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Peter Cramton - One of the best experts on this subject based on the ideXlab platform.
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the clock proxy auction a practical combinatorial auction design
Papers of Peter Cramton, 2006Co-Authors: Lawrence M Ausubel, Peter Cramton, Paul MilgromAbstract:We propose the clock-proxy auction as a practical means for auctioning many related items. A clock auction phase is followed by a last-and-final proxy round. The approach combines the simple and transparent price discovery of the clock auction with the efficiency of the proxy auction. Linear pricing is maintained as long as possible, but then is abandoned in the proxy round to improve efficiency and enhance seller revenues. The approach has many advantages over the simultaneous ascending auction. In particular, the clock-proxy auction has no exposure problem, eliminates incentives for demand reDuction, and prevents most collusive bidding strategies.
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money out of thin air the nationwide narrowband pcs auction
Journal of Economics and Management Strategy, 1995Co-Authors: Peter CramtonAbstract:The Federal Communications Commission held its first auction of radio spectrum at the Nationwide Narrowband PCS Auction in July 1994. The simultaneous multiple-round auction, which lasted five days, was an ascending bid auction in which all licenses were offered simultaneously. This paper describes the auction rules and how bidders prepared for the auction. The full history of bidding is presented. Several questions for auction theory are discussed. In the end, the government collected $617 million for ten licenses. The auction was viewed by all as a huge success-an excellent example of bringing economic theory to bear on practical problems of allocating scarce resources. Copyright 1995 by MIT Press.
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money out of thin air the nationwide narrowband pcs auction
Papers of Peter Cramton, 1995Co-Authors: Peter CramtonAbstract:The Federal Communications Commission held its first auction of radio spectrum at the Nationwide Narrowband PCS Auction in July 1994. The simultaneous multiple-round auction, which lasted five days, was an ascending bid auction in which all licenses were offered simultaneously. This paper describes the auction rules and how bidders prepared for the auction. The full history of bidding is presented. Several questions for auction theory are discussed. In the end, the government collected $617 million for ten licenses. The auction was viewed by all as a huge success-an excellent example of bringing economic theory to bear on practical problems of allocating scarce resources.
Jeongmin Hwang - One of the best experts on this subject based on the ideXlab platform.
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Recurrence and overcorrection rates up to 2 years in patients who received unilateral lateral rectus recession and medial rectus resection without performing the forced Duction test (RR group) and those who received unilateral lateral rectus recessio
2018Co-Authors: Jeongmin Hwang, Seonghwan Kim, Hee Kyung YangAbstract:Recurrence and overcorrection rates up to 2 years in patients who received unilateral lateral rectus recession and medial rectus resection without performing the forced Duction test (RR group) and those who received unilateral lateral rectus recession and medial rectus resection considering forced Duction test results (RR-FDT group).
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persistent diplopia after retrobulbar anesthesia
Journal of Cataract and Refractive Surgery, 2004Co-Authors: Soo Kyung Han, Jeonghun Kim, Jeongmin HwangAbstract:Abstract Purpose: To determine the causative factors of persistent diplopia after retrobulbar anesthesia. Setting: Strabismus Section, Department of Ophthalmology, Seoul National University, Seoul, South Korea. Methods: Prism and alternate cover tests in the diagnostic positions of gaze and Ductions/versions were performed in 28 patients with persistent diplopia 6 months after retrobulbar anesthesia. The Lancaster test, Bielshowsky head tilt test, double Maddox rod test, fundoscopic examination for torsion, forced Duction test, force generation test, tensilon test, thyroid function test, and/or orbit computed tomography were performed when necessary. Results: Most of the patients (26 patients, 93%) did not have diplopia before retrobulbar anesthesia. Of the 14 patients with extraocular muscles imbalance, 12 patients showed vertical rectus overaction (11 superior recti, 1 inferior rectus) and 2 patients, mild vertical rectus underaction. Nine patients were presumed to have a sensory strabismus related to the preoperative poor vision, but this went unnoticed preoperatively. Three patients showed a small vertical deviation without any specific causative factors. Conclusions : Fifty percent of the cases of diplopia were associated with either direct trauma or anesthetic myotoxicity to the extraocular muscles, in which overactions were more common than underactions. Thirty-two percent of the patients were presumed to have sensory strabismus, which suggested the importance of preoperative examination for strabismus as well as providing an explanation about the risk of postoperative diplopia before surgery.
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childhood ocular myasthenia gravis
Ophthalmology, 2003Co-Authors: Jong Hyun Kim, Jeongmin Hwang, Yong Seung Hwang, Ki Joong Kim, Jonghee ChaeAbstract:Abstract Purpose To investigate the clinical manifestations and ocular findings in children with ocular myasthenia gravis (MG) that rarely have been reported in the literature. Design Retrospective, noncomparative case series. Participants Twenty-four consecutive patients less than 15 years of age with ocular MG treated between June 1988 and July 2001. Methods The medical records of 6 boys and 18 girls with ocular MG were reviewed retrospectively. Main outcome measures Alternate prism cover and uncover test, examination of Ductions and versions, and visual acuity. Results Mean age at onset was 38 months. Ptosis was found in 23 patients (96%), strabismus in 21 patients (88%), and amblyopia in 5 patients (21%). Exotropia combined with vertical heterotropia was the most frequent type of strabismus. Ductions were limited in 17 patients (71%), among whom supraDuction or infraDuction limitations were most frequently observed. Contrary to previous reports, medial rectus underaction was less common than lateral rectus underaction. Manifestations of strabismus and limitation of Duction were variable and changed frequently during the follow-up period. The combined use of prednisone and pyridostigmine was found to be the predominant form of maintenance therapy, and ptosis was more responsive to drug therapy than limited ocular motility. Conclusions Children with ocular MG were found to have a high incidence of ptosis (96%) and exotropia and vertical hyperdeviation. Limitation on adDuction was less common than that on abDuction. First reported incidence of amblyopia (21%) and a relative nonresponsiveness of the limitation of eye movement to treatment were also noted.
Jonghee Chae - One of the best experts on this subject based on the ideXlab platform.
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childhood ocular myasthenia gravis
Ophthalmology, 2003Co-Authors: Jong Hyun Kim, Jeongmin Hwang, Yong Seung Hwang, Ki Joong Kim, Jonghee ChaeAbstract:Abstract Purpose To investigate the clinical manifestations and ocular findings in children with ocular myasthenia gravis (MG) that rarely have been reported in the literature. Design Retrospective, noncomparative case series. Participants Twenty-four consecutive patients less than 15 years of age with ocular MG treated between June 1988 and July 2001. Methods The medical records of 6 boys and 18 girls with ocular MG were reviewed retrospectively. Main outcome measures Alternate prism cover and uncover test, examination of Ductions and versions, and visual acuity. Results Mean age at onset was 38 months. Ptosis was found in 23 patients (96%), strabismus in 21 patients (88%), and amblyopia in 5 patients (21%). Exotropia combined with vertical heterotropia was the most frequent type of strabismus. Ductions were limited in 17 patients (71%), among whom supraDuction or infraDuction limitations were most frequently observed. Contrary to previous reports, medial rectus underaction was less common than lateral rectus underaction. Manifestations of strabismus and limitation of Duction were variable and changed frequently during the follow-up period. The combined use of prednisone and pyridostigmine was found to be the predominant form of maintenance therapy, and ptosis was more responsive to drug therapy than limited ocular motility. Conclusions Children with ocular MG were found to have a high incidence of ptosis (96%) and exotropia and vertical hyperdeviation. Limitation on adDuction was less common than that on abDuction. First reported incidence of amblyopia (21%) and a relative nonresponsiveness of the limitation of eye movement to treatment were also noted.
Joseph L Demer - One of the best experts on this subject based on the ideXlab platform.
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progressive deformation of the optic nerve head and peripapillary structures by graded horizontal Duction
Investigative Ophthalmology & Visual Science, 2017Co-Authors: Joseph L Demer, Soh Youn Suh, Andrew Shin, Joseph ParkAbstract:Purpose We investigated the effect of graded range of horizontal Duction on the shape of the peripapillary Bruch's membrane (ppBM) and optic nerve head (ONH). Methods In 50 eyes of 25 normal subjects, the ONH and peripapillary retina were imaged by optical coherence tomography (OCT) in central gaze and incremental angles of add- and abDuction. Displacements of the Bruch's membrane opening (BMO), optic cup (OC), and change in ONH angle in eccentric gazes were compared to those of central gaze, in add- and abDuction. Results With increasing Duction, the nasal edge of the BMO (nBMO) shifted progressively anteriorly in adDuction and posteriorly in abDuction, while the temporal edge of the BMO (tBMO) shifted posteriorly in adDuction and anteriorly in abDuction. The summed absolute nBMO and tBMO displacements in 30° and 35° adDuction significantly exceeded those in comparable abDuction angles (P < 0.005 for both). The ONH progressively tilted temporally in adDuction and nasally in abDuction; absolute ONH tilt in adDuction was significantly greater than that in abDuction for 30° and 35° Ductions (P < 0.005 for both). BMO displacement and ONH tilt in adDuction exhibited bilinear behavior, with greater effects for both at angles exceeding 26°. The OC shifted significantly farther anteriorly in abDuction than adDuction at every angle from 10° to 35°. Conclusions Horizontal Duction deforms the ONH and ppBM, but more in adDuction than in abDuction, and increasingly so for angles greater than 26°. This behavior is consistent with optic nerve sheath tethering for adDuction exceeding 26°.
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posterior fixation sutures a revised mechanical explanation for the fadenoperation based on rectus extraocular muscle pulleys
American Journal of Ophthalmology, 1999Co-Authors: Robert A Clark, Sherwin J Isenberg, Arthur L Rosenbaum, Joseph L DemerAbstract:Abstract PURPOSE: To determine the effect of the rectus extraocular muscle pulleys on the fadenoperation, an operation designed to fixate the posterior muscle belly to the underlying retroequatorial sclera. METHODS: First, Duction into the field of action of the operated-on muscle was quantified retrospectively after fadenoperation. Magnetic resonance imaging was then performed prospectively after surgery to verify anatomic changes. Forced Duction testing was performed prospectively during surgery before and after faden placement. Finally, computed tomography in a cadaver containing radiographic markers was performed prospectively to determine the effect of fadenoperation on the position of the medial rectus insertion relative to its pulley. RESULTS: Mean maximum adDuction after medial rectus fadenoperation was 18 degrees (range, 10 to 25 degrees; 13 eyes). Fadenoperations combined with large medial rectus recessions restricted adDuction more than fadenoperations combined with smaller recessions ( P = .019), but even fadenoperations without recessions substantially restricted adDuction. Mean maximum abDuction after lateral rectus fadenoperation was 40 degrees (range, 25 to 45 degrees; four eyes). Axial magnetic resonance imaging in two eyes demonstrated a smaller loss of muscle tangency to the globe during contraction than predicted by geometric models. Forced Ductions in nine patients performed immediately after faden placement demonstrated a new mechanical restriction to Duction toward the operated-on muscle. Cadaveric computed tomographic scans demonstrated posterior displacement of the medial rectus pulley during adDuction after fadenoperation. CONCLUSIONS: Posterior fixation sutures do not significantly decrease muscle torque during contraction. Because posterior fixation sutures posteriorly displace the pulley sleeve during Duction toward the operated-on muscle, the mechanical restriction after surgery probably represents the force deforming the pulley. This mechanical restriction may account for the limitation in Duction seen after fadenoperation.
Atsuko Miyaji - One of the best experts on this subject based on the ideXlab platform.
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a second price sealed bid auction with verifiable discriminant of ρ o th root
Financial Cryptography, 2002Co-Authors: Kazumasa Omote, Atsuko MiyajiAbstract:A second-price sealed-bid auction is that a bidder who offers the highest price gets a good in the second highest price. This style of auction solves the problems of both an English auction and a first-price sealed-bid auction. An electronic first-price sealed-bid auction cannot directly be applied to a second-price sealed-bid auction which keeps the highest bid secret. We propose the verifiable discriminant function of the po-th root. Our auction scheme satisfies public verifiability of auction results, and also does not have a single entity who knows the highest bid value even after an auction. Furthermore the bidding cost of our scheme is lower than that of the previous one.
