Vickrey Auctions for Irregular Distributions

The classic result of Bulow and Klemperer \cite{BK96} says that in a single-item auction recruiting one more bidder and running the Vickrey auction achieves a higher revenue than the optimal auction's revenue on the original set of bidders, when values are drawn i.i.d. from a regular distribution. We give a version of Bulow and Klemperer's result in settings where bidders' values are drawn from non-i.i.d. irregular distributions. We do this by modeling irregular distributions as some convex combination of regular distributions. The regular distributions that constitute the irregular distribution correspond to different population groups in the bidder population. Drawing a bidder from this collection of population groups is equivalent to drawing from some convex combination of these regular distributions. We show that recruiting one extra bidder from each underlying population group and running the Vickrey auction gives at least half of the optimal auction's revenue on the original set of bidders

Mark-and-Recapture Methods for Studying Domestic Cockroach Populations

Mark and recapture methods were used to estimate populations of American cockroaches, Periplenata americana (Linnaeus), and brown-banded cockroaches, Supella supellectilium (Serville) inhabiting various rooms in the Science Hall, Iowa State University. These methods also permitted estimates of sex ratios, length-frequencies, movement, and activity patterns. Food appeared to be the limiting factor in determining size of cockroach populations. Males outnumbered females in both species with total sex ratios being.8 and.6 for brown-banded and American cockroaches, respectively. Most of the American cockroaches caught were over 28.0 mm. with the 36.1 - 40.0 mm. class being the largest. The brown-banded cockroach catch contained two large length classes, 2.5 - 4.0 mm. and 12.5 - 14.0 mm., suggesting two major age classes. Room-to-room movement of cockroaches was limited, and over 93 percent of the catch occurred during the dark hours

Simple, optimal and efficient auctions

Proceedings of the 7th International Workshop, WINE 2011, Singapore, December 11-14, 2011.We study the extent to which simple auctions can simultaneously achieve good revenue and efficiency guarantees in single-item settings. Motivated by the optimality of the second price auction with monopoly reserves when the bidders’ values are drawn i.i.d. from regular distributions [12], and its approximate optimality when they are drawn from independent regular distributions [11], we focus our attention to the second price auction with general (not necessarily monopoly) reserve prices, arguably one of the simplest and most intuitive auction formats. As our main result, we show that for a carefully chosen set of reserve prices this auction guarantees at least 20% of both the optimal welfare and the optimal revenue, when the bidders’ values are distributed according to independent, not necessarily identical, regular distributions. We also prove a similar guarantee, when the values are drawn i.i.d. from a—possibly irregular—distribution.National Science Foundation (U.S.) (award CCF-0953960)National Science Foundation (U.S.) (CCF-1101491

Combinatorial Roles of Heparan Sulfate Proteoglycans and Heparan Sulfates in Caenorhabditis elegans Neural Development

Heparan sulfate proteoglycans (HSPGs) play critical roles in the development and adult physiology of all metazoan organisms. Most of the known molecular interactions of HSPGs are attributed to the structurally highly complex heparan sulfate (HS) glycans. However, whether a specific HSPG (such as syndecan) contains HS modifications that differ from another HSPG (such as glypican) has remained largely unresolved. Here, a neural model in C. elegans is used to demonstrate for the first time the relationship between specific HSPGs and HS modifications in a defined biological process in vivo. HSPGs are critical for the migration of hermaphrodite specific neurons (HSNs) as genetic elimination of multiple HSPGs leads to 80% defect of HSN migration. The effects of genetic elimination of HSPGs are additive, suggesting that multiple HSPGs, present in the migrating neuron and in the matrix, act in parallel to support neuron migration. Genetic analyses suggest that syndecan/sdn-1 and HS 6-O-sulfotransferase, hst-6, function in a linear signaling pathway and glypican/lon-2 and HS 2-O-sulfotransferase, hst-2, function together in a pathway that is parallel to sdn-1 and hst-6. These results suggest core protein specific HS modifications that are critical for HSN migration. In C. elegans, the core protein specificity of distinct HS modifications may be in part regulated at the level of tissue specific expression of genes encoding for HSPGs and HS modifying enzymes. Genetic analysis reveals that there is a delicate balance of HS modifications and eliminating one HS modifying enzyme in a compromised genetic background leads to significant changes in the overall phenotype. These findings are of importance with the view of HS as a critical regulator of cell signaling in normal development and disease

Entry in the ADHD drugs market: Welfare impact of generics and me-toos

Recent decades have seen a growth in treatments for attention deficit hyperactivity disorder (ADHD) including many branded and generic drugs. In the early 2000's, new drug entry dramatically altered market shares. We estimate a demand system for ADHD drugs and assess the welfare impact of new drugs. We find that entry induced large welfare gains by reducing prices of substitute drugs, and by providing alternative delivery mechanisms for existing molecules. Our results suggest that the success of follow-on patented drugs may come from unanticipated innovations like delivery mechanisms, a factor ignored by proposals to retard new follow-on drug approvals

Parenting adolescents in times of a pandemic:Changes in relationship quality, autonomy support, and parental control?

This Dutch multi-informant study examined effects of the first COVID-19 lockdown (LD; e.g., school closure and social restrictions) on parent-adolescent relationships. Four biweekly measurements before and 4 biweekly measurements during the LD were collected among adolescents (N = 179, Mage = 14.26 years, 69% girls) and their parents (N = 144, Mage = 47.01 years, 81% female). Parents' educational level was relatively diverse: 12% low (high school or lower), 33% medium (vocational training), and 55% high (college or university). Adolescents and parents reported on parental support, parent-adolescent conflict, autonomy support, psychological control, behavioral control, and time spent on various activities. Adolescents spent more time with their parents during LD (before M = 8.6 hr, during M = 12.7 hr), but less time with friends (before M = 8.1 hr, during M = 2.1 hr), and reported on average 13 COVID-19-related rules. Preregistered piecewise growth models confirmed that autonomy support decreased immediately during the LD, but no mean level changes were observed in the other relationship dimensions. During the first 2 months of the LD, parents reported gradual increases in autonomy support and decreases in behavioral control. Moreover, significant differences between families were found in sudden and more gradual relationship changes, which correlated strongly with pre-LD characteristics of the relationship, and in some models with adolescent oppositional defiance and legitimacy beliefs. In sum, findings suggest resilience in most families, but also heterogeneity: Some families were negatively affected, and others were positively affected. A tailored approach is therefore needed to mitigate the impact of COVID-19 on family functioning. (PsycInfo Database Record (c) 2021 APA, all rights reserved)

Long-term methimazole therapy in Graves' hyperthyroidism and adverse reactions: a Danish multicenter study

PURPOSE: In this prospective multicenter study with patients newly diagnosed with Graves’ hyperthyroidism (GH), we studied the timing and characteristics of adverse drug reactions in patients treated with anti-thyroid drugs (ATD) for up to 48 months. METHODS: Patients with GH were treated with ATD until remission and hereafter with a low-dose regime to keep the patients in remission. The patients were followed with blood samples and recording of adverse events approximately every second month for the first 2 years and every third month for the following 2 years. RESULTS: We included 208 patients and the patients were treated for a median of 22 (range: 0.5–49) months. Ten percent of the patients experienced adverse drug reactions and 75% of the cases occurred during the first 6 months. After 24 months, the methimazole dose was lowered to 5 mg/day, and after this time point, no further adverse drug reactions were recorded. Skin reactions were the most prominent reaction, comprising 68% of the registered reactions, and no hepatic and bonemarrow affection was recorded. CONCLUSION: With this study, we report the frequency, timing of occurrence, and characteristics of adverse drug reactions when treating GH with the ATD drug methimazole for up to 48 months. Long-term low-dose methimazole treatment can be a cost-effective and straightforward treatment option if adverse drug reactions such as severe hepatic and bone marrow affection are kept in mind

Rejuvenation of the term Sarcopenia

It is our viewpoint that the recent consensus definitions of sarcopenia are dysfunctional for clinical and experimental practice as well as in theory. In 1989, the term sarcopenia was introduced to describe the phenomenon of age-related loss of lean body mass (10). Since 2010, six consensus definitions have been presented, and in 2016, it was assigned its own ICD-10 code (1, 3, 5, 6, 8, 9, 11). A comparison of the original definition with the new consensus definitions clarifies how the term sarcopenia no longer describes the phenomenon it originally addressed. Rather, the term is now caught in tautological association, which causes confusion and hinders rather than helps understanding of this condition

Estimating strategic models of international treaty formation

This article develops an empirical framework for analysing the timing of international treaties. Atreaty is modelled as a dynamic game among governments that decide on participation in every period.The net benefit of treaty membership increases over time. Spillovers among members and non-membersaccelerate or delay treaty formation by transforming participation into a strategic complement or substitute,respectively. The predictions of the model inform the estimation of the structural parameters, based on across section of treaty ratification dates.With this approach, I estimate the sign and magnitude of strategicinteraction in the ratification of the Montreal Protocol, in the formation of Europe's preferential tradeagreements, and in the growth of Germany's network of bilateral investment treaties. Through a seriesof counterfactual experiments, I explore different mechanisms that give rise to strategic interaction in theformation of these treaties