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RISS 인기검색어
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- 저자 : Mandelbaum, R. (검색결과 10 건)
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Precision cluster mass determination from weak lensing
Mandelbaum, Rachel,Seljak, Uroš,Baldauf, Tobias,Smith, Robert E. Blackwell Publishing Ltd 2010 MONTHLY NOTICES- ROYAL ASTRONOMICAL SOCIETY Vol.405 No.3
<P>ABSTRACT</P><P>Weak gravitational lensing has been used extensively in the past decade to constrain the masses of galaxy clusters, and is the most promising observational technique for providing the mass calibration necessary for precision cosmology with clusters. There are several challenges in estimating cluster masses, particularly (a) the sensitivity to astrophysical effects and observational systematics that modify the signal relative to the theoretical expectations, and (b) biases that can arise due to assumptions in the mass estimation method, such as the assumed radial profile of the cluster. All of these challenges are more problematic in the inner regions of the cluster, suggesting that their influence would ideally be suppressed for the purpose of mass estimation. However, at any given radius the differential surface density measured by lensing is sensitive to all mass within that radius, and the corrupted signal from the inner parts is spread out to all scales. We develop a new statistic ϒ(<I>R</I>; <I>R</I><SUB>0</SUB>) that is ideal for estimation of cluster masses because it completely eliminates mass contributions below a chosen scale (which we suggest should be about 20 per cent of the virial radius), and thus reduces sensitivity to systematic and astrophysical effects. We use simulated and analytical profiles including shape noise to quantify systematic biases on the estimated masses for several standard methods of mass estimation, finding that these can lead to significant mass biases that range from 10 to over 50 per cent. The mass uncertainties when using the new statistic ϒ(<I>R</I>; <I>R</I><SUB>0</SUB>) are reduced by up to a factor of 10 relative to the standard methods, while only moderately increasing the statistical errors. This new method of mass estimation will enable a higher level of precision in future science work with weak lensing mass estimates for galaxy clusters.</P>
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Photometric redshift requirements for lens galaxies in galaxy–galaxy lensing analyses
Nakajima, R.,Mandelbaum, R.,Seljak, U.,Cohn, J. D.,Reyes, R.,Cool, R. Blackwell Publishing Ltd 2012 Monthly notices of the Royal Astronomical Society Vol.420 No.4
<P><B>ABSTRACT</B></P><P>Weak gravitational lensing is a valuable probe of galaxy formation and cosmology. Here we quantify the effects of using photometric redshifts (photo‐<I>z</I>) in galaxy–galaxy lensing, for both sources and lenses, both for the immediate goal of using galaxies with photo‐<I>z</I> as lenses in the Sloan Digital Sky Survey (SDSS) and as a demonstration of methodology for large, upcoming weak lensing surveys that will by necessity be dominated by lens samples with photo‐<I>z</I>. We calculate the bias in the lensing mass calibration as well as consequences for absolute magnitude (i.e. <I>k</I>‐corrections) and stellar mass estimates for a large sample of SDSS Data Release 8 (DR8) galaxies. The redshifts are obtained with the template‐based photo‐<I>z</I> code <SMALL>zebra</SMALL> on the SDSS DR8 <I>ugriz</I> photometry. We assemble and characterize the calibration samples (∼9000 spectroscopic redshifts from four surveys) to obtain photometric redshift errors and lensing biases corresponding to our full SDSS DR8 lens and source catalogues. Our tests of the calibration sample also highlight the impact of observing conditions in the imaging survey when the spectroscopic calibration covers a small fraction of its footprint; atypical imaging conditions in calibration fields can lead to incorrect conclusions regarding the photo‐<I>z</I> of the full survey.</P><P>For the SDSS DR8 catalogue, we find σ<SUB>Δ<I>z</I>/(1+<I>z</I>)</SUB>= 0.096 and 0.113 for the lens and source catalogues, with flux limits of <I>r</I>= 21 and 21.8, respectively. The photo‐<I>z</I> bias and scatter is a function of photo‐<I>z</I> and template types, which we exploit to apply photo‐<I>z</I> quality cuts. By using photo‐<I>z</I> rather than spectroscopy for lenses, dim blue galaxies and <I>L</I><SUB>*</SUB> galaxies up to <I>z</I>∼ 0.4 can be used as lenses, thus expanding into unexplored areas of parameter space. We also explore the systematic uncertainty in the lensing signal calibration when using source photo‐<I>z</I>, and both lens and source photo‐<I>z</I>; given the size of existing training samples, we can constrain the lensing signal calibration (and therefore the normalization of the surface mass density) to within 2 and 4 per cent, respectively.</P>
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Koji Matsuo,Rachel S. Mandelbaum,Hiroko Machida,Sanjay Purushothamdas, FRCS,Brendan H. Grubbs,Lynda D. Roman,Jason D. Wright 대한부인종양학회 2018 Journal of Gynecologic Oncology Vol.29 No.6
Objective: To examine the association between tumor grade and survival for women with squamous cervical cancer. Methods: This retrospective observational study utilized the Surveillance, Epidemiology, and End Result program data between 1983 and 2013 to examine women with squamous cervical cancer with known tumor differentiation grade. Multivariable analyses were performed to assess independent associations between tumor differentiation grade and survival. Results: A total of 31,536 women were identified including 15,175 (48.1%) with grade 3 tumors, 14,084 (44.7%) with grade 2 neoplasms and 2,277 (7.2%) with grade 1 tumors. Higher tumor grade was significantly associated with older age, higher stage disease, larger tumor size, and lymph node metastasis (all, p<0.001). In a multivariable analysis, grade 2 tumors (adjusted-hazard ratio [HR]=1.21; p<0.001) and grade 3 tumors (adjusted-HR=1.45; p<0.001) were independently associated with decreased cause-specific survival (CSS) compared to grade 1 tumors. Among the 7,429 women with stage II–III disease who received radiotherapy without surgical treatment, grade 3 tumors were independently associated with decreased CSS compared to grade 2 tumors (adjusted-HR=1.16; p<0.001). Among 4,045 women with node-negative stage I disease and tumor size ≤4 cm who underwent surgical treatment without radiotherapy, grade 2 tumors (adjusted-HR=2.54; p=0.028) and grade 3 tumors (adjusted-HR=4.48; p<0.001) were independently associated with decreased CSS compared to grade 1 tumors. Conclusion: Our study suggests that tumor differentiation grade may be a prognostic factor in women with squamous cervical cancer, particularly in early-stage disease. Higher tumor grade was associated with poorer survival.
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Adequate pelvic lymphadenectomy and survival of women with early-stage epithelial ovarian cancer
Koji Matsuo,Hiroko Machida,Andrea Mariani,Rachel S. Mandelbaum,Gretchen E. Glaser,Bobbie S. Gostout,Lynda D. Roman,Jason D. Wright 대한부인종양학회 2018 Journal of Gynecologic Oncology Vol.29 No.5
Objective: To examine the trends and survival for women with early-stage epithelial ovarian cancer who underwent adequate lymphadenectomy during surgical treatment. Methods: This is a retrospective observational study examining the Surveillance, Epidemiology, End Results program between 1988 and 2013. We evaluated 21,537 cases of stage I–II epithelial ovarian cancer including serous (n=7,466), clear cell (n=6,903), mucinous (n=4,066), and endometrioid (n=3,102) histology. A time-trend analysis of the proportion of patients who underwent adequate pelvic lymphadenectomy (≥8 per Gynecologic Oncology Group [GOG] criteria, ≥12 per Collaborative Group Report [CGR] criteria for bladder cancer, and >22 per Mayo criteria for endometrial cancer) and a survival analysis associated with adequate pelvic lymphadenectomy were performed. Results: There were significant increases in the proportion of women who underwent adequate lymphadenectomy: GOG criteria 3.6% to 28.6% (1988–2010); CGR criteria 2.4% to 22.4% (1988–2013); and Mayo criteria 0.7% to 9.5% (1988–2013) (all, p<0.05). On multivariable analysis, adequate lymphadenectomy was independently associated with improved cause-specific survival compared to inadequate lymphadenectomy: GOG criteria, adjusted-hazard ratio (HR)=0.75, CGR criteria, adjusted-HR=0.77, and Mayo criteria, adjusted-HR=0.85 (all, p<0.05). Compared to inadequate lymphadenectomy, adequate lymphadenectomy was significantly associated with improved cause-specific survival for serous (HR range=0.67–0.73), endometrioid (HR range=0.59–0.61), and clear cell types (HR range=0.66–0.73) (all, p<0.05) but not in mucinous type (HR range=0.80–0.91; p>0.05). Conclusion: Quality of lymphadenectomy during the surgical treatment for early-stage epithelial ovarian cancer has significantly improved. Adequate lymphadenectomy is associated with a 15%–25% reduction in ovarian cancer mortality compared to inadequate lymphadenectomy.
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A unified analysis of four cosmic shear surveys
Chang, Chihway,Wang, Michael,Dodelson, Scott,Eifler, Tim,Heymans, Catherine,Jarvis, Michael,Jee, M James,Joudaki, Shahab,Krause, Elisabeth,Malz, Alex,Mandelbaum, Rachel,Mohammed, Irshad,Schneider, Mic Oxford University Press 2019 Monthly notices of the Royal Astronomical Society Vol.482 No.3
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