Yahoo!

About: Yahoo! is a company organization based out in London, United Kingdom. It is known for research contribution in the topics: Population & Web search query. The organization has 26749 authors who have published 29915 publications receiving 732583 citations. The organization is also known as: Yahoo! Inc. & Maudwen-Yahoo! Inc.

Multiplier method for predicting limb-length discrepancy.

Abstract: Background: In patients with a congenital or developmental limb-length discrepancy, the short limb grows at a rate proportional to that of the normal, long limb This is the basis of predicting limb-length discrepancy with existing methods, which are complicated and require multiple data points The purpose of our study was to derive a simple arithmetic formula that can easily and accurately predict limb-length discrepancy at skeletal maturity Methods: Using available databases, we divided the femoral and tibial lengths at skeletal maturity by the femoral and tibial lengths at each age for each percentile group The resultant number was called the multiplier Using the multiplier, we derived formulae to predict the limb-length discrepancy and the amount of growth remaining We verified the accuracy of these formulae by evaluating two groups of patients with congenital shortening who were managed with epiphysiodesis or limb-lengthening We also calculated and compared the multipliers for other databases according to radiographic, clinical, and anthropological lower-limb measurements Results: The multipliers for the femur and tibia were equivalent in all percentile groups, varying only by age and gender Because congenital limb-length discrepancy increases at a rate proportional to growth, the discrepancy at maturity can be calculated as the current discrepancy times the multiplier for the current age and the gender This calculation can be performed with use of a single measurement of limb-length discrepancy For progressive developmental (noncongenital) discrepancies, the discrepancy at skeletal maturity can be calculated as the current discrepancy plus the growth inhibition times the amount of growth remaining The timing of the epiphysiodesis can also be calculated with the multiplier The predictions made with use of the multiplier method correlated well with those made with use of the Moseley method as well as with the actual limb-length discrepancy in both the limb-lengthening and epiphysiodesis groups The multipliers derived from the radiographic, clinical, and anthropological measurements of femora and tibiae were all similar to each other despite differences in race, ethnicity, and generation Conclusions: The multiplier method allows for a quick calculation of the predicted limb-length discrepancy at skeletal maturity, without the need to plot graphs, and is based on as few as one or two measurements This method is independent of percentile groups and is the same for the prediction of femoral, tibial, and total-limb lengths The multiplier values are also independent of generation, height, socioeconomic class, ethnicity, and race We verified the accuracy of this method clinically by evaluating patients who had been managed with limb-lengthening or epiphysiodesis The method was also comparable with or more accurate than the Moseley method of limb-length prediction

Interestingness ranking of media objects

Abstract: Media objects, such as images or soundtracks, may be ranked according to a new class of metrics known as “interestingness.” These rankings may be based at least in part on the quantity of user-entered metadata concerning the media object, the number of users who have assigned metadata to the media object, access patterns related to the media object, and/or a lapse of time related to the media object.

High occurrence rate of glaucoma among patients with Alzheimer's disease.

Abstract: The purpose of the current study was to reveal the occurrence rate of glaucoma among patients with Alzheimer's disease (AD). All 112 patients of four nursing homes in Upper Bavaria, Germany, who met the diagnostic criteria of probable AD, were incorporated into the study. Visual field defects and/or optic disc cupping compatible with the diagnosis of glaucoma were found in 29 out of 112 patients with AD (25.9%). When compared to a control group (5.2%) and to the prevalence of glaucoma in western countries revealed in a number of glaucoma surveys (2.6-4.7%), patients with AD may have a significantly increased occurrence rate of glaucoma. In addition, ocular hypertension with normal visual fields and normal optic nerve heads was not found in patients with AD. The prevalence of ocular hypertension in the control group was 7.8% and parallels previous surveys. Therefore, we assume that the optic nerve seems to be less resistant to elevated intraocular pressure levels in AD patients.

Dynamics of bid optimization in online advertisement auctions

Abstract: We consider the problem of online keyword advertising auctions among multiple bidders with limited budgets, and study a natural bidding heuristic in which advertisers attempt to optimize their utility by equalizing their return-on-investment across all keywords. We show that existing auction mechanisms combined with this heuristic can experience cycling (as has been observed in many current systems), and therefore propose a modified class of mechanisms with small random perturbations. This perturbation is reminiscent of the small time-dependent perturbations employed in the dynamical systems literature to convert many types of chaos into attracting motions. We show that the perturbed mechanism provably converges in the case of first-price auctions and experimentally converges in the case of second-price auctions. Moreover, the point of convergence has a natural economic interpretation as the unique market equilibrium in the case of first-price mechanisms. In the case of second-price auctions, we conjecture that it converges to the "supply-aware" market equilibrium. Thus, our results can be alternatively described as a tâtonnement process for convergence to market equilibriumin which prices are adjusted on the side of the buyers rather than the sellers. We also observe that perturbation in mechanism design is useful in a broader context: In general, it can allow bidders to "share" a particular item, leading to stable allocations and pricing for the bidders, and improved revenue for the auctioneer.

The Discrete Basis Problem

Abstract: Matrix decomposition methods represent a data matrix as a product of two factor matrices: one containing basis vectors that represent meaningful concepts in the data, and another describing how the observed data can be expressed as combinations of the basis vectors. Decomposition methods have been studied extensively, but many methods return real-valued matrices. Interpreting real-valued factor matrices is hard if the original data is Boolean. In this paper, we describe a matrix decomposition formulation for Boolean data, the Discrete Basis Problem. The problem seeks for a Boolean decomposition of a binary matrix, thus allowing the user to easily interpret the basis vectors. We also describe a variation of the problem, the Discrete Basis Partitioning Problem. We show that both problems are NP-hard. For the Discrete Basis Problem, we give a simple greedy algorithm for solving it; for the Discrete Basis Partitioning Problem we show how it can be solved using existing methods. We present experimental results for the greedy algorithm and compare it against other, well known methods. Our algorithm gives intuitive basis vectors, but its reconstruction error is usually larger than with the real-valued methods. We discuss about the reasons for this behavior.