Essays on Search and Matching in the Labor Market

I study the matching of heterogeneous workers and firms in the labor market. In particular, I examine how firm productivity shocks and the nature of decreasing returns affect positive assortative matching: outcomes where the best, most productive workers are employed by the most productive firms and the least productive workers are assigned to the least productive firms. Chapter one studies the relationship between worker-firm sorting and firm growth both empirically and theoretically. I use U.S. Census microdata to show that faster growing firms hire more productive workers, as measured by their lagged wages. This appears to be the first time that such a pattern has been documented. I interpret the pattern as evidence of positive assortative matching: faster growing, more productive firms tend to hire more productive workers. I develop a novel, analytically tractable search model and show that it can reproduce the observed patterns if there are strong complementarities in the production function. I also discuss the relationship between my empirical results and the previous literature on assortative matching. I argue that it is important to control for observable firm characteristics, which may proxy for the nature of the labor market facing the firm. Chapter two assesses the theoretical properties of several models, some novel and some drawn from the previous literature. I focus on each model's sufficient conditions for positive assortative matching. The models in the existing literature have a variety of sufficient conditions for positive sorting, and it has not been clear why these conditions vary across models. To answer this question I develop generalizations of each model that preserve their sorting properties. By comparing the generalized models I am able to show that the differences stem from how firm size, or scale, is dealt with. This result suggests caution when developing and interpreting models of sorting, since seemingly innocuous assumptions can result in significantly different behavior

The Amsterdam Declaration on Fungal Nomenclature

The Amsterdam Declaration on Fungal Nomenclature was agreed at an international symposium convened in Amsterdam on 19–20 April 2011 under the auspices of the International Commission on the Taxonomy of Fungi (ICTF). The purpose of the symposium was to address the issue of whether or how the current system of naming pleomorphic fungi should be maintained or changed now that molecular data are routinely available. The issue is urgent as mycologists currently follow different practices, and no consensus was achieved by a Special Committee appointed in 2005 by the International Botanical Congress to advise on the problem. The Declaration recognizes the need for an orderly transitition to a single-name nomenclatural system for all fungi, and to provide mechanisms to protect names that otherwise then become endangered. That is, meaning that priority should be given to the first described name, except where that is a younger name in general use when the first author to select a name of a pleomorphic monophyletic genus is to be followed, and suggests controversial cases are referred to a body, such as the ICTF, which will report to the Committee for Fungi. If appropriate, the ICTF could be mandated to promote the implementation of the Declaration. In addition, but not forming part of the Declaration, are reports of discussions held during the symposium on the governance of the nomenclature of fungi, and the naming of fungi known only from an environmental nucleic acid sequence in particular. Possible amendments to the Draft BioCode (2011) to allow for the needs of mycologists are suggested for further consideration, and a possible example of how a fungus only known from the environment might be described is presented

Creating and curating an archive: Bury St Edmunds and its Anglo-Saxon past

This contribution explores the mechanisms by which the Benedictine foundation of Bury St Edmunds sought to legitimise and preserve their spurious pre-Conquest privileges and holdings throughout the Middle Ages. The archive is extraordinary in terms of the large number of surviving registers and cartularies which contain copies of Anglo-Saxon charters, many of which are wholly or partly in Old English. The essay charts the changing use to which these ancient documents were put in response to threats to the foundation's continued enjoyment of its liberties. The focus throughout the essay is to demonstrate how pragmatic considerations at every stage affects the development of the archive and the ways in which these linguistically challenging texts were presented, re-presented, and represented during the Abbey’s history

A study on the numerical variation in the bladders of Utricularia vulgaris.

http://deepblue.lib.umich.edu/bitstream/2027.42/52240/1/671.pdfDescription of 671.pdf : Access restricted to on-site users at the U-M Biological Station

The Relics of Witchcraft in Italy in the Work of Charles Godfrey Leland (Comments on the Origin of WICCA)

Lo studio presenta le attività del folclorista americano Charles Godfrey Leland (1824–1903) in Italia. L'obiettivo del Leland era quello di trovare e raccogliere testimonianze orali dell'antica religione degli Etruschi e dei Romani tra i contadini ed i pastori dell'alto Appennino. Le raccolte di leggende e racconti degli abitanti dell'Appennino Tosco-emiliano edite da Ch. G. Leland negli anni '90 dell'Ottocento, divennero la fonte primaria a cui fanno riferimento gli odierni rappresentanti del movimento religioso Wicca. Le attività etnografiche di Leland furono considerate relativamente controverse, tanto da non trovare eco non solo nell’Italia del tempo, ma anche nello spazio accademico americano. Il contributo non cerca di dare ai seguaci della Wicca alcuna risposta alla domanda se l'attuale Wicca possa ancora fare riferimento al lavoro di Leland o meno, ma vuole offrire uno sguardo critico alla figura del Leland ed al suo metodo di raccolta dei dati.The study presents the activities of the American folklorist Charles Godfrey Leland (1824–1903) in Italy. Leland‘s aim was to find relics of the ancient religion of the Etruscans and the ancient Romans among the peasants and shepherds living in the upper regions of Apennine, between Florence and Bologna. Collections of legends and tales of the local inhabitants of Apennine published by Ch. G. Leland in the 1890s, became the primary sources which the current representatives of the Wicca religious movement refer to. Leland‘s ethnographic activities can be described as quite controversial, and have found very little response not only in Italy at the time, but also in the American academic space. The contribution does not attempt to give Wicca followers any answer to the question if the current Wicca may still refer to Leland‘s work or not but wants to provide a critical view of his personage and his method of collecting data

The oldest fossil mushroom.

A new fossil mushroom is described and illustrated from the Lower Cretaceous Crato Formation of northeast Brazil. Gondwanagaricites magnificus gen. et sp. nov. is remarkable for its exceptional preservation as a mineralized replacement in laminated limestone, as all other fossil mushrooms are known from amber inclusions. Gondwanagaricites represents the oldest fossil mushroom to date and the first fossil mushroom from Gondwana

Scanning electron micrographs of the gills of <i>Gondwanagaricites magnificus</i> gen. et sp. nov.

<p>(<i>A</i>) Section of preserved gills (location indicated by red box on <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0178327#pone.0178327.g001" target="_blank">Fig 1B</a>). (<i>B</i>) close-up view of (<i>A</i>) showing detailed structure.</p