Simulation of optical interstellar scintillation

Stars twinkle because their light propagates through the atmosphere. The same phenomenon is expected on a longer time scale when the light of remote stars crosses an interstellar turbulent molecular cloud, but it has never been observed at optical wavelengths. The aim of the study described in this paper is to fully simulate the scintillation process, starting from the molecular cloud description as a fractal object, ending with the simulations of fluctuating stellar light curves. Fast Fourier transforms are first used to simulate fractal clouds. Then, the illumination pattern resulting from the crossing of background star light through these refractive clouds is calculated from a Fresnel integral that also uses fast Fourier transform techniques. Regularisation procedure and computing limitations are discussed, along with the effect of spatial and temporal coherency (source size and wavelength passband). We quantify the expected modulation index of stellar light curves as a function of the turbulence strength --characterised by the diffraction radius $R_{diff}$-- and the projected source size, introduce the timing aspects, and establish connections between the light curve observables and the refractive cloud. We extend our discussion to clouds with different structure functions from Kolmogorov-type turbulence. Our study confirms that current telescopes of ~4m with fast-readout, wide-field detectors have the capability of discovering the first interstellar optical scintillation effects. We also show that this effect should be unambiguously distinguished from any other type of variability through the observation of desynchronised light curves, simultaneously measured by two distant telescopes.Comment: 11 pages, 11 figures, accepted for publication in Astronomy and Astrophysic

A new method to improve photometric redshift reconstruction. Applications to the Large Synoptic Survey Telescope

In the next decade, the LSST will become a major facility for the astronomical community. However accurately determining the redshifts of the observed galaxies without using spectroscopy is a major challenge. Reconstruction of the redshifts with high resolution and well-understood uncertainties is mandatory for many science goals, including the study of baryonic acoustic oscillations. We investigate different approaches to establish the accuracy that can be reached by the LSST six-band photometry. We construct a realistic mock galaxy catalog, based on the GOODS survey luminosity function, by simulating the expected apparent magnitude distribution for the LSST. To reconstruct the photometric redshifts (photo-z's), we consider a template-fitting method and a neural network method. The photo-z reconstruction from both of these techniques is tested on real CFHTLS data and also on simulated catalogs. We describe a new method to improve photo-z reconstruction that efficiently removes catastrophic outliers via a likelihood ratio statistical test. This test uses the posterior probability functions of the fit parameters and the colors. We show that the photometric redshift accuracy will meet the stringent LSST requirements up to redshift $\sim2.5$ after a selection that is based on the likelihood ratio test or on the apparent magnitude for galaxies with $S/N>5$ in at least 5 bands. The former selection has the advantage of retaining roughly 35% more galaxies for a similar photo-z performance compared to the latter. Photo-z reconstruction using a neural network algorithm is also described. In addition, we utilize the CFHTLS spectro-photometric catalog to outline the possibility of combining the neural network and template-fitting methods. We conclude that the photo-z's will be accurately estimated with the LSST if a Bayesian prior probability and a calibration sample are used.Comment: 19 pages, 25 figures, accepted for publication in Astronomy and Astrophysics Astronomy and Astrophysics, 201

Pseudoprogression after proton beam irradiation for a choroid plexus carcinoma in pediatric patient: MRI and PET imaging patterns

Purpose: Pseudoprogression is a rare complication of radiation therapy, and discrimination between true progression and pseudoprogression is of paramount importance for further medical care. We present a case of intra-axial pseudoprogression following complementary proton radiation therapy for a choroid plexus carcinoma in a child. We aim to highlight radiological patterns of pseudoprogression after proton beam therapy. Case report: A 6-year-old girl presented with choroid plexus carcinoma, manifesting as change in behavior, tremor, and balance disorder. Partial resection and chemotherapy were performed. Complementary localized proton beam therapy (54Gy) was administered on the residual tumor. Eight month follow-up MRI showed an abnormal, irregular, rim-like enhancement in the pons and both temporal lobes within the field of irradiation. These lesions had a low cerebral blood volume (CBV) on perfusion MR imaging and no restricted diffusion. However, the lesions were hypermetabolic on O-(2-[18F]fluoroethyl)-l-tyrosine (FET)-PET MRI. Follow-up MRI showed disappearance of these lesions confirming the perfusion MR diagnosis of pseudoprogression. Conclusion: Based on this case, radiological patterns of pseudoprogression after proton beam therapy may be a low CBV and no restricted diffusion. Lesions can be hypermetabolic on FET-PET imagin

Epirubicin With Cyclophosphamide Followed by Docetaxel With Trastuzumab and Bevacizumab as Neoadjuvant Therapy for HER2-Positive Locally Advanced Breast Cancer or as Adjuvant Therapy for HER2-Positive Pathologic Stage III Breast Cancer: A Phase II Trial of the NSABP Foundation Research Group, FB-5

Background The purpose of this study was to determine the cardiac safety and clinical activity of trastuzumab and bevacizumab with docetaxel after epirubicin with cyclophosphamide (EC) in patients with HER2-positive locally advanced breast cancer (LABC) or pathologic stage 3 breast cancer (PS3BC). Patients and Methods Patients received every 3 week treatment with 4 cycles of EC (90/600 mg/m2) followed by 4 cycles of docetaxel (100 mg/m2). Targeted therapy with standard-dose trastuzumab with bevacizumab 15 mg/kg was given for a total of 1 year. Coprimary end points were (1) rate of cardiac events (CEs) in all patients defined as clinical congestive heart failure with a significant decrease in left ventricular ejection fraction or cardiac deaths; and (2) pathologic complete response (pCR) in breast and nodes in the neoadjuvant cohort. An independent cardiac review panel determined whether criteria for a CE were met. Results A total of 105 patients were accrued, 76 with LABC treated with neoadjuvant therapy and 29 with PS3BC treated with adjuvant therapy. Median follow-up was 59.2 months. Among 99 evaluable patients for cardiac safety, 4 (4%; 95% confidence interval [CI], 1.1%-10.0%) met CE criteria. The pCR percentage in LABC patients was 46% (95% CI, 34%-59%). Five-year recurrence-free survival (RFS) and overall survival (OS) for all patients was 79.9% and 90.8%, respectively. Conclusion The regimen met predefined criteria for activity of interest with an acceptable rate of CEs. Although the pCR percentage was comparable with chemotherapy regimens with trastuzumab alone the high RFS and OS are of interest in these high-risk populations

A novel method for quantification of sulfolane (a metabolite of busulfan) in plasma by gas chromatography-tandem mass spectrometry

The role of busulfan (Bu) metabolites in the adverse events seen during hematopoietic stem cell transplantation and in drug interactions is not explored. Lack of availability of established analytical methods limits our understanding in this area. The present work describes a novel gas chromatography-tandem mass spectrometric assay for the analysis of sulfolane (Su) in plasma of patients receiving high-dose Bu. Su and Bu were extracted from a single 100 μL plasma sample by liquid-liquid extraction. Bu was separately derivatized with 2,3,5,6-tetrafluorothiophenolfluorinated agent. Mass spectrometric detection of the analytes was performed in the selected reaction monitoring mode on a triple quadrupole instrument after electronic impact ionization. Bu and Su were analyzed with separate chromatographic programs, lasting 5min each. The assay for Su was found to be linear in the concentration range of 20-400ng/mL. The method has satisfactory sensitivity (lower limit of quantification, 20ng/mL) and precision (relative standard deviation less than 15%) for all the concentrations tested with a good trueness (100 ± 5%). This method was applied to measure Su from pediatric patients with samples collected 4h after dose 1 (n = 46), before dose 7 (n = 56), and after dose 9 (n = 54) infusions of Bu. Su (mean ± SD) was detectable in plasma of patients 4h after dose 1, and higher levels were observed after dose 9 (249.9 ± 123.4ng/mL). This method may be used in clinical studies investigating the role of Su on adverse events and drug interactions associated with Bu therapy. Figure Overall sample preparation procedure for quantification of sulfolane and busulfan in plasma from patients receiving higher doses of busulfa

Validation of questionnaire-reported hearing with medical records: A report from the Swiss Childhood Cancer Survivor Study

BACKGROUND: Hearing loss is a potential late effect after childhood cancer. Questionnaires are often used to assess hearing in large cohorts of childhood cancer survivors and it is important to know if they can provide valid measures of hearing loss. We therefore assessed agreement and validity of questionnaire-reported hearing in childhood cancer survivors using medical records as reference. PROCEDURE: In this validation study, we studied 361 survivors of childhood cancer from the Swiss Childhood Cancer Survivor Study (SCCSS) who had been diagnosed after 1989 and had been exposed to ototoxic cancer treatment. Questionnaire-reported hearing was compared to the information in medical records. Hearing loss was defined as ≥ grade 1 according to the SIOP Boston Ototoxicity Scale. We assessed agreement and validity of questionnaire-reported hearing overall and stratified by questionnaire respondents (survivor or parent), sociodemographic characteristics, time between follow-up and questionnaire and severity of hearing loss. RESULTS: Questionnaire reports agreed with medical records in 85% of respondents (kappa 0.62), normal hearing was correctly assessed in 92% of those with normal hearing (n = 249), and hearing loss was correctly assessed in 69% of those with hearing loss (n = 112). Sensitivity of the questionnaires was 92%, 74%, and 39% for assessment of severe, moderate and mild bilateral hearing loss; and 50%, 33% and 10% for severe, moderate and mild unilateral hearing loss, respectively. Results did not differ by sociodemographic characteristics of the respondents, and survivor- and parent-reports were equally valid. CONCLUSIONS: Questionnaires are a useful tool to assess hearing in large cohorts of childhood cancer survivors, but underestimate mild and unilateral hearing loss. Further research should investigate whether the addition of questions with higher sensitivity for mild degrees of hearing loss could improve the results