Chromoelectric fields and quarkonium-hadron interactions at high energies

We develop a simple model to study the heavy quarkonium-hadron cross section in the high energy limit. The hadron is represented by an external electric color field (capacitor) and the heavy quarkonium is represented by a small color dipole. Using high energy approximations we compute the relevant cross sections, which are then compared with results obtained with other methods. Our calculations are presented in a pedagogical way accessible to undergraduate students.Comment: To appear in Physical Review C, 24 pages, 10 eps figure

Uma adapta??o da Cifra de Hill para estudo de matrizes.

Programa de P?s-Gradua??o em Matem?tica em Rede Nacional. Departamento de Matem?tica, Instituto de Ci?ncias Exatas e Biol?gicas, Universidade Federal de Ouro Preto.Neste trabalho ser?o apresentados alguns dos principais resultados matem?ticos a respeito de Aritm?tica Modular, dando ?nfase ?s rela??es de equival?ncia e classes residuais. ? feito tamb?m um estudo sobre matrizes e suas propriedades operacionais; a fun??o determinante ? constru?da e apresentada como instrumento para o c?lculo de matrizes inversas. Tais temas s?o abordados com o intuito de fundamentar os processos matem?ticos aplicados para funcionamento da Cifra de Hill. Essa cifra ? um dos m?todos de criptografia apresentados neste texto e ao qual daremos destaque. Para finalizar, foi desenvolvida uma atividade voltada para turmas do Ensino M?dio e baseada na Cifra de Hill, cujo principal objetivo ? despertar o interesse dos alunos para o estudo de matrizes.In this paper, some of the main mathematical results will be presented about Modular Arithmetic, emphasizing the relations of equivalence and residue classes. Besides, a study on matrices and their operational properties; the determinant function is constructed and presented as an instrument for the calculation of inverse matrices. These themes are approached in order to base the mathematical processes applied to the operation of the Hill Cipher. This cipher is one of the cryptographic methods presented in this text and we will highlight it. To conclude, an activity was developed, focused on high school classes and based on Hill Cipher, which main objective is to arouse students? interest in studying matrices

Uma adapta??o da Cifra de Hill para estudo de matrizes.

Neste artigo ser?o apresentados alguns dos principais resultados matem?ticos a respeito de Aritm?tica Modular, dando ?nfase ?s rela??es de equival?ncia e classes residuais, al?m de alguns fatos sobre matrizes em Zp. Tais temas s?o abordados com o intuito de fundamentar os processos matem?ticos aplicados para funcionamento da Cifra de Hill, que ? um modelo de criptografia utilizado como inspira??o para o desenvolvimento de uma atividade voltada para turmas de Ensino M?dio

Entanglement study of the 1D Ising model with Added Dzyaloshinsky-Moriya interaction

We have studied occurrence of quantum phase transition in the one-dimensional spin-1/2 Ising model with added Dzyaloshinsky-Moriya (DM) interaction from bi- partite and multi-partite entanglement point of view. Using exact numerical solutions, we are able to study such systems up to 24 qubits. The minimum of the entanglement ratio R $\equiv$ \tau 2/\tau 1 < 1, as a novel estimator of QPT, has been used to detect QPT and our calculations have shown that its minimum took place at the critical point. We have also shown both the global-entanglement (GE) and multipartite entanglement (ME) are maximal at the critical point for the Ising chain with added DM interaction. Using matrix product state approach, we have calculated the tangle and concurrence of the model and it is able to capture and confirm our numerical experiment result. Lack of inversion symmetry in the presence of DM interaction stimulated us to study entanglement of three qubits in symmetric and antisymmetric way which brings some surprising results.Comment: 18 pages, 9 figures, submitte

Impact of extreme weather events frequency and intensity in shaping phytoplankton communities

Lake habitats and communities can often be correlated with general morphometric and geographic characteristics such as depth, latitude, altitude, or watershed area. Further, communities are typically correlated with average environmental conditions such as seasonal temperature and nutrient levels. The frequency and intensity of extreme weather events (rain and wind) are typically not encompassed by average environmental descriptors, yet, can modify the physical habitats of lakes, significantly influencing phytoplankton growth and survival. We tested the hypothesis that lakes with a higher frequency and intensity of extreme weather events have a functionally different phytoplankton assemblage from lakes with a lower frequency of extreme weather events. We compiled long-term (mean = 20±13 years, range 0.6-44 years) phytoplankton datasets for 22 lakes across a wide gradient of altitude, latitude, depth, and trophic state. We classified the phytoplankton genera into morpho-functional groups and C-S-R strategists, and compared among lake phytoplankton assemblages’ characteristics across the gradient of wind and rain conditions experienced by the lakes. We discuss how the frequency of extreme weather events can affect phytoplankton functional groups, the dominance of differing life history strategies and ultimately community structure. The frequency and intensity of extreme events is expected to increase with climate change, with the potential to drive shifts in phytoplankton composition

A global dataset on weather, lake physics, and phytoplankton dynamics

We compiled data from over 30 lakes across the globe to address how storms influence thermal structure and phytoplankton community dynamics mediated by lake conditions and functional traits. In addition to (generally) fortnightly phytoplankton samples (mean ± SD temporal coverage across all lakes = 20 ± 13 years), the dataset includes limnological variables from standard long-term monitoring programs (24 ± 15 years coverage), daily weather observations (16 ± 10 years coverage) and, when available, high-frequency lake water temperature and water chemistry profiles (12 ± 7 years coverage). All data have been standardized to similar formats and include complete metadata. We used the dataset to develop an R-package (“algaeClassify”), which assigns phytoplankton genus/species information to multiple functional trait groups, and here we provide a summary of ongoing research using the dataset to investigate: 1) the influence of storm events on seasonal phytoplankton succession, 2) the impact of storms on lake thermal structure, and 3) whether lake phytoplankton communities are shaped by long-term patterns in disturbance frequency and intensity. We give an overview on how to access these data, and we further highlight the opportunities the dataset provides for asking both basic and applied questions in limnology, ecology, climate change, and lake management

Decision Making with Asymmetric Information

Every day individuals make numerous choices. What is important for making the right choice is that individuals have good information about the consequences of the different alternatives. However, investigating the full consequences of the different alternatives is complicated and costly. Consequently, individuals sometimes do not possess all relevant information to take a decision. This thesis discusses models in which an agent decides whether or not to perform a task on behalf of the principal. A key element in the models we consider is incomplete and asymmetric information. Broadly, the thesis can be split up into two parts. The first part of the thesis deals with models in which the principal is better informed than the agent. The agent has to decide whether or not to perform a task, but lacks information about his ability. We analyze how the agent makes a self-assessment of his ability, based on appraisals of others (the principal) and experience. Based on this self-assessment the agent takes a decision. The second part of the thesis deals with models in which the agent is better informed than the principal. On behalf of the principal the agent takes a decision about a project. Sometimes agents do not act in the interest of the principal. We analyze how the principal can use retention contracts to discipline the agent. In the remainder of the Introduction we discuss the two parts of the thesis and we provide an overview of the chapters of this thesis

Selection of common bean families for resistance to anthracnose, grain yield and carioca grain type

Na obten??o de cultivares de feij?o com resist?ncia ? antracnose, outros atributos agron?micos tamb?m devem ser considerados para atender a prefer?ncia do consumidor e do produtor. Neste trabalho, objetivou-se identificar fam?lias de feij?o que re?nam, al?m da resist?ncia ? antracnose, alta produtividade, gr?os tipo Carioca e porte ereto. Foram cruzados os genitores CNFC 10706, B1 portador do alelo de resist?ncia ? antracnose Co-4 e H147 portador do alelo de resist?ncia Co-5. Os tr?s possuem gr?os semelhantes ao Carioca. Inicialmente foram avaliadas 224 fam?lias F2:3, derivadas dos tr?s cruzamentos, mais a cultivar Talism? como testemunha, no inverno/primavera de 2004, em Lavras, com base no tipo de gr?o. Foram selecionadas 99 fam?lias F2:4 e avaliadas com a testemunha Talism?, na seca de 2005 em Lavras e Lambari. Essas 99 fam?lias foram tamb?m inoculadas com as ra?as 593 e 337 de C. lindemuthianum, para auxiliar na sele??o daquelas portadoras dos alelos de resist?ncia Co-4 e Co-5. As 35 fam?lias F2:5 remanescentes, foram avaliadas no inverno/primavera de 2005, em Ijaci, MG. Em todos os experimentos foi utilizado, o delineamento l?tice quadrado. As 35 fam?lias foram novamente inoculadas com as ra?as 65 e 321. Por meio das inocula??es e tamb?m com o uso de um marcador molecular SCAR ligado ao alelo Co-4, foi poss?vel identificar a constitui??o gen?tica da maioria das 35 fam?lias quanto ? rea??o antracnose e selecionar quatro que re?nem, simultaneamente, tipo de gr?os semelhante ao Carioca, porte ereto e boa produtividade, al?m de serem portadoras dos alelos Co-4 e Co-5 de resist?ncia ? antracnose.Funda??o de Amparo ? Pesquisa do Estado de Minas Gerais (FAPEMIG)Empresa de Pesquisa Agropecu?ria de Minas Gerais (EPAMIG)Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq)Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES)In the common bean breeding, besides anthracnose resistance other agronomical traits need to be considered for achieving the producer and consumer requirements. So the aims of this research were to select common bean families resistant to anthracnose, high grain yield, Carioca grain type and upright plant type. The lines CNFC 10706, B1 and H147 were crossed. All of them have Carioca grain type. The B1 line is resistant to anthracnose due to the Co-4 allele, and the H147 due to the Co-5 allele. From the CNFC 10706 x H147, CNFC 10706 x B1 and H147x B1, 224 F2:3 families plus the check Talism? were evaluated in the winter/spring of 2004, in Lavras county, based on grain type. Ninety nine families were selected and evaluated, plus the check, in the seca of 2005 at Lavras and Lambari county. The families were also inoculated with the 337 and 593 races of C. lindemunthianum for selecting those with the Co-4 and Co-5 resistant alleles. The 35 selected families (F2:5) were evaluated in the winter/spring of 2005, in Ijaci county. The square lattice design was used in all experiments. Those 35 families were also inoculated with the 65 and 321 races of C. lindemunthianum. Through the inoculations and the Co-4 SCAR marker the genetic constitutions of most of the 35 families were identified. Four families were selected with Carioca grain type, upright plant type, high grain yield and besides bearing the Co-4 and Co-5 alleles for anthracnose resistance

Incubation of ovine scrapie with environmental matrix results in biological and biochemical changes of PrPSc over time

Ovine scrapie can be transmitted via environmental reservoirs. A pool of ovine scrapie isolates were incubated on soil for one day or thirteen months and eluted prion was used to challenge tg338 mice transgenic for ovine PrP. After one-day incubation on soil, two PrPSc phenotypes were present: G338 or Apl338ii. Thirteen months later some divergent PrPSc phenotypes were seen: a mixture of Apl338ii with either G338 or P338, and a completely novel PrPSc deposition, designated Cag338. The data show that prolonged ageing of scrapie prions within an environmental matrix may result in changes in the dominant PrPSc biological/biochemical properties