Alternative Size and Lifetime Measurements for High-Energy Heavy-Ion Collisions

Two-Particle correlations based on the interference of identical particles has provided the chief means for determining the shape and lifetime of sources in relativistic heavy ion collisions. Here, Strong and Coulomb induced correlations are shown to provide equivalent information.Comment: Two confusing typographical errors were correcte

Statistical and Dynamic Models of Charge Balance Functions

Charge balance functions, which identify balancing particle-antiparticle pairs on a statistical basis, have been shown to be sensitive to whether hadronization is delayed by several fm/c in relativistic heavy ion collisions. Results from two classes of models are presented here, microscopic hadronic models and thermal models. The microscopic models give results which are contrary to recently published pi+pi- balance functions from the STAR collaboration, whereas the thermal model roughly reproduce the experimental results. This suggests that charge conservation is local at breakup, which is in line with expectations for a delayed hadronization. Predictions are also presented for balance functions binned as a function of Q_inv.Comment: 12 pages 6 figure

Production of resonances in a thermal model: invariant-mass spectra and balance functions

We present a calculation of the pi+ pi- invariant-mass correlations and the pion balance functions in the single-freeze-out model. A satisfactory agreement with the data for Au+Au collisions is found.Comment: Contribution to QM 2004 (4 pages, 2 figures

The geochemical cycling of reactive chlorine through the marine troposphere

Heterogeneous reactions involving sea‐salt aerosol in the marine troposphere are the major global source for volatile inorganic chlorine. We measured reactant and product species hypothesized to be associated with these chemical transformations as a function of phase, particle size, and altitude over the North Atlantic Ocean during the summer of 1988. Concentrations of HCl were typically less than 1.0 ppbv near the sea surface and decreased with altitude and with distance from the U.S. east coast. Concentrations of Cl volatilized from aerosols were generally equivalent to the corresponding concentrations of HCl and ranged from less than detection limits to 125 nmol m−3 STP. Highest absolute and percentage losses of particulate Cl were typically associated with elevated concentrations of anthropogenic combustion products. Concentrations of product nss SO42− and N03− in coarse aerosol fractions indicate that on average only 38% of measured Cl− deficits could be accounted for by the combined effects of acid‐base desorption and reactions involving nonacidic N gases. We hypothesize a mechanism for the Cl loss initiated by reaction of O3 at sea‐salt aerosol surfaces, generating Cl2 followed by rapid photochemical conversion of Cl2 to HCl via Cl atoms (Cl˙) and eventual recapture of HCl by the aerosol. Simulations with a zero‐dimension (0‐D) photochemical model suggest that oxidation by Cl˙ may be an important tropospheric sink for dimethyl sulfide and hydrocarbons. Under low‐NOx conditions, the rapid cycling of reactive Cl would provide a catalytic loss mechanism for O3, which would possibly explain the low O3 concentrations often observed above the world\u27s oceans

Essays on information and competition in banking and service industries

This thesis investigates the relation between information and competition in two particular settings. In the first chapter, I ask which screening and lending choices banks make if their loan offers can be observed by uninformed competitors. I show that banks grant excessive credit and underinvest in screening in order to deter borrower poaching; more competition exacerbates this problem. In a dynamic setting, the model reproduces many stylized facts of lending booms. The second chapter (jointly with Doh-Shin Jeon) investigates the incentives behind commercial open source software. We find that the production of open source software by profit-maximizing firms can be understood as a form of optimal information sharing: by releasing source code, service firms create their own competition which mitigates customer concerns about hold-up problems. We show that the resulting increases in customer investment and collaboration can yield higher profits for the service firm.Aquesta tesi investiga la relació entre la informació i la competència en dues situacions. En el primer capítol, s'analitzen les opcions de cribratge i de préstecs que els bancs fan si les seves ofertes de préstecs poden ser observats pels competidors desinformats. Mostro que els bancs concedeixen préstecs excessius i inverteixen poc en el cribratge per tal de dissuadir la caça furtiva prestatari; més competència exacerba aquest problema. En un entorn dinàmic, el model reprodueix molts fets estilitzats dels auges de crèdit. El segon capítol (en col•laboració amb Doh-Shin Jeon) investiga els incentius darrere de programari de codi obert comercial. Ens trobem que la producció de programari de codi obert per les empreses pot ser entesa com una forma de compartir la informació de manera òptima: alliberant el codi font, les empreses de serveis creen la seva pròpia competència, que mitiga les preocupacions dels clients sobre problemes de captivitat. Es demostra que els augments resultants de la inversió del client i la col•laboració poden rendir més beneficis per a l'empresa de serveis

Chorioretinopathia centralis serosa (CCS): klinisch-angiographische Befunde und Risikofaktoren

Retrospektive Studie über 100 konsekutive Patienten mit Chorioretinopathia centralis serosa: Untersucht wurden die demographische Struktur, das Risikoprofil und die ophthalmoskopischen und fluoreszenzangiographischen Befunde