8 research outputs found
Dynamic and Thermodynamic Stability and Negative Modes in Schwarzschild-Anti-de Sitter
The thermodynamic properties of Schwarzschild-anti-de Sitter black holes
confined within finite isothermal cavities are examined. In contrast to the
Schwarzschild case, the infinite cavity limit may be taken which, if suitably
stated, remains double valued. This allows the correspondence between
non-existence of negative modes for classical solutions and local thermodynamic
stability of the equilibrium configuration of such solutions to be shown in a
well defined manner. This is not possible in the asymptotically flat case.
Furthermore, the non-existence of negative modes for the larger black hole
solution in Schwarzschild-anti-de Sitter provides strong evidence in favour of
the recent positive energy conjecture by Horowitz and Myers.Comment: 21 pages, 5 figures, LaTe
Higher Spin Field Equation in a Virtual Black Hole Metric
In a quantum theory of gravity, fluctuations about the vacuum may be
considered as Planck scale virtual black holes appearing and annihilating in
pairs. Incident fields scattering from such fluctuations would lose quantum
coherence.
In a recent paper (hep-th/9705147), Hawking and Ross obtained an estimate for
the magnitude of this loss in the case of a scalar field. Their calculation
exploited the separability of the conformally invariant scalar wave equation in
the electrovac C metric background, which is justified as a sufficiently good
description of a virtual black hole pair in the limit considered.
In anticipation of extending this result, the Teukolsky equations for
incident fields of higher spin are separated on the vacuum C metric background
and solved in the same limit. With the exception of spin 2 fields, these
equations are shown in addition to be valid on the electrovac C metric
background. The angular solutions are found to reduce to the spin- weighted
spherical harmonics, and the radial solutions are found to approach
hypergeometrics close to the horizons.
By defining appropriate scattering boundary conditions, these solutions are
then used to estimate the transmission and reflection coefficients for an
incident field of spin s. The transmission coefficient is required in order to
estimate the loss of quantum coherence of an incident field through scattering
off virtual black holes.Comment: 23 pages, 3 figures, LaTeX, minor typo correcte
Reduced-intensity Transplantation For Lymphomas Using Haploidentical Related Donors Versus Hla-matched Sibling Donors: A Center For International Blood And Marrow Transplant Research Analysis
Purpose: Related donor haploidentical hematopoietic cell transplantation (Haplo-HCT) using post-transplantation cyclophosphamide (PT-Cy) is increasingly used in patients lacking HLA-matched sibling donors (MSD). We compared outcomes after Haplo-HCT using PT-Cy with MSD-HCT in patients with lymphoma, using the Center for International Blood and Marrow Transplant Research registry. Materials and Methods: We evaluated 987 adult patients undergoing either Haplo-HCT (n = 180) or MSD-HCT (n = 807) following reduced-intensity conditioning regimens. The haploidentical group received graft-versus-host disease (GVHD) prophylaxis with PT-Cy with or without a calcineurin inhibitor and mycophenolate. The MSD group received calcineurin inhibitor-based GVHD prophylaxis. Results: Median follow-up of survivors was 3 years. The 28-day neutrophil recovery was similar in the two groups (95% v 97%; P = .31). The 28-day platelet recovery was delayed in the haploidentical group compared with the MSD group (63% v 91%; P = .001). Cumulative incidence of grade II to IV acute GVHD at day 100 was similar between the two groups (27% v 25%; P = .84). Cumulative incidence of chronic GVHD at 1 year was significantly lower after Haplo-HCT (12% v 45%; P < .001), and this benefit was confirmed on multivariate analysis (relative risk, 0.21; 95% CI, 0.14 to 0.31; P < .001). For Haplo-HCT v MSD-HCT, 3-year rates of nonrelapse mortality (15% v 13%; P = .41), relapse/progression (37% v 40%; P = .51), progression-free survival (48% v 48%; P = .96), and overall survival (61% v 62%; P = .82) were similar. Multivariate analysis showed no significant difference between Haplo-HCT and MSD-HCT in terms of nonrelapse mortality (P = .06), progression/relapse (P = .10), progression-free survival (P = .83), and overall survival (P = .34). Conclusion: Haplo-HCT with PT-Cy provides survival outcomes comparable to MSD-HCT, with a significantly lower risk of chronic GVHD
Second Allogeneic Hematopoietic Cell Transplantation for Patients with Fanconi Anemia and Bone Marrow Failure
A second allogeneic hematopoietic cell transplantation (HCT) is the sole salvage option for individuals who develop graft failure after their first HCT. Data on outcomes after second HCT in patients with Fanconi anemia (FA) are scarce. Here we report outcomes after second allogeneic HCT for FA (n = 81). The indication for second HCT was graft failure after the first HCT. Transplantations were performed between 1990 and 2012. The timing of the second HCT predicted subsequent graft failure and survival. Graft failure was high when the second HCT was performed less than 3 months from the first. The 3-month probability of graft failure was 69% when the interval between the first HCT and second HCT was less than 3 months, compared with 23% when the interval was longer (P <.001). Consequently, the 1-year survival rate was substantially lower when the interval between the first and second HCTs was less than 3 months compared with longer (23% vs 58%; P = .001). The corresponding 5-year probability of survival was 16% and 45%, respectively (P = .006). Taken together, these data suggest that fewer than one-half of patients with FA undergoing a second HCT for graft failure are long-term survivors. There is an urgent need to develop strategies to reduce the rate of graft failure after first HCT. (C) 2015 American Society for Blood and Marrow Transplantation
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Subsequent neoplasms and late mortality in children undergoing allogeneic transplantation for nonmalignant diseases
We examined the risk of subsequent neoplasms (SNs) and late mortality in children and adolescents undergoing allogeneic hematopoietic cell transplantation (HCT) for nonmalignant diseases (NMDs). We included 6028 patients (median age, 6 years; interquartile range, 1-11; range, <1 to 20) from the Center for International Blood and Marrow Transplant Research (1995-2012) registry. Standardized mortality ratios (SMRs) in 2-year survivors and standardized incidence ratios (SIRs) were calculated to compare mortality and SN rates with expected rates in the general population. Median follow-up of survivors was 7.8 years. Diagnoses included severe aplastic anemia (SAA; 24%), Fanconi anemia (FA; 10%), other marrow failure (6%), hemoglobinopathy (15%), immunodeficiency (23%), and metabolic/leukodystrophy syndrome (22%). Ten-year survival was 93% (95% confidence interval [95% CI], 92% to 94%; SMR, 4.2; 95% CI, 3.7-4.8). Seventy-one patients developed SNs (1.2%). Incidence was highest in FA (5.5%), SAA (1.1%), and other marrow failure syndromes (1.7%); for other NMDs, incidence was <1%. Hematologic (27%), oropharyngeal (25%), and skin cancers (13%) were most common. Leukemia risk was highest in the first 5 years posttransplantation; oropharyngeal, skin, liver, and thyroid tumors primarily occurred after 5 years. Despite a low number of SNs, patients had an 11-fold increased SN risk (SIR, 11; 95% CI, 8.9-13.9) compared with the general population. We report excellent long-term survival and low SN incidence in an international cohort of children undergoing HCT for NMDs. The risk of SN development was highest in patients with FA and marrow failure syndromes, highlighting the need for long-term posttransplantation surveillance in this population