3,496 research outputs found
Quantitative and empirical demonstration of the Matthew effect in a study of career longevity
The Matthew effect refers to the adage written some two-thousand years ago in
the Gospel of St. Matthew: "For to all those who have, more will be given."
Even two millennia later, this idiom is used by sociologists to qualitatively
describe the dynamics of individual progress and the interplay between status
and reward. Quantitative studies of professional careers are traditionally
limited by the difficulty in measuring progress and the lack of data on
individual careers. However, in some professions, there are well-defined
metrics that quantify career longevity, success, and prowess, which together
contribute to the overall success rating for an individual employee. Here we
demonstrate testable evidence of the age-old Matthew "rich get richer" effect,
wherein the longevity and past success of an individual lead to a cumulative
advantage in further developing his/her career. We develop an exactly solvable
stochastic career progress model that quantitatively incorporates the Matthew
effect, and validate our model predictions for several competitive professions.
We test our model on the careers of 400,000 scientists using data from six
high-impact journals, and further confirm our findings by testing the model on
the careers of more than 20,000 athletes in four sports leagues. Our model
highlights the importance of early career development, showing that many
careers are stunted by the relative disadvantage associated with inexperience.Comment: 13 pages, 7 figures, 4 Tables; Revisions in response to critique and
suggestions of referee
Towards Content-based Pixel Retrieval in Revisited Oxford and Paris
This paper introduces the first two pixel retrieval benchmarks. Pixel
retrieval is segmented instance retrieval. Like semantic segmentation extends
classification to the pixel level, pixel retrieval is an extension of image
retrieval and offers information about which pixels are related to the query
object. In addition to retrieving images for the given query, it helps users
quickly identify the query object in true positive images and exclude false
positive images by denoting the correlated pixels. Our user study results show
pixel-level annotation can significantly improve the user experience.
Compared with semantic and instance segmentation, pixel retrieval requires a
fine-grained recognition capability for variable-granularity targets. To this
end, we propose pixel retrieval benchmarks named PROxford and PRParis, which
are based on the widely used image retrieval datasets, ROxford and RParis.
Three professional annotators label 5,942 images with two rounds of
double-checking and refinement. Furthermore, we conduct extensive experiments
and analysis on the SOTA methods in image search, image matching, detection,
segmentation, and dense matching using our pixel retrieval benchmarks. Results
show that the pixel retrieval task is challenging to these approaches and
distinctive from existing problems, suggesting that further research can
advance the content-based pixel-retrieval and thus user search experience. The
datasets can be downloaded from
\href{https://github.com/anguoyuan/Pixel_retrieval-Segmented_instance_retrieval}{this
link}
The effect of low temperature aging on the mechanical property & phase stability of Y-TZP ceramics
STATEMENT OF PROBLEM. Recently Yttrium-stabilized tetragonal zirconia polycrystal (Y-TZP) has been introduced due to superior flexural
strength and fracture toughness compared to other dental ceramic systems. Although zirconia has outstanding mechanical properties, the
phenomenon of decrease in the life-time of zirconia resulted from degradation in flexural strength after low temperature aging has been reported.
PURPOSE. The objective of this study was to investigate degradation of flexural strength of Y-TZP ceramics after various low temperature
aging treatments and to evaluate the phase stability and micro-structural change after aging by using X-ray diffraction analysis and a scanning
electron microscope (SEM). MATERIAL AND METHODS. Y-TZP blocks of Vita In-Ceram YZ (Vita Zahnfabrik, Bad Sa ¨ckingen,
Germany) were prepared in 40 mm (length) x 4 mm (width) x 3 mm (height) samples. Specimens were artificially aged in distilled water by heattreatment
at a temperature of 75, 100, 125, 150, 175, 200, and 225℃ for 10 hours, in order to induce the phase transformation at the surface.
To measure the mechanical property, the specimens were subjected to a four-point bending test using a universal testing machine (Instron model
3365; Instron, Canton, Mass, USA). In addition, X-ray diffraction analysis (DMAX 2500; Rigaku, Tokyo, Japan) and SEM (Hitachi s4700; Jeol
Ltd, Tokyo, Japan) were performed to estimate the phase transformation. The statistical analysis was done using SAS 9.1.3 (SAS institute,
USA). The flexural strength data of the experimental groups were analyzed by one-way analysis of variance and to detect statistically significant
differences (α= .05). RESULTS. The mean flexural strength of sintered Vita In-Ceram YZ without autoclaving was 798 MPa. When applied
aging temperature at below 125℃ for 10 hours, the flexural strength of Vita In-Ceram YZ increased up to 1,161 MPa. However, at above 150℃,
the flexural strength started to decrease. Although low temperature aging caused the tetragonal-to-monoclinic phase transformation related
to temperature, the minimum flexural strength was above 700 MPa. CONCLUSION. The monoclinic phase started to appear after aging treatment
above 100℃. With the higher aging temperature, the fraction of monoclinic phase increased. The ratio of monoclinic/tetragonal + monoclinic
phase reached a plateau value, circa 75% above 175℃. The point of monoclinic concentration at which the flexural strength begins to
decrease was between 12% and 54%.This work was supported by the Korea Science and Engineering Foundation (KOSEF) grant funded by the Korea government(MOST)
(No. R01-2007-000-10977-0)
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