAg seroconversion. However, the two regimens have their own advantages and disadvantages and should be selected according to clinical situation.

  11. ON FEEDBACK CONTROL OF DELAYED CHAOTIC SYSTEM

    Institute of Scientific and Technical Information of China (English)

    李丽香; 彭海朋; 卢辉斌; 关新平

    2001-01-01

    In this paper two different types of feedback control technique are discussed: the standard feedback control and the time-delay feedback control which have been successfully used in many control systems. In order to understand to what extent the two different types of control technique are useful in delayed chaotic systems, some analytic stabilization conditions for chaos control from the two types of control technique are derived based on Lyapunov stabilization arguments. Similarly, we discuss the tracking problem by applying the time-delay feedback control. Finally, numerical examples are provided.

  12. Delayed self-synchronization in homoclinic chaos

    Science.gov (United States)

    Arecchi, F. T.; Meucci, R.; Allaria, E.; di Garbo, A.; Tsimring, L. S.

    2002-04-01

    The chaotic spike train of a homoclinic dynamical system is self-synchronized by applying a time-delayed correction proportional to the laser output intensity. Due to the sensitive nature of the homoclinic chaos to external perturbations, stabilization of very long-periodic orbits is possible. On these orbits, the dynamics appears chaotic over a finite time, but then it repeats with a recurrence time that is slightly longer than the delay time. The effect, called delayed self-synchronization, displays analogies with neurodynamic events that occur in the buildup of long-term memories.

  13. Statistical Elmore delay of RC interconnect tree

    Institute of Scientific and Technical Information of China (English)

    Dong Gang; Yang Yang; Chai Chang-Chun; Yang Yin-Tang

    2010-01-01

    As feature size keeps scaling down, process variations can dramatically reduce the accuracy in the estimation of interconnect performance. This paper proposes a statistical Elmore delay model for RC interconnect tree in the presence of process variations. The suggested method translates the process variations into parasitic parameter extraction and statistical Elmore delay evaluation. Analytical expressions of mean and standard deviation of interconnect delay can be obtained in a given fluctuation range of interconnect geometric parameters. Experimental results demonstrate that the approach matches well with Monte Carlo simulations. The errors of proposed mean and standard deviation are less than 1% and 7%, respectively. Simulations prove that our model is efficient and accurate.

  14. Transcriptional delay stabilizes bistable gene networks

    Science.gov (United States)

    Gupta, Chinmaya; López, José Manuel; Ott, William; Josić, Krešimir; Bennett, Matthew R.

    2014-01-01

    Transcriptional delay can significantly impact the dynamics of gene networks. Here we examine how such delay affects bistable systems. We investigate several stochastic models of bistable gene networks and find that increasing delay dramatically increases the mean residence times near stable states. To explain this, we introduce a non-Markovian, analytically tractable reduced model. The model shows that stabilization is the consequence of an increased number of failed transitions between stable states. Each of the bistable systems that we simulate behaves in this manner. PMID:23952450

  15. Technical Progress of China's Delayed Coking Technology

    Institute of Scientific and Technical Information of China (English)

    Zhang Lixin; Li Hejie

    2005-01-01

    This article introduces the recent advances of China in the fields of process technology of delayed coking, enlarged equipment size, hydraulic decoking, automatic control and environmental protection. By the end of 2004 the total capacity of delayed coking units in China had reached 37.24Mt/a with the maximum coke drum diameter equating to 9.4 m. This article also presents the investment in delayed cokers and the current production status while pointing out the existing problems and future development trends.

  16. Synchronisation of time-delay systems

    CERN Document Server

    Bünner, M J; Bünner, Martin J.; Just, Wolfram

    1998-01-01

    We present the linear-stability analysis of synchronised states in coupled time-delay systems. There exists a synchronisation threshold, for which we derive upper bounds, which does not depend on the delay time. We prove that at least for scalar time-delay systems synchronisation is achieved by transmitting a single scalar signal, even if the synchronised solution is given by a high-dimensional chaotic state with a large number of positive Lyapunov-exponents. The analytical results are compared with numerical simulations of two coupled Mackey-Glass equations.

  17. Delayed encephalopathy after acute carbon monoxide poisoning

    Directory of Open Access Journals (Sweden)

    Mehmet İbrahim Turan

    2014-03-01

    Full Text Available Carbon monoxide poisoning is a major cause of death following attempted suicide and accidental exposures. Although clinical presentation depends on the duration and the intensity of exposure, the assessment of the severity of intoxication is difficult. A small percentage of patients who show complete initial recovery may develop delayed neurological deficits. Delayed encephalopathy after acute carbon monoxide poisoning is a rare and poor prognosis neurologic disorders and there is no specific treatment. We present a case with early onset of delayed encephalopathy after acute carbon monoxide poisoning with typical cranial imaging findings in a child with atypical history and clinical presentation.

  18. Endotoxin contamination delays the foreign body reaction

    NARCIS (Netherlands)

    van Putten, Sander M.; Wubben, Maike; Plantinga, Josee A.; Hennink, Wim E.; van Luyn, Marja J. A.; Harmsen, Martin C.

    2011-01-01

    Biomaterials are at continuous risk of bacterial contamination during production and application. In vivo, bacterial contamination of biomaterials delays the foreign body reaction (FBR). Endotoxins such as lipopolysaccharides (LPS), major constituents of the bacterial cell wall, are potent stimulato

  19. Anharmonic resonances with recursive delay feedback

    Energy Technology Data Exchange (ETDEWEB)

    Goldobin, Denis S., E-mail: Denis.Goldobin@gmail.com [Department of Mathematics, University of Leicester, Leicester LE1 7RH (United Kingdom); Institute of Continuous Media Mechanics, UB RAS, Perm 614013 (Russian Federation)

    2011-09-12

    We consider application of time-delayed feedback with infinite recursion for control of anharmonic (nonlinear) oscillators subject to noise. In contrast to the case of a single delay feedback, recursive delay feedback exhibits resonances between feedback and nonlinear harmonics, leading to a resonantly strong or weak oscillation coherence even for a small anharmonicity. Remarkably, these small-anharmonicity induced resonances can be stronger than the harmonic ones. Analytical results are confirmed numerically for van der Pol and van der Pol-Duffing oscillators. -- Highlights: → We construct general theory of noisy limit-cycle oscillators with linear feedback. → We focus on coherence and 'reliability' of oscillators. → For recursive delay feedback control the theory shows importance of anharmonicity. → Anharmonic resonances are studied both numerically and analytically.

  20. How Can Atherosclerosis Be Prevented or Delayed?

    Science.gov (United States)

    ... page from the NHLBI on Twitter. How Can Atherosclerosis Be Prevented or Delayed? Taking action to control ... Rate This Content: NEXT >> Featured Video What is atherosclerosis? 05/22/2014 Describes how the build-up ...

  1. Continuous retrieval of delayed Raman polaritons

    CERN Document Server

    Smartsev, Slava; Davidson, Nir; Firstenberg, Ofer

    2016-01-01

    We use a Raman four-wave mixing process to read out light from an atomic coherence which is continuously written. This realizes a continuous source of polaritons having been delayed or effectively stored for a finite duration. Contrary to slow-light delay, which depends on the atom number and population distribution, here the effective storage duration is determined solely by intensive properties of the system, approaching the ground-state natural lifetime at the weak driving limit. The generated polaritons are background free. We experimentally probe these properties utilizing spatial atomic diffusion as an 'internal clock' for the write-read delay. A continuous source of delayed polaritons can replace discrete write-read procedures when the atomic evolution is the subject of interest, for example, when dipolar interactions lead to retrieval of non-classical light.

  2. Phase synchronization in time-delay systems.

    Science.gov (United States)

    Senthilkumar, D V; Lakshmanan, M; Kurths, J

    2006-09-01

    Though the notion of phase synchronization has been well studied in chaotic dynamical systems without delay, it has not been realized yet in chaotic time-delay systems exhibiting non-phase-coherent hyperchaotic attractors. In this paper we report identification of phase synchronization in coupled time-delay systems exhibiting hyperchaotic attractor. We show that there is a transition from nonsynchronized behavior to phase and then to generalized synchronization as a function of coupling strength. These transitions are characterized by recurrence quantification analysis, by phase differences based on a transformation of the attractors, and also by the changes in the Lyapunov exponents. We have found these transitions in coupled piecewise linear and in Mackey-Glass time-delay systems.

  3. Does Bilingualism Delay the Development of Dementia?

    Directory of Open Access Journals (Sweden)

    Amy L Atkinson

    2016-08-01

    Full Text Available It has been suggested that bilingualism (where individuals speak two languages may delay the development of dementia. However, much of the research is inconclusive. Some researchers have reported that bilingualism delays the onset and diagnosis of dementia, whilst other studies have found weak or even detrimental effects. This paper reviews a series of nine empirical studies, published up until March 2016, which investigated whether bilingualism significantly delays the onset of dementia. The article also explores whether the inconsistent findings can be attributed to differences in study designs or the definitions of bilingualism used between studies. Based on current evidence, it appears that lifelong bilingualism, where individuals frequently use both languages, may be protective against dementia. However, becoming bilingual in adulthood or using the second language infrequently is unlikely to substantially delay onset of the disease.

  4. Time to implement delayed cord clamping.

    Science.gov (United States)

    McAdams, Ryan M

    2014-03-01

    Immediate umbilical cord clamping after delivery is routine in the United States despite little evidence to support this practice. Numerous trials in both term and preterm neonates have demonstrated the safety and benefit of delayed cord clamping. In premature neonates, delayed cord clamping has been shown to stabilize transitional circulation, lessening needs for inotropic medications and reducing blood transfusions, necrotizing enterocolitis, and intraventricular hemorrhage. In term neonates, delayed cord clamping has been associated with decreased iron-deficient anemia and increased iron stores with potential valuable effects that extend beyond the newborn period, including improvements in long-term neurodevelopment. The failure to more broadly implement delayed cord clamping in neonates ignores published benefits of increased placental blood transfusion at birth and may represent an unnecessary harm for vulnerable neonates.

  5. Framework to Delay Corn Rootworm Resistance

    Science.gov (United States)

    This proposed framework is intended to delay the corn rootworm pest becoming resistant to corn genetically engineered to produce Bt proteins, which kill corn rootworms but do not affect people or wildlife. It includes requirements on Bt corn manufacturers.

  6. Uranium Determination by Delayed Neutron Counting

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>Uranium is a very important resource in nuclear industry, especially in the exploiture of nuclear energy. Determination of uranium using delayed neutron counting (DNC) is simple, non-destructive, and

  7. Lauch of CERN particle accelerator delayed

    CERN Multimedia

    2007-01-01

    "Scientists seeking to uncover the secrets of the universe will have to wait a little longer after the CERN laboratory inSwitzerland yesterday confirmed a delay in tests of its massive new particle accelerator." (1 page)

  8. Performance Evaluation of Blind Tropospheric Delay correction ...

    African Journals Online (AJOL)

    Performance Evaluation of Blind Tropospheric Delay correction Models over Africa. ... consisting of surface meteorological models and global empirical models. ... GPT2w and UNB3M models with accurate International GNSS Service (IGS)- ...

  9. Internet end-to-end delay dynamics

    Institute of Scientific and Technical Information of China (English)

    Zhu Changhua; Pei Changxing; Li Jiandong; Chen Nan; Yi Yunhui

    2006-01-01

    End-to-end delay is one of the most important characteristics of Internet end-to-end packet dynamics, which can be applied to quality of services (QoS) management, service level agreement (SLA) management, congestion control algorithm development, etc. Nonstationarity and nonlinearity are found by the analysis of various delay series measured from different links. The fact that different types of links have different degree of Self-Similarity is also obtained. By constructing appropriate network architecture and neural functions, functional networks can be used to model the Internet end-to-end nonlinear delay time series. Furthermore, by using adaptive parameter studying algorithm, the nonstationarity can also be well modeled. The numerical results show that the provided functional network architecture and adaptive algorithm can precisely characterize the Internet end-to-end delay dynamics.

  10. The SAS-3 delayed command system

    Science.gov (United States)

    Hoffman, E. J.

    1975-01-01

    To meet the requirements arising from the increased complexity of the power, attitude control and telemetry systems, a full redundant high-performance control section with delayed command capability was designed for the Small Astronomy Satellite-3 (SAS-3). The relay command system of SAS-3 is characterized by 56 bystate relay commands, with capability for handling up to 64 commands in future versions. The 'short' data command service of SAS-1 and SAS-2 consisting of shifting 24-bit words to two users was expanded to five users and augmented with a 'long load' data command service (up to 4080 bits) used to program the telemetry system and the delayed command subsystem. The inclusion of a delayed command service ensures a program of up to 30 relay or short data commands to be loaded for execution at designated times. The design and system operation of the SAS-3 command section are analyzed, with special attention given to the delayed command subsystem.

  11. Monolithic Time Delay Integrated APD Arrays Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The overall goal of the proposed program by Epitaxial Technologies is to develop monolithic time delay integrated avalanche photodiode (APD) arrays with sensitivity...

  12. The Economic Promise of Delayed Aging.

    Science.gov (United States)

    Goldman, Dana

    2015-12-18

    Biomedicine has made enormous progress in the last half century in treating common diseases. However, we are becoming victims of our own success. Causes of death strongly associated with biological aging, such as heart disease, cancer, Alzheimer's disease, and stroke-cluster within individuals as they grow older. These conditions increase frailty and limit the benefits of continued, disease-specific improvements. Here, we show that a "delayed-aging" scenario, modeled on the biological benefits observed in the most promising animal models, could solve this problem of competing risks. The economic value of delayed aging is estimated to be $7.1 trillion over 50 years. Total government costs, including Social Security, rise substantially with delayed aging--mainly caused by longevity increases--but we show that these can be offset by modest policy changes. Expanded biomedical research to delay aging appears to be a highly efficient way to forestall disease and extend healthy life.

  13. Improved control of delayed measured systems

    Science.gov (United States)

    Claussen, Jens Christian; Schuster, Heinz Georg

    2004-11-01

    In this paper, we address the question of how the control of delayed measured chaotic systems can be improved. Both unmodified Ott-Grebogi-Yorke control and difference control can be successfully applied only for a certain range of Lyapunov numbers depending on the delay time. We show that this limitation can be overcome by at least two classes of methods, namely, by rhythmic control and by the memory methods of linear predictive logging control and memory difference control.

  14. Improvement of Delayed Neutron Counting System

    Institute of Scientific and Technical Information of China (English)

    YUAN; Guo-jun; XIAO; Cai-jin; YANG; Wei; ZHANG; Gui-ying; JIN; Xiang-chun; WANG; Ping-sheng; NI; Bang-fa

    2012-01-01

    <正>A new delayed neutron counting system, which is good at qualitative and quantitative analysis of fissionable nuclide mixture, will be established at China Advanced Research Reactor (CARR). We use 3 He proportional counters to count the delayed neutrons after the samples irradiated by reactor neutrons, including U3O8-stantard, uranium ore and enriched uranium. Then, the counting efficiency and limit of this system were calculated.

  15. Ignition Delay Studies on Hypergolic Fuel Grains

    Directory of Open Access Journals (Sweden)

    S. R. Jain

    1988-07-01

    Full Text Available The ignition delays of several solid hypergolic fuel compositions, casted using various polymeric binders, or as melts, have been determined with fuming nitric acid as oxidizer. The ignition delays of various hypergolic fuel compositions increase drasticaliy on casting with binders like. carboxyl or hydroxyl termninated polybutadiene. Fuel grains cast using some newly syhthesised epoxy  resins with other ingrcdients, such as curing agent, magnesium powder and fuel, have short ignition delays of the order of 200 ms, and also good mechanical strength. Increasing the amount of binder in the composition retards the hypergolicity of the rain. Similar studies have been made on melt-cast systems using low melting hypergolic fuels for casting fuel powders. The ignition delays of the melt-cast grains, are longer than those determined taking the composition in the powder form. The effect of highly hypergolic additives, and metal powders, on the ignition delay of the cast compositions has been determined. Grains having good mechanical strength and short ignition delays have been obtained by optimising the fuel grain composition.

  16. Operant variability when reinforcement is delayed.

    Science.gov (United States)

    Wagner, Katie; Neuringer, Allen

    2006-05-01

    Operant responses are often weakened when delays are imposed between the responses and reinforcers. We examined what happens when delayed reinforcers were contingent upon operant response variability. Three groups of rats were rewardedfor varying their response sequences, with onegroup rewarded for high variability, another for middle, and the third for low levels. Consistent with many reports in the literature, responding slowed significantly in all groups as delays were lengthened. Consistent with other reports, large differences in variability were maintained across the three groups despite the delays. Reinforced variability appears to be relatively immune to disruption by such things as delays, response slowing, prefeeding, and noncontingent reinforcement. Furthermore, the small effects on variability depended on baseline levels: As delays lengthened, variability increased in the low group, was statistically unchanged in the middle group, and decreased in the high group, an interaction similar to that reported previously when reinforcement frequencies were lowered. Thus, variable operant responding is controlled by reinforcement contingencies, but sometimes differently than more commonly studied repetitive responding.

  17. Beyond Linear Delay Multipliers in Air Transport

    Directory of Open Access Journals (Sweden)

    Seddik Belkoura

    2017-01-01

    Full Text Available Delays are considered one of the most important burdens of air transport, both for their social and environmental consequences and for the cost they cause for airlines and passengers. It is therefore not surprising that a large effort has been devoted to study how they propagate through the system. One of the most important indicators to assess such propagation is the delay multiplier, a ratio between outbound and inbound average delays; in spite of its widespread utilisation, its simplicity precludes capturing all details about the dynamics behind the diffusion process. Here we present a methodology that extracts a more complete relationship between the in- and outbound delays, distinguishing a linear and a nonlinear phase and thus yielding a richer description of the system’s response as a function of the delay magnitude. We validate the methodology through the study of a historical data set of flights crossing the European airspace and show how its most important airports have heterogeneous ways of reacting to extreme delays and that this reaction strongly depends on some of their global properties.

  18. The reasons for delay lumbar puncture

    Directory of Open Access Journals (Sweden)

    MH. Lotfi

    2017-04-01

    Full Text Available Early diagnosis of meningitis and encephalitis and prompt initiation of appropriate therapy is vital and any delay will lead to high mortality and serious and permanent morbidity. The main purpose of this study was to evaluate the management of 220 patients with suspected central nervous system (CNS infections (meningitis and encephalitis to determine the percentage of patients’ suspected CNS infection undergo lumbar puncture in acceptable time (in accordance with conventional algorithms. In this descriptive study, patients with suspected CNS infections admitted to Bu-Ali and Qods hospitals, in the period July 2013 to December 2015 were studied. Information of 220 patients was collected. Continuous variables were summarized as means ± standard deviation and categorical variables as frequencies and percentages. Lumbar puncture (LP in patients was delayed in 200 cases (91%. Most common causes of delay in performing LP were prolongation of the process of determining patient needs to puncture, satisfying patients, CT scan delay and the delay in allowing LP by neurologist. In this study, delaying LP rate was higher than other studies. It seems certain pattern in assistants’ visits for counseling. CT requests and neurologic consultation before LP performed for all adult patients.

  19. Locomotive Assignment Optimization Including Train Delays

    Directory of Open Access Journals (Sweden)

    Sandra Kasalica

    2013-10-01

    Full Text Available Intention– Cyclic locomotive assignment planning is a specific type of organization of locomotive usage, and in fact, it means putting the complete workload to a closed chain, which is repeated periodically. The concept of cyclic locomotive assignment planning type organization in the area of train traction has proven in practice as the best one, but as it is made for in-advance defined timetable and without considering the stochastic nature of the timetable realization process, it leads to incompatibility in using locomotives. Methodology – Methodology defined in this paper contains: research of train delays on the Serbian Railways and Montenegrin Railways networks, analysis of the real system organization of locomotive usage in conditions of train delays, theoretical thesis of solving the problem of optimal cyclic locomotive assignment planning in conditions of train delays, designing of a model with algorithms, preparing the software package, testing the model and program with results, as well as the conclusions drawn from the complete research project. Results– The optimization model of cyclic locomotive assignment planning during the process of making timetable including train delays has been defined. Conclusion –The obtained results have shown as expected, that the larger delays of trains required a larger number of locomotives. However, by using this model it is possible to optimize the required number of locomotives, taking into account the real time delays of trains.

  20. Optimal Control with Time Delays via the Penalty Method

    Directory of Open Access Journals (Sweden)

    Mohammed Benharrat

    2014-01-01

    Full Text Available We prove necessary optimality conditions of Euler-Lagrange type for a problem of the calculus of variations with time delays, where the delay in the unknown function is different from the delay in its derivative. Then, a more general optimal control problem with time delays is considered. Main result gives a convergence theorem, allowing us to obtain a solution to the delayed optimal control problem by considering a sequence of delayed problems of the calculus of variations.

  1. Delay-dependent H-infinity control for continuous time-delay systems via state feedback

    Institute of Scientific and Technical Information of China (English)

    Xinchun JIA; Yibo GAO; Jingmei ZHANG; Nanning ZHENG

    2007-01-01

    The delay-dependent H-infinity analysis and H-infinity control problems for continuous time-delay systems are studied. By introducing an equality with some free weighting matrices, an improved criterion of delay-dependent stability with H-infinity performance for such systems is presented, and a criterion of existence and some design methods of delay-dependent H-infinity controller for such systems are proposed in term of a set of matrix inequalities, which is solved efficiently by an iterative algorithm. Further, the corresponding results for the delay-dependent robust H-infinity analysis and robust H-infinity control problems for continuous time-delay uncertain systems are given. Finally, two numerical examples are given to illustrate the efficiency of the proposed method by comparing with the other existing results.

  2. Delayed antibiotic prescriptions for respiratory infections.

    Science.gov (United States)

    Spurling, Geoffrey Kp; Del Mar, Chris B; Dooley, Liz; Foxlee, Ruth; Farley, Rebecca

    2017-09-07

    Concerns exist regarding antibiotic prescribing for respiratory tract infections (RTIs) owing to adverse reactions, cost, and antibacterial resistance. One proposed strategy to reduce antibiotic prescribing is to provide prescriptions, but to advise delay in antibiotic use with the expectation that symptoms will resolve first. This is an update of a Cochrane Review originally published in 2007, and updated in 2010 and 2013. To evaluate the effects on clinical outcomes, antibiotic use, antibiotic resistance, and patient satisfaction of advising a delayed prescription of antibiotics in respiratory tract infections. For this 2017 update we searched the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library, Issue 4, 2017), which includes the Cochrane Acute Respiratory Infection Group's Specialised Register; Ovid MEDLINE (2013 to 25 May 2017); Ovid Embase (2013 to 2017 Week 21); EBSCO CINAHL Plus (1984 to 25 May 2017); Web of Science (2013 to 25 May 2017); WHO International Clinical Trials Registry Platform (1 September 2017); and ClinicalTrials.gov (1 September 2017). Randomised controlled trials involving participants of all ages defined as having an RTI, where delayed antibiotics were compared to immediate antibiotics or no antibiotics. We defined a delayed antibiotic as advice to delay the filling of an antibiotic prescription by at least 48 hours. We considered all RTIs regardless of whether antibiotics were recommended or not. We used standard Cochrane methodological procedures. Three review authors independently extracted and collated data. We assessed the risk of bias of all included trials. We contacted trial authors to obtain missing information. For this 2017 update we added one new trial involving 405 participants with uncomplicated acute respiratory infection. Overall, this review included 11 studies with a total of 3555 participants. These 11 studies involved acute respiratory infections including acute otitis media (three studies

  3. Interconnected delay and state observer for nonlinear systems with time-varying input delay

    OpenAIRE

    Léchappé, V; Moulay, Emmanuel; Plestan, F; Glumineau, A.

    2016-01-01

    International audience; This work presents a general framework to estimate both state and delay thanks to two interconnected observers. This scheme can be applied to a large class of nonlinear systems with time-varying input delay. In order to illustrate this approach, a new delay observer based on an optimization technique is proposed. Theoretical results are illustrated and compared with existing works in simulation.

  4. Delay dependent stability criteria for recurrent neural networks with time varying delays

    Institute of Scientific and Technical Information of China (English)

    Zhanshan WANG; Huaguang ZHANG

    2009-01-01

    This paper aims to present some delay-dependent global asymptotic stability criteria for recurrent neural networks with time varying delays.The obtained results have no restriction on the magnitude of derivative of time varying delay,and can be easily checked due to the form of linear matrix inequality.By comparison with some previous results,the obtained results are less conservative.A numerical example is utilized to demonstrate the effectiveness of the obtained results.

  5. Improving Delay-Range-Dependent Stability Condition for Systems with Interval Time-Varying Delay

    Directory of Open Access Journals (Sweden)

    Wei Qian

    2013-01-01

    Full Text Available This paper discusses the delay-range-dependent stability for systems with interval time-varying delay. Through defining the new Lyapunov-Krasovskii functional and estimating the derivative of the LKF by introducing new vectors, using free matrices and reciprocally convex approach, the new delay-range-dependent stability conditions are obtained. Two well-known examples are given to illustrate the less conservatism of the proposed theoretical results.

  6. Delay-dependent guaranteed cost control for uncertain systems with both state and input delays

    Institute of Scientific and Technical Information of China (English)

    Xuanfang YANG; Wuhua CHEN; Huajing FANG

    2004-01-01

    This paper considers the guaranteed cost control problem for a class of uncertain linear systems with both state and input delays.By representing the time-delay system in the descriptor system form and using a recent result on bounding of cross products of vectors,we obtain new delay-dependent sufficient conditions for the existence of the guaranteed cost controller in terms of linear matrix inequalities.Two examples are presented which show the effectiveness of our approach.

  7. Design of a Novel Current Balanced Voltage Controlled Delay Element

    Directory of Open Access Journals (Sweden)

    Pooja Saxena

    2014-04-01

    Full Text Available This paper presents a design of fast voltage controlled delay element based on modified version of low noise Current Balanced Logic (CBL. This delay element provides identical rising and falling edge delays controlled by the single control voltage. The post layout tunable delay range is from 140 ps to 800 ps over control voltage range of 0 to 2.1 V. An analysis for the delay element is also presented, which is in agreement with the simulated delays. A Delay Lock Loop (DLL is designed using this delay element to verify its performance.

  8. Apparatus and Method for Compensating for Process, Voltage, and Temperature Variation of the Time Delay of a Digital Delay Line

    Science.gov (United States)

    Seefeldt, James (Inventor); Feng, Xiaoxin (Inventor); Roper, Weston (Inventor)

    2013-01-01

    A process, voltage, and temperature (PVT) compensation circuit and a method of continuously generating a delay measure are provided. The compensation circuit includes two delay lines, each delay line providing a delay output. The two delay lines may each include a number of delay elements, which in turn may include one or more current-starved inverters. The number of delay lines may differ between the two delay lines. The delay outputs are provided to a combining circuit that determines an offset pulse based on the two delay outputs and then averages the voltage of the offset pulse to determine a delay measure. The delay measure may be one or more currents or voltages indicating an amount of PVT compensation to apply to input or output signals of an application circuit, such as a memory-bus driver, dynamic random access memory (DRAM), a synchronous DRAM, a processor or other clocked circuit.

  9. Delay-dependent robust H∞ control for uncertain fuzzy hyperbolic systems with multiple delays

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The robust H∞ control problem was considered for a class of fuzzy hyperbolic model (FHM) systems with parametric uncertainties and multiple delays. First, FHM modeling method was presented for time-delay nonlinear systems. Then, by using Lyapunov-Krasovskii approaches, delay-dependent sufficient condition for the existence of a kind of state feedback controller was proposed, which was expressed as linear matrix inequalities (LMIs). The controller can guarantee that the resulting closed-loop system is robustly asymptotically stable with a prescribed H∞ performance level for all admissible uncertainties and time-delay. Finally, a simulation example was provided to illustrate the effectiveness of the proposed approach.

  10. Deriving real delay time statistics from the complex delay time statistics in weakly disordered optical media

    OpenAIRE

    Pradhan, Prabhakar; Sahay, Peeyush; Almabadi, Huda M.

    2016-01-01

    Considering the complex reflection amplitude R=|R|exp(i{\\theta}) of a light wave, real delay time {\\tau}_r (i.e., sojourn or Wigner delay time), which is the energy derivative of the real phase ({\\tau}_r =d{\\theta}/cdk), and complex delay time {\\tau}_i , which is the energy derivative of the reflection coefficient ({\\tau}_i=d{\\theta}_i/cdk, |R|=r^1/2=exp(-{\\theta}_i)), have the same statistical form and a mirror image with a shift in time in weak disorder and short length regime. Real delay t...

  11. Adaptive global synchronization of a general complex dynamical network with non-delayed and delayed coupling

    Science.gov (United States)

    Wen, Sun; Chen, Shihua; Guo, Wanli

    2008-10-01

    This Letter investigates the global synchronization of a general complex dynamical network with non-delayed and delayed coupling. Based on Lasalle's invariance principle, adaptive global synchronization criteria is obtained. Analytical result shows that under the designed adaptive controllers, a general complex dynamical network with non-delayed and delayed coupling can globally asymptotically synchronize to a given trajectory. What is more, the node dynamic need not satisfy the very strong and conservative uniformly Lipschitz condition and the coupling matrix is not assumed to be symmetric or irreducible. Finally, numerical simulations are presented to verify the effectiveness of the proposed synchronization criteria.

  12. Adaptive global synchronization of a general complex dynamical network with non-delayed and delayed coupling

    Energy Technology Data Exchange (ETDEWEB)

    Wen Sun [College of Mathematics and Statistics, Wuhan University, Wuhan 430072 (China)], E-mail: sunwen_2201@163.com; Chen Shihua; Guo Wanli [College of Mathematics and Statistics, Wuhan University, Wuhan 430072 (China)

    2008-10-13

    This Letter investigates the global synchronization of a general complex dynamical network with non-delayed and delayed coupling. Based on Lasalle's invariance principle, adaptive global synchronization criteria is obtained. Analytical result shows that under the designed adaptive controllers, a general complex dynamical network with non-delayed and delayed coupling can globally asymptotically synchronize to a given trajectory. What is more, the node dynamic need not satisfy the very strong and conservative uniformly Lipschitz condition and the coupling matrix is not assumed to be symmetric or irreducible. Finally, numerical simulations are presented to verify the effectiveness of the proposed synchronization criteria.

  13. Delayed Hopf bifurcation in time-delayed slow-fast systems

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    This paper presents an investigation on the phenomenon of delayed bifurcation in time-delayed slow-fast differential systems.Here the two delayed’s have different meanings.The delayed bifurcation means that the bifurcation does not happen immediately at the bifurcation point as the bifurcation parameter passes through some bifurcation point,but at some other point which is above the bifurcation point by an obvious distance.In a time-delayed system,the evolution of the system depends not only on the present state but also on past states.In this paper,the time-delayed slow-fast system is firstly simplified to a slow-fast system without time delay by means of the center manifold reduction,and then the so-called entry-exit function is defined to characterize the delayed bifurcation on the basis of Neishtadt’s theory.It shows that delayed Hopf bifurcation exists in time-delayed slow-fast systems,and the theoretical prediction on the exit-point is in good agreement with the numerical calculation,as illustrated in the two illustrative examples.

  14. Controlling a time-delay system using multiple delay feedback control

    Institute of Scientific and Technical Information of China (English)

    Qi Wei; Zhang Yan; Wang Ying-Hai

    2007-01-01

    In this paper multiple delay feedback control (MDFC) with different and independent delay times is shown to be an efficient method for stabilizing fixed points in finite-dimensional dynamical systems. Whether MDFC can be applied to infinite-dimensional systems has been an open question. In this paper we find that for infinite-dimensional systems modelled by delay differential equations, MDFC works well for stabilizing (unstable) steady states in long-, moderate-and short-time delay regions, in particular for the hyperchaotic case.

  15. Time-Delay Estimation using the Characteristic Roots of Delay Differential Equations

    Directory of Open Access Journals (Sweden)

    Sun Yi

    2012-01-01

    Full Text Available Problem statement: For ordinary dynamic systems (i.e., non-delayed, various methods such as linear least-squares, gradient-weighted least-squares, Kalman filtering and other robust techniques have been widely used in signal processing, robotics, civil engineering. On the other hand, time-delay estimation of systems with unknown time-delay is still a challenging problem due to difficulty in formulation caused. Approach: The presented method makes use of the Lambert W function and analytical solutions of scalar first-order Delay Differential Equations (DDEs. The Lambert W function has been known to be useful in solving delay differential equations. From the solutions in terms of the Lambert W function, the dominant characteristic roots can be obtained and used to estimate time-delays. The function is already embedded in various software packages (e.g., MATLAB and thus, the presented method can be readily used for time-delay systems. Results: The presented method and the provided examples show ease of formulation and accuracy of time-delay estimation. Conclusion: Estimation of time-delays can be conducted in an analytical way. The presented method will be extended to general systems of DDEs and application to physical systems.

  16. Multivariate Markov processes for stochastic systems with delays: application to the stochastic Gompertz model with delay.

    Science.gov (United States)

    Frank, T D

    2002-07-01

    Using the method of steps, we describe stochastic processes with delays in terms of Markov diffusion processes. Thus, multivariate Langevin equations and Fokker-Planck equations are derived for stochastic delay differential equations. Natural, periodic, and reflective boundary conditions are discussed. Both Ito and Stratonovich calculus are used. In particular, our Fokker-Planck approach recovers the generalized delay Fokker-Planck equation proposed by Guillouzic et al. The results obtained are applied to a model for population growth: the Gompertz model with delay and multiplicative white noise.

  17. Delay-dependent criteria for the robust stability of systems with time-varying delay

    Institute of Scientific and Technical Information of China (English)

    Min WU; Yong HE; Jinhua SHE

    2003-01-01

    The problem of delay-dependent robust stability for systems with titne-varying delay has been considered. By using the S-procedure and the Park' s inequality in the recent issue, a delay-dependent robust stability criterion which is less conservative than the previous results has been derived for time-delay systems with time-varying structured uncertainties. The same idea has also been easily extended to the systems with nonlinear perturbations. Numerical examples illustrated the effectiveness and the improvement of the proposed approach.

  18. Delayed feedback control of time-delayed chaotic systems: Analytical approach at Hopf bifurcation

    Energy Technology Data Exchange (ETDEWEB)

    Vasegh, Nastaran [Faculty of Electrical Engineering, K.N. Toosi University of Technology, PO Box 16315-1355, Tehran (Iran, Islamic Republic of)], E-mail: vasegh@eetd.kntu.ac.ir; Sedigh, Ali Khaki [Faculty of Electrical Engineering, K.N. Toosi University of Technology, PO Box 16315-1355, Tehran (Iran, Islamic Republic of)

    2008-07-28

    This Letter is concerned with bifurcation and chaos control in scalar delayed differential equations with delay parameter {tau}. By linear stability analysis, the conditions under which a sequence of Hopf bifurcation occurs at the equilibrium points are obtained. The delayed feedback controller is used to stabilize unstable periodic orbits. To find the controller delay, it is chosen such that the Hopf bifurcation remains unchanged. Also, the controller feedback gain is determined such that the corresponding unstable periodic orbit becomes stable. Numerical simulations are used to verify the analytical results.

  19. A prospective cohort study on positive seroconversion of HIV and Treponema pallidum antibodies among men who have sex with men in Hangzhou%杭州市男男性行为人群HIV和梅毒螺旋体血清抗体阳转情况队列研究

    Institute of Scientific and Technical Information of China (English)

    李西婷; 罗艳; 武海滨; 金洁; 许珂

    2013-01-01

    Objective To understand the positive seroconversion of human immunodeficiency virus ( HIV) and Treponema pallidum antibodies among men who have sex with men ( MSM) in Hangzhou. Methods MSM were recruited from HIV voluntary counsel and test (VCT) clinics in 5 districts in Hangzhou, and follow up for 3 and 6 months was made among them to learn about their high risk behaviors. Blood samples were taken from them to detect the antibodies to HIV and Treponema pallidum. Results Among 80 HIV negative MSM recruited, 3. 75% (3/80) were Treponema pallidum positive, 92. 5% (74/80) completed the 6 month follow up. The positive seroconversion rates of HIV and Treponema pallidum antibodies were 10.7/100 person-years and 13.9/100 person-years respectively. Conclusion The positive seroconversion of HIV and Treponema pallidum in this MSM cohort was very serious. More effective measures should be taken to reduce the prevalence of HIV infection and syphilis in MSM in Hangzhou.%目的 了解杭州市男男性行为人群(MSM)的艾滋病病毒(HIV)和梅毒螺旋体血清抗体阳转情况.方法 于2011年6月在杭州市上城区、下城区、江干区、拱墅区和西湖区5个主要城区的自愿咨询检测门诊招募80名MSM组建队列.在基线、3个月和6个月调查其高危行为情况,并采集血样检测HIV和梅毒螺旋体血清抗体.结果 基线调查纳入80名HIV抗体阴性的调查对象,梅毒螺旋体阳性率为3.75% (3/80).队列随访6个月,MSM队列保持率为92.5% (74/80),HIV血清抗体阳转率为10.7/100人年,梅毒阳转率为13.9/100人年.结论 杭州市MSM人群HIV和梅毒血清阳转情况十分严重.应加大该人群的艾滋病宣传干预力度,探索开展更为有效的干预措施.

  20. Impulsive control of time-delay systems using delayed impulse and its application to impulsive master-slave synchronization

    Energy Technology Data Exchange (ETDEWEB)

    Sun Jitao [Department of Mathematics, Tongji University, Shanghai 200092 (China); Centre for Intelligent and Networked Systems, Central Queensland University, Rockhampton Qld 4702 (Australia); Han Qinglong [Centre for Intelligent and Networked Systems, Central Queensland University, Rockhampton Qld 4702 (Australia); School of Computing Sciences, Central Queensland University, Rockhampton Qld 4702 (Australia)], E-mail: q.han@cqu.edu.au; Jiang Xiefu [Centre for Intelligent and Networked Systems, Central Queensland University, Rockhampton Qld 4702 (Australia); School of Automation, Hangzhou Dianzi University, Hangzhou 310018, Zhejiang (China)

    2008-10-13

    This Letter is concerned with impulsive control of a class of nonlinear time-delay systems. Some uniform stability criteria for the closed-loop time-delay system under delayed impulsive control are derived by using piecewise Lyapunov functions. Then the criteria are applied to impulsive master-slave synchronization of some secure communication systems with transmission delays and sample delays under delayed impulsive control. Two numerical examples are given to illustrate the effectiveness of the derived results.

  1. Delayed Random Walks: Modeling Human Posture Control

    Science.gov (United States)

    Ohira, Toru

    1998-03-01

    We consider a phenomenological description of a noisy trajectory which appears on a stabiliogram platform during human postural sway. We hypothesize that this trajectory arises due to a mixture of uncontrollable noise and a corrective delayed feedback to an upright position. Based on this hypothesis, we model the process with a biased random walk whose transition probability depends on its position at a fixed time delay in the past, which we call a delayed random walk. We first introduce a very simple model (T. Ohira and J. G. Milton, Phys.Rev.E. 52), 3277, (1995), which can nevertheless capture the rough qualitative features of the two--point mean square displacement of experimental data with reasonable estimation of delay time. Then, we discuss two approaches toward better capturing and understanding of the experimental data. The first approach is an extension of the model to include a spatial displacement threshold from the upright position below which no or only weak corrective feedback motion takes place. This can be incorporated into an extended delayed random walk model. Numerical simulations show that this extended model can better capture the three scaling region which appears in the two--point mean square displacement. The other approach studied the autocorrelation function of the experimental data, which shows oscillatory behavior. We recently investigated a delayed random walk model whose autocorrelation function has analytically tractable oscillatory behavior (T. Ohira, Phys.Rev.E. 55), R1255, (1997). We discuss how this analytical understanding and its application to delay estimation (T. Ohira and R. Sawatari, Phys.Rev.E. 55), R2077, (1997) could possibly be used to further understand the postural sway data.

  2. Delay differential analysis of time series.

    Science.gov (United States)

    Lainscsek, Claudia; Sejnowski, Terrence J

    2015-03-01

    Nonlinear dynamical system analysis based on embedding theory has been used for modeling and prediction, but it also has applications to signal detection and classification of time series. An embedding creates a multidimensional geometrical object from a single time series. Traditionally either delay or derivative embeddings have been used. The delay embedding is composed of delayed versions of the signal, and the derivative embedding is composed of successive derivatives of the signal. The delay embedding has been extended to nonuniform embeddings to take multiple timescales into account. Both embeddings provide information on the underlying dynamical system without having direct access to all the system variables. Delay differential analysis is based on functional embeddings, a combination of the derivative embedding with nonuniform delay embeddings. Small delay differential equation (DDE) models that best represent relevant dynamic features of time series data are selected from a pool of candidate models for detection or classification. We show that the properties of DDEs support spectral analysis in the time domain where nonlinear correlation functions are used to detect frequencies, frequency and phase couplings, and bispectra. These can be efficiently computed with short time windows and are robust to noise. For frequency analysis, this framework is a multivariate extension of discrete Fourier transform (DFT), and for higher-order spectra, it is a linear and multivariate alternative to multidimensional fast Fourier transform of multidimensional correlations. This method can be applied to short or sparse time series and can be extended to cross-trial and cross-channel spectra if multiple short data segments of the same experiment are available. Together, this time-domain toolbox provides higher temporal resolution, increased frequency and phase coupling information, and it allows an easy and straightforward implementation of higher-order spectra across time

  3. Delay Differential Analysis of Time Series

    Science.gov (United States)

    Lainscsek, Claudia; Sejnowski, Terrence J.

    2015-01-01

    Nonlinear dynamical system analysis based on embedding theory has been used for modeling and prediction, but it also has applications to signal detection and classification of time series. An embedding creates a multidimensional geometrical object from a single time series. Traditionally either delay or derivative embeddings have been used. The delay embedding is composed of delayed versions of the signal, and the derivative embedding is composed of successive derivatives of the signal. The delay embedding has been extended to nonuniform embeddings to take multiple timescales into account. Both embeddings provide information on the underlying dynamical system without having direct access to all the system variables. Delay differential analysis is based on functional embeddings, a combination of the derivative embedding with nonuniform delay embeddings. Small delay differential equation (DDE) models that best represent relevant dynamic features of time series data are selected from a pool of candidate models for detection or classification. We show that the properties of DDEs support spectral analysis in the time domain where nonlinear correlation functions are used to detect frequencies, frequency and phase couplings, and bispectra. These can be efficiently computed with short time windows and are robust to noise. For frequency analysis, this framework is a multivariate extension of discrete Fourier transform (DFT), and for higher-order spectra, it is a linear and multivariate alternative to multidimensional fast Fourier transform of multidimensional correlations. This method can be applied to short or sparse time series and can be extended to cross-trial and cross-channel spectra if multiple short data segments of the same experiment are available. Together, this time-domain toolbox provides higher temporal resolution, increased frequency and phase coupling information, and it allows an easy and straightforward implementation of higher-order spectra across time

  4. Facilitating tolerance of delayed reinforcement during functional communication training.

    Science.gov (United States)

    Fisher, W W; Thompson, R H; Hagopian, L P; Bowman, L G; Krug, A

    2000-01-01

    Few clinical investigations have addressed the problem of delayed reinforcement. In this investigation, three individuals whose destructive behavior was maintained by positive reinforcement were treated using functional communication training (FCT) with extinction (EXT). Next, procedures used in the basic literature on delayed reinforcement and self-control (reinforcer delay fading, punishment of impulsive responding, and provision of an alternative activity during reinforcer delay) were used to teach participants to tolerate delayed reinforcement. With the first case, reinforcer delay fading alone was effective at maintaining low rates of destructive behavior while introducing delayed reinforcement. In the second case, the addition of a punishment component reduced destructive behavior to near-zero levels and facilitated reinforcer delay fading. With the third case, reinforcer delay fading was associated with increases in masturbation and head rolling, but prompting and praising the individual for completing work during the delay interval reduced all problem behaviors and facilitated reinforcer delay fading.

  5. Relation between treatment efficacy and cumulative dose of alpha interferon in chronic hepatitis B. European Concerted Action on Viral Hepatitis (Eurohep)

    DEFF Research Database (Denmark)

    Krogsgaard, K; Christensen, E; Bindslev, N;

    1996-01-01

    Alpha interferon (IFN) is an established treatment of chronic hepatitis B. The effect has been shown to be dose related, recommended dose regimens being associated with a doubling of the spontaneous, baseline HBeAg to anti-HBe seroconversion rate. However, the efficacy of IFN treatment in relation...

  6. Is combination therapy with lamivudine and interferon-alpha superior to monotherapy with either drug?

    NARCIS (Netherlands)

    van Nunen, A B; Janssen, H L; Wolters, L M; Niesters, H G; de Man, R A; Schalm, S W

    2001-01-01

    For the treatment of chronic hepatitis B (CHB) two drugs have been licensed world-wide: interferon-alpha (IFN) and lamivudine. Both drugs significantly increase the hepatitis B e-antigen (HBeAg) seroconversion rate, but a sustained treatment response occurs in less than 40% of patients. To explore w

  7. Ataxia telangiectasia: presentation and diagnostic delay.

    Science.gov (United States)

    Devaney, Rebecca; Pasalodos, Sara; Suri, Mohnish; Bush, Andy; Bhatt, Jayesh M

    2017-04-01

    Ataxia telangiectasia (A-T) is a rare progressive, multisystem genetic disease. Families of children with ultra-rare diseases often experience significant diagnostic delays. We reviewed the diagnostic process for A-T in order to identify causes of delay in an attempt to facilitate earlier identification of A-T in the future. A retrospective case note review of 79 children at the National Paediatric A-T clinic seen since May 2009. Data were collected on the nature and age of initial symptoms, the age at first presentation, measurement of alpha feto-protein (AFP) and age of genetic diagnostic confirmation. At presentation, 71 children (90%) had ataxia. The median presentation delay (from first parental concern to presentation) was 8 months (range 0-118 months), and the median diagnostic delay (genetic confirmation of diagnosis) was 12 months (range 1-109 months). There are significant delays in presentation and diagnostic confirmation of A-T. A greater awareness of A-T and early measurement of AFP may help to improve this. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  8. Wigner photoemission time delay from endohedral anions

    Science.gov (United States)

    Kumar, Ashish; Varma, Hari R.; Deshmukh, Pranawa C.; Manson, Steven T.; Dolmatov, Valeriy K.; Kheifets, Anatoli

    2016-10-01

    Characteristic features of Wigner photoemission time delay from endohedral anions A@C60q along with their dependence on the anion charge q are unraveled. Specifically, significant enhancement of the time delay in the innermost dipole photoionization channels near threshold is found, owing to the presence of the Coulomb confined resonances (CRs). Moreover, it is shown that interchannel coupling of the inner-shell Coulomb CRs with outer-shell photoionization channels results in resonantly enhanced time delay in the release of the outer-shell photoelectron well above, several hundreds eV, the outer-shell thresholds. It is also demonstrated that, and explained why, photoionization cross sections of the innermost subshells as well as outer subshells (near the inner-subshell threshold) depends only very weakly on the anion charge q , but the dependence of the corresponding time delays on q can be significant. Furthermore, Coulomb CRs are found to emerge in the innermost quadrupole photoionization channels as well, thereby causing considerable time delay in the quadrupole photoemission. These findings are illustrated in calculations of the photoionization of inner and outer subshells of the endohedral anions Ne@C60-1 and Ne@C60-5 that were chosen as case studies.

  9. Time Delay for the Dirac Equation

    Science.gov (United States)

    Naumkin, Ivan; Weder, Ricardo

    2016-10-01

    We consider time delay for the Dirac equation. A new method to calculate the asymptotics of the expectation values of the operator {intlimits0 ^{∞}e^{iH0t}ζ(\\vert x\\vert /R) e^{-iH0t}dt}, as {R → ∞}, is presented. Here, H 0 is the free Dirac operator and {ζ(t)} is such that {ζ(t) = 1} for {0 ≤ t ≤ 1} and {ζ(t) = 0} for {t > 1}. This approach allows us to obtain the time delay operator {δ {T}(f)} for initial states f in {{H} 2^{3/2+ɛ}({R}3;{C}4)}, {ɛ > 0}, the Sobolev space of order {3/2+ɛ} and weight 2. The relation between the time delay operator {δ{T}(f)} and the Eisenbud-Wigner time delay operator is given. In addition, the relation between the averaged time delay and the spectral shift function is presented.

  10. Theory of attosecond delays in molecular photoionization

    Science.gov (United States)

    Baykusheva, Denitsa; Wörner, Hans Jakob

    2017-03-01

    We present a theoretical formalism for the calculation of attosecond delays in molecular photoionization. It is shown how delays relevant to one-photon-ionization, also known as Eisenbud-Wigner-Smith delays, can be obtained from the complex dipole matrix elements provided by molecular quantum scattering theory. These results are used to derive formulae for the delays measured by two-photon attosecond interferometry based on an attosecond pulse train and a dressing femtosecond infrared pulse. These effective delays are first expressed in the molecular frame where maximal information about the molecular photoionization dynamics is available. The effects of averaging over the emission direction of the electron and the molecular orientation are introduced analytically. We illustrate this general formalism for the case of two polyatomic molecules. N2O serves as an example of a polar linear molecule characterized by complex photoionization dynamics resulting from the presence of molecular shape resonances. H2O illustrates the case of a non-linear molecule with comparably simple photoionization dynamics resulting from a flat continuum. Our theory establishes the foundation for interpreting measurements of the photoionization dynamics of all molecules by attosecond metrology.

  11. Clinical application of estimating hepatitis B virus quasispecies complexity by massive sequencing: correlation between natural evolution and on-treatment evolution.

    Directory of Open Access Journals (Sweden)

    Maria Homs

    Full Text Available AIM: To evaluate HBV quasispecies (QA complexity in the preCore/Core regions in relation to HBeAg status, and explore QA changes under natural evolution and nucleoside analogue (NUC treatment. METHODS: Ultra-deep pyrosequencing of HBV preCore/Core regions in 30 sequential samples (baseline [diagnosis], treatment-free, and treatment-nonresponse from 10 retrospectively selected patients grouped according to HBeAg status over time: HBeAg+ (N = 4, HBeAg- (N = 2, and fluctuating HBeAg (transient seroreversion/seroconversion pattern (N = 4. QA complexity was defined by Shannon entropy, mutation frequency, nucleotide diversity, and mutation frequency of amino acids (MfAA in preCore and Core. RESULTS: The QA was less complex in HBeAg+ than in HBeAg- or fluctuating HBeAg. High complexity in preCore was associated with decreased viral replication (preCore MfAA negatively correlated with HBV-DNA, p = 0.005. QA complexity in the treatment-free period negatively correlated with values seen during treatment. Specific variants were mainly selected in the Core region in HBeAg- and fluctuating HBeAg patients, suggesting higher immune pressure than in HBeAg+. CONCLUSIONS: The negative correlation between QA natural evolution and on-treatment evolution indicates the importance of pre-treatment QA study to predict QA changes in NUC nonresponders. Study of QA complexity could be useful for managing HBV infection.

  12. Clinical Application of Estimating Hepatitis B Virus Quasispecies Complexity by Massive Sequencing: Correlation between Natural Evolution and On-Treatment Evolution

    Science.gov (United States)

    Homs, Maria; Caballero, Andrea; Gregori, Josep; Tabernero, David; Quer, Josep; Nieto, Leonardo; Esteban, Rafael; Buti, Maria; Rodriguez-Frias, Francisco

    2014-01-01

    Aim To evaluate HBV quasispecies (QA) complexity in the preCore/Core regions in relation to HBeAg status, and explore QA changes under natural evolution and nucleoside analogue (NUC) treatment. Methods Ultra-deep pyrosequencing of HBV preCore/Core regions in 30 sequential samples (baseline [diagnosis], treatment-free, and treatment-nonresponse) from 10 retrospectively selected patients grouped according to HBeAg status over time: HBeAg+ (N = 4), HBeAg- (N = 2), and fluctuating HBeAg (transient seroreversion/seroconversion pattern) (N = 4). QA complexity was defined by Shannon entropy, mutation frequency, nucleotide diversity, and mutation frequency of amino acids (MfAA) in preCore and Core. Results The QA was less complex in HBeAg+ than in HBeAg- or fluctuating HBeAg. High complexity in preCore was associated with decreased viral replication (preCore MfAA negatively correlated with HBV-DNA, p = 0.005). QA complexity in the treatment-free period negatively correlated with values seen during treatment. Specific variants were mainly selected in the Core region in HBeAg- and fluctuating HBeAg patients, suggesting higher immune pressure than in HBeAg+. Conclusions The negative correlation between QA natural evolution and on-treatment evolution indicates the importance of pre-treatment QA study to predict QA changes in NUC nonresponders. Study of QA complexity could be useful for managing HBV infection. PMID:25393280

  13. Adaptive synchronization of neural networks with time-varying delay and distributed delay

    Science.gov (United States)

    Wang, Kai; Teng, Zhidong; Jiang, Haijun

    2008-01-01

    In this paper, the adaptive synchronization of neural networks with time-varying delay and distributed delay is discussed. Based on the LaSalle invariant principle of functional differential equations and the adaptive feedback control technique, some sufficient conditions for adaptive synchronization of such a system are obtained. Finally, a numerical example is given to show the effectiveness of the proposed synchronization method.

  14. Effect of Delay on Children's Delay-Execute Prospective Memory Performance

    Science.gov (United States)

    Rendell, Peter G.; Vella, Melissa J.; Kliegel, Matthias; Terrett, Gill

    2009-01-01

    To date, little work has been done investigating prospective memory in children, particularly using a delay-execute paradigm. Two experiments were conducted to investigate this issue with children aged 5-11 years. While playing a computer driving game, children's ability to carry out a delayed intention either immediately a target cue appeared or…

  15. Robust delay-dependent feedforward control of neutral time-delay systems via dynamic IQCs

    Science.gov (United States)

    Ucun, L.; Küçükdemiral, I. B.

    2014-05-01

    This paper studies the design problem of delay-dependent ? based robust and optimal feedforward controller design for a class of time-delay control systems having state, control and neutral type delays which are subject to norm-bounded uncertainties and ? type measurable or observable disturbance signals. Two independent loops which include state-feedback and dynamic feedforward controller form the basis of the proposed control scheme in this study. State-feedback controller is generally used in stabilisation of the nominal delay-free system, whereas the feedforward controller is used for improving disturbance attenuation performance of the overall system. In order to obtain less conservative results, the delay and parametric uncertainty effects are treated in operator view point and represented by frequency-dependent (dynamic) integral quadratic constraints (IQCs). Moreover, sufficient delay-dependent criterion is developed in terms of linear matrix inequalities (LMIs) such that the time-delay system having parametric uncertainties is guaranteed to be asymptotically stable with minimum achievable disturbance attenuation level. Plenty of numerical examples are provided at the end, in order to illustrate the efficiency of the proposed technique. The achieved results on minimum achievable disturbance attenuation level and maximum allowable delay bounds are exhibited to be less conservative in comparison to those of controllers having only feedback loop.

  16. A Comparison of Motor Delays in Young Children: Autism Spectrum Disorder, Developmental Delay, and Developmental Concerns

    Science.gov (United States)

    Provost, Beth; Lopez, Brian R.; Heimerl, Sandra

    2007-01-01

    This study assessed motor delay in young children 21-41 months of age with autism spectrum disorder (ASD), and compared motor scores in children with ASD to those of children without ASD. Fifty-six children (42 boys, 14 girls) were in three groups: children with ASD, children with developmental delay (DD), and children with developmental concerns…

  17. Controllability of Linear Discrete-Time Systems with Both Delayed States and Delayed Inputs

    Directory of Open Access Journals (Sweden)

    Hong Shi

    2013-01-01

    Full Text Available The controllability issues for discrete-time linear systems with delay in state and control are addressed. By introducing a new concept, the controllability realization index (CRI, the characteristic of controllability is revealed. An easily testable necessary and sufficient condition for the controllability of discrete-time linear systems with state and control delay is established.

  18. Delay-Dependent Exponential Stability Criterion for BAM Neural Networks with Time-Varying Delays

    Institute of Scientific and Technical Information of China (English)

    Wei-Wei Su; Yi-Ming Chen

    2008-01-01

    By employing the Lyapunov stability theory and linear matrix inequality (LMI) technique, delay dependent stability criterion is derived to ensure the exponential stability of bi-directional associative memory (BAM) neural networks with time-varying delays. The proposed condition can be checked easily by LMI control toolbox in Matlab. A numerical example is given to demonstrate the effectiveness of our results.

  19. A DELAY-DEPENDENT STABILITY CRITERION FOR NONLINEAR STOCHASTIC DELAY-INTEGRO-DIFFERENTIAL EQUATIONS

    Institute of Scientific and Technical Information of China (English)

    Niu Yuanling; Zhang Chengjian; Duan Jinqiao

    2011-01-01

    A type of complex systems under both random influence and memory effects is considered.The systems are modeled by a class of nonlinear stochastic delay-integrodifferential equations.A delay-dependent stability criterion for such equations is derived under the condition that the time lags are small enough.Numerical simulations are presented to illustrate the theoretical result.

  20. The Effects of Delay of Feedback on a Delayed Concept Formation Transfer Task.

    Science.gov (United States)

    Schroth, Marvin L.

    1992-01-01

    Delay and completeness of verbal information feedback were investigated within a transfer of learning paradigm involving concept formation. An experiment with 192 undergraduates indicates that, although delay of feedback (up to 30 seconds) slows speed of learning on the initial task, it has positive effects on the transfer task. (SLD)

  1. 乙肝疫苗联合乙肝免疫球蛋白预防HBeAg阴性的HBV感染母亲母婴传播的效果评估%Evaluation for Effects of Routine Administration of Hepatitis B Vaccine and Hepatitis B Immunoglobulin on Preventing Mother-to-Infant Transmission of HBV-infected Mothers with Negative HBeAg

    Institute of Scientific and Technical Information of China (English)

    芮燕京; 宋文英; 陈洁; 周乙华; 胡娅莉; 王志群

    2013-01-01

    2.3 years.Although 32 (16.08%) children showed HBsAg-positive in their cord blood,all 252 children were negative at the follow-up moment for both HBsAg and anti-HBc,and the positive rate of anti-HBs was 74.21%.The positive rate of anti-HBs in 92 children of the 87 mothers administered HBIG during pregnancy was 65.22%,while that in 150 children of the 137 women without HBIG was 73.33% (x2 =1.797,P>0.05).The anti-HBs positive rate in 108 children delivered with cesarean section was similar to that in 144 other children delivered spontaneously (76.85% vs 72.22%,x2 =0.691,P>0.05).The positive rate of anti-HBs in 111 children with breastfeeding,65 with artificial feeding,and 76 with mixed feeding were 68.47%,78.46%,and 78.95%,respectively (x 2 =3.417,P > 0.05).Conclusion:With the availability of current immunoprophylaxis,infants of HBV-infected mothers with negative HBeAg are scarcely infected with HBV.Detection of HBsAg in cord blood is useless to define the perinatal infection.HBIG administration in pregnant women,cesarean section,and artificial feeding have no effect on preventing perinatal HBV infection and enhancing the anti-HBs response.

  2. Delayed Sequential Coding of Correlated Sources

    CERN Document Server

    Ma, Nan; Ishwar, Prakash

    2007-01-01

    Motivated by video coding applications, we study the problem of sequential coding of correlated sources with (noncausal) encoding and/or decoding frame-delays. The fundamental tradeoffs between individual frame rates, individual frame distortions, and encoding/decoding frame-delays are derived in terms of a single-letter information-theoretic characterization of the rate-distortion region for general inter-frame source correlations and certain types of (potentially frame-specific and coupled) single-letter fidelity criteria. For video sources which are spatially stationary memoryless and temporally Gauss--Markov, MSE frame distortions, and a sum-rate constraint, our results expose the optimality of differential predictive coding among all causal sequential coders. Somewhat surprisingly, causal sequential encoding with one-step delayed noncausal sequential decoding can exactly match the sum-rate-MSE performance of joint coding for all nontrivial MSE-tuples satisfying certain positive semi-definiteness conditio...

  3. Elimination of Delays to Oculomotor Research Equipment

    Directory of Open Access Journals (Sweden)

    Saulius Niauronis

    2012-04-01

    Full Text Available Optic stimulus used for human oculomotor system or eye-hand coordination researches is often represented on a computer screen. They must be synchronised with the eye tracker to achieve the accurate results of the conducted experiments. Relation between stimulus presence and eye image capturing times can be defined only with reference to knowledge of all system delays. The suggested research evaluates our eye tracking system delay and propose a practical method for measuring and evaluating delays to the computer graphic subsystem. Experimental research shows that LC Technologies eye tracker reports gaze angle with 28 ms lag and the average stimulus lag of the computer graphic subsystem is 9,5 ms.Article in Lithuanian

  4. Time delay measurement in the frequency domain

    Energy Technology Data Exchange (ETDEWEB)

    Durbin, Stephen M., E-mail: durbin@purdue.edu; Liu, Shih-Chieh [Purdue University, West Lafayette, IN 47907 (United States); Dufresne, Eric M.; Li, Yuelin; Wen, Haidan [Argonne National Laboratory, Argonne, IL 60439 (United States)

    2015-08-06

    A simple frequency domain technique for determining the time delay between laser pump and X-ray probe pulses achieves 1 ps resolution even for ∼100 ps synchrotron pulses, permitting improved pump–probe characterization of ultrafast processes. Pump–probe studies at synchrotrons using X-ray and laser pulses require accurate determination of the time delay between pulses. This becomes especially important when observing ultrafast responses with lifetimes approaching or even less than the X-ray pulse duration (∼100 ps). The standard approach of inspecting the time response of a detector sensitive to both types of pulses can have limitations due to dissimilar pulse profiles and other experimental factors. Here, a simple alternative is presented, where the frequency response of the detector is monitored versus time delay. Measurements readily demonstrate a time resolution of ∼1 ps. Improved precision is possible by simply extending the data acquisition time.

  5. Time-delayed autosynchronous swarm control.

    Science.gov (United States)

    Biggs, James D; Bennet, Derek J; Dadzie, S Kokou

    2012-01-01

    In this paper a general Morse potential model of self-propelling particles is considered in the presence of a time-delayed term and a spring potential. It is shown that the emergent swarm behavior is dependent on the delay term and weights of the time-delayed function, which can be set to induce a stationary swarm, a rotating swarm with uniform translation, and a rotating swarm with a stationary center of mass. An analysis of the mean field equations shows that without a spring potential the motion of the center of mass is determined explicitly by a multivalued function. For a nonzero spring potential the swarm converges to a vortex formation about a stationary center of mass, except at discrete bifurcation points where the center of mass will periodically trace an ellipse. The analytical results defining the behavior of the center of mass are shown to correspond with the numerical swarm simulations.

  6. Why do delayed summaries improve metacomprehension accuracy?

    Science.gov (United States)

    Anderson, Mary C M; Thiede, Keith W

    2008-05-01

    We showed that metacomprehension accuracy improved when participants (N=87 college students) wrote summaries of texts prior to judging their comprehension; however, accuracy only improved when summaries were written after a delay, not when written immediately after reading. We evaluated two hypotheses proposed to account for this delayed-summarization effect (the accessibility hypothesis and the situation model hypothesis). The data suggest that participants based metacomprehension judgments more on the gist of texts when they generated summaries after a delay; whereas, they based judgments more on details when they generated summaries immediately after reading. Focusing on information relevant to the situation model of a text (the gist of a text) produced higher levels of metacomprehension accuracy, which is consistent with situation model hypothesis.

  7. Delay estimation for CMOS functional cells

    DEFF Research Database (Denmark)

    Madsen, Jan

    1991-01-01

    Presents a new RC tree network model for delay estimation of CMOS functional cells. The model is able to reflect topological changes within a cell, which is of particular interest when doing performance driven layout synthesis. Further, a set of algorithms to perform worst case analysis on arbitr......Presents a new RC tree network model for delay estimation of CMOS functional cells. The model is able to reflect topological changes within a cell, which is of particular interest when doing performance driven layout synthesis. Further, a set of algorithms to perform worst case analysis...... on arbitrary CMOS functional cells using the proposed delay model, is presented. Both model and algorithms have been implemented as a part of a cell compiler (CELLO) working in an experimental silicon compiler environment....

  8. Delayed reconstruction of a quadriceps tendon.

    Science.gov (United States)

    Pocock, C A J; Trikha, S P; Bell, J S P

    2008-01-01

    Rupture of the quadriceps tendon is an uncommon injury and rapid diagnosis is important because delay in surgical repair generally is believed to adversely affect outcome. One study of 20 patients suggests repair should be done during the first 48 to 72 hours postinjury to achieve a successful outcome and late repair led to unsatisfactory recovery. Cases of delayed tendon repair have been reported, the longest to our knowledge being 11 months before surgical intervention. We present a case of successful outcome of a quadriceps tendon rupture reconstructed at least 8 years after occurrence and a review of the literature of delayed reconstructions. We show that successful restoration of extensor mechanism function can be achieved several years after tendon rupture.

  9. Delayed feedback control in quantum transport.

    Science.gov (United States)

    Emary, Clive

    2013-09-28

    Feedback control in quantum transport has been predicted to give rise to several interesting effects, among them quantum state stabilization and the realization of a mesoscopic Maxwell's daemon. These results were derived under the assumption that control operations on the system are affected instantaneously after the measurement of electronic jumps through it. In this contribution, I describe how to include a delay between detection and control operation in the master equation theory of feedback-controlled quantum transport. I investigate the consequences of delay for the state stabilization and Maxwell's daemon schemes. Furthermore, I describe how delay can be used as a tool to probe coherent oscillations of electrons within a transport system and how this formalism can be used to model finite detector bandwidth.

  10. Reasons for diagnostic delay in gynecological malignancies

    DEFF Research Database (Denmark)

    Vandborg, Mai Partridge; Christensen, René dePont Christensen; Kragstrup, Jakob;

    2011-01-01

    Aim The primary aim of this study was to identify and describe different delay types in women with gynecologic cancer, and to analyze the relationship between diagnostic delay and a number of characteristics for patients, cancers and the health care system. Setting A cohort study of women newly...... diagnosed with gynecological cancer at the Department of Gynecology and Obstetrics at Odense University Hospital (OUH) Denmark, during a 15-month period from October 1st 2006 to December 31st 2007. Method Data were obtained from four different questionnaires, the Electronic Patient Journal (EPJ......) and The Danish Gynecological Cancer Database (DGCD). 161 women were included; ovarian cancer: 63, endometrial cancer: 50, cervical cancer: 34 and vulvar cancer: 14. Outcome measures were different delay types counted in days and the influence of four clinical important variables: Presence of alarm symptoms, age...

  11. Opportunistic Secrecy with a Strict Delay Constraint

    CERN Document Server

    Khalil, Karim; Gamal, Hesham El; Youssef, Moustafa

    2009-01-01

    We investigate the delay limited secrecy capacity of the flat fading channel under two different assumptions on the available transmitter channel state information (CSI). The first scenario assumes perfect prior knowledge of both the main and eavesdropper channel gains. Here, upper and lower bounds on the delay limited secrecy capacity are derived, and shown to be tight in the high signal-to-noise ratio (SNR) regime. In the second scenario, only the main channel CSI is assumed to be available at the transmitter where, remarkably, we establish the achievability of a non-zero delay-limited secure rate, for a wide class of channel distributions, with a high probability. In the two cases, our achievability arguments are based on a novel two-stage key-sharing approach that overcomes the secrecy outage phenomenon observed in earlier works.

  12. Abdominal CT findings of delayed postoperative complications

    Energy Technology Data Exchange (ETDEWEB)

    Zissin, R.; Osadchy, A. [Sapir Medical Center, Dept. of Diagnostic Imaging, Kfar Saba (Israel)]. E-mail: zisinrivka@clalit.org.il; Gayer, G. [Assaf Harofe Medical Center, Dept. of Diagnostic Imaging, Zrifin (Israel)

    2007-10-15

    Despite progress in surgical techniques and modern medical treatment, postoperative complications occur not infrequently and vary according to type of surgery, clinical setting, and time elapsed since surgery. In general, they can be divided into early and delayed complications. Delayed postoperative complications can be classified as specific and nonspecific. The common nonspecific delayed complications are incisional hernia and postoperative bowel obstruction. Bowel obstruction can be further categorized as obstruction related to benign or neoplastic etiology, the latter occurring in oncology patients in whom the primary surgery was related to an underlying abdominal neoplasm. Gossypiboma is another, fortunately rare, postoperative complication. Specific complications appear after specific operations and include the following: Splenosis - following splenectomy. Retained gallstones and spilled gallstones - following cholecystectomy, mainly laparoscopic. Dropped appendicolith and stump appendicitis - following appendectomy, mainly laparoscopic. Obturation obstruction by a bezoar - following gastric surgery. Afferent loop syndrome (ALS) - following Bilroth II gastrectomy. (author)

  13. Delay-dependent robust stability of uncertain networked control systems with multiple state time-delays

    Institute of Scientific and Technical Information of China (English)

    Huaicheng YAN; Xinhan HUANG; Min WANG

    2007-01-01

    In this paper, delay-dependent robust stability for a class of uncertain networked control systems (NCSs)with multiple state time-delays is investigated. Modeling of multi-input and multi-output (MIMO) NCSs with networkinduced delays and uncertainties through new methods are proposed. Some new stability criteria in terms of LMIs are derived by using Lyapunov stability theory combined with linear matrix inequalities (LMIs) techniques. We analyze the delay-dependent asymptotic stability and obtain maximum allowable delay bound (MADB) for the NCSs with the proposed methods. Compared with the reported results, the proposed results obtain a much less conservative MADB which are more general. Numerical example and simulation is used to illustrate the effectiveness of the proposed methods.

  14. Classic conditioning in aged rabbits: delay, trace, and long-delay conditioning.

    Science.gov (United States)

    Solomon, P R; Groccia-Ellison, M E

    1996-06-01

    Young (0.5 years) and aged (2+, 3+, and 4+ years) rabbits underwent acquisition of the classically conditioned nictitating membrane response in a delay (500-ms conditioned stimulus [CS], 400-ms interstimulus interval [ISI]), long-delay (1,000-ms CS, 900-ms ISI), or trace (500-ms CS, 400-ms stimulus-free period) paradigm. Collapsing across age groups, there is a general tendency for animals to acquire trace conditioning more slowly than delay conditioning. Collapsing across conditioning paradigms, there is a general tendency for aged animals to acquire more slowly than younger animals. Of greater significance, however, are the age differences in the different conditioning paradigms. In the delay and long-delay paradigms, significant conditioning deficits first appeared in the 4(+)-year-old group. In the trace conditioning paradigm, significant conditioning deficits became apparent in the 2(+)-year-old animals.

  15. Information transfer via implicit encoding with delay time modulation in a time-delay system

    Energy Technology Data Exchange (ETDEWEB)

    Kye, Won-Ho, E-mail: whkye@kipo.go.kr [Korean Intellectual Property Office, Government Complex Daejeon Building 4, 189, Cheongsa-ro, Seo-gu, Daejeon 302-701 (Korea, Republic of)

    2012-08-20

    A new encoding scheme for information transfer with modulated delay time in a time-delay system is proposed. In the scheme, the message is implicitly encoded into the modulated delay time. The information transfer rate as a function of encoding redundancy in various noise scales is presented and it is analyzed that the implicit encoding scheme (IES) has stronger resistance against channel noise than the explicit encoding scheme (EES). In addition, its advantages in terms of secure communication and feasible applications are discussed. -- Highlights: ► We propose new encoding scheme with delay time modulation. ► The message is implicitly encoded with modulated delay time. ► The proposed scheme shows stronger resistance against channel noise.

  16. Linear delay-differential systems with commensurate delays an algebraic approach

    CERN Document Server

    Gluesing-Luerssen, Heide

    2002-01-01

    The book deals with linear time-invariant delay-differential equations with commensurated point delays in a control-theoretic context. The aim is to show that with a suitable algebraic setting a behavioral theory for dynamical systems described by such equations can be developed. The central object is an operator algebra which turns out to be an elementary divisor domain and thus provides the main tool for investigating the corresponding matrix equations. The book also reports the results obtained so far for delay-differential systems with noncommensurate delays. Moreover, whenever possible it points out similarities and differences to the behavioral theory of multidimensional systems, which is based on a great deal of algebraic structure itself. The presentation is introductory and self-contained. It should also be accessible to readers with no background in delay-differential equations or behavioral systems theory. The text should interest researchers and graduate students.

  17. Delay-dependent stability and stabilization criteria of networked control systems with multiple time-delays

    Institute of Scientific and Technical Information of China (English)

    Huaicheng YAN; Xinhan HUANG; Min WANG

    2006-01-01

    This paper deals with the problem of delay-dependent stability and stabilization for networked control systems(NCSs)with multiple time-delays. In view of multi-input and multi-output(MIMO) NCSs with many independent sensors and actuators, a continuous time model with distributed time-delays is proposed. Utilizing the Lyapunov stability theory combined with linear matrix inequalities(LMIs) techniques, some new delay-dependent stability criteria for NCSs in terms of generalized Lyapunov matrix equation and LMIs are derived. Stabilizing controller via state feedback is formulated by solving a set of LMIs. Compared with the reported methods, the proposed methods give a less conservative delay bound and more general results. Numerical example and simulation show that the methods are less conservative and more effective.

  18. Relation between delayed feedback and delay-coupled systems and its application to chaotic lasers

    Energy Technology Data Exchange (ETDEWEB)

    Soriano, Miguel C., E-mail: miguel@ifisc.uib-csic.es; Flunkert, Valentin; Fischer, Ingo [Instituto de Física Interdisciplinar y Sistemas Complejos, IFISC (CSIC-UIB), Campus Universitat Illes Balears, E-07122 Palma de Mallorca (Spain)

    2013-12-15

    We present a systematic approach to identify the similarities and differences between a chaotic system with delayed feedback and two mutually delay-coupled systems. We consider the general case in which the coupled systems are either unsynchronized or in a generally synchronized state, in contrast to the mostly studied case of identical synchronization. We construct a new time-series for each of the two coupling schemes, respectively, and present analytic evidence and numerical confirmation that these two constructed time-series are statistically equivalent. From the construction, it then follows that the distribution of time-series segments that are small compared to the overall delay in the system is independent of the value of the delay and of the coupling scheme. By focusing on numerical simulations of delay-coupled chaotic lasers, we present a practical example of our findings.

  19. Delay-dependent robust stability for neutral systems with mixed discrete-and-neutral delays

    Institute of Scientific and Technical Information of China (English)

    Yong HE; Min WU; Jinhua SHE

    2004-01-01

    This paper focuses on the problem of delay-dependent robust stability of neutral systems with different discrete-and-neutral delays and time-varying structured uncertainties.Some new criteria are presented,in which some free weighting matrices are used to express the relationships between the terms in the Leibniz-Newton formula.The criteria include the information on the size of both neutral-and-discrete delays.It is shown that the present results also include the results for identical discrete-and-neutral delays as special cases.A numerical example illustrates the improvement of the proposed methods over the previous methods and the influences between the discrete and neutral delays.

  20. The Strong Lensing Time Delay Challenge (2014)

    Science.gov (United States)

    Liao, Kai; Dobler, G.; Fassnacht, C. D.; Treu, T.; Marshall, P. J.; Rumbaugh, N.; Linder, E.; Hojjati, A.

    2014-01-01

    Time delays between multiple images in strong lensing systems are a powerful probe of cosmology. At the moment the application of this technique is limited by the number of lensed quasars with measured time delays. However, the number of such systems is expected to increase dramatically in the next few years. Hundred such systems are expected within this decade, while the Large Synoptic Survey Telescope (LSST) is expected to deliver of order 1000 time delays in the 2020 decade. In order to exploit this bounty of lenses we needed to make sure the time delay determination algorithms have sufficiently high precision and accuracy. As a first step to test current algorithms and identify potential areas for improvement we have started a "Time Delay Challenge" (TDC). An "evil" team has created realistic simulated light curves, to be analyzed blindly by "good" teams. The challenge is open to all interested parties. The initial challenge consists of two steps (TDC0 and TDC1). TDC0 consists of a small number of datasets to be used as a training template. The non-mandatory deadline is December 1 2013. The "good" teams that complete TDC0 will be given access to TDC1. TDC1 consists of thousands of lightcurves, a number sufficient to test precision and accuracy at the subpercent level, necessary for time-delay cosmography. The deadline for responding to TDC1 is July 1 2014. Submissions will be analyzed and compared in terms of predefined metrics to establish the goodness-of-fit, efficiency, precision and accuracy of current algorithms. This poster describes the challenge in detail and gives instructions for participation.

  1. Delayed-onset akathisia due to amisulpride

    Directory of Open Access Journals (Sweden)

    Murad Atmaca

    2011-01-01

    Full Text Available Despite the fact that second-generation antipsychotics have a lower potential to cause extrapyramidal side-effects, including akathisia, their incidence is not negligible. Recent work suggests that tardive akathisia may have pharmacological differences from acute akathisia. In the present study, we have evaluated the nature of delayed-onset akathisia in patients on amisülpride monotherapy. Overall, we screened 56 patients on amisulpride treatment for 2 months at a stabilized amisulpride dose. However, 18 patients with diagnostic and statistical manual of mental disorders-IV (DSM-IV presented with acute or delayed-onset akathisia, and all of them also met the entry criteria. The patients were evaluated at baseline and at the time when akathisia presented clinically, with respect to the Positive and Negative Syndrome Scale and Barnes Akathisia Scale (BAS. Using the primary categorical criterion of akathisia (≥2 points of the BAS global scale, 12 (21.4% of the 56 patients experienced delayed-onset akathisia, and six (10.7% showed acute akathisia. The mean time for onset of acute or delayed-onset akathisia was 5.8 ± 2.1 and 39.4 ± 11.3 days, respectively. The mean BAS scores at baseline and after the period of 2 months were 1.3 ± 0.6 and 3.9 ± 2.4, respectively (P < 0.001. Our results revealed that amisulpride could considerably lead to delayed-onset akathisia. However, studies comprising larger samples receiving different antipsychotics, and more comprehensive assessment, will help to ascertain the role of amisulpride in delayed-onset akathisia.

  2. Delayed recompression for decompression sickness: retrospective analysis.

    Directory of Open Access Journals (Sweden)

    Amir Hadanny

    Full Text Available Most cases of decompression sickness (DCS occur soon after surfacing, with 98% within 24 hours. Recompression using hyperbaric chamber should be administrated as soon as feasible in order to decrease bubble size and avoid further tissue injury. Unfortunately, there may be a significant time delay from surfacing to recompression. The time beyond which hyperbaric treatment is non effective is unclear. The aims of the study were first to evaluate the effect of delayed hyperbaric treatment, initiated more than 48 h after surfacing for DCS and second, to evaluate the different treatment protocols.From January 2000 to February 2014, 76 divers had delayed hyperbaric treatment (≥48 h for DCS in the Sagol center for Hyperbaric medicine and Research, Assaf-Harofeh Medical Center, Israel. Data were collected from their medical records and compared to data of 128 patients treated earlier than 48 h after surfacing at the same hyperbaric institute.There was no significant difference, as to any of the baseline characteristics, between the delayed and early treatment groups. With respect to treatment results, at the delayed treatment divers, complete recovery was achieved in 76% of the divers, partial recovery in 17.1% and no improvement in 6.6%. Similar results were achieved when treatment started early, where 78% of the divers had complete recovery, 15.6% partial recovery and 6.2% no recovery. Delayed hyperbaric treatment using US Navy Table 6 protocol trended toward a better clinical outcome yet not statistically significant (OR=2.786, CI95%[0.896-8.66], p=0.07 compared to standard hyperbaric oxygen therapy of 90 minutes at 2 ATA, irrespective of the symptoms severity at presentation.Late recompression for DCS, 48 hours or more after surfacing, has clinical value and when applied can achieve complete recovery in 76% of the divers. It seems that the preferred hyperbaric treatment protocol should be based on US Navy Table 6.

  3. 48 CFR 42.1304 - Government delay of work.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 1 2010-10-01 2010-10-01 false Government delay of work... CONTRACT MANAGEMENT CONTRACT ADMINISTRATION AND AUDIT SERVICES Suspension of Work, Stop-Work Orders, and Government Delay of Work 42.1304 Government delay of work. (a) The clause at 52.242-17, Government Delay of...

  4. Asymptotic Hyperstability of Dynamic Systems with Point Delays

    Directory of Open Access Journals (Sweden)

    M. De la Sen

    2005-01-01

    Full Text Available It is proved that a linear time-invariant system with internal point delays is asymptotically hyperstable independent of the delays if an associate delay-free system is asymptotically hyperstable and the delayed dynamics are sufficiently small.

  5. Patient delay in patients with ST-elevation myocardial infarction

    DEFF Research Database (Denmark)

    Nielsen, Christel Ga; Laut, Kristina G; Jensen, Lisette O

    2016-01-01

    BACKGROUND AND AIMS: To improve treatment success of ST-elevation myocardial infarction, a minimal delay from symptom onset to reperfusion therapy is crucial. The patient's response to initial symptoms (patient delay) substantially affects the delay. We investigated time patterns of patient delay...

  6. Delay generation methods with reduced memory requirements

    DEFF Research Database (Denmark)

    Tomov, Borislav Gueorguiev; Jensen, Jørgen Arendt

    2003-01-01

    Modern diagnostic ultrasound beamformers require delay information for each sample along the image lines. In order to avoid storing large amounts of focusing data, delay generation techniques have to be used. In connection with developing a compact beamformer architecture, recursive algorithms were......) For the best parametric approach, the gate count was 2095, the maximum operation speed was 131.9 MHz, the power consumption at 40 MHz was 10.6 mW, and it requires 4 12-bit words for each image line and channel. 2) For the piecewise-linear approximation, the corresponding numbers are 1125 gates, 184.9 MHz, 7...

  7. TSM control of the delayed input system

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The paper proposed a terminal sliding mode control method for the delayed input system with uncertainties. Firstly, through the state transformation, the original system was transformed into the non-delayed controllable canonical form system. Then the paper designed a terminal sliding mode and terminal sliding control law with Lyapunov method for the transformed system. Through the method, the reaching time of the any initial state and the convergencing time to the equilibrium points are constrained in finite time. The simulation results show the validation of the method.

  8. On the time delay between ultrarelativistic particles

    CERN Document Server

    Fleury, Pierre

    2016-01-01

    The time delay between the receptions of ultrarelativistic particles emitted simultaneously is an observable for both fundamental physics and cosmology. The expression of the delay when the particles travel through an arbitrary spacetime has been derived recently in arXiv:1512.08489, using a particular coordinate system and self-consistent assumptions. In this article I show that this formula enjoys a simple physical interpretation: the relative velocity between two ultrarelativistic particles is constant. This result reveals an interesting kinematical property of general relativity, namely that the tidal forces experienced by ultrarelativistic particles in the direction of their motion are much smaller than those experienced orthogonally to their motion.

  9. Delayed presentation of traumatic intraperitoneal bladder rupture

    Energy Technology Data Exchange (ETDEWEB)

    Brown, D.; Magill, H.L.; Black, T.L.

    1986-03-01

    A child with urine ascites as a delayed manifestation of post-traumatic intraperitoneal bladder rupture is presented. The diagnosis was suggested by abdominal CT scan and confirmed with a cystogram. While uncommon, late presentation of intraperitoneal bladder rupture following trauma may occur from masking of a primary laceration or development of secondary rupture at the site of a hematoma in the bladder wall. Since CT may be a primary diagnostic study performed following abdominal trauma, the radiologist should be aware of CT findings suggesting bladder rupture and of the possibility of delayed presentation of this injury.

  10. Global Synchronization of General Delayed Dynamical Networks

    Institute of Scientific and Technical Information of China (English)

    LI Zhi

    2007-01-01

    Global synchronization of general delayed dynamical networks with linear coupling are investigated. A sufficient condition for the global synchronization is obtained by using the linear matrix inequality and introducing a reference state. This condition is simply given based on the maximum nonzero eigenvalue of the network coupling matrix. Moreover, we show how to construct the coupling matrix to guarantee global synchronization of network,which is very convenient to use. A two-dimension system with delay as a dynamical node in network with global coupling is finally presented to verify the theoretical results of the proposed global synchronization scheme.

  11. Psychosocial correlates of delayed decisions to abort.

    Science.gov (United States)

    Bracken, M B; Kasl, S V

    1976-01-01

    Two samples of women aborting in New York and Connecticut during 1972 and 1973 were studied. In all, six hundred and fifty eight women about to undergo first and second trimester procedures completed a self-administered questionnaire. Items include: demographic, psychosocial and personality parameters, and a detailed review of the decision process leading to abortion. Analyses of the correlates of delay are organized around four components: acknowledgment of pregnancy; seeing a physician ; deciding to abort; and locating a clinic. Other analyses focus on the role of decisional conflict in delay. Methodological issues, implications for educational practice and for theory of decision-making are discussed.

  12. 河南省驻马店市HIV单阳家庭阴性配偶抗体阳转率及其影响因素研究%HIV sero-conversion rate and risk factors among HIV discordant couples in Zhumadian city,Henan province

    Institute of Scientific and Technical Information of China (English)

    陈方方; 王岚; 韩娟; 王丽艳; 何文生; 郭巍; 周建平; 王璐

    2013-01-01

    目的 了解河南省驻马店市HIV单阳家庭阴性配偶抗体阳转率及其影响因素.方法 收集分析当地2006-2011年艾滋病综合防治信息系统和HIV单阳家庭随访管理信息系统中HIV单阳家庭随访信息,每6个月随访一次,包括HIV单阳家庭阴性配偶的人口学信息、原阳性配偶感染特征和抗病毒治疗情况,以及夫妻间性行为特征和社会支持情况,并检测阴性配偶的HIV血清阳转情况.采用Cox比例风险模型分析HIV单阳家庭阴性配偶抗体阳转的影响因素.结果 4813户HIV单阳家庭中,127例阴性配偶发生HIV抗体阳转,2006-2011年总HIV抗体阳转率为0.63/100人年,各年抗体阳转率为0.29/100人年~1.28/100人年,维持在1%左右.HIV阴性配偶受教育程度为初中以下(RR=1.50,95%CI:1.02 ~ 2.21,P=0.04)、原阳性配偶为未接受抗病毒治疗(RR=3.16,95%CI:2.20 ~ 4.56,P<0.01)和最近一次CD4+T淋巴细胞检测结果<200 cell/μl (RR=2.11,95%CI:1.40~ 3.19,P<0.01)、最近半年夫妻性生活中性行为频率≥4次/月(RR=4.27,95%CI:2.89~6.30,P<0.01)和从不使用安全套(RR=6.40,95%CI:3.67~11.17,P<0.01)以及最近半年家庭未获得过经济支持和关怀救助(RR=4.75,95%CI:2.34~9.64,P<0.01)均是阴性配偶HIV抗体阳转的影响因素.结论 近年来驻马店市HIV单阳家庭阴性配偶抗体阳转率趋于稳定,并较之前水平有所下降.随访中需加强感染者抗病毒治疗和依从性管理及夫妻性行为干预,宣传正确的安全套使用知识及搭建社会支持平台.%Objective To analyze the sero-conversion rate and risk factors among HIV discordant couples in Zhumadian.Methods Sero-discordant couples had been followed up during 2006-2011.Information were collected from the National Comprehensive HIV/AIDS Information Management System and the HIV discordant couples Follow-up Management Information System including demographic characteristics of sero

  13. Delay correlation analysis and representation for vital complaint VHDL models

    Science.gov (United States)

    Rich, Marvin J.; Misra, Ashutosh

    2004-11-09

    A method and system unbind a rise/fall tuple of a VHDL generic variable and create rise time and fall time generics of each generic variable that are independent of each other. Then, according to a predetermined correlation policy, the method and system collect delay values in a VHDL standard delay file, sort the delay values, remove duplicate delay values, group the delay values into correlation sets, and output an analysis file. The correlation policy may include collecting all generic variables in a VHDL standard delay file, selecting each generic variable, and performing reductions on the set of delay values associated with each selected generic variable.

  14. Absolute Stability for Lurie Control System with Unbound Time Delays

    Institute of Scientific and Technical Information of China (English)

    王天成; 王耀才; 洪留荣

    2004-01-01

    Time delay existes widely in various real engineering systems and can result in unsatisfactory performance or even an instability of control systems. Therefore, to investigate the stability for time delay systems is of vitul importance in control theory and its applications. Many researchers have studied the stability criteria of systems with constant delay or bound varying time delay, but few of them studied large time delay or unbound time delay. Large time delay existes commonly in various engineering applications. In this paper, the absolute stability of Lurie type direct control systems and indirect control systems with several time delays are discussed. Based on Lyapunov theory, the new delay dependent absolute stability criteria are derived. In our theorem, time delays can be unbound functions, which shows that the results are less conservative than that of existed criteria.

  15. Modeling of Random Delays in Networked Control Systems

    Directory of Open Access Journals (Sweden)

    Yuan Ge

    2013-01-01

    Full Text Available In networked control systems (NCSs, the presence of communication networks in control loops causes many imperfections such as random delays, packet losses, multipacket transmission, and packet disordering. In fact, random delays are usually the most important problems and challenges in NCSs because, to some extent, other problems are often caused by random delays. In order to compensate for random delays which may lead to performance degradation and instability of NCSs, it is necessary to establish the mathematical model of random delays before compensation. In this paper, four major delay models are surveyed including constant delay model, mutually independent stochastic delay model, Markov chain model, and hidden Markov model. In each delay model, some promising compensation methods of delays are also addressed.

  16. Distributed Time Delay Goodwin's Models of the Business Cycle

    Science.gov (United States)

    Antonova, A. O.; Reznik, S. N.; Todorov, M. D.

    2011-11-01

    We consider continuously distributed time delay Goodwin's model of the business cycle. We show that the delay induced sawtooth oscillations, similar to those detected by R. H. Strotz, J. C. McAnulty, J. B. Naines, Econometrica, 21, 390-411 (1953) for Goodwin's model with fixed investment time lag, exist only for very narrow delay distribution when the variance of the delay distribution much less than the average delay.

  17. Dynamics of delayed-coupled chaotic logistic maps: Influence of network topology, connectivity and delay times

    Indian Academy of Sciences (India)

    Arturo C Martí; Marcelo Ponce; Cristina Masoller

    2008-06-01

    We review our recent work on the synchronization of a network of delay-coupled maps, focusing on the interplay of the network topology and the delay times that take into account the finite velocity of propagation of interactions. We assume that the elements of the network are identical ( logistic maps in the regime where the individual maps, without coupling, evolve in a chaotic orbit) and that the coupling strengths are uniform throughout the network. We show that if the delay times are su±ciently heterogeneous, for adequate coupling strength the network synchronizes in a spatially homogeneous steady state, which is unstable for the individual maps without coupling. This synchronization behavior is referred to as `suppression of chaos by random delays' and is in contrast with the synchronization when all the interaction delay times are homogeneous, because with homogeneous delays the network synchronizes in a state where the elements display in-phase time-periodic or chaotic oscillations. We analyze the influence of the network topology considering four different types of networks: two regular (a ring-type and a ring-type with a central node) and two random (free-scale Barabasi-Albert and small-world Newman-Watts). We find that when the delay times are sufficiently heterogeneous the synchronization behavior is largely independent of the network topology but depends on the network's connectivity, i.e., on the average number of neighbors per node.

  18. Delays in seeking treatment for symptomatic tuberculosis in Sabah, East Malaysia: factors for patient delay.

    Science.gov (United States)

    Rundi, C; Fielding, K; Godfrey-Faussett, P; Rodrigues, L C; Mangtani, P

    2011-09-01

    The state of Sabah contributes one third of the tuberculosis (TB) cases in Malaysia. To collect information on factors that affect the time period from the onset of symptoms to first contact with health care providers, whether private or government. A cross-sectional study using a pre-tested questionnaire was conducted among 296 newly registered smear-positive TB patients in 10 districts in Sabah. Univariable and multivariable analyses were used to determine which risk factors were associated with patient delay (>30 days) and 'extreme' patient delay (>90 days). The percentage of patients who sought treatment after 30 and 90 days was respectively 51.8% (95%CI 45.7-57.9) and 23.5% (95%CI 18.6-29.0). The strongest factors associated with patient delay and 'extreme' patient delay was when the first choice for treatment was a non-government health facility and in 30-39-year-olds. 'Extreme' patient delay was also weakly associated, among other factors, with comorbidity and livestock ownership. Delay and extreme delay in seeking treatment were more common when the usual first treatment choice was a non-government health facility. Continuous health education on TB aimed at raising awareness and correcting misconceptions is needed, particularly among those who use non-government facilities.

  19. Time-delayed electromagnetic radiation reaction

    CERN Document Server

    Faci, Sofiane

    2016-01-01

    The Lorentz-Abraham-Dirac (LAD) equation has proved valuable in describing the motion of radiating electric charges but suffers from runaway, pre-acceleration and other ambiguities. The usual scheme is problematic because of locality, which leads to self-interaction with the propagating radiation (i.e. real photons). Instead, the present heuristic model relies on an infinitesimal time delay between the action of external forces and the inertial reaction by the charge. This yields a new and pathology-free equation of motion whereas the radiated energy-momentum is expressed as an infinite series that generalises Larmor's formula and leads to testable predictions using current and near future ultra-intense lasers. The time-delay hypothesis is to be put in parallel with recently observed delays of order $10^{-18}$s (attosecond) in photoemission by atoms and small molecules. Such behaviour is extended here to elementary charges which are supposed to exhibit delays given by the time taken by light to cross the char...

  20. Delayed Equation for Charged Rigid Nonrelativistic Ball

    CERN Document Server

    Vlasov, A A

    2002-01-01

    Simple expression for self-force acting on radiating rigid charged ball is derived (Sommerfeld ball). It is shown that appropriate delayed equation of motion has solutions in general differ from that for Sommerfeld sphere - there are no "radiationless" solutions, but there are oscillating without damping solutions though self-force has nonzero value.

  1. Time Delay Interferometry with Moving Spacecraft Arrays

    CERN Document Server

    Tinto, M; Armstrong, J W; Tinto, Massimo; Estabrook, Frank B.; Armstrong, adn J.W.

    2004-01-01

    Space-borne interferometric gravitational wave detectors, sensitive in the low-frequency (millihertz) band, will fly in the next decade. In these detectors the spacecraft-to-spacecraft light-travel-times will necessarily be unequal, time-varying, and (due to aberration) have different time delays on up- and down-links. Reduction of data from moving interferometric laser arrays in solar orbit will in fact encounter non-symmetric up- and downlink light time differences that are about 100 times larger than has previously been recognized. The time-delay interferometry (TDI) technique uses knowledge of these delays to cancel the otherwise dominant laser phase noise and yields a variety of data combinations sensitive to gravitational waves. Under the assumption that the (different) up- and downlink time delays are constant, we derive the TDI expressions for those combinations that rely only on four inter-spacecraft phase measurements. We then turn to the general problem that encompasses time-dependence of the light...

  2. Delay-insensitive Multi-ring Structures

    DEFF Research Database (Denmark)

    Sparsø, Jens; Staunstrup, Jørgen

    1993-01-01

    This paper describes a set of simple design and performance analysis techniques that have been successfully used to design a number of non-trivial delay-insensitive circuits. Examples are building blocks for digital filters and a vector multiplier using a serial-parallel multiply and accumulate a...

  3. Delay differential equations with homogeneous integral conditions

    Directory of Open Access Journals (Sweden)

    Abdur Raheem

    2013-03-01

    Full Text Available In this article we prove the existence and uniqueness of a strong solution of a delay differential equation with homogenous integral conditions using the method of semidiscretization in time. As an application, we include an example that illustrates the main result.

  4. 78 FR 36820 - List of Applications Delayed

    Science.gov (United States)

    2013-06-19

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF TRANSPORTATION... days. SUMMARY: In accordance with the requirements of 49 U.S.C. 5117(c), PHMSA is publishing the... Application No. Applicant delay of completion New Special Permit Applications 15720-N Digital Wave 3,1...

  5. Assessing Visual Delays using Pupil Oscillations

    Science.gov (United States)

    Mulligan, Jeffrey B.

    2012-01-01

    Stark (1962) demonstrated vigorous pupil oscillations by illuminating the retina with a beam of light focussed to a small spot near the edge of the pupil. Small constrictions of the pupil then are sufficient to completely block the beam, amplifying the normal relationship between pupil area and retinal illuminance. In addition to this simple and elegant method, Stark also investigated more complex feedback systems using an electronic "clamping box" which provided arbitrary gain and phase delay between a measurement of pupil area and an electronically controlled light source. We have replicated Stark's results using a video-based pupillometer to control the luminance of a display monitor. Pupil oscillations were induced by imposing a linear relationship between pupil area and display luminance, with a variable delay. Slopes of the period-vs-delay function for 3 subjects are close to the predicted value of 2 (1.96-2.39), and the implied delays range from 254 to 376 508 to 652 milliseconds. Our setup allows us to extend Stark's work by investigating a broader class of stimuli.

  6. The Organization of Delayed Second Language Correction

    Science.gov (United States)

    Rolin-Ianziti, Jeanne

    2010-01-01

    The present study uses a conversation analytic framework to examine the organization of a type of classroom talk: the delayed correction sequence. Such talk occurs when teacher and students interactively correct errors after the students have completed a communicative activity. This study investigates naturally occurring instances of correction…

  7. Delay Discounting and Social Policy Issues

    Science.gov (United States)

    Weatherly, Jeffrey N.; Plumm, Karyn M.; Derenne, Adam

    2011-01-01

    The present study used a delay discounting framework to study decisions about six social policy issues and one monetary outcome. For outcomes that nearly all participants discounted, social policies were discounted significantly more than money. A similar result was observed when analyzing all outcomes using data only from participants who…

  8. Pigeons' Discounting of Probabilistic and Delayed Reinforcers

    Science.gov (United States)

    Green, Leonard; Myerson, Joel; Calvert, Amanda L.

    2010-01-01

    Pigeons' discounting of probabilistic and delayed food reinforcers was studied using adjusting-amount procedures. In the probability discounting conditions, pigeons chose between an adjusting number of food pellets contingent on a single key peck and a larger, fixed number of pellets contingent on completion of a variable-ratio schedule. In the…

  9. Delay Discounting and Social Policy Issues

    Science.gov (United States)

    Weatherly, Jeffrey N.; Plumm, Karyn M.; Derenne, Adam

    2011-01-01

    The present study used a delay discounting framework to study decisions about six social policy issues and one monetary outcome. For outcomes that nearly all participants discounted, social policies were discounted significantly more than money. A similar result was observed when analyzing all outcomes using data only from participants who…

  10. Load sharing in models with communication delays

    NARCIS (Netherlands)

    Geest, R.A.B. van der

    1994-01-01

    Computer systems may be connected in a network to share workload. A control problem then is to decide which computer should carry out which task. Novel in this report is a model for load sharing with communication delays. It takes nonnegligible time for information from one computer to reach the oth

  11. Oscillatority Conditions for Nonlinear Systems with Delay

    Directory of Open Access Journals (Sweden)

    Denis V. Efimov

    2007-01-01

    Full Text Available Sufficient conditions for oscillatority in the sense of Yakubovich for a class of time delay nonlinear systems are proposed. Under proposed conditions, upper and lower bounds for oscillation amplitude are given. Examples illustrating analytical results by computer simulation are presented.

  12. Performance Evaluation of Blind Tropospheric Delay correction ...

    African Journals Online (AJOL)

    lekky

    with accurate International GNSS Service (IGS)-tropospheric estimations for fifteen IGS stations over a period of 1 year on the Africa continent. ... Tropospheric delay is one of the main error sources in the analysis of space geodetic techniques ...

  13. Traumatic and alternating delayed intracranial hematomas

    Energy Technology Data Exchange (ETDEWEB)

    Lesoin, F.; Redford, H.; Jomin, M.; Viaud, C.; Pruvo, J.

    1984-11-01

    Repeat computed tomography has enabled us to confirm the concept of delayed hematomas. With this in mind we report two cases of alternating, post-traumatic intracranial hematomas; confirming also the role of tamponade after surgical removal of an intracranial hematoma.

  14. Delayed presentation and diagnosis of metastatic hepatocellular ...

    African Journals Online (AJOL)

    often incidental, and the diagnosis of early-stage HCC may be delayed as the symptoms are ... and 1+ proteinuria. There was also a history of shortness of breath. ... Further blood tests were done and the most notable findings were as follows: ...

  15. Characteristics of delayed admission to stroke unit.

    Science.gov (United States)

    Silvestrelli, Giorgio; Parnetti, Lucilla; Tambasco, Nicola; Corea, Francesco; Capocchi, Giuseppe

    2006-01-01

    Early admission to stroke unit (SU) and factors that may cause admission delay represent relevant issues to obtain an optimal management of acute stroke. This study was aimed at recording timing from clinical onset to admission to our SU and to identify the reasons for delay. We prospectively examined acute stroke patients consecutively admitted to the Perugia SU. Baseline characteristics of stroke patients, stroke type and etiology, time from symptom onset to arrival in the SU were obtained from the Hospital-Based Perugia Stroke Registry. 60.8% of 2,213 consecutive stroke patients admitted to the SU arrived within 6 hrs and 39.2% after 6 hrs. Underestimation of symptoms was the cause of delay in 48.7% of cases. Younger age, especially for females, ischemic stroke, mild and/or unspecific symptoms and the underestimation of symptoms seem to be the main reasons for delayed arrival in the SU. To increase the proportion of stroke patients arriving in the SU within 3 hr of symptom onset, it is necessary to improve public and general practitioner awareness of stroke through educational programs.

  16. Recursive Delay Calculation Unit for Parametric Beamformer

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav; Jensen, Jørgen Arendt; Tomov, Borislav Gueorguiev

    2006-01-01

    . The non-pipelined circuit occupies about 0.5 % of the FPGA resources and the pipelined one about 1 %. When the square root is found with a pipelined CORDIC processor, 2 % of the FPGA slices are used to deliver 150 million delays per second. © (2006) COPYRIGHT SPIE--The International Society for Optical...

  17. Feedback Control of Chaos in Delay Maps

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In this paper, we discuss feedback control of a class of delay chaotic maps. Our aim is to drive the chaoticmaps to its initially unstable fixed points by using linear and nonlinear state feedback control. The control is achievedby using small, bounded perturbations. Some numerical simulations are given to demonstrate the effectiveness of theproposed control method.

  18. Delayed-release lansoprazole plus naproxen.

    Science.gov (United States)

    Curran, Monique P; Wellington, Keri

    2004-01-01

    A combination package containing delayed-release capsules of the proton pump inhibitor lansoprazole (15 mg once daily) and tablets of the NSAID naproxen (375 or 500 mg twice daily) has been approved for reducing the risk of NSAID-associated gastric ulcers in NSAID-requiring patients with a documented history of gastric ulcer. In a large, 12-week trial in NSAID (including naproxen)-requiring patients with a documented history of gastric ulcer, significantly more recipients of delayed-release lansoprazole 15 mg once daily than placebo recipients were free from gastric ulcer (p ulcer were 80% with lansoprazole 15 mg and 51% with placebo. In a subgroup analysis of recipients of naproxen (89% received 750-1000 mg/day), the percentage of patients free from gastric ulcer after 12 weeks of treatment was significantly higher with delayed-release lansoprazole 15 mg than with placebo (89% vs 33%; p ulcer, the incidence of treatment-related adverse events in recipients of delayed-release lansoprazole 15 mg once daily was low (7%), and similar to that in recipients of placebo (10%).

  19. Quasi-Hyperbolicity and Delay Semigroups

    Directory of Open Access Journals (Sweden)

    Shard Rastogi

    2016-01-01

    Full Text Available We study quasi-hyperbolicity of the delay semigroup associated with the equation u′(t=Bu(t+Φut, where ut is the history function and (B,D(B is the generator of a quasi-hyperbolic semigroup. We give conditions under which the associated solution semigroup of this equation generates a quasi-hyperbolic semigroup.

  20. Child obesity and motor development delays

    Science.gov (United States)

    Childhood obesity has been associated with delays in motor development using weight-for-length z-scores and subcutaneous fat. To study this further, percent body fat and motor development were assessed in children ages 3 to 24 months. Included were 455 children with a total of 1882 longitudinal obse...

  1. Accelerating Smaller Cutbacks to Delay Larger Ones?

    DEFF Research Database (Denmark)

    2012-01-01

    This chapter investigates the politics of delays in pension generosity cutbacks in 18 OECD democracies between 1981 and 1999 by using event history analysis. In the context of fiscal austerity, policymakers are assumed to have a strong incentive to manipulate the timing of cutbacks strategically....

  2. Delayed onset of clozapine-induced leucopenia.

    Science.gov (United States)

    Nongpiur, Arvind; Praharaj, Samir Kumar; Sarkar, Sukanto; Das, Basudeb

    2012-05-01

    Clozapine has been reported to cause agranulocytosis, neutropenia, and leucopenia that usually occur within 18 weeks of initiation of treatment. We report a case of delayed onset leucopenia after 11 years of treatment with clozapine, which reversed within a few days after discontinuation of medication.

  3. DYNAMIC LABELING BASED FPGA DELAY OPTIMIZATION ALGORITHM

    Institute of Scientific and Technical Information of China (English)

    吕宗伟; 林争辉; 张镭

    2001-01-01

    DAG-MAP is an FPGA technology mapping algorithm for delay optimization and the labeling phase is the algorithm's kernel. This paper studied the labeling phase and presented an improved labeling method. It is shown through the experimental results on MCNC benchmarks that the improved method is more effective than the original method while the computation time is almost the same.

  4. Structural Controllability of Discrete-Time Linear Control Systems with Time-Delay: A Delay Node Inserting Approach

    OpenAIRE

    Ailing Qi; Xuewei Ju; Qing Zhang; Zengqiang Chen

    2016-01-01

    This paper is concerned with the structural controllability analysis for discrete-time linear control systems with time-delay. By adding virtual delay nodes, the linear systems with time-delay are transformed into corresponding linear systems without time-delay, and the structural controllability of them is equivalent. That is to say, the time-delay does not affect or change the controllability of the systems. Several examples are also presented to illustrate the theoretical results.

  5. Delay-dependent robust stabilization for uncertain singular:systems with discrete and distributed delays

    Institute of Scientific and Technical Information of China (English)

    Zhengguang WU; Wuneng ZHOU

    2008-01-01

    This paper investigates the problem of delay-dependent robust stabilization for uncertain singular systems with discrete and distributed delays in terms of linear matrix inequality(LMI)approach.Based on a delay-dependent stability condition for the nominal system,a state feedback controller is designed,which guarantees the resultant closedloop system to be robustly stable.An explicit expression for the desired controller is also given by solving a set of matrix inequalities.Some numerical examples are provided to illustrate the less conservativeness of the proposed methods.

  6. Delay-dependent stabilization of singular Markovian jump systems with state delay

    Institute of Scientific and Technical Information of China (English)

    Zhengguang WU; Hongye SU; Jian CHU

    2009-01-01

    This paper deals with the delay-dependent stabilization problem for singular systems with Markovian jump parameters and time delays.A delay-dependent condition is established for the considered system to be regular,impulse free and stochastically stable.Based on the condition,a design algorithm of the desired state feedback controller which guarantees the resultant closed-loop system to be regular,impulse free and stochastically stable is proposed in terms of a set of strict linear matrix inequalities (LMIs).Numerical examples show the effectiveness of the proposed methods.

  7. New delay-dependent stability criteria for neural networks with time-varying interval delay

    Energy Technology Data Exchange (ETDEWEB)

    Chen Jie, E-mail: chenjie@bit.edu.c [School of Automation, Beijing Institute of Technology, Beijing, 100081 (China); Sun Jian, E-mail: helios1225@yahoo.com.c [School of Automation, Beijing Institute of Technology, Beijing, 100081 (China); Liu, G.P., E-mail: gpliu@glam.ac.u [Faculty of Advanced Technology, University of Glamorgan, Pontypridd CF37 1DL (United Kingdom); CTGT Center in Harbin Institute of Technology, Harbin, 150001 (China); Rees, D., E-mail: drees@glam.ac.u [Faculty of Advanced Technology, University of Glamorgan, Pontypridd CF37 1DL (United Kingdom)

    2010-09-27

    The problem of stability analysis of neural networks with time-varying delay in a given range is investigated in this Letter. By introducing a new Lyapunov functional which uses the information on the lower bound of the delay sufficiently and an augmented Lyapunov functional which contains some triple-integral terms, some improved delay-dependent stability criteria are derived using the free-weighting matrices method. Numerical examples are presented to illustrate the less conservatism of the obtained results and the effectiveness of the proposed method.

  8. Delay-Dependent H∞ Filtering for Singular Time-Delay Systems

    Directory of Open Access Journals (Sweden)

    Zhenbo Li

    2011-01-01

    Full Text Available This paper deals with the problem of delay-dependent H∞ filtering for singular time-delay systems. First, a new delay-dependent condition which guarantees that the filter error system has a prescribed H∞ performance γ is given in terms of linear matrix inequalities (LMIs. Then, the sufficient condition is obtained for the existence of the H∞ filter, and the explicit expression for the desired H∞ filter is presented by using LMIs and the cone complementarity linearization iterative algorithm. A numerical example is provided to illustrate the effectiveness of the proposed method.

  9. Delay-dependent robust H∞ control for uncertain discrete time-delay fuzzy systems

    Institute of Scientific and Technical Information of China (English)

    Gong Cheng; Su Baoku

    2009-01-01

    The robust H∞ control problem of norm bounded uncertain discrete Takagi-Sugeno (T-S) fuzzy tems with state delay is addressed. First, by constructing an appropriate basis-dependent Lyapunov-Krasovskii function, a new delay-dependent sufficient condition on robust H∞-disturbance attenuation is presented, in which both robust stability and prescribed H∞ performance are guaranteed to be achieved. Then based on the condition, a delay-dependent robust H∞ controller design scheme is developed in term of a convex algorithm. Finally, examples are given to illustrate the effectiveness of the proposed method.

  10. Nonlinear Control of Delay and PDE Systems

    Science.gov (United States)

    Bekiaris-Liberis, Nikolaos

    In this dissertation we develop systematic procedures for the control and analysis of general nonlinear systems with delays and of nonlinear PDE systems. We design predictor feedback laws (i.e., feedback laws that use the future, rather than the current state of the system) for the compensation of delays (i.e., after the control signal reaches the system for the first time, the system behaves as there were no delay at all) that can be time-varying or state-dependent, on the input and on the state of nonlinear systems. We also provide designs of predic- tor feedback laws for linear systems with constant distributed delays and known or unknown plant parameters, and for linear systems with simultaneous known or unknown constant delays on the input and the state. Moreover, we intro- duce infinite-dimensional backstepping transformations for each particular prob-lem, which enables us to construct Lyapunov-Krasovskii functionals. With the available Lyapunov-Krasovskii functionals we study stability, as well as, robust- ness of our control laws to plant uncertainties. We deal with coupled PDE-ODE systems. We consider nonlinear systems with wave actuator dynamics, for which we design a predictor inspired feedback law. We study stability of the closed-loop system either by constructing Lyapunov functionals, or using arguments of explicit solutions. We also consider linear sys- tems with distributed actuator and sensor dynamics governed by diffusion or wave PDEs, for which we design stabilizing feedback laws. We study stability of the closed-loop systems using Lyapunov functionals that we construct with the intro- duction of infinite-dimensional transformations of forwarding type. Finally, we develop a control design methodology for coupled nonlinear first-order hyperbolic PDEs through an application to automotive catalysts.

  11. Angular dependence of Wigner time delay: Relativistic Effects

    Science.gov (United States)

    Mandal, A.; Deshmukh, P. C.; Manson, S. T.; Kkeifets, A. S.

    2016-05-01

    Laser assisted photoionization time delay mainly consists of two parts: Wigner time delay, and time delay in continuum-continuum transition. Wigner time delay results from the energy derivative of the phase of the photoionization amplitude (matrix element). In general, the photoionization time delay is not the same in all directions relative to the incident photon polarization, although when a single transition dominates the amplitude, the resultant time delay is essentially isotropic. The relativistic-random-phase approximation is employed to determine the Wigner time delay in photoionization from the outer np subshells of the noble gas atoms, Ne through Xe. The time delay is found to significantly depend on angle, as well as energy. The angular dependence of the time delay is found to be quite sensitive to atomic dynamics and relativistic effects, and exhibit strong energy and angular variation in the neighborhood of Cooper minima. Work supported by DOE, Office of Chemical Sciences and DST (India).

  12. Adaptive modification of the delayed feedback control algorithm with a continuously varying time delay

    Energy Technology Data Exchange (ETDEWEB)

    Pyragas, V. [Semiconductor Physics Institute, Center for Physical Sciences and Technology, A. Gostauto 11, LT-01108 Vilnius (Lithuania); Pyragas, K. [Semiconductor Physics Institute, Center for Physical Sciences and Technology, A. Gostauto 11, LT-01108 Vilnius (Lithuania)

    2011-10-24

    We propose a simple adaptive delayed feedback control algorithm for stabilization of unstable periodic orbits with unknown periods. The state dependent time delay is varied continuously towards the period of controlled orbit according to a gradient-descent method realized through three simple ordinary differential equations. We demonstrate the efficiency of the algorithm with the Roessler and Mackey-Glass chaotic systems. The stability of the controlled orbits is proven by computation of the Lyapunov exponents of linearized equations. -- Highlights: → A simple adaptive modification of the delayed feedback control algorithm is proposed. → It enables the control of unstable periodic orbits with unknown periods. → The delay time is varied continuously according to a gradient descend method. → The algorithm is embodied by three simple ordinary differential equations. → The validity of the algorithm is proven by computation of the Lyapunov exponents.

  13. Stability domains of the delay and PID coefficients for general time-delay systems

    Science.gov (United States)

    Almodaresi, Elham; Bozorg, Mohammad; Taghirad, Hamid D.

    2016-04-01

    Time delays are encountered in many physical systems, and they usually threaten the stability and performance of closed-loop systems. The problem of determining all stabilising proportional-integral-derivative (PID) controllers for systems with perturbed delays is less investigated in the literature. In this study, the Rekasius substitution is employed to transform the system parameters to a new space. Then, the singular frequency (SF) method is revised for the Rekasius transformed system. A novel technique is presented to compute the ranges of time delay for which stable PID controller exists. This stability range cannot be readily computed from the previous methods. Finally, it is shown that similar to the original SF method, finite numbers of singular frequencies are sufficient to compute the stable regions in the space of time delay and controller coefficients.

  14. Logistic map with a delayed feedback: Stability of a discrete time-delay control of chaos.

    Science.gov (United States)

    Buchner, T; Zebrowski, J J

    2001-01-01

    The logistic map with a delayed feedback is studied as a generic model. The stability of the model and its bifurcation scheme is analyzed as a function of the feedback amplitude and of the delay. Stability analysis is performed semianalytically. A relation between the delay and the periodicity of the orbit, which explains why some terms used in chaos control are ineffective, was found. The consequences for chaos control are discussed. The structure of bifurcations is found to depend strongly on the parity and on the length of the delay. Boundary crisis, the tangent, the Neimark, as well as the period-doubling bifurcations occur in this system. The effective dimension of the model is also discussed.

  15. Integrity modelling of tropospheric delay models

    Science.gov (United States)

    Rózsa, Szabolcs; Bastiaan Ober, Pieter; Mile, Máté; Ambrus, Bence; Juni, Ildikó

    2017-04-01

    The effect of the neutral atmosphere on signal propagation is routinely estimated by various tropospheric delay models in satellite navigation. Although numerous studies can be found in the literature investigating the accuracy of these models, for safety-of-life applications it is crucial to study and model the worst case performance of these models using very low recurrence frequencies. The main objective of the INTegrity of TROpospheric models (INTRO) project funded by the ESA PECS programme is to establish a model (or models) of the residual error of existing tropospheric delay models for safety-of-life applications. Such models are required to overbound rare tropospheric delays and should thus include the tails of the error distributions. Their use should lead to safe error bounds on the user position and should allow computation of protection levels for the horizontal and vertical position errors. The current tropospheric model from the RTCA SBAS Minimal Operational Standards has an associated residual error that equals 0.12 meters in the vertical direction. This value is derived by simply extrapolating the observed distribution of the residuals into the tail (where no data is present) and then taking the point where the cumulative distribution has an exceedance level would be 10-7.While the resulting standard deviation is much higher than the estimated standard variance that best fits the data (0.05 meters), it surely is conservative for most applications. In the context of the INTRO project some widely used and newly developed tropospheric delay models (e.g. RTCA MOPS, ESA GALTROPO and GPT2W) were tested using 16 years of daily ERA-INTERIM Reanalysis numerical weather model data and the raytracing technique. The results showed that the performance of some of the widely applied models have a clear seasonal dependency and it is also affected by a geographical position. In order to provide a more realistic, but still conservative estimation of the residual

  16. Do Longer Delays Matter? The Effect of Prolonging Delay in CTL Activation

    CERN Document Server

    Gallegos, Angela

    2010-01-01

    The activation of a specific immune response takes place in the lymphoid organs such as the spleen. We present here a simplified model of the proliferation of specific immune cells in the form of a single delay equation. We show that the system can undergo switches in stability as the delay is increased, and we interpret these results in the context of sustaining an effective immune response to a dendritic cell vaccine.

  17. Topology identification of the complex networks with non-delayed and delayed coupling

    Science.gov (United States)

    Guo, Wanli; Chen, Shihua; Sun, Wen

    2009-10-01

    In practical situation, there exists many uncertain information in complex networks, such as the topological structures. So the topology identification is an important issue in the research of the complex networks. Based on LaSalle's invariance principle, in this Letter, an adaptive controlling method is proposed to identify the topology of a weighted general complex network model with non-delayed and delayed coupling. Finally, simulation results show that the method is effective.

  18. Topology identification of the complex networks with non-delayed and delayed coupling

    Energy Technology Data Exchange (ETDEWEB)

    Guo Wanli, E-mail: guowanliff@163.co [School of Mathematics and Statistics, Wuhan University, Wuhan 430072 (China); Chen Shihua; Sun Wen [School of Mathematics and Statistics, Wuhan University, Wuhan 430072 (China)

    2009-10-05

    In practical situation, there exists many uncertain information in complex networks, such as the topological structures. So the topology identification is an important issue in the research of the complex networks. Based on LaSalle's invariance principle, in this Letter, an adaptive controlling method is proposed to identify the topology of a weighted general complex network model with non-delayed and delayed coupling. Finally, simulation results show that the method is effective.

  19. Delay-Dependent Asymptotic Stability of Cohen-Grossberg Models with Multiple Time-Varying Delays

    Directory of Open Access Journals (Sweden)

    Xiaofeng Liao

    2007-01-01

    Full Text Available Dynamical behavior of a class of Cohen-Grossberg models with multiple time-varying delays is studied in detail. Sufficient delay-dependent criteria to ensure local and global asymptotic stabilities of the equilibrium of this network are derived by constructing suitable Lyapunov functionals. The obtained conditions are shown to be less conservative and restrictive than those reported in the known literature. Some numerical examples are included to demonstrate our results.

  20. Systematic delay-driven power optimisation and power-driven delay optimisation of combinational circuits

    OpenAIRE

    Mehrotra, Rashmi

    2013-01-01

    With the proliferation of mobile wireless communication and embedded systems, the energy efficiency becomes a major design constraint. The dissipated energy is often referred as the product of power dissipation and the input-output delay. Most of electronic design automation techniques focus on optimising only one of these parameters either power or delay. Industry standard design flows integrate systematic methods of optimising either area or timing while for power consumption optimisation o...

  1. Chaos control in delayed chaotic systems via sliding mode based delayed feedback

    Energy Technology Data Exchange (ETDEWEB)

    Vasegh, Nastaran [Faculty of Electrical Engineering, K.N. Toosi University of Technology, Seyed Khandan Bridge, Shariati St. 16314, P.O. Box 16315-1355, Tehran (Iran, Islamic Republic of)], E-mail: vasegh@eetd.kntu.ac.ir; Sedigh, Ali Khaki [Faculty of Electrical Engineering, K.N. Toosi University of Technology, Seyed Khandan Bridge, Shariati St. 16314, P.O. Box 16315-1355, Tehran (Iran, Islamic Republic of)

    2009-04-15

    This paper investigates chaos control for scalar delayed chaotic systems using sliding mode control strategy. Sliding surface design is based on delayed feedback controller. It is shown that the proposed controller can achieve stability for an arbitrary unstable fixed point (UPF) or unstable periodic orbit (UPO) with arbitrary period. The chaotic system used in this study to illustrate the theoretical concepts is the well known Mackey-Glass model. Simulation results show the effectiveness of the designed nonlinear sliding mode controller.

  2. Analysis and optimization of delays in networked control systems

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The minimization problem of time delays in networked control system (NCS) is concered, which is a hot area of such research field. First, some analysis and comments on time-delayed NCS model listed in previous work are given.Then, time delay minimization problem based on average behavior of network queuing delay is presented. Under fixed routing scheme and certain optimization performance indexes, the delay minimization problem is translated into convex optimization problem. And the solution of the delay minimization problems is attained through optimized allocation of flow rates among network links.

  3. Patient delay is the main cause of treatment delay in acute limb ischemia: an investigation of pre- and in-hospital time delay

    DEFF Research Database (Denmark)

    Londero, Louise Skovgaard; Nørgaard, Birgitte; Houlind, Kim Christian

    2014-01-01

    Abstract BACKGROUND: The prognosis of acute limb ischemia is severe, with amputation rates of up to 25% and in-hospital mortality of 9-15%. Delay in treatment increases the risk of major amputation and may be present at different stages, including patient delay, doctors´ delay and waiting time...... in the emergency department. It is important to identify existing problems in order to reduce time delay. The aim of this study was to collect data for patients with acute limb ischemia and to evaluate the time delay between the different events from onset of symptoms to specialist evaluation and further treatment...... with focus on pre-hospital and in-hospital time delays. METHODS: We conducted a prospective cross-sectional cohort study including all patients suspected with acute limb ischemia who were admitted to the emergency department of a community hospital in a six months period. Temporal delay in the different...

  4. Minimum Expected Delay-Based Routing Protocol (MEDR for Delay Tolerant Mobile Sensor Networks

    Directory of Open Access Journals (Sweden)

    Haigang Gong

    2010-09-01

    Full Text Available It is a challenging work to develop efficient routing protocols for Delay Tolerant Mobile Sensor Networks (DTMSNs, which have several unique characteristics such as sensor mobility, intermittent connectivity, energy limit, and delay tolerability. In this paper, we propose a new routing protocol called Minimum Expected Delay-based Routing (MEDR tailored for DTMSNs. MEDR achieves a good routing performance by finding and using the connected paths formed dynamically by mobile sensors. In MEDR, each sensor maintains two important parameters: Minimum Expected Delay (MED and its expiration time. According to MED, messages will be delivered to the sensor that has at least a connected path with their hosting nodes, and has the shortest expected delay to communication directly with the sink node. Because of the changing network topology, the path is fragile and volatile, so we use the expiration time of MED to indicate the valid time of the path, and avoid wrong transmissions. Simulation results show that the proposed MEDR achieves a higher message delivery ratio with lower transmission overhead and data delivery delay than other DTMSN routing approaches.

  5. Delay-correlation landscape reveals characteristic time delays of brain rhythms and heart interactions.

    Science.gov (United States)

    Lin, Aijing; Liu, Kang K L; Bartsch, Ronny P; Ivanov, Plamen Ch

    2016-05-13

    Within the framework of 'Network Physiology', we ask a fundamental question of how modulations in cardiac dynamics emerge from networked brain-heart interactions. We propose a generalized time-delay approach to identify and quantify dynamical interactions between physiologically relevant brain rhythms and the heart rate. We perform empirical analysis of synchronized continuous EEG and ECG recordings from 34 healthy subjects during night-time sleep. For each pair of brain rhythm and heart interaction, we construct a delay-correlation landscape (DCL) that characterizes how individual brain rhythms are coupled to the heart rate, and how modulations in brain and cardiac dynamics are coordinated in time. We uncover characteristic time delays and an ensemble of specific profiles for the probability distribution of time delays that underly brain-heart interactions. These profiles are consistently observed in all subjects, indicating a universal pattern. Tracking the evolution of DCL across different sleep stages, we find that the ensemble of time-delay profiles changes from one physiologic state to another, indicating a strong association with physiologic state and function. The reported observations provide new insights on neurophysiological regulation of cardiac dynamics, with potential for broad clinical applications. The presented approach allows one to simultaneously capture key elements of dynamic interactions, including characteristic time delays and their time evolution, and can be applied to a range of coupled dynamical systems.

  6. Delay-correlation landscape reveals characteristic time delays of brain rhythms and heart interactions

    Science.gov (United States)

    Lin, Aijing; Liu, Kang K. L.; Bartsch, Ronny P.; Ivanov, Plamen Ch.

    2016-05-01

    Within the framework of `Network Physiology', we ask a fundamental question of how modulations in cardiac dynamics emerge from networked brain-heart interactions. We propose a generalized time-delay approach to identify and quantify dynamical interactions between physiologically relevant brain rhythms and the heart rate. We perform empirical analysis of synchronized continuous EEG and ECG recordings from 34 healthy subjects during night-time sleep. For each pair of brain rhythm and heart interaction, we construct a delay-correlation landscape (DCL) that characterizes how individual brain rhythms are coupled to the heart rate, and how modulations in brain and cardiac dynamics are coordinated in time. We uncover characteristic time delays and an ensemble of specific profiles for the probability distribution of time delays that underly brain-heart interactions. These profiles are consistently observed in all subjects, indicating a universal pattern. Tracking the evolution of DCL across different sleep stages, we find that the ensemble of time-delay profiles changes from one physiologic state to another, indicating a strong association with physiologic state and function. The reported observations provide new insights on neurophysiological regulation of cardiac dynamics, with potential for broad clinical applications. The presented approach allows one to simultaneously capture key elements of dynamic interactions, including characteristic time delays and their time evolution, and can be applied to a range of coupled dynamical systems.

  7. Delay or anticipatory synchronization in one-way coupled systems using variable delay with reset

    Indian Academy of Sciences (India)

    G Ambika; R E Amritkar

    2011-11-01

    We present a mechanism for the synchronization of one-way coupled nonlinear systems in which the coupling uses a variable delay, that is reset at finite intervals. Here the delay varies in the same way as the system in time and so the coupling function remains constant for the reset interval at the end of which it is reset to the value at that time. This leads to a novel and discrete error dynamics and the resulting general stability analysis is applicable to chaotic or hyperchaotic systems. We apply this method to standard chaotic systems and hyperchaotic time delay systems. The results of the detailed numerical analysis agree with the results from stability analysis in both cases. This method has the advantage that it is cost-effective since information from the driving system is needed only at intervals of reset. Further, in the context of time delay systems, optimization among the different time-scales depending upon the application is possible due to the flexibility among the four different time-scales in our method, viz. delay in the driving system, anticipation in the response system, system delay time and reset time. We suggest a bi-channel scheme for implementing this method in communication field with enhanced security

  8. 建立我国HIV阳转血浆盘并评价HIV酶免血筛试剂窗口期%Evaluation of HIV diagnosis kits used for blood screening with NIFDC-established HIV-1 seroconver-sion panels

    Institute of Scientific and Technical Information of China (English)

    黄维金; 宋爱京; 许四宏; 王佑春

    2016-01-01

    目的:建立我国HIV系列阳转血清盘并用其评价HIV酶免血筛诊断试剂的窗口期。方法收集HIV感染者的系列血清,利用Western blot确认试剂、HIV抗原定量检测试剂、核酸定量检测试剂等检测系列样品,RT-PCR的方法扩增HIV env序列并测序和分型,以确认HIV感染。对国内外5种第四代和14种第三代酶免HIV血液筛查诊断试剂的检测窗口期进行评价。结果共收集确认8套HIV感染者的阳转系列血浆,AE亚型6套,B亚型1套,未分型1套,共含有36份样品。用HIV系列阳转血清盘评价发现四代抗原抗体联合检测试剂较三代抗体检测试剂具有更早的窗口期检测能力,前者评分9.4分,后者3.6分,差异具有统计学意义(t=8.547,P<0.01);部分国产四代试剂质量已经达到进口试剂的水平;核酸试剂的窗口期检测能力高于酶免试剂,在3套血清盘中至少提高2周以上;确认试剂的灵敏度低于血筛试剂的灵敏度;4/5四代试剂在检测感染早期样品时会出现检测信号值/界值( S/CO)下降的情况,存在第二窗口期漏检风险。结论本研究建立了8套我国的HIV系列阳转血清盘,评价发现我国HIV血液筛查酶免诊断试剂窗口期检测能力存在差异。%Objective To establish HIV-1 seroconversion panels with the samples collected by National Institutes for Food and Drug Control ( NIFDC) and to evaluate the window periods of HIV enzyme immunoassay ( EIA) diagnostic kits used for blood screening with them. Methods Serum specimens were collected from different plasma donation stations in China. All suspected HIV infection specimens were screened for HIV by using the nucleic acid amplification testing (NAT), Western blot confirmatory assay and P24 quantitative detection assay. The HIV env gene sequences were amplified by RT-PCR for further confirmation of HIV infection. The PCR products were sequenced and genotyped. The confirmed seroconver-sion panels were used to

  9. 驻马店市抗病毒治疗“单阳家庭”夫妻间性传播HIV影响因素分析%Risk factors associated with HIV sero-conversion of negative partners in discordant couples under treatment in Zhumadian

    Institute of Scientific and Technical Information of China (English)

    明帅; 王岚; 王璐; 葛增; 周建平; 何文生; 王俊杰

    2012-01-01

    Objective To examine HIV sero-conversion of uninfected partners in discordant couples under treatment and associated factors, and provide scientific evidence for HIV intervention program. Methods Discordant couples, who were followed up in 2006 and received treatment as well, were selected as a fix cohort. Data regarding sero-conversion status of former negative partners, sexual behaviors, infection, treatment and serologic characteristics of the positive partners were retrospectively analyzed between October of 2010 and April of 2011. Results In 2 119 discordant couples, a total of 80 previously negative partners were sero-converted in 4. 5 years, achieving a sero-conversion rate of 3. 78% (80/2119). Results from multivariate Logistic regression showed that male negative partners (RR=2. 20, 95% CI; 1. 11-4.36), DDI based regimens (RR=3. 08, 95% CI: 1.58-5.99), using the same therapeutic regimens (RR = i. 33, 95% Cl: 1. 92-9. 75) and higher log value of viral load (KR=1. 43, 95% Cl: 1. 18-1. 74) were independent risk factors, while a higher educational background with above junior secondary schooling among negative partners(RR = 0. 27, 95% CI, 0. 13 - 0. 60) and persistent condom use (RR = 0. 08, 95% CI; 0. 04 - 0. 15) may decrease the risk of sero-conversion. Conclusion In Zhumadian city, the sero-conversion of negative partners in discordant couples is relatively low. It is important to switch and standardize treatment regimens according to individual conditions, and promotion of condom use is also of great importance.%目的 了解驻马店市抗病毒治疗的艾滋病病毒(HIV)“单阳家庭”阴性配偶抗体阳转情况,分析其影响因素.方法 2010年10月-2011年4月,对驻马店市2006年7月1日开始随访,2010年10月仍在访的、目前正在接受抗病毒治疗的2119个“单阳家庭”配偶双方进行回顾性问卷调查和实验室检测,收集夫妻双方一般人口学信息、性行为特征、阴性配偶阳转信息等情况,

  10. A hypothesis for delayed dynamic earthquake triggering

    Science.gov (United States)

    Parsons, T.

    2005-01-01

    It's uncertain whether more near-field earthquakes are triggered by static or dynamic stress changes. This ratio matters because static earthquake interactions are increasingly incorporated into probabilistic forecasts. Recent studies were unable to demonstrate all predictions from the static-stress-change hypothesis, particularly seismicity rate reductions. However, current dynamic stress change hypotheses do not explain delayed earthquake triggering and Omori's law. Here I show numerically that if seismic waves can alter some frictional contacts in neighboring fault zones, then dynamic triggering might cause delayed triggering and an Omori-law response. The hypothesis depends on faults following a rate/state friction law, and on seismic waves changing the mean critical slip distance (Dc) at nucleation zones.

  11. Fundamentals of Delayed Coking Joint Industry Project

    Energy Technology Data Exchange (ETDEWEB)

    Michael Volk; Keith Wisecarver

    2004-09-26

    Delayed coking evolved steadily over the early to mid 1900s to enable refiners to convert high boiling, residual petroleum fractions to light products such as gasoline. Pound for pound, coking is the most energy intensive of any operation in a modern refinery. Large amounts of energy are required to heat the thick, poor-quality petroleum residuum to the 900 to 950 degrees F required to crack the heavy hydrocarbon molecules into lighter, more valuable products. One common misconception of delayed coking is that the product coke is a disadvantage. Although coke is a low valued (near zero economic value) byproduct, compared to transportation fuels, there is a significant worldwide trade and demand for coke as it is an economical fuel. Coke production has increased steadily over the last ten years, with further increases forecast for the foreseeable future. Current domestic production is near 111,000 tons per day. A major driving force behind this increase is the steady decline in crude quality available to refiners. Crude slates are expected to grow heavier with higher sulfur contents while environmental restrictions are expected to significantly reduce the demand for high-sulfur residual fuel oil. Light sweet crudes will continue to be available and in even greater demand than they are today. Refiners will be faced with the choice of purchasing light sweet crudes at a premium price, or adding bottom of the barrel upgrading capability, through additional new investments, to reduce the production of high-sulfur residual fuel oil and increase the production of low-sulfur distillate fuels. A second disadvantage is that liquid products from cokers frequently are unstable, i.e., they rapidly form gum and sediments. Because of intermediate investment and operating costs, delayed coking has increased in popularity among refiners worldwide. Based on the 2000 Worldwide Refining Survey published in the Oil and Gas, the delayed coking capacity for 101 refineries around the world

  12. Delayed Interval Delivery in a Triplet Pregnancy

    Directory of Open Access Journals (Sweden)

    Sheng-Po Kao

    2006-02-01

    Full Text Available Due to a surge in the availability of assisted reproductive techniques (ART, the incidence of multiple pregnancies is increasing. Preterm labor is a major complication in such pregnancies. Preterm delivery of the first fetus is often followed by delivery of the remaining fetuses. However, conservative management and delayed interval delivery in the remaining fetuses might allow for fetal lung maturity and would reduce perinatal morbidities. A 32-year-old female had a quadruplet pregnancy after receiving ART. Fetal reduction to triplet pregnancy was performed at 11 weeks of gestation. The remaining triplet pregnancy was stable until 29 weeks of gestation, when the first triplet was delivered after spontaneous rupture of membranes. Under intensive monitoring, the remaining 2 fetuses were delivered by cesarean section at 31 weeks of gestation. Only the first fetus had retinopathy after discharge. In conclusion, delayed interval delivery of the remaining fetuses should be attempted after preterm delivery of the first fetus.

  13. Time delay measurement in the frequency domain

    Science.gov (United States)

    Durbin, Stephen M.; Liu, Shih-Chieh; Dufresne, Eric M.; Li, Yuelin; Wen, Haidan

    2015-01-01

    Pump–probe studies at synchrotrons using X-ray and laser pulses require accurate determination of the time delay between pulses. This becomes especially important when observing ultrafast responses with lifetimes approaching or even less than the X-ray pulse duration (∼100 ps). The standard approach of inspecting the time response of a detector sensitive to both types of pulses can have limitations due to dissimilar pulse profiles and other experimental factors. Here, a simple alternative is presented, where the frequency response of the detector is monitored versus time delay. Measurements readily demonstrate a time resolution of ∼1 ps. Improved precision is possible by simply extending the data acquisition time. PMID:26289282

  14. Differential AR algorithm for packet delay prediction

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Different delay prediction algorithms have been applied in multimedia communication, among which linear prediction is attractive because of its low complexity. AR (auto regressive) algorithm is a traditional one with low computation cost, while NLMS (normalize least mean square) algorithm is more precise. In this paper, referring to ARIMA (auto regression integrated with moving averages) model, a differential AR algorithm (DIAR) is proposed based on the analyses of both AR and NLMS algorithms. The prediction precision of the new algorithm is about 5-10 db higher than that of the AR algorithm without increasing the computation complexity.Compared with NLMS algorithm, its precision slightly improves by 0.1 db on average, but the algorithm complexity reduces more than 90%. Our simulation and tests also demonstrate that this method improves the performance of the average end-to-end delay and packet loss ratio significantly.

  15. Exploiting Deterministic TPG for Path Delay Testing

    Institute of Scientific and Technical Information of China (English)

    李晓维

    2000-01-01

    Detection of path delay faults requires two-pattern tests. BIST technique provides a low-cost test solution. This paper proposes an approach to designing a cost-effective deterministic test pattern generator (TPG) for path delay testing. Given a set of pre-generated test-pairs with pre-determined fault coverage, a deterministic TPG is synthesized to apply the given test-pair set in a limited test time. To achieve this objective, configurable linear feedback shift register (LFSR) structures are used. Techniques are developed to synthesize such a TPG, which is used to generate an unordered deterministic test-pair set. The resulting TPG is very efficient in terms of hardware size and speed performance. Simulation of academic benchmark circuits has given good results when compared to alternative solutions.

  16. Causal Analysis of Railway Running Delays

    DEFF Research Database (Denmark)

    Cerreto, Fabrizio; Nielsen, Otto Anker; Harrod, Steven

    Operating delays and network propagation are inherent characteristics of railway operations. These are traditionally reduced by provision of time supplements or “slack” in railway timetables and operating plans. Supplement allocation policies must trade off reliability in the service commitments...... against service transit times and railway asset productivity. Methods to investigate the quality of supplement time allocation are necessary to reduce the behavioral response and the waste of resources. This is a preliminary study that investigates train delay data from the year 2014 supplied by Rail Net...... overall aggregate timetable supplement, reduced transport travel times, and higher productive utilization of train rolling stock. The study results will lead eventually to both better allocation of time supplements in timetable structures, and identification of areas that should be a high priority...

  17. Neutral Delay and a Generalization of Electrodynamics

    CERN Document Server

    De Luca, Jayme

    2010-01-01

    The equations for the electromagnetic two-body problem are neutral-delay equations that for generic initial data have solutions with discontinuous derivatives. If one wants to use these neutral-delay equations with arbitrary initial data, solutions with discontinuous derivatives must be allowed. Surprisingly, this same neutrality is compatible with the recently developed variational method with mixed-type boundaries for the Wheeler-Feynman electrodynamics. We show that two-body electromagnetic orbits with discontinuous velocities are physically necessary by showing that orbits with vanishing far-fields amost everywhere must have some discontinuous velocities on a few points. We generalize the Wheeler-Feynman electrodynamics with the variational method to include all continuous trajectories, allowing piecewise-differentiable weak solutions represented by trajectories with fields defined almost everywhere (but on a set of points of zero measure where velocities jump). Along with this generalization we formulate...

  18. Energy management - The delayed flap approach

    Science.gov (United States)

    Bull, J. S.

    1976-01-01

    Flight test evaluation of a Delayed Flap approach procedure intended to provide reductions in noise and fuel consumption is underway using the NASA CV-990 test aircraft. Approach is initiated at a high airspeed (240 kt) and in a drag configuration that allows for low thrust. The aircraft is flown along the conventional ILS glide slope. A Fast/Slow message display signals the pilot when to extend approach flaps, landing gear, and land flaps. Implementation of the procedure in commercial service may require the addition of a DME navigation aid co-located with the ILS glide slope transmitter. The Delayed Flap approach saves 250 lb of fuel over the Reduced Flap approach, with a 95 EPNdB noise contour only 43% as large.

  19. Dynamical Models of Dyadic Interactions with Delay

    CERN Document Server

    Bielczyk, Natalia; Płatkowski, Tadeusz

    2012-01-01

    When interpersonal interactions between individuals are described by the (discrete or continuous) dynamical systems, the interactions are usually assumed to be instantaneous: the rates of change of the actual states of the actors at given instant of time are assumed to depend on their states at the same time. In reality the natural time delay should be included in the corresponding models. We investigate a general class of linear models of dyadic interactions with a constant discrete time delay. We prove that in such models the changes of stability of the stationary points from instability to stability or vice versa occur for various intervals of the parameters which determine the intensity of interactions. The conditions guaranteeing arbitrary number (zero, one ore more) of switches are formulated and the relevant theorems are proved. A systematic analysis of all generic cases is carried out. It is obvious that the dynamics of interactions depend both on the strength of reactions of partners on their own sta...

  20. Approximating chaotic saddles for delay differential equations

    Science.gov (United States)

    Taylor, S. Richard; Campbell, Sue Ann

    2007-04-01

    Chaotic saddles are unstable invariant sets in the phase space of dynamical systems that exhibit transient chaos. They play a key role in mediating transport processes involving scattering and chaotic transients. Here we present evidence (long chaotic transients and fractal basins of attraction) of transient chaos in a “logistic” delay differential equation. We adapt an existing method (stagger-and-step) to numerically construct the chaotic saddle for this system. This is the first such analysis of transient chaos in an infinite-dimensional dynamical system, and in delay differential equations in particular. Using Poincaré section techniques we illustrate approaches to visualizing the saddle set, and confirm that the saddle has the Cantor-like fractal structure consistent with a chaotic saddle generated by horseshoe-type dynamics.

  1. Delayed onset muscle soreness: is massage effective?

    Science.gov (United States)

    Nelson, Nicole

    2013-10-01

    Despite the widespread occurrence of delayed onset muscle soreness (DOMS), there is little consensus as to the exact cause or which treatments may be most effective at alleviating symptoms. Greater understanding of DOMS can give sports medicine and fitness professionals an opportunity to help prevent or speed recovery of this performance limiting condition. This article will review the DOMS literature, including the potential role of psychosocial factors and explore studies which involve massage therapy as a treatment modality. Articles from PubMed, MEDLINE, Google Scholar, and references from articles are included in this review. Search words and phrases included delayed onset muscle soreness, repeated bout effect, massage effectiveness, exercise induced muscle damage, and eccentric exercise.

  2. Dynamics of delayed piecewise linear systems

    Directory of Open Access Journals (Sweden)

    Laszlo E. Kollar

    2003-02-01

    Full Text Available In this paper the dynamics of the controlled pendulum is investigated assuming backlash and time delays. The upper equilibrium of the pendulum is stabilized by a piecewise constant control force which is the linear combination of the sampled values of the angle and the angular velocity of the pendulum. The control force is provided by a motor which drives one of the wheels of the cart through an elastic teeth belt. The contact between the teeth of the gear (rigid and the belt (elastic introduces a nonlinearity known as ``backlash" and causes the oscillation of the controlled pendulum around its upper equilibrium. The processing and sampling delays in the determination of the control force tend to destabilize the controlled system as well. We obtain conditions guaranteeing that the pendulum remains in the neighborhood of the upper equilibrium. Experimental findings obtained on a computer controlled inverted pendulum cart structure are also presented showing good agreement with the simulation results.

  3. Fundamentals of Delayed Coking Joint Industry Project

    Energy Technology Data Exchange (ETDEWEB)

    Michael Volk; Keith Wisecarver

    2003-09-26

    Delayed coking evolved steadily over the early to mid 1900s to enable refiners to convert high boiling, residual petroleum fractions to light products such as gasoline. Pound for pound, coking is the most energy intensive of any operation in a modern refinery. Large amounts of energy are required to heat the thick, poor-quality petroleum residuum to the 900 to 950 degrees F required to crack the heavy hydrocarbon molecules into lighter, more valuable products. One common misconception of delayed coking is that the product coke is a disadvantage. Although coke is a low valued (near zero economic value) byproduct, compared to transportation fuels, there is a significant worldwide trade and demand for coke as it is an economical fuel. Coke production has increased steadily over the last ten years, with further increases forecast for the foreseeable future. Current domestic production is near 111,000 tons per day. A major driving force behind this increase is the steady decline in crude quality available to refiners. Crude slates are expected to grow heavier with higher sulfur contents while environmental restrictions are expected to significantly reduce the demand for high-sulfur residual fuel oil. Light sweet crudes will continue to be available and in even greater demand than they are today. Refiners will be faced with the choice of purchasing light sweet crudes at a premium price, or adding bottom of the barrel upgrading capability, through additional new investments, to reduce the production of high-sulfur residual fuel oil and increase the production of low-sulfur distillate fuels. A second disadvantage is that liquid products from cokers frequently are unstable, i.e., they rapidly form gum and sediments. Because of intermediate investment and operating costs, delayed coking has increased in popularity among refiners worldwide. Based on the 2000 Worldwide Refining Survey published in the Oil and Gas, the delayed coking capacity for 101 refineries around the world

  4. Experimental delayed-choice entanglement swapping

    Science.gov (United States)

    Ma, Xiao-Song; Zotter, Stefan; Kofler, Johannes; Ursin, Rupert; Jennewein, Thomas; Brukner, Časlav; Zeilinger, Anton

    2012-06-01

    Motivated by the question of which kind of physical interactions and processes are needed for the production of quantum entanglement, Peres has put forward the radical idea of delayed-choice entanglement swapping. There, entanglement can be `produced a posteriori, after the entangled particles have been measured and may no longer exist'. Here, we report the realization of Peres's gedanken experiment. Using four photons, we can actively delay the choice of measurement--implemented through a high-speed tunable bipartite-state analyser and a quantum random-number generator--on two of the photons into the time-like future of the registration of the other two photons. This effectively projects the two already registered photons onto one of two mutually exclusive quantum states in which the photons are either entangled (quantum correlations) or separable (classical correlations). This can also be viewed as `quantum steering into the past'.

  5. Experimental delayed-choice entanglement swapping

    CERN Document Server

    Ma, Xiao-song; Kofler, Johannes; Ursin, Rupert; Jennewein, Thomas; Brukner, Časlav; Zeilinger, Anton

    2012-01-01

    Motivated by the question, which kind of physical interactions and processes are needed for the production of quantum entanglement, Peres has put forward the radical idea of delayed-choice entanglement swapping. There, entanglement can be "produced a posteriori, after the entangled particles have been measured and may no longer exist". In this work we report the first realization of Peres' gedanken experiment. Using four photons, we can actively delay the choice of measurement-implemented via a high-speed tunable bipartite state analyzer and a quantum random number generator-on two of the photons into the time-like future of the registration of the other two photons. This effectively projects the two already registered photons onto one definite of two mutually exclusive quantum states in which either the photons are entangled (quantum correlations) or separable (classical correlations). This can also be viewed as "quantum steering into the past".

  6. Energy management - The delayed flap approach

    Science.gov (United States)

    Bull, J. S.

    1976-01-01

    Flight test evaluation of a Delayed Flap approach procedure intended to provide reductions in noise and fuel consumption is underway using the NASA CV-990 test aircraft. Approach is initiated at a high airspeed (240 kt) and in a drag configuration that allows for low thrust. The aircraft is flown along the conventional ILS glide slope. A Fast/Slow message display signals the pilot when to extend approach flaps, landing gear, and land flaps. Implementation of the procedure in commercial service may require the addition of a DME navigation aid co-located with the ILS glide slope transmitter. The Delayed Flap approach saves 250 lb of fuel over the Reduced Flap approach, with a 95 EPNdB noise contour only 43% as large.

  7. Slow photon delay and the neutrino velocity

    CERN Document Server

    Gonzalez-Martin, Gustavo R

    2011-01-01

    Starting from the coordinate system used by Einstein to find the bending of light rays by gravitational fields we calculate the effect of the Earth gravitational energy along a hypothetical photon null path on the geoid non inertial system. There is an energy term, relative to an inertial system, which may be interpreted as a small time-relative "dressed" physical rest mass correction to the photon null mass. This relative gravitational potential energy determines a proper time delay proportional to the laboratory non inertial flying time interval along the trajectory with a small factor 5.276x10-5. Applying this delay to a hypothetical photon trajectory from the CERN SPS/CNGS target to the LNGS OPERA detector we may interpret the reported neutrino time anomaly, which is of the same order of magnitude, by saying that the OPERA neutrino is faster than our slow photon but its speed is smaller than the fundamental constant c.

  8. Oscillations in SIRS model with distributed delays

    Science.gov (United States)

    Gonçalves, S.; Abramson, G.; Gomes, M. F. C.

    2011-06-01

    The ubiquity of oscillations in epidemics presents a long standing challenge for the formulation of epidemic models. Whether they are external and seasonally driven, or arise from the intrinsic dynamics is an open problem. It is known that fixed time delays destabilize the steady state solution of the standard SIRS model, giving rise to stable oscillations for certain parameters values. In this contribution, starting from the classical SIRS model, we make a general treatment of the recovery and loss of immunity terms. We present oscillation diagrams (amplitude and period) in terms of the parameters of the model, showing how oscillations can be destabilized by the shape of the distributions of the two characteristic (infectious and immune) times. The formulation is made in terms of delay equations which are both numerically integrated and linearized. Results from simulations are included showing where they support the linear analysis and explaining why not where they do not. Considerations and comparison with real diseases are presented along.

  9. Model Epidemi Sirs Dengan Time Delay

    OpenAIRE

    Sinuhaji, Ferdinand

    2016-01-01

    The epidemic is an outbreak of an infectious disease situation in the population at a place that exceeds the normal approximation in a short period. When the disease is always contained in any place as well as with the causes, it is called endemic. This study discusses decrease SIRS epidemic models with time delay through a mathematical model based on the model of SIRS epidemic (Susceptible, Infective, Recovered, Susceptible). SIRS models used in this study with the assumption ...

  10. Multiple application delayed onset contact urticaria

    DEFF Research Database (Denmark)

    Andersen, Klaus Ejner; Maibach, H I

    1984-01-01

    An unusual type of contact urticaria to formalin is described, based on 4 patients and experiments in 14 volunteers. The contact urticaria appeared on healthy skin only following repeated open applications or after a single application on slightly diseased skin. The possible relation...... of this phenomenon for patients claiming textile intolerance is discussed. Further tests are required to reveal the mechanism of this delayed onset contact urticaria to formalin....

  11. Delayed Commutation in Quantum Computer Networks

    Science.gov (United States)

    García-Escartín, Juan Carlos; Chamorro-Posada, Pedro

    2006-09-01

    In the same way that classical computer networks connect and enhance the capabilities of classical computers, quantum networks can combine the advantages of quantum information and communication. We propose a nonclassical network element, a delayed commutation switch, that can solve the problem of switching time in packet switching networks. With the help of some local ancillary qubits and superdense codes, we can route a qubit packet after part of it has left the network node.

  12. Delayed commutation in quantum computer networks

    CERN Document Server

    Garcia-Escartin, J C; Chamorro-Posada, Pedro; Garcia-Escartin, Juan Carlos

    2005-01-01

    In the same way that classical computer networks connect and enhance the capabilities of classical computers, quantum networks can combine the advantages of quantum information and communications. We propose a non-classical network element, a delayed commutation switch, that can solve the problem of switching time in packet switching networks. With the help of some local ancillary qubits and superdense codes we can route the information after part of it has left the network node.

  13. Cost of delay and endogenous price leadership

    OpenAIRE

    Pastine, Tuvana

    2004-01-01

    We study the effects of discounting in a standard endogenous price leadership model. We show that there will be occasional changes in the identity of the leader with any cost of delay or discounting, however small. By analyzing the incentives that induce a firm to take up the leader position, we derive positive predictions about which firm will lead most price changes. Firms with shorter reaction times will be more likely to become the price leader, as will firms with lower cost o...

  14. Coherence delay augmented laser beam homogenizer

    Science.gov (United States)

    Rasmussen, P.; Bernhardt, A.

    1993-06-29

    The geometrical restrictions on a laser beam homogenizer are relaxed by ug a coherence delay line to separate a coherent input beam into several components each having a path length difference equal to a multiple of the coherence length with respect to the other components. The components recombine incoherently at the output of the homogenizer, and the resultant beam has a more uniform spatial intensity suitable for microlithography and laser pantogography. Also disclosed is a variable aperture homogenizer, and a liquid filled homogenizer.

  15. Inverse Problems for Nonlinear Delay Systems

    Science.gov (United States)

    2011-03-15

    Ba82]. For nonlinear delay systems such as those discussed here, approximation in the context of a linear semigroup framework as presented [BBu1, BBu2...linear part generates a linear semigroup as in [BBu1, BBu2, BKap]. One then uses the linear semigroup in a vari- ation of parameters implicit...BBu2, BKap] (for the linear semigroup ) plus a Gronwall inequality. An alternative (and more general) approach given in [Ba82] eschews use of the Trotter

  16. dependent time-delay: Stability and stabilizability

    Directory of Open Access Journals (Sweden)

    E. K. Boukas

    2002-01-01

    Full Text Available This paper considers stochastic stability and stochastic stabilizability of linear discrete-time systems with Markovian jumps and mode-dependent time-delays. Linear matrix inequality (LMI techniques are used to obtain sufficient conditions for the stochastic stability and stochastic stabilizability of this class of systems. A control design algorithm is also provided. A numerical example is given to demonstrate the effectiveness of the obtained theoretical results.

  17. CERN boss quashes LHC delay rumours

    CERN Multimedia

    2007-01-01

    "Robert Aymar, the director general of CERN, has dispelled rumours that a series of buckled electrical connectors at the Large Hadron Collider will delay the accelerator's official start-up date of May 2008. Writing in this week's CERN Bulletin, Aymar says that the problem concerns only a small percentage of the connectors and that it is "business as usual" for bringing the new accelerator online." (1,5 page)

  18. The last Bulletin of the year delayed

    CERN Multimedia

    2006-01-01

    In order to report on the December session of the CERN Council, which will take place on 14 and 15 December, the publication of the next issue of the Bulletin - and the last of the year - will be delayed. The Bulletin will be available on Monday 18 December, at end of the morning for the electronic version, in the afternoon for the paper version. Thank you for your understanding. The Bulletin team Information.Bulletin@cern.ch

  19. Cosmic Neutrino Time Delay Relative to Photons

    Institute of Scientific and Technical Information of China (English)

    LUO Xin-Lian; PENG Qiu-He; ZHANG Ling-Di; BAI Hua; CHOU Chih-Kang

    2004-01-01

    By solving the Friedmann-Robertson-Walker (FRW) geodesic equations for a free test particle with finite mass,we extend the widely used time-of-flight delay expression, which is just valid locally in the neighbourhood of our Galaxy, to the cosmic distance scale. If neutrino masses are known, this may provide a potential method to determine a large scale geometry of the Universe.

  20. Delayed extradural hematoma : a case report.

    Directory of Open Access Journals (Sweden)

    Alappat J

    2002-07-01

    Full Text Available Three patients of delayed extradural hematoma (EDH were seen in the last one year among forty eight consecutively treated cases of EDH. All the three hematomas were evacuated. Awareness of this entity and a high degree of vigilance are strongly recommended to detect such cases. Repeat CT should always be done, especially after decompression by either surgical or medical means, recovery from shock or whenever there is evidence of even minimal bleeding under a skull fracture on initial CT scan.

  1. Earth system commitments due to delayed mitigation

    Science.gov (United States)

    Pfister, Patrik L.; Stocker, Thomas F.

    2016-01-01

    As long as global CO2 emissions continue to increase annually, long-term committed Earth system changes grow much faster than current observations. A novel metric linking this future growth to policy decisions today is the mitigation delay sensitivity (MDS), but MDS estimates for Earth system variables other than peak temperature (ΔT max) are missing. Using an Earth System Model of Intermediate Complexity, we show that the current emission increase rate causes a ΔT max increase roughly 3-7.5 times as fast as observed warming, and a millenial steric sea level rise (SSLR) 7-25 times as fast as observed SSLR, depending on the achievable rate of emission reductions after the peak of emissions. These ranges are only slightly affected by the uncertainty range in equilibrium climate sensitivity, which is included in the above values. The extent of ocean acidification at the end of the century is also strongly dependent on the starting time and rate of emission reductions. The preservable surface ocean area with sufficient aragonite supersaturation for coral reef growth is diminished globally at an MDS of roughly 25%-80% per decade. A near-complete loss of this area becomes unavoidable if mitigation is delayed for a few years to decades. Also with respect to aragonite, 12%-18% of the Southern Ocean surface become undersaturated per decade, if emission reductions are delayed beyond 2015-2040. We conclude that the consequences of delaying global emission reductions are much better captured if the MDS of relevant Earth system variables is communicated in addition to current trends and total projected future changes.

  2. Delayed Antiwindup Control Using a Decoupling Structure

    Directory of Open Access Journals (Sweden)

    Huawei Zhu

    2013-01-01

    Full Text Available This paper investigates the antiwindup (AW control problem for plants with input saturation. The AW compensator is not activated as soon as input saturation occurs as usual. A delayed decoupling structure is first proposed. Then, appropriate linear matrix inequalities (LMIs are developed to determine a plant-order AW compensator. Effectiveness of the presented AW technique is illustrated by a fighter aircraft model.

  3. Delays in the operating room: signs of an imperfect system.

    Science.gov (United States)

    Wong, Janice; Khu, Kathleen Joy; Kaderali, Zul; Bernstein, Mark

    2010-06-01

    Delays in the operating room have a negative effect on its efficiency and the working environment. In this prospective study, we analyzed data on perioperative system delays. One neurosurgeon prospectively recorded all errors, including perioperative delays, for consecutive patients undergoing elective procedures from May 2000 to February 2009. We analyzed the prevalence, causes and impact of perioperative system delays that occurred in one neurosurgeon's practice. A total of 1531 elective surgical cases were performed during the study period. Delays were the most common type of error (33.6%), and more than half (51.4%) of all cases had at least 1 delay. The most common cause of delay was equipment failure. The first cases of the day and cranial cases had more delays than subsequent cases and spinal cases, respectively. A delay in starting the first case was associated with subsequent delays. Delays frequently occur in the operating room and have a major effect on patient flow and resource utilization. Thorough documentation of perioperative delays provides a basis for the development of solutions for improving operating room efficiency and illustrates the principles underlying the causes of operating room delays across surgical disciplines.

  4. Dark energy with gravitational lens time delays

    CERN Document Server

    Treu, T; Cyr-Racine, F -Y; Fassnacht, C D; Keeton, C R; Linder, E V; Moustakas, L A; Bradac, M; Buckley-Geer, E; Collett, T; Courbin, F; Dobler, G; Finley, D A; Hjorth, J; Kochanek, C S; Komatsu, E; Koopmans, L V E; Meylan, G; Natarajan, P; Oguri, M; Suyu, S H; Tewes, M; Wong, K C; Zabludoff, A I; Zaritsky, D; Anguita, T; Brunner, R J; Cabanac, R; Falco, E E; Fritz, A; Seidel, G; Howell, D A; Giocoli, C; Jackson, N; Lopez, S; Metcalf, R B; Motta, V; Verdugo, T

    2013-01-01

    Strong lensing gravitational time delays are a powerful and cost effective probe of dark energy. Recent studies have shown that a single lens can provide a distance measurement with 6-7 % accuracy (including random and systematic uncertainties), provided sufficient data are available to determine the time delay and reconstruct the gravitational potential of the deflector. Gravitational-time delays are a low redshift (z~0-2) probe and thus allow one to break degeneracies in the interpretation of data from higher-redshift probes like the cosmic microwave background in terms of the dark energy equation of state. Current studies are limited by the size of the sample of known lensed quasars, but this situation is about to change. Even in this decade, wide field imaging surveys are likely to discover thousands of lensed quasars, enabling the targeted study of ~100 of these systems and resulting in substantial gains in the dark energy figure of merit. In the next decade, a further order of magnitude improvement will...

  5. Delays to the diagnosis of cervical dystonia.

    Science.gov (United States)

    Bertram, Kelly L; Williams, David R

    2016-03-01

    The diagnosis of cervical dystonia (CD) is based on physical examination and is therefore reliant on clinician experience. Due to variability of presenting symptoms it may be misdiagnosed, thus delaying the provision of effective treatment. We sought to determine the average time taken to make a diagnosis of CD in our clinical cohort and explore contributing factors to diagnostic delay. Forty-nine patients with a diagnosis of CD attending a movement disorder specialist for treatment completed a questionnaire regarding symptoms and clinical interactions at onset and diagnosis. The mean time from symptom onset to diagnosis was 6.8 years (range 0-53 years). More than 50% of patients sought physical therapies initially, prior to consulting their general practitioner. Only 40% of patients sought medical advice within the first 6 months of symptom onset and only 10% were given an initial diagnosis of CD. The first referral from the general practitioner was to a specialist other than a neurologist in 31% of patients. Patients were seen by a mean of three doctors (range one to nine) before being given the correct diagnosis of CD. Delay to diagnosis of CD may in part be due to lack of awareness of the condition amongst health care professionals. Improved diagnostic skill appears likely to have had a substantial impact on the delivery of appropriate treatment in this population.

  6. Atrial fibrillation and delayed gastric emptying.

    Directory of Open Access Journals (Sweden)

    Isadora C Botwinick

    Full Text Available BACKGROUND: Atrial fibrillation and delayed gastric emptying (DGE are common after pancreaticoduodenectomy. Our aim was to investigate a potential relationship between atrial fibrillation and DGE, which we defined as failure to tolerate a regular diet by the 7(th postoperative day. METHODS: We performed a retrospective chart review of 249 patients who underwent pancreaticoduodenectomy at our institution between 2000 and 2009. Data was analyzed with Fisher exact test for categorical variables and Mann-Whitney U or unpaired T-test for continuous variables. RESULTS: Approximately 5% of the 249 patients included in the analysis experienced at least one episode of postoperative atrial fibrillation. Median age of patients with atrial fibrillation was 74 years, compared with 66 years in patients without atrial fibrillation (p = 0.0005. Patients with atrial fibrillation were more likely to have a history of atrial fibrillation (p = 0.03. 92% of the patients with atrial fibrillation suffered from DGE, compared to 46% of patients without atrial fibrillation (p = 0.0007. This association held true when controlling for age. CONCLUSION: Patients with postoperative atrial fibrillation are more likely to experience delayed gastric emptying. Interventions to manage delayed gastric function might be prudent in patients at high risk for postoperative atrial fibrillation.

  7. Delayed coupling theory of vertebrate segmentation.

    Science.gov (United States)

    Morelli, Luis G; Ares, Saúl; Herrgen, Leah; Schröter, Christian; Jülicher, Frank; Oates, Andrew C

    2009-01-01

    Rhythmic and sequential subdivision of the elongating vertebrate embryonic body axis into morphological somites is controlled by an oscillating multicellular genetic network termed the segmentation clock. This clock operates in the presomitic mesoderm (PSM), generating dynamic stripe patterns of oscillatory gene-expression across the field of PSM cells. How these spatial patterns, the clock's collective period, and the underlying cellular-level interactions are related is not understood. A theory encompassing temporal and spatial domains of local and collective aspects of the system is essential to tackle these questions. Our delayed coupling theory achieves this by representing the PSM as an array of phase oscillators, combining four key elements: a frequency profile of oscillators slowing across the PSM; coupling between neighboring oscillators; delay in coupling; and a moving boundary describing embryonic axis elongation. This theory predicts that the segmentation clock's collective period depends on delayed coupling. We derive an expression for pattern wavelength across the PSM and show how this can be used to fit dynamic wildtype gene-expression patterns, revealing the quantitative values of parameters controlling spatial and temporal organization of the oscillators in the system. Our theory can be used to analyze experimental perturbations, thereby identifying roles of genes involved in segmentation.

  8. Microwave photonic delay line signal processing.

    Science.gov (United States)

    Diehl, John F; Singley, Joseph M; Sunderman, Christopher E; Urick, Vincent J

    2015-11-01

    This paper provides a path for the design of state-of-the-art fiber-optic delay lines for signal processing. The theoretical forms for various radio-frequency system performance metrics are derived for four modulation types: X- and Z-cut Mach-Zehnder modulators, a phase modulator with asymmetric Mach-Zehnder interferometer, and a polarization modulator with control waveplate and polarizing beam splitter. Each modulation type is considered to cover the current and future needs for ideal system designs. System gain, compression point, and third-order output intercept point are derived from the transfer matrices for each modulation type. A discussion of optical amplifier placement and fiber-effect mitigation is offered. The paper concludes by detailing two high-performance delay lines, built for unique applications, that exhibit performance levels an order of magnitude better than commercial delay lines. This paper should serve as a guide to maximizing the performance of future systems and offer a look into current and future research being done to further improve photonics technologies.

  9. What Do Gravitational Lens Time Delays Measure?

    CERN Document Server

    Kochanek, C S

    2002-01-01

    Gravitational lens time delays depend on the Hubble constant, the observed image positions, and the surface mass density of the lens in the annulus between the images. Simple time delay lenses like PG1115+080, SBS1520+530, B1600+434, PKS1830-211 and HE2149-2745 have H0 = A(1-)+B(e-1) where the two coefficients A ~ 90km/s Mpc and B ~ 10km/s Mpc depend on the measured delays and the observed image positions, is the mean surface density in the annulus between the images, and there is a small correction from the logarithmic slope e ~ 2 of the surface density profile, k ~ R^(1-e), in the annulus. These 5 systems are very homogeneous, since for fixed H0=100h km/s Mpc they must have the same surface density, =1.11-1.22 h +/- 0.04, with an upper bound of 0.07 on any dispersion in beyond those due to the measurement errors. If the lenses have their expected dark halos, ~ 0.5 and H0=51+/-5 km/s Mpc, while if they have constant mass-to-light ratios, ~ 0.1-0.2 and H0=73+/-8 km/s Mpc. More complicated lenses with mult...

  10. Assessment of Confounding in Studies of Delay and Survival

    DEFF Research Database (Denmark)

    Tørring, Marie Louise; Vedsted, Peter; Frydenberg, Morten

    of the influence of delay on survival have been subject to great uncertainties due to unmeasured confounding and measurement error. Systematic evaluation of confounding is needed. AIM: The purpose of this project is to assess confounding in studies of delay and survival in breast cancer patients. We aim to: 1...... delay and survival time in different ways. We therefore assume that the impact of confounding factors depends on the type of delay studied (e.g., patient delay, GP delay, referral delay, or treatment delay). MATERIALS & METHODS: The project includes systematic review and methodological developments...... Pathology Registry, and Statistics Denmark. Among other statistical methods the empirical study will involve use of sensitivity analysis. The statistical analyses will be performed using Stata 9. PERSPECTIVES: A systematic evaluation of confounding will improve our ability to interpret observational studies...

  11. Time Delay Tracking for Multiuser Synchronization in CDMA Networks

    Directory of Open Access Journals (Sweden)

    Zahid Ali

    2013-09-01

    Full Text Available Multipath propagation, multiple access interference and non-line of sight propagation, etc. have impeded the accuracy in mobile data measurements. Multiuser receivers in asynchronous Code Division Multiple Access (CDMA systems require the knowledge of several parameters such as timing delay between users. In this paper, the problem of time delay estimation for CDMA systems is examined by proposing an approach based on blind nonlinear least mean squares (LMS based early-late delay tracker. A system model is developed and a delay tracking algorithm is presented. The simulation results of the proposed delay tracker are compared with the classical delay-locked loop (DLL approach in a multipath scenario and these show that the proposed delay tracker provides very good performance in challenging cases of closely spaced multipath delays.

  12. Phase and Complete Synchronizations in Time-Delay Systems

    Science.gov (United States)

    Senthilkumar, D. V.; Manju Shrii, M.; Kurths, J.

    2013-01-01

    Synchronization is a fundamental nonlinear phenomenon that has been intensively investigated during a couple of decades. Recently, synchronization of time-delay systems with or without delay coupling and even synchronization of low-dimensional dynamical systems described by ordinary differential equations and maps with delay coupling have become an active area of research in view of its potential applications. In this article, we provide an overview of our recent results on phase synchronization in time-delay systems, which usually exhibits hyperchaotic attractors with complex topological properties, noise-enhanced phase and noise-induced complete synchronizations in time-delay systems. Further, we demonstrate the phenomena of delay-enhanced and delay-induced stable synchronous chaos in a delay coupled network of time continuous dynamical system using the framework of master stability formalism (MSF) for the first time.

  13. ALMOST PERIODIC SOLUTIONS TO SOME NONLINEAR DELAY DIFFERENTIAL EQUATION

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The existence of an almost periodic solutions to a nonlinear delay diffierential equation is considered in this paper. A set of sufficient conditions for the existence and uniqueness of almost periodic solutions to some delay diffierential equations is obtained.

  14. Construction disputes in Denmark: the case of concurrent delay

    DEFF Research Database (Denmark)

    Cavaleri, Sylvie Cécile

    2015-01-01

    Through a case study of decisions on concurrent delay, the article discusses the defining features of Danish construction arbitration.......Through a case study of decisions on concurrent delay, the article discusses the defining features of Danish construction arbitration....

  15. Controlling flow time delays in flexible manufacturing cells

    NARCIS (Netherlands)

    Slomp, J.; Caprihan, R.; Bokhorst, J. A. C.

    2009-01-01

    Flow time delays in Flexible Manufacturing Cells (FMCs) are caused by transport and clamping/reclamping activities. This paper shows how dynamic scheduling parameters may control the flow times of jobs and the available task windows for flow time delays.

  16. Risk factors of ophthalmic disorders in children with developmental delay

    DEFF Research Database (Denmark)

    Sandfeld, L.N.; Jensen, H.; Skov, L.

    2008-01-01

    PURPOSE: To identify diagnoses that increase the risk of ophthalmic disorders in developmentally delayed children. METHODS: A cross-sectional study of 1126 Danish children with developmental delay (IQ Udgivelsesdato: 2008/12......PURPOSE: To identify diagnoses that increase the risk of ophthalmic disorders in developmentally delayed children. METHODS: A cross-sectional study of 1126 Danish children with developmental delay (IQ Udgivelsesdato: 2008/12...

  17. Analytical delay models for RLC interconnects under ramp input

    Institute of Scientific and Technical Information of China (English)

    REN Yinglei; MAO Junfa; LI Xiaochun

    2007-01-01

    Analytical delay models for Resistance Inductance Capacitance (RLC)interconnects with ramp input are presented for difierent situations,which include overdamped,underdamped and critical response cases.The errors of delay estimation using the analytical models proposed in this paper are less bv 3%in comparison to the SPICE-computed delay.These models are meaningful for the delay analysis of actual circuits in which the input signal is ramp but not ideal step input.

  18. Online Delay-Evaluation Approach in Networked Control Systems

    Institute of Scientific and Technical Information of China (English)

    魏震; 马向华; 谢剑英

    2003-01-01

    This paper presents an online evaluation approach of time delays for networked control systems (NCS), which characterizes the time delays without any synchronized clock in the network and any assumptions of time delays. With this approach, an optimal control scheme based on the approach is designed to achieve the desired performance despite the uncertain delays in the system. The experimental results based on CANbus illustrate the effectiveness of the proposed control design and satisfactory performance of the closed-loop system.

  19. Reatividade do anticorpo IgM anti-Treponema pallidum na soroconversão e na resposta sorológica ao tratamento de sífilis IgM antibody reactivity to Treponema pallidum in seroconversion and in the serologic response to syphilis treatment

    Directory of Open Access Journals (Sweden)

    Neuza Satomi Sato

    2012-12-01

    Full Text Available INTRODUÇÃO: A utilidade da detecção de anticorpos da imunoglobulina da classe M (IgM no diagnóstico da sífilis tem sido discutida há tempos. OBJETIVO: No presente estudo foi analisada a ocorrência de anticorpo IgM anti-T. pallidum (Tp-IgMAc nas amostras de pacientes com sífilis recente, na fase de soroconversão e no monitoramento da resposta sorológica pós-tratamento. MÉTODOS: Amostras séricas de 11 indivíduos. RESULTADOS: Na soroconversão, o Tp-IgMAc foi detectado nas amostras de 10 indivíduos, e em um paciente a reatividade IgM ocorreu anteriormente ao Venereal Disease Research Laboratory (VDRL. A sororreversão foi evidenciada nas amostras de três pacientes com sífilis secundária tratada, e em um indivíduo com reinfecção. CONCLUSÃO: A detecção de Tp-IgMAc mostrou ser um potencial marcador diagnóstico de sífilis ativa e o desempenho do ensaio imunoenzimático de captura de IgM (ELISA-IgM para o monitoramento pós-tratamento foi similar ao da VDRL.INTRODUCTION: The appropriateness of IgM antibody detection in the diagnosis of syphilis has been extensively discussed. OBJECTIVE: This study aimed at assessing the detection of anti-T. pallidum IgM antibody (TP-IgMAb in serum samples from patients with recent syphilis in seroconversion and in the monitoring of post-treatment serological response. METHODS: Serum samples from 11 individuals. RESULTS: At seroconversion, positive Tp-IgMAb was detected in 10 samples and IgM reactivity previous to Venereal Disease Research Laboratory (VDRL was detected in one sample. Seroreversion was found in samples from three treated patients with secondary syphilis and in one individual with reinfection. CONCLUSION: Tp-IgMAb detection proved to be a potential diagnostic marker for active syphilis, and IgM capture enzyme linked immunosorbent assay (ELISA-IgM performance was similar to VDRL in post-treatment monitoring.

  20. 40 CFR 60.482-9 - Standards: Delay of repair.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Standards: Delay of repair. 60.482-9... Standards: Delay of repair. (a) Delay of repair of equipment for which leaks have been detected will be allowed if repair within 15 days is technically infeasible without a process unit shutdown. Repair of...