Dynamic Reserves in Matching Markets

We study a school choice problem under affirmative action policies where authorities reserve a certain fraction of the slots at each school for specific student groups, and where students have preferences not only over the schools they are matched to but also the type of slots they receive. Such reservation policies might cause waste in instances of low demand from some student groups. To propose a solution to this issue, we construct a family of choice functions, dynamic reserves choice functions, for schools that respect within-group fairness and allow the transfer of otherwise vacant slots from low-demand groups to high-demand groups. We propose the cumulative offer mechanism (COM) as an allocation rule where each school uses a dynamic reserves choice function and show that it is stable with respect to schools' choice functions, is strategy-proof, and respects improvements. Furthermore, we show that transferring more of the otherwise vacant slots leads to strategy-proof Pareto improvement under the COM

College Admission with Multidimensional Privileges: The Brazilian Affirmative Action Case

In 2012 Brazilian public universities were mandated to use affirmative action policies for candidates from racial and income minorities. We show that the policy makes the students' affirmative action status a strategic choice, and may reject high-achieving minority students while admitting low-achieving majority students. Empirical data shows evidence consistent with this type of unfairness in more than 49\% of the programs. We propose a selection criterion and an incentive-compatible mechanism that, for a wider range of similar problems and the one in Brazil in particular, removes any gain from strategizing over the privileges claimed and is fair

Behçet Hastalığında Arka Segment Yapıların Multimodal Görüntülenmesi

Purpose The aim of this study was to describe multimodal imaging modalities including optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA) findings in eyes with Behçet's uveitis (BU) and to compare these findings with those of nonocular Behçet's and healthy controls. Material and Methods Clinically active and inactive BU, NOB and healthy controls were evaluated using OCT (Heidelberg Spectralis) and OCTA (Zeiss Angioplex). On OCT, central macular thickness, retinal segmentation analysis of nerve fiber, ganglion cell, inner plexiform, inner nuclear, outer plexiform, outer nuclear retinal pigment epithelial layer thickness were done with the software of the device. Superficial capillary plexus vascular and perfusion densities (mm / mm2 and %) were measured on 3x3, 6x6 and 8x8 mm images with the software of the OCTA device (Angioplex Metrix). Perfusion density and flow index of optic nerve head were measured by the software of the OCTA device (Angioplex Metrix). Foveal avascular zone (FAZ) area, FAZ perimetry and FAZ circularity was measured for superficial capillary plexus with Angioplex Metrix, for the measurements in deep capillary plexus Image J program was employed. Results Seventeen active active (28 eyes), 38 inactive (62 eyes), 20 NOB (40 eyes) patients and 33 healthy controls (66 eyes) were included in the study. The mean visual acuity was 0.63 in active BU, 0.55 in inactive BU, and 1.0 in nonocular Behçet's disease. In the eyes with inactive BU; central macular thickness, nerve fiber layer, ganglion cell layer, inner plexiform layer thickness were significantly lower than those of active BP, NOB and control groups. In eyes with inactive BP, capillary vessel density was lower than both NOB and control groups. This also applied to perfusion density. The perfusion density in the deep capillary plexus was lower in inactive BU groups when compared to NOB and control groups. In the superficial capillary plexus, there was no significant difference between the groups in terms of FAZ area and circularity, but FAZ circularity was significantly higher in inactive BP. In the deep capillary plexus, the FAZ area and perimetry were significantly higher and there was a significant deterioration in the circularity values of both active and inactive BU compared to NOB and controls. Discussion OCT and OCTA provides important information for the evaluation of anatomical structure and superficial and deep capillary plexuses of the posterior segment. Superficial capillary plexus vascular density and perfusion densities were found to be affected in inactive BP, and significant differences were found in the measurement of FAZ area and perimetry in the active and inactive BP in the deep capillary plexus.Çalışmanın Amacı Behçet üveitli (BÜ) gözlerde multimodal görüntüleme yöntemleri olan optik koherens tomografi (OKT) ve optik koherens tomografi anjiyografi (OKTA) bulgularını tanımlamak ve bu bulguları, nonoküler Behçet (NOB) ve sağlıklı kontrol grubundakilerle (SKG) karşılaştırmaktır. Gereç ve Yöntem Klinik olarak aktif ve inaktif BÜ, NOB ve SKG, OKT (Heidelberg Spectralis ) ve OKTA (Zeiss Angioplex) kullanılarak değerlendirildi. OKT ile santral makula kalınlığı, koroid kalınlığı, retina segmentasyon analizi ile sinir lifi, ganglion hücre, iç pleksiform, iç nükleer, dış pleksiform, dış nükleer, retina pigment epiteli tabaka kalınlıkları ölçüldü. OKTA ile yüzeysel ve derin kapiller pleksuslar için 3x3, 6x6 ve 8x8 mm görüntülerde cihazın yazılımı (Angioplex Metrix) kullanılarak damar ve perfüzyon yoğunlukları (mm / mm2 ve %) ölçüldü. Optik sinir başı anjiografik görüntülerinde, cihazın yazılımı ile perfüzyon dansitesi ve akım indeksleri ölçüldü. Yüzeysel kapiller pleksusta foveal avasküler zon (FAZ) alanı, FAZ perimetrisi ve FAZ daireselliği Angioplex Metrix ile, derin kapiller pleksusta Image J görüntü analiz programı ile değerlendirildi. Bulgular 17 aktif BÜ (28 göz), 38 inaktif BÜ (62 göz), 20 NOB (40 göz) olgusu ve 33 sağlıklı katılımcı (66 göz) çalışmaya dahil edildi. Ortalama en iyi düzeltilmiş görme keskinliği (EİDGK) aktif BÜ'de 0.63, inaktif BÜ' de 0.55, NOB hastalığında 1.0 idi. İnaktif BÜ olan gözlerde retinal segmentasyon analizi ile santral makula, sinir lifi, ganglion hücre, iç pleksiform tabaka kalınlıkları aktif BÜ, NOB ve SKG’ ye göre anlamlı şekilde daha düşüktü. İnaktif BÜ olan gözlerde kapiller damar yoğunluğu hem NOB hem de kontrol grubundan daha düşüktü. Bu durum perfüzyon yoğunluğu için de geçerliydi. Derin kapiller pleksusta perfüzyon yoğunluğu, inaktif BU grubunda NOB ve kontrol grubuna kıyasla daha düşüktü. Yüzeyel kapiller pleksusta, FAZ alanı ve daireselliği değerlerinde gruplar arasında anlamlı bir fark yoktu, ancak FAZ daireselliği inaktif BÜ'de anlamlı şekilde daha yüksek bulundu. Derin kapiller pleksusta FAZ alanı ve çevresi anlamlı şekilde artmıştı ve hem aktif hem de inaktif BÜ'de NOB ve kontrollere kıyasla dairesellik değerlerinde anlamlı bir bozulma vardı. Sonuç BH’de OKT ve OKTA, arka segment yapılarının anatomik ve vasküler yapıların değerlendirilmesinde önemli bilgiler sağlar. Çalışmamızda inaktif BÜ'de, OKT’da retina katlarında incelme saptandı. OKTA’da yüzeyel kapiller pleksus damar yoğunluğu ve perfüzyon yoğunluğunun etkilendiği görüldü. Derin kapiller pleksusta, aktif ve inaktif BÜ’de perfüzyon yoğunluğundaki etkilenmenin yanı sıra FAZ alanı ve çevresi ölçümlerinde önemli farklılıklar saptandı

2014a). The importance of irrelevance of rejected contracts in matching under weakened substitutes conditions. Boston College Working Paper

Abstract We show that Hatfield and Kojima (2010) inherits a critical ambiguity from its predecesso

Affirmative Action in India: Restricted Strategy Space, Complex Constraints, and Direct Mechanism Design

Since the 1950s, India has instituted an intricate affirmative action program through a meticulously designed reservation system. This system incorporates vertical and horizontal reservations to address historically marginalized groups’ socioeconomic imbalances. Vertical reservations designate specific quotas of available positions for Scheduled Castes, Scheduled Tribes, Other Backward Classes, and Economically Weaker Sections. Concurrently, horizontal reservations are employed within each vertical category to allocate positions for additional subgroups, such as women and individuals with disabilities. In educational admissions, the legal framework recommended that unfilled positions reserved for the OBC category revert to unreserved status. Moreover, we document that individuals from vertically reserved categories have more complicated preferences over institution-vertical category position pairs, even though authorities only elicit their preferences over institutions. To address these challenges, the present paper proposes a novel class of Generalized Lexicographic (GL) choice rules. This class is comprehensive, subsuming the most salient priority structures discussed in the extant matching literature. Utilizing the GL choice rules and the deferred acceptance mechanism, we present a robust framework that generates equitable and effective solutions for resource allocation problems in the Indian context.JEL Classification: C78, D02, D47, I38Length: 41 pages Original Release Date: October 4, 2023Revision: November 1, 2023Latest Revision: November 22, 2023 Copyright 2023, The Author