36 research outputs found
The Refractive Index of Curved Spacetime II: QED, Penrose Limits and Black Holes
This work considers the way that quantum loop effects modify the propagation
of light in curved space. The calculation of the refractive index for scalar
QED is reviewed and then extended for the first time to QED with spinor
particles in the loop. It is shown how, in both cases, the low frequency phase
velocity can be greater than c, as found originally by Drummond and Hathrell,
but causality is respected in the sense that retarded Green functions vanish
outside the lightcone. A "phenomenology" of the refractive index is then
presented for black holes, FRW universes and gravitational waves. In some
cases, some of the polarization states propagate with a refractive index having
a negative imaginary part indicating a potential breakdown of the optical
theorem in curved space and possible instabilities.Comment: 62 pages, 14 figures, some signs corrected in formulae and graph
The Causal Structure of QED in Curved Spacetime: Analyticity and the Refractive Index
The effect of vacuum polarization on the propagation of photons in curved
spacetime is studied in scalar QED. A compact formula is given for the full
frequency dependence of the refractive index for any background in terms of the
Van Vleck-Morette matrix for its Penrose limit and it is shown how the
superluminal propagation found in the low-energy effective action is reconciled
with causality. The geometry of null geodesic congruences is found to imply a
novel analytic structure for the refractive index and Green functions of QED in
curved spacetime, which preserves their causal nature but violates familiar
axioms of S-matrix theory and dispersion relations. The general formalism is
illustrated in a number of examples, in some of which it is found that the
refractive index develops a negative imaginary part, implying an amplification
of photons as an electromagnetic wave propagates through curved spacetime.Comment: 54 pages, 19 figures, corrected some signs in formulae and graph
Increased survival with enzalutamide in prostate cancer after chemotherapy
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108324.pdf (publisher's version ) (Open Access)BACKGROUND: Enzalutamide (formerly called MDV3100) targets multiple steps in the androgen-receptor-signaling pathway, the major driver of prostate-cancer growth. We aimed to evaluate whether enzalutamide prolongs survival in men with castration-resistant prostate cancer after chemotherapy. METHODS: In our phase 3, double-blind, placebo-controlled trial, we stratified 1199 men with castration-resistant prostate cancer after chemotherapy according to the Eastern Cooperative Oncology Group performance-status score and pain intensity. We randomly assigned them, in a 2:1 ratio, to receive oral enzalutamide at a dose of 160 mg per day (800 patients) or placebo (399 patients). The primary end point was overall survival. RESULTS: The study was stopped after a planned interim analysis at the time of 520 deaths. The median overall survival was 18.4 months (95% confidence interval [CI], 17.3 to not yet reached) in the enzalutamide group versus 13.6 months (95% CI, 11.3 to 15.8) in the placebo group (hazard ratio for death in the enzalutamide group, 0.63; 95% CI, 0.53 to 0.75; P<0.001). The superiority of enzalutamide over placebo was shown with respect to all secondary end points: the proportion of patients with a reduction in the prostate-specific antigen (PSA) level by 50% or more (54% vs. 2%, P<0.001), the soft-tissue response rate (29% vs. 4%, P<0.001), the quality-of-life response rate (43% vs. 18%, P<0.001), the time to PSA progression (8.3 vs. 3.0 months; hazard ratio, 0.25; P<0.001), radiographic progression-free survival (8.3 vs. 2.9 months; hazard ratio, 0.40; P<0.001), and the time to the first skeletal-related event (16.7 vs. 13.3 months; hazard ratio, 0.69; P<0.001). Rates of fatigue, diarrhea, and hot flashes were higher in the enzalutamide group. Seizures were reported in five patients (0.6%) receiving enzalutamide. CONCLUSIONS: Enzalutamide significantly prolonged the survival of men with metastatic castration-resistant prostate cancer after chemotherapy. (Funded by Medivation and Astellas Pharma Global Development; AFFIRM ClinicalTrials.gov number, NCT00974311.)
Improved Effective Potential in Curved Spacetime and Quantum Matter - Higher Derivative Gravity Theory
\noindent{\large\bf Abstract.} We develop a general formalism to study the
renormalization group (RG) improved effective potential for renormalizable
gauge theories ---including matter--gravity--- in curved spacetime. The
result is given up to quadratic terms in curvature, and one-loop effective
potentials may be easiliy obtained from it. As an example, we consider scalar
QED, where dimensional transmutation in curved space and the phase structure of
the potential (in particular, curvature-induced phase trnasitions), are
discussed. For scalar QED with higher-derivative quantum gravity (QG), we
examine the influence of QG on dimensional transmutation and calculate QG
corrections to the scalar-to-vector mass ratio. The phase structure of the
RG-improved effective potential is also studied in this case, and the values of
the induced Newton and cosmological coupling constants at the critical point
are estimated. Stability of the running scalar coupling in the Yukawa theory
with conformally invariant higher-derivative QG, and in the Standard Model with
the same addition, is numerically analyzed. We show that, in these models, QG
tends to make the scalar sector less unstable.Comment: 23 pages, Oct 17 199
Role of genetic testing for inherited prostate cancer risk: Philadelphia prostate cancer consensus conference 2017
Purpose: Guidelines are limited for genetic testing for prostate cancer (PCA). The goal of this conference was to develop an expert consensus-dri
Immunotherapy for castration-resistant prostate cancer: Progress and new paradigms
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153073.pdf (Publisher’s version ) (Open Access)BACKGROUND: The approval of sipuleucel-T in conjunction with data from other immunotherapeutic trials for prostate cancer and other solid tumors demonstrates the potential of harnessing the patients immune system for long-term survival. Thus, a range of therapeutic approaches are under evaluation. This review describes the rationale for immunotherapy for prostate cancer, summarizes the approaches under evaluation, and discusses sequencing options for immunotherapy in the current treatment paradigm. DESIGN: References for this review were identified through searches of PubMed with the search terms "prostate cancer," "immune system," "vaccine," "immunotherapy," and "T cells." Articles were also identified through searches of the authors own files. The final reference list was generated based on originality and relevance. RESULTS: The immune system can recognize and respond to prostate tumor antigens, effected through tumor-associated antigens and tumor infiltration of immune effector cells. However, evidence also suggests that prostate tumors are adept at escaping immunological recognition, thus hypothesizing multiple therapeutic strategies. Therapeutic approaches could include vaccination and modulation of T-cell function via the blockade of checkpoint receptors such as cytotoxic T-lymphocyte antigen-4 and programmed death 1. In phase III trials, sipuleucel-T improved overall survival for an M1 patient population with castration-resistant prostate cancer and ipilimumab also did so when given after radiotherapy in a subset of better risk patients. In randomized phase II trials, prostate-specific antigen-TRICOM improved overall survival and tasquinimod improved progression-free survival. CONCLUSION: Although immunotherapy has the potential to affect advanced prostate cancer, additional research is needed to (1) identify predictive or surrogate markers of activity, (2) understand which agents are clinically effective alone or in combination with other therapies, and (3) define the optimal timing for an immunotherapy to achieve maximal benefit
Urinary Molecular Biomarker Test Impacts Prostate Biopsy Decision Making in Clinical Practice
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