Richard Gebhardt Responds

Gebhardt, Richard C.

doi:10.2307/376908

Cited by 3 publications

(5 citation statements)

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“…Gebhardt [27] tabulated updated values of masses and distances of many MDOs. In Table 4, we consider most of those and arrange in the decreasing order of M/D d (i.e., the ratio of mass M and the distance D d ) of MDOs.…”

Section: Gravitational Lensing By Mdos At Centers Of Many Galaxiesmentioning

confidence: 99%

“…In this section, we model MDOs at centers of 40 galaxies as Schwarzschild black hole lenses and, like in the previous section, study point source GL by them. Gebhardt [27] tabulated updated values of masses and distances of many MDOs. In Table 4, we consider most of those and arrange in the decreasing order of M/D d (i.e., the ratio of mass M and the distance D d ) of MDOs.…”

Section: Gravitational Lensing By Mdos At Centers Of Many Galaxiesmentioning

confidence: 99%

“…Masses and distances of MDOs at centers of 40 galaxies are presented in the decreasing order of dimensionless ratio of mass to distance [i.e., M/D d ≡ M G/(c 2 D d )] of MDOs. The mass and distance of the Galactic MDO and all other MDOs are, respectively, taken from[26] and[27].…”

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confidence: 99%

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Relativistic images of Schwarzschild black hole lensing

2009

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We model massive dark objects at centers of many galaxies as Schwarzschild black hole lenses and study gravitational lensing by them in detail. We show that the ratio of mass of a Schwarzschild lens to the differential time delay between outermost two relativistic images (both of them either on the primary or on the secondary image side) is extremely insensitive to changes in the angular source position as well as the lens-source and lens-observer distances. Therefore, this ratio can be used to obtain very accurate values for masses of black holes at centers of galaxies. Similarly, angular separations between any two relativistic images are also extremely insensitive to changes in the angular source position and the lens-source distance. Therefore, with the known value of mass of a black hole, angular separation between two relativistic images would give a very accurate result for the distance of the black hole. Accuracies in determination of masses and distances of black holes would however depend on accuracies in measurements of differential time delays and angular separations between images. Deflection angles of primary and secondary images as well as effective deflection angles of relativistic images on the secondary image side are always positive. However, the effective deflection angles of relativistic images on the primary image side may be positive, zero, or negative depending on the value of angular source position and the ratio of mass of the lens to its distance. We show that effective deflection angles of relativistic images play significant role in analyzing and understanding strong gravitational field lensing.

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Section: Gravitational Lensing By Mdos At Centers Of Many Galaxiesmentioning

confidence: 99%

Section: Gravitational Lensing By Mdos At Centers Of Many Galaxiesmentioning

confidence: 99%

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Relativistic images of Schwarzschild black hole lensing

2009

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“…The feedback that the learners receive from this new model of writing can be extremely positive since collaborative writing is reflective both of the business world and the academic field in which students study (Bruffee, 1984). Thus, collaborative writing in the learners' writing achievement in the classroom setting can positively improve in paired writing environment (Bruffee, 1981;Gebhardt, 1980Gebhardt, , 1981.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Collaboration on Iranian EFL Learners’ Writing Accuracy

Narges¹,

Ansari²

2012

IES

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This study aims at finding the effect of group work on Iranian EFL learners' writing accuracy. Moreover, the effect of gender on text production has also been investigated. Over a month, sixty Iranian EFL learners were chosen as the participants of this study. They were divided into two groups. The experimental group wrote collaboratively while the control group underwent individual writing tasks. Both groups participated in four essay writing sessions. The participants wrote on the same topics and genre. The results revealed that the students in the collaborative writing group outperformed the students in the control group, hence emphasizing the significant role of collaboration in L2 writing. Regarding gender effect, the data analysis showed the females in the collaborative group outperformed males in the same group proving that gender plays a significant role in Iranian EFL collaborative writing setting. The results have some implications for English writing instructors and learners.

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“…[12][13][14] Conversely, regardless of the assembly method, polymersomes demonstrate increased mechanical stability compared to liposomes, efficient drug entrapment, long shelf life, and controllable stimuli-triggered delivery of cargo. [15][16][17][18][19][20][21] In addition, although temperature can be used as a trigger for drug release from nanovesicles due to the elevated temperature in tumor microenvironments because of the high rate of tumor metabolism, 22 imbuing liposomes with precise temperature sensitivity in biologically relevant ranges can be difficult due to the complex nature of their formulations, 23,24 as well as controlling their size to promote predictable ensemble behavior can be challenging due to liposome propensity for wide size distributions upon self-assembly. 25 Therefore, the development of polymersomes that are mechanically robust, have efficient drug loading capacity, and can intelligently respond to environmental stimuli such as temperature or pH, has become of great importance.…”

Section: Introductionmentioning

confidence: 99%

Effect of Temperature and Hydrophilic Ratio on the Structure of Poly(N-vinylcaprolactam)-block-poly(dimethylsiloxane)-block-poly(N-vinylcaprolactam) Polymersomes

Yang

Alford

Kozlovskaya

et al. 2019

ACS Appl. Polym. Mater.

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Nanosized polymeric vesicles (polymersomes) assembled from ABA triblock copolymers of poly(N-vinylcaprolactam)-poly(dimethylsiloxane)-poly(N-vinylcaprolactam) (PVCL-PDMS-PVCL) are a promising platform for biomedical applications, as the temperature-responsiveness of the PVCL blocks enables reversible vesicle shrinkage and permeability of the polymersome shell at elevated temperatures. Herein, we explore the effects of molecular weight, polymer block weight ratios, and temperature on the structure of these polymersomes via electron microscopy, dynamic light scattering, small angle neutron scattering (SANS), and all-atom molecular dynamic methods. We show that the shell structure and overall size of the polymersome can be tuned by varying the hydrophilic (PVCL) weight fraction of the polymer: at room temperature, polymers of

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Richard Gebhardt Responds

Cited by 3 publications

References 0 publications

Relativistic images of Schwarzschild black hole lensing

Relativistic images of Schwarzschild black hole lensing

The Effect of Collaboration on Iranian EFL Learners’ Writing Accuracy

Effect of Temperature and Hydrophilic Ratio on the Structure of Poly(N-vinylcaprolactam)-block-poly(dimethylsiloxane)-block-poly(N-vinylcaprolactam) Polymersomes

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