Observation of the antimatter helium-4 nucleus

High-energy nuclear collisions create an energy density similar to that of the Universe microseconds after the Big Bang(1); in both cases, matter and antimatter are formed with comparable abundance. However, the relatively short-lived expansion in nuclear collisions allows antimatter to decouple quickly from matter, and avoid annihilation. Thus, a high-energy accelerator of heavy nuclei provides an efficient means of producing and studying antimatter. The antimatter helium-4 nucleus ((4)(He) over bar), also known as the anti-alpha ((alpha) over bar), consists of two antiprotons and two antineutrons (baryon number B = -4). It has not been observed previously, although the alpha-particle was identified a century ago by Rutherford and is present in cosmic radiation at the ten per cent level(2). Antimatter nuclei with B -1 have been observed only as rare products of interactions at particle accelerators, where the rate of antinucleus production in high-energy collisions decreases by a factor of about 1,000 with each additional antinucleon(3-5). Here we report the observation of (4)<(He) over bar, the heaviest observed antinucleus to date. In total, 18 (4)(He) over bar counts were detected at the STAR experiment at the Relativistic Heavy Ion Collider (RHIC; ref. 6) in 10(9) recorded gold-on-gold (Au+Au) collisions at centre-of-mass energies of 200 GeV and 62 GeV per nucleon-nucleon pair. The yield is consistent with expectations from thermodynamic(7) and coalescent nucleosynthesis(8) models, providing an indication of the production rate of even heavier antimatter nuclei and a benchmark for possible future observations of (4)(He) over bar in cosmic radiation.

Energy and system size dependence of phi meson production in Cu plus Cu and Au plus Au collisions

We study the beam-energy and system-size dependence of phi meson production (using the hadronic decay mode phi -> K(+) K(-)) by comparing the new results from Cu + Cu collisions and previously reported Au + Au collisions at root s(NN) = 62.4 and 200 GeV measured in the STAR experiment at RHIC. Data presented in this Letter are from mid-rapidity (vertical bar y vertical bar < 0.5) for 0.4 < p(T) < 5 GeV/c. At a given beam energy, the transverse momentum distributions for phi mesons are observed to be similar in yield and shape for Cu + Cu and Au + Au colliding systems with similar average numbers of participating nucleons. The phi meson yields in nucleus-nucleus collisions, normalized by the average number of participating nucleons, are found to be enhanced relative to those from p + p collisions. The enhancement for phi mesons lies between strange hadrons having net strangeness = 1 (K(-) and <(A)over bar>) and net strangeness = 2 (Xi). The enhancement for phi mesons is observed to be higher at root s(NN) = 200 GeV compared to 62.4 GeV. These observations for the produced phi(s (s) over bar) mesons clearly suggest that, at these collision energies, the source of enhancement of strange hadrons is related to the formation of a dense partonic medium in high energy nucleus-nucleus collisions and cannot be alone due to canonical suppression of their production in smaller systems. (C) 2009 Elsevier B.V. All rights reserved.

Förklaringar till Förintelsen? : En historiedidaktisk studie som undersöker de olika förklaringar till Förintelsen som man kan eventuellt kan finna i ...om detta må ni berätta...

Studien behandlar, den av myndigheten Forum för levande historia utgivna boken …om detta må ni berätta…, av Stéphane Bruchfeld och Paul A. Levine. I studien analyseras olika förklaringar till Förintelsen, som mer explicit eller implicit kan skönjas i texten. Det hela relateras till vad några andra författare och förintelseforskare, beskriver, och kommit till för slutsatser angående de olika förklaringarna dessa representerar, i den av mig utvalda litteraturen. Dessa författare är Zygmunt Bauman och hans bok Auschwitz och det moderna samhället (1989). Yehuda Bauer i boken rethinking the holocaust (2001), Harald Welzer, och hans bok Gärningsmän (2007), slutligen Saul Friedländer och hans bokverk, Förföljelsens år 1933-1939, Utrotningens år 1939-1945. Analysens verktyg består av en indelning i sju, olika förklaringsmodeller, som förekommer och som dessa författare också, representerar eller lyfter fram. Resultatet är slutligen att jag fann den ideologiska förklaringsmodellen framträdande i boken …om detta må ni berätta…, men också beskrivningen av en antisemitism, med rötter långt bak i tiden, är framträdande i denna text. Studien utvisar också att det finns inslag även från andra förklaringsmodeller.

Rosenthal, Bob, interviewed by Becky Muller on January 17, 2009: Audio

Some of the themes discussed are: • Civic engagement (2) • The Levine family (2) • High school—private (3) • Colby (4) • Colby—student interaction with Waterville Jews (5) • Dating (6, 7, 18-20) • Life in Waterville (8, 10) • Life in Waterville—movies (12-13) • Colby—Greek life (9) • Colby—administration (9-10) • Occupation—real estate development (10-12, 13, 17) • Camp—Arcadia (13-14) • Military service (16) • Civic engagement (22) • Jewish education (23) • Holidays (23-24)

Rosenthal, Bob, interviewed by Becky Muller on January 17, 2009: Audio Part Two

Some of the themes discussed are: • Civic engagement (2) • The Levine family (2) • High school—private (3) • Colby (4) • Colby—student interaction with Waterville Jews (5) • Dating (6, 7, 18-20) • Life in Waterville (8, 10) • Life in Waterville—movies (12-13) • Colby—Greek life (9) • Colby—administration (9-10) • Occupation—real estate development (10-12, 13, 17) • Camp—Arcadia (13-14) • Military service (16) • Civic engagement (22) • Jewish education (23) • Holidays (23-24)

Rosenthal, Bob, interviewed by Becky Muller on January 17, 2009: Transcript

Some of the themes discussed are: • Civic engagement (2) • The Levine family (2) • High school—private (3) • Colby (4) • Colby—student interaction with Waterville Jews (5) • Dating (6, 7, 18-20) • Life in Waterville (8, 10) • Life in Waterville—movies (12-13) • Colby—Greek life (9) • Colby—administration (9-10) • Occupation—real estate development (10-12, 13, 17) • Camp—Arcadia (13-14) • Military service (16) • Civic engagement (22) • Jewish education (23) • Holidays (23-24)

Big House Scrapbook

This scrapbook contains photographs and family memories of the big Levine family house on Ticonic Street, of the Levine family "camp," of going to temple, and of various members of the family.

Levines and Colby Scrapbook

Includes covers and articles from the Colby alumni magazine and from the Echo, correspondence, donor lists for the Mayflower Associates, and photographs.

Collateral, default penalties and almost finite-time solvency

We argue that it is possible to adapt the approach of imposing restrictions on available plans through finitely effective debt constraints, introduced by Levine and Zame (1996), to encompass models with default and collateral. Along this line, we introduce in the setting of Araujo, Páscoa and Torres-Martínez (2002) and Páscoa and Seghir (2008) the concept of almost finite-time solvency. We show that the conditions imposed in these two papers to rule out Ponzi schemes implicitly restrict actions to be almost finite-time solvent. We define the notion of equilibrium with almost finite-time solvency and look on sufficient conditions for its existence. Assuming a mild assumption on default penalties, namely that agents are myopic with respect to default penalties, we prove that existence is guaranteed (and Ponzi schemes are ruled out) when actions are restricted to be almost finite-time solvent. The proof is very simple and intuitive. In particular, the main existence results in Araujo et al. (2002) and Páscoa and Seghir (2008) are simple corollaries of our existence result.

Improvements and alternatives to intellectual property: a survey

Uma parcela importante do crescimento econômico é devida a inovações. Esta dissertação revisa a literatura recente em propriedade intelectual. Esta revisão discute os seguintes artigos: Kremer (1998), Boldrin e Levine (2001), Kremer (2001), Shavell e Ypersele (2001), Lerner (2002) e DiMasi, Hansen e Grabowski (2003). Estes contém tanto artigos empíricos quanto teóricos. Na primeira categoria está um artigo sobre efeitos na inovação de mudanças na força das patentes e outro sobre custo de desenvolver novos medicamentos. Os estudos teóricos propõem melhorias e alternativas ao sistema de patentes, por exemplo, recompensas opcionais, compras de patentes, eliminação de patentes em alguns setores e compromisso de compra prévio.

Endogenous debt constraints in collateralized economies with default penalties

In infinite horizon financial markets economies, competitive equilibria fail to exist if one does not impose restrictions on agents' trades that rule out Ponzi schemes. When there is limited commitment and collateral repossession is the unique default punishment, Araujo, Páscoa and Torres-Martínez (2002) proved that Ponzi schemes are ruled out without imposing any exogenous/endogenous debt constraints on agents' trades. Recently Páscoa and Seghir (2009) have shown that this positive result is not robust to the presence of additional default punishments. They provide several examples showing that, in the absence of debt constraints, harsh default penalties may induce agents to run Ponzi schemes that jeopardize equilibrium existence. The objective of this paper is to close a theoretical gap in the literature by identifying endogenous borrowing constraints that rule out Ponzi schemes and ensure existence of equilibria in a model with limited commitment and (possible) default. We appropriately modify the definition of finitely effective debt constraints, introduced by Levine and Zame (1996) (see also Levine and Zame (2002)), to encompass models with limited commitment, default penalties and collateral. Along this line, we introduce in the setting of Araujo, Páscoa and Torres-Martínez (2002), Kubler and Schmedders (2003) and Páscoa and Seghir (2009) the concept of actions with finite equivalent payoffs. We show that, independently of the level of default penalties, restricting plans to have finite equivalent payoffs rules out Ponzi schemes and guarantees the existence of an equilibrium that is compatible with the minimal ability to borrow and lend that we expect in our model. An interesting feature of our debt constraints is that they give rise to budget sets that coincide with the standard budget sets of economies having a collateral structure but no penalties (as defined in Araujo, Páscoa and Torres-Martínez (2002)). This illustrates the hidden relation between finitely effective debt constraints and collateral requirements.

Modelos de equilíbrio geral dinâmico com custo de default

Neste trabalho fazemos um resumo de alguns artigos que tratam de equilíbrio geral dinâmico com custos de default. Focamos no estudo dos modelos de Kehoe e Levine (1993) e de Alvarez e Jermann (2000). Também descrevemos algumas adaptações do modelo de Alvarez e Jermann, como os trabalhos de Hellwig e Lorenzoni (2009) e de Azariadis e Kaas (2008), e comparamos os resultados desses modelos com os de Huggett (1993), no qual os mercados são exogenamente incompletos. Finalmente, expomos uma falha no algoritmo computacional sugerido por Krueger e Perry (2010) para se computar os equilíbrios estacionários de economias como as de Alvarez e Jermann (2000).

Asset pricing when risk sharing is limited by default: a theoretical framework

We study the asset pricing implications of an endowment economy when agents can default on contracts that would leave them otherwise worse off. We specialize and extend the environment studied by Kocherlakota (1995) and Kehoe and Levine (1993) to make it comparable to standard studies of asset pricillg. We completely charactize efficient allocations for several special cases. We illtroduce a competitive equilibrium with complete markets alld with elldogellous solvency constraints. These solvellcy constraints are such as to prevent default -at the cost of reduced risk sharing. We show a version of the classical welfare theorems for this equilibrium definition. We characterize the pricing kernel, alld compare it with the one for economies without participation constraints : interest rates are lower and risk premia can be bigger depending on the covariance of the idiosyncratic and aggregate shocks. Quantitative examples show that for reasonable parameter values the relevant marginal rates of substitution fali within the Hansen-Jagannathan bounds.

Contribution to the study of diarrhea etiology in neonate dairy calves in São Paulo state, Brazil

Amostras fecais de 203 bezerros com diarréia, idade inferior a 30 dias, de ambos os sexos e de diferentes propriedades do Estado de São Paulo foram examinadas num período de dois anos. Cultivos para pesquisa bacteriana foram feitos em agar acrescido de 10% de sangue bovino e agar Levine. As placas foram incubadas por até 96 horas, em condições aeróbias, a 37°C, com observação dos aspectos de colônia e estudos morfológicos, bioquímicos e realização de outros testes, quando pertinentes. O teste de ELISA foi aplicado para pesquisa de Rotavirus. Cryptosporidium spp. também foi pesquisado e identificado. Resultados revelaram envolvimento de vários patógenos de forma isolada, assim como associados. Rotavirus foi encontrado em 51 (25,1%) das amostras, sendo em 58,8% só, em 41.7% associado a outros microrganismos. Cryptosporydium spp foi isolado em 43 (21.3%) das amostras, sendo só em 65,1% delas e associado a outros enteropatógenos em 34,9%. No exame parasitológico foram encontrados ovos de estrongilídeos em 5 (2,5%) das amostras, não excedendo mais de dois ovos por campo examinado. Ao exame microbiológico, um ou mais microrganismos foram isolados. Escherichia coli foi encontrada em 100% das amostras. As pesquisas de toxina termoestável e do antígeno de aderência K99 realizada nas 73 amostras de E.coli foram negativas, e o grupo sorológico das mesmas foi determinado, sendo 34,2%, 17,8% e 47,9% das amostras pertencentes aos sorogrupos O8, O11 e O101, respectivamente. Salmonella Dublin e Salmonella typhimurium foram isoladas em 5,4% e 6,1% das amostras examinadas, respectivamente.