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Kazunari Shibata - One of the best experts on this subject based on the ideXlab platform.
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magnetohydrodynamical accretion flows formation of magnetic tower jet and subsequent quasi steady state
Progress of Theoretical Physics Supplement, 2004Co-Authors: Yoshiaki Kato, Shin Mineshige, Kazunari ShibataAbstract:We present three-dimensional (3-D) magnetohydrodynamical (MHD) simulations of both radiatively inefficient accretion flow (RIAF) into and jet from black holes (BHs). When the bulk of torus material reaches the innermost region close to a central BH, a magnetically driven jet emerges. This magnetic jet is derived by vertically inflating toroidal fields ('magnetic tower') and has a two-component structure: low-β (< 1) plasmas threaded with poloidal fields are surrounded by that with toroidal fields. The collimation width of the jet depends on external pressure, pressure of ambient medium; the weaker the external pressure is, the wider and the longer-lasting becomes the jet. Unless the external pressure is negligible, the bipolar jet phase ceases after several dynamical timescales at the original torus position and a subsequent quasi-steady state starts.
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magnetohydrodynamic accretion flows formation of magnetic tower jet and subsequent quasi steady state
The Astrophysical Journal, 2004Co-Authors: Yoshiaki Kato, Shin Mineshige, Kazunari ShibataAbstract:We present three-dimensional magnetohydrodynamic (MHD) simulations of radiatively inefficient accretion flow around black holes. General relativistic effects are simulated by using the pseudo-Newtonian potential. We start calculations with a rotating torus threaded by localized poloidal magnetic fields with plasma-β, a ratio of the gas pressure to the magnetic pressure, β = 10 and 100. When the bulk of torus material reaches the innermost region close to a central black hole, a magnetically driven jet emerges. This magnetic jet is derived by vertically inflating toroidal fields ("magnetic tower") and has a two-component structure: low-β (1) plasmas threaded with poloidal (vertical) fields are surrounded by those with toroidal fields. The collimation width of the jet depends on external pressure, the pressure of ambient medium; the weaker the external pressure is, the wider and the longer lasting becomes the jet. Unless the external pressure is negligible, the bipolar jet phase ceases after several dynamical timescales at the original torus position and a subsequent quasi-steady state starts. The black hole is surrounded by a quasi-spherical zone with highly inhomogeneous structure in which toroidal fields are dominant except near the rotation axis. Mass accretion takes place mainly along the equatorial plane. Comparisons with other MHD simulation results and observational implications are discussed.
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magnetohydrodynamical accretion flows formation of magnetic tower jet and subsequent quasi steady state
arXiv: Astrophysics, 2003Co-Authors: Yoshiaki Kato, Shin Mineshige, Kazunari ShibataAbstract:We present three-dimensional (3-D) magnetohydrodynamical (MHD) simulations of radiatively inefficient accretion flow around black holes. General relativistic effects are simulated by using the pseudo-Newtonian potential. We start calculations with a rotating torus threaded by localized poloidal magnetic fields with plasma beta, a ratio of the gas pressure to the magnetic pressure, $\beta =10$ and 100. When the bulk of torus material reaches the innermost region close to a central black hole, a magnetically driven jet emerges. This magnetic jet is derived by vertically inflating toroidal fields (`magnetic tower') and has a two-component structure: low-$\beta$ ($\lsim 1$) plasmas threaded with poloidal (vertical) fields are surrounded by that with toroidal fields. The collimation width of the jet depends on external pressure, pressure of ambient medium; the weaker the external pressure is, the wider and the longer-lasting becomes the jet. Unless the external pressure is negligible, the bipolar jet phase ceases after several dynamical timescales at the original torus position and a subsequent quasi-steady state starts. The black hole is surrounded by quasi-spherical zone with highly inhomogeneous structure in which toroidal fields are dominant except near the rotation axis. Mass accretion takes place mainly along the equatorial plane. Comparisons with other MHD simulation results and observational implications are discussed.
Antonia F Chen - One of the best experts on this subject based on the ideXlab platform.
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positive cultures during reimplantation increase the risk of subsequent failure in two stage exchange arthroplasty
Orthopaedic Proceedings, 2018Co-Authors: Jorge Manrique, Miguel M Gomez, Antonia F Chen, Javad ParviziAbstract:It is strongly recommended that tissue and synovial fluid culture samples be obtained during reimplantation performed as part of a two-stage exchange arthroplasty. The incidence of positive cultures during reimplantation and the influence of positive cultures on subsequent outcome are unknown. This aim of this study was to determine the incidence of positive cultures during reimplantation and to investigate the association between positive cultures at reimplantation and the subsequent outcomeA retrospective review was conducted on 267 patients that met the Musculoskeletal Infection Society (MSIS) criteria for PJI that completed both stages of two-stage exchange arthroplasty (Table 1). Intraoperative culture results from tissue and/or synovial fluid were obtained. Cultures were positive in 33 cases (12.4%) undergoing reimplantation surgery (Figure 1). Treatment failure was assessed based on the Delphi consensus definition. Logistic regression analysis was performed to assess the predictors of positive cult...
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positive culture during reimplantation increases the risk of subsequent failure in two stage exchange arthroplasty
Journal of Bone and Joint Surgery American Volume, 2016Co-Authors: Miguel M Gomez, Jorge Manrique, Javad Parvizi, Antonia F ChenAbstract:Background: It is strongly recommended that tissue and synovial fluid culture samples be obtained during reimplantation performed as part of a 2-stage exchange arthroplasty. The rate of positive cultures during reimplantation and the influence of positive cultures on subsequent outcomes, to our knowledge, are unknown. This study was designed to determine the rate of positive cultures during reimplantation and to investigate the association between positive cultures at reimplantation and subsequent outcomes. Methods: We retrospectively reviewed the data of 259 patients who met the Musculoskeletal Infection Society criteria for periprosthetic joint infection (PJI) and who underwent both stages of 2-stage exchange arthroplasty at our institution from 1999 to 2013. Among these patients were 267 PJIs (186 knees and 81 hips); 33 (12.4%) had ≥1 positive culture result at reimplantation. Treatment failure was assessed according to the Delphi-based consensus definition. Logistic regression analysis was performed to assess the predictors of positive culture and risk factors for failure of 2-stage exchange arthroplasty. Results: Of the 33 cases with PJI, 15 (45.5%) had a subsequent failure of the 2-stage exchange arthroplasty compared with 49 (20.9%) of the cases that were culture-negative at reimplantation. When controlling for other variables using multivariate analyses, the risk of treatment failure was higher (odds ratio = 2.53; 95% confidence interval [CI] = 1.13 to 5.64) and reinfection occurred earlier (hazard ratio = 2.00; 95% CI = 1.05 to 3.82) for the cases with a positive culture during reimplantation. The treatment failure rate did not differ (p = 0.73) between cases with ≥2 positive cultures (36.4%) and 1 positive culture (50%). Conclusions: Positive intraoperative culture at the time of reimplantation, regardless of the number of positive samples, was independently associated with >2 times the risk of subsequent treatment failure and earlier reinfection. Surgeons should be aware that a positive culture at the time of reimplantation independently increases the risk of subsequent failure. Level of Evidence: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.
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positive cultures during reimplantation increase the risk of subsequent failure in two stage exchange arthroplasty
Journal of Bone and Joint Surgery-british Volume, 2015Co-Authors: Jorge Manrique, Miguel M Gomez, Antonia F Chen, Javad ParviziAbstract:It is strongly recommended that tissue and synovial fluid culture samples be obtained during reimplantation performed as part of a two-stage exchange arthroplasty. The incidence of positive cultures during reimplantation and the influence of positive cultures on subsequent outcome are unknown. This aim of this study was to determine the incidence of positive cultures during reimplantation and to investigate the association between positive cultures at reimplantation and the subsequent outcome A retrospective review was conducted on 267 patients that met the Musculoskeletal Infection Society (MSIS) criteria for PJI that completed both stages of two-stage exchange arthroplasty (Table 1). Intraoperative culture results from tissue and/or synovial fluid were obtained. Cultures were positive in 33 cases (12.4%) undergoing reimplantation surgery (Figure 1). Treatment failure was assessed based on the Delphi consensus definition. Logistic regression analysis was performed to assess the predictors of positive culture and risk factors for failure of two-stage exchange arthroplasty. Treatment failure was 45.5% for those with a positive intraoperative culture and 20.9% in those with negative cultures at the time of reimplantation. When controlling for organism virulence, comorbidities, and other confounding factors, treatment failure was higher (odds ratio [OR]: 3.3; 95% confidence interval [CI]: 1.3–4.5) and occurred at an earlier time point (hazard ratio: 2.5; 95% CI: 1.3–4.5) in patients with a positive reimplantation culture. The treatment failure rate was not different between cases with two or more positive cultures (36.4%) and one positive culture (42.8%). Positive intraoperative cultures during reimplantation, regardless of the number of positive samples were independently associated with two times the risk of subsequent infection and earlier treatment failure. Surgeons should be aware that a positive culture at the time of reimplantation independently increases the risk of subsequent failure and needs to be taken seriously. Given the significance of these findings, future studies are needed to evaluate the optimal management of positive cultures during reimplantation surgery.
Javad Parvizi - One of the best experts on this subject based on the ideXlab platform.
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positive cultures during reimplantation increase the risk of subsequent failure in two stage exchange arthroplasty
Orthopaedic Proceedings, 2018Co-Authors: Jorge Manrique, Miguel M Gomez, Antonia F Chen, Javad ParviziAbstract:It is strongly recommended that tissue and synovial fluid culture samples be obtained during reimplantation performed as part of a two-stage exchange arthroplasty. The incidence of positive cultures during reimplantation and the influence of positive cultures on subsequent outcome are unknown. This aim of this study was to determine the incidence of positive cultures during reimplantation and to investigate the association between positive cultures at reimplantation and the subsequent outcomeA retrospective review was conducted on 267 patients that met the Musculoskeletal Infection Society (MSIS) criteria for PJI that completed both stages of two-stage exchange arthroplasty (Table 1). Intraoperative culture results from tissue and/or synovial fluid were obtained. Cultures were positive in 33 cases (12.4%) undergoing reimplantation surgery (Figure 1). Treatment failure was assessed based on the Delphi consensus definition. Logistic regression analysis was performed to assess the predictors of positive cult...
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positive culture during reimplantation increases the risk of subsequent failure in two stage exchange arthroplasty
Journal of Bone and Joint Surgery American Volume, 2016Co-Authors: Miguel M Gomez, Jorge Manrique, Javad Parvizi, Antonia F ChenAbstract:Background: It is strongly recommended that tissue and synovial fluid culture samples be obtained during reimplantation performed as part of a 2-stage exchange arthroplasty. The rate of positive cultures during reimplantation and the influence of positive cultures on subsequent outcomes, to our knowledge, are unknown. This study was designed to determine the rate of positive cultures during reimplantation and to investigate the association between positive cultures at reimplantation and subsequent outcomes. Methods: We retrospectively reviewed the data of 259 patients who met the Musculoskeletal Infection Society criteria for periprosthetic joint infection (PJI) and who underwent both stages of 2-stage exchange arthroplasty at our institution from 1999 to 2013. Among these patients were 267 PJIs (186 knees and 81 hips); 33 (12.4%) had ≥1 positive culture result at reimplantation. Treatment failure was assessed according to the Delphi-based consensus definition. Logistic regression analysis was performed to assess the predictors of positive culture and risk factors for failure of 2-stage exchange arthroplasty. Results: Of the 33 cases with PJI, 15 (45.5%) had a subsequent failure of the 2-stage exchange arthroplasty compared with 49 (20.9%) of the cases that were culture-negative at reimplantation. When controlling for other variables using multivariate analyses, the risk of treatment failure was higher (odds ratio = 2.53; 95% confidence interval [CI] = 1.13 to 5.64) and reinfection occurred earlier (hazard ratio = 2.00; 95% CI = 1.05 to 3.82) for the cases with a positive culture during reimplantation. The treatment failure rate did not differ (p = 0.73) between cases with ≥2 positive cultures (36.4%) and 1 positive culture (50%). Conclusions: Positive intraoperative culture at the time of reimplantation, regardless of the number of positive samples, was independently associated with >2 times the risk of subsequent treatment failure and earlier reinfection. Surgeons should be aware that a positive culture at the time of reimplantation independently increases the risk of subsequent failure. Level of Evidence: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.
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positive cultures during reimplantation increase the risk of subsequent failure in two stage exchange arthroplasty
Journal of Bone and Joint Surgery-british Volume, 2015Co-Authors: Jorge Manrique, Miguel M Gomez, Antonia F Chen, Javad ParviziAbstract:It is strongly recommended that tissue and synovial fluid culture samples be obtained during reimplantation performed as part of a two-stage exchange arthroplasty. The incidence of positive cultures during reimplantation and the influence of positive cultures on subsequent outcome are unknown. This aim of this study was to determine the incidence of positive cultures during reimplantation and to investigate the association between positive cultures at reimplantation and the subsequent outcome A retrospective review was conducted on 267 patients that met the Musculoskeletal Infection Society (MSIS) criteria for PJI that completed both stages of two-stage exchange arthroplasty (Table 1). Intraoperative culture results from tissue and/or synovial fluid were obtained. Cultures were positive in 33 cases (12.4%) undergoing reimplantation surgery (Figure 1). Treatment failure was assessed based on the Delphi consensus definition. Logistic regression analysis was performed to assess the predictors of positive culture and risk factors for failure of two-stage exchange arthroplasty. Treatment failure was 45.5% for those with a positive intraoperative culture and 20.9% in those with negative cultures at the time of reimplantation. When controlling for organism virulence, comorbidities, and other confounding factors, treatment failure was higher (odds ratio [OR]: 3.3; 95% confidence interval [CI]: 1.3–4.5) and occurred at an earlier time point (hazard ratio: 2.5; 95% CI: 1.3–4.5) in patients with a positive reimplantation culture. The treatment failure rate was not different between cases with two or more positive cultures (36.4%) and one positive culture (42.8%). Positive intraoperative cultures during reimplantation, regardless of the number of positive samples were independently associated with two times the risk of subsequent infection and earlier treatment failure. Surgeons should be aware that a positive culture at the time of reimplantation independently increases the risk of subsequent failure and needs to be taken seriously. Given the significance of these findings, future studies are needed to evaluate the optimal management of positive cultures during reimplantation surgery.
Sindhu K Srinivas - One of the best experts on this subject based on the ideXlab platform.
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length of second stage of labor and preterm birth in a subsequent pregnancy
American Journal of Obstetrics and Gynecology, 2016Co-Authors: Lisa D Levine, Sindhu K SrinivasAbstract:Background During the second stage of labor, it is plausible that the pressure of the fetal head against a completely dilated cervix may lead to changes in the cervical integrity and cervical strength lending it susceptible to premature dilation in a subsequent pregnancy. Therefore, a prolonged second stage of labor has been hypothesized to be a risk factor for cervical insufficiency and spontaneous preterm birth (sPTB). Objective We sought to evaluate the effect that the length of second stage of labor in one pregnancy has on the risk of sPTB in a subsequent pregnancy. Study Design This was a planned secondary analysis of a large retrospective cohort study of women with 2 consecutive deliveries at our institution from 2005 through 2010. Women with a term pregnancy that reached the second stage were included; women with a prior sPTB were excluded. The primary outcome was sPTB Results In all, 757 women were included. The overall length of the second stage ranged from 0-7.3 hours. The sPTB rate in a subsequent pregnancy was 8.7%. There was no association between length of second stage (hours) as a continuous variable and sPTB after adjusting for confounders (adjusted odds ratio, 0.83; [95% CI 0.58-1.20]). A prolonged second stage ≥3 hours occurred in 48 (6.3%) women. Women with a second stage ≥3 hours were older, less likely to be African American, and were less likely to be overweight or obese as compared to women with a second stage P = .5. The sPTB risk was, however, modified by mode of delivery in the second stage. There was no difference in sPTB rate among women with a vaginal delivery when comparing those with and without a prolonged second stage (7.4 vs 7.8%, P = .9). There also was no difference among women with a cesarean when comparing those with and without a prolonged second stage (11.8 vs 14.3%, P = .8). While not statistically significant, the absolute risk of a subsequent sPTB after a cesarean delivery with a second stage ≥3 hours is twice as high as the risk of a sPTB after a vaginal delivery with a second stage ≥3 hours (adjusted odds ratio, 2.08; [0.32-13.78]). Conclusion A prolonged second stage of labor alone does not increase the risk of sPTB in a subsequent pregnancy. Cesarean delivery after a prolonged second stage of labor may confer a possible increased risk. It is important to continue to evaluate potential risk factors for sPTB. If these risk factors are confirmed in future studies, it will aid in the counseling of women and may open the door for therapeutic strategies to be studied among these newly identified at-risk women.
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does stage of labor at time of cesarean delivery affect risk of subsequent preterm birth
American Journal of Obstetrics and Gynecology, 2015Co-Authors: Lisa D Levine, Mary D Sammel, Adi Hirshberg, Michal A Elovitz, Sindhu K SrinivasAbstract:Objective The effect of a cesarean delivery in different stages of labor on spontaneous preterm birth (sPTB) in a subsequent pregnancy has not been studied extensively. The objective of the study was to evaluate the risk of subsequent sPTB after a first-stage or second-stage cesarean delivery compared with a vaginal delivery. Study Design This was a planned secondary analysis of a large retrospective cohort study of women with 2 consecutive deliveries from 2005-2010. Women with a previous sPTB were excluded. First-stage ( 2 analyses, and logistic regression was used to calculate odds and control for confounders. Results Eight hundred eighty-seven women were included (721 vaginal deliveries; 129 first-stage and 37 second-stage cesarean deliveries). The sPTB rate varied between groups (7.8%, 2.3%, and 13.5%, respectively; P = .03). When compared with women with a vaginal delivery, women with a first-stage cesarean delivery had a decreased risk of sPTB, which remained after adjustment for confounders (adjusted odds ratio, 0.30; 95% confidence interval, 0.09–0.99; P = .049). There was a nonsignificant increase in odds of sPTB after a second-stage cesarean delivery compared with a vaginal delivery (adjusted odds ratio, 2.4; 95% confidence interval, 0.77–7.43; P = .13). Women with a second-stage cesarean delivery had a 6-fold higher odds of sPTB compared with women with a first-stage cesarean delivery, which remained after adjustment for confounders (adjusted odds ratio, 5.8; 95% confidence interval, 1.08–30.8; P = .04). Conclusion Women with a full-term second-stage cesarean delivery have a significantly higher than expected rate of subsequent sPTB (13.5%) compared with both the overall national sPTB rate (7-8%) and to a first-stage cesarean delivery (2.3%). As the cesarean delivery rate continues to rise, this potential impact on pregnancy outcomes cannot be ignored.
Klaus Fischer - One of the best experts on this subject based on the ideXlab platform.
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carried over heat stress in the egg stage reduces subsequent performance in a butterfly
PLOS ONE, 2017Co-Authors: Michael Klockmann, Friederike Kleinschmidt, Klaus FischerAbstract:Increasing heat stress caused by anthropogenic climate change may pose a substantial challenge to biodiversity due to associated detrimental effects on survival and reproduction. Therefore, heat tolerance has recently received substantial attention, but its variation throughout ontogeny and effects carried over from one developmental stage to another remained largely neglected. To explore to what extent stress experienced early in life affects later life stages, we here investigate effects of heat stress experienced in the egg stage throughout ontogeny in the tropical butterfly Bicyclus anynana. We found that detrimental effects of heat stress in the egg stage were detectable in hatchlings, larvae and even resulting adults, as evidenced by decreased survival, growth, and body mass. This study shows that even in holometabalous insects with discrete life stages effects of stress experienced early in life are carried over to later stages, substantially reducing subsequent fitness. We argue that such effects need to be considered when trying to forecast species responses to climate change.
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Carried over: Heat stress in the egg stage reduces subsequent performance in a butterfly - Fig 3
2017Co-Authors: Michael Klockmann, Friederike Kleinschmidt, Klaus FischerAbstract:Survival rates until pupation and adult eclosion (a) and male and female adult body mass (b) in relation to egg temperature (24 h at 27, 29, 31, 33, 35 or 37°C) in Bicyclus anynana. Given are means ± 1 SE. Sample size were 5 cages with 30 individuals each (a) and 29 to 73 individuals each (b). Different lower case letters above bars indicate significant differences among temperatures (Tukey’s HSD for equal sample size).
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Carried over: Heat stress in the egg stage reduces subsequent performance in a butterfly - Fig 2
2017Co-Authors: Michael Klockmann, Friederike Kleinschmidt, Klaus FischerAbstract:Egg survival rates in relation to temperature (a; 24 h at 27, 29, 31, 33, 35 or 37°C), hatchling survival rates in relation to egg temperature and heat stress (b; exposure of hatchlings for 24 h to 27°C or 37°C), and head capsule (HC) width in relation to egg temperature and heat stress for dead and alive individuals (c) in Bicyclus anynana. Given are means ± 1 SE. Sample sizes range between 132 and 199 groups (a), 23 and 55 groups (b), and 6 and 55 groups (c) with 10 individuals each. Different lower case letters above bars indicate significant differences among egg temperatures (Tukey’s HSD for unequal sample size).
