Algebraic treatments of the problems of the spin-1/2 particles in the one and two-dimensional geometry: a systematic study

We consider solutions of the 2x2 matrix Hamiltonians of the physical systems within the context of the su(2) and su(1,1) Lie algebra. Our technique is relatively simple when compared with the others and treats those Hamiltonians which can be treated in a unified framework of the $$ algebra. The systematic study presented here reproduces a number of earlier results in a natural way as well as leads to a novel findings. Possible generalizations of the method are also suggested.Comment: Annals of Physics (2005) to be publishe

Relativistic confinement of neutral fermions with a trigonometric tangent potential

The problem of neutral fermions subject to a pseudoscalar potential is investigated. Apart from the solutions for $E=\pm mc^{2}$, the problem is mapped into the Sturm-Liouville equation. The case of a singular trigonometric tangent potential ($\sim \mathrm{tan} \gamma x$) is exactly solved and the complete set of solutions is discussed in some detail. It is revealed that this intrinsically relativistic and true confining potential is able to localize fermions into a region of space arbitrarily small without the menace of particle-antiparticle production.Comment: 12 page

Trapping neutral fermions with kink-like potentials

The intrinsically relativistic problem of neutral fermions subject to kink--like potentials ($\sim \mathrm{tanh} \gamma x$) is investigated and the exact bound-state solutions are found. Apart from the lonely hump solutions for $E=\pm mc^{2}$, the problem is mapped into the exactly solvable Surm-Liouville problem with a modified P\"{o}schl-Teller potential. An apparent paradox concerning the uncertainty principle is solved by resorting to the concepts of effective mass and effective Compton wavelength.Comment: 13 page

Fighting Enemies and Noise: Competition of Residents and Invaders in a Stochastically Fluctuating Environment

The possible control of competitive invasion by infection of the invader and multiplicative noise is studied. The basic model is the Lotka-Volterra competition system with emergent carrying capacities. Several stationary solutions of the non-infected and infected system are identified as well as parameter ranges of bistability. The latter are used for the numerical study of invasion phenomena. The diffusivities, the infection but in particular the white and coloured multiplicative noise are the control parameters. It is shown that not only competition, possible infection and mobilities are important drivers of the invasive dynamics but also the noise and especially its color and the functional response of populations to the emergence of noise

Solution of spin-boson systems in one and two-dimensional geometry via the asymptotic iteration method

We consider solutions of the $2\times 2$ matrix Hamiltonian of physical systems within the context of the asymptotic iteration method. Our technique is based on transformation of the associated Hamiltonian in the form of the first order coupled differential equations. We construct a general matrix Hamiltonian which includes a wide class of physical models. The systematic study presented here reproduces a number of earlier results in a natural way as well as leading to new findings. Possible generalizations of the method are also suggested.Comment: 13 pages, 5 figures. Please check "http://www1.gantep.edu.tr/~ozer/" for other studies of Nuclear Physics Group at University of Gaziante

Environmental, social and economic impacts of organic, Fairtrade soybean production in Brazil:risk assessment study for Paraná state

This work assessed the environmental, social and economic impacts associated with the production of soybeans in Brazil. Standards and legislation for organic and Fairtrade production are investigated. Based on the literature review, a Risk Assessment of organic and Fairtrade soybeans from Paraná-Brazil was performed using a risk matrix. The risks were assessed based on scientific articles, newspapers, and reports to consider the view from different stakeholders such as farmers, population, and importers. Risks were classified by levels (level 1 as the lowest, and level 5 as the highest). Two matrices were produced; one from the farmers’ point of view and the other form the importers’ point of view. The analyzed negative events that produces the risks are: Social conflicts; Working conditions; Limestone extraction and use; Deforestation; Pesticide contamination; Nutrient contamination; Erosion; Weather conditions; Weed, pests, and diseases; GM contamination; Lack of inputs; Infrastructure; Price and Supply vs. Demand; and Fairtrade popularity. From the analysis, it was possible to conclude that risks, in general, are higher for farmers. However, organic and Fairtrade certifications reduce the environmental, social and even economic risks. Notwithstanding, there are risks related to market requirements, which can lead to the loss of certification. The matrices presented on this study can be utilized as starting point for risk analysis and management. Farmers, cooperatives, and importers who deal with the cultivation and trade of organic and Fairtrade soybeans from Paraná-Brazil can benefit from understanding the environmental and social risks associated with the production methods. Ultimately, this can be used in prioritization and decision making regarding risk management strategies.Tässä työssä analysoitiin soijan Brasilian tuotantoon liittyviä ympäristöllisiä, sosiaalisia ja taloudellisia vaikutuksia. Lisäksi tarkasteltiin luonnonmukaista ja reilun kaupan tuotantoa koskevia standardeja ja lainsäädäntöä. Kirjallisuuskatsauksen perusteella laadittiin riskimatriisi, jonka avulla tehtiin riskiarviointi Paraná-Brasiliassa tuotetuille luonnonmukaisille ja reilun kaupan soijapavuille. Vaikutusten suuruus ja todennäköisyys arvioitiin tieteellisten artikkeleiden, sanomalehtien ja raporttien perusteella, eri sidosryhmien, kuten maanviljelijöiden, väestöryhmien ja maahantuojien näkökulmista. Riskit luokiteltiin tasoilla (taso 1 oli alin ja taso 5 korkein). Arviointia varten tuotettiin kaksi matriisia;. toinen matriisi tuotettiin viljelijän näkökulmasta ja toinen maahantuojan näkökulmasta. Analysoitavat riskit olivat: yhteiskunnalliset ristiriidat, työolot, kalkkikiven louhinta/hankinta ja käyttö, metsäkato, torjunta-aineiden saastuminen, ravinnekuormitus, eroosio, sääolosuhteet, rikkakasvit, tuholaiset ja taudit, GM-kontaminaatio, panosten puute, infrastruktuuri, hinta ja tarjonta vs. kysyntä sekä Reilun kaupan hyväksyttävyys. Analyysistä voitiin päätellä, että riskit ovat yleisesti korkeammat viljelijöille. Tulosten perusteella havaittiin selvästi, että orgaaniset ja Reilun kaupan sertifikaatit vähensivät ympäristöllisiä, sosiaalisia ja jopa taloudellisia riskejä. Kuitenkin kyseisiin markkinoihin liittyi riskejä, jotka voivat johtaa sertifioinnin menettämiseen. Tässä tutkimuksessa esitettyjä matriiseja voidaan käyttää lähtökohtana riskianalyysille ja -hallinnalle, soijan tuotannon ja maahantuonnin arvioinnissa., Luomun ja Reilun kaupan tuotantotapojen mukaisesti tuotetun Paraná-Brasiliaisen soijan viljelijät, osuuskunnat ja maahantuojat, voivat hyötyä tuotantoon liittyvien ympäristö- ja sosiaalisten riskien ymmärtämisestä ja edelleen, voivat priorisoida tärkeimmät riskit ja päättää hallintastrategioista

Electric paralyzation and reduction of weight loss in the processing of round-cooked spiny lobsters Paralisação elétrica da lagosta e redução da perda de peso no processamento de lagosta inteira-cozida

This study proposes alternatives to the current methods of processing round-cooked lobster. The paralyzation of lobsters with direct electric shock consumes 10.526 x 10-3 kWh, which is significantly less than the 11 kWh required by the traditional thermal-shock method (based on 60 kg of lobsters). A better weight gain was obtained by immersion of paralyzed lobsters in brine before cooking. Systematic trials combining 3, 6, or 9% brine concentrations with immersion periods of 15, 30, or 45 minutes were performed in order to determine the best combinations. A mathematical model was designed to predict the weight gain of lobsters of different sizes in any combination of treatments. For small lobsters, a 45 minutes immersion in 6% brine gave the best response in terms of weight gain (4.7%) and cooking produced a weight loss of only 1.34% in relation to fresh lobster weight. For medium-sized lobsters, a 45 minutes immersion in 9% brine produced a weight gain of 2.64%, and cooking a weight gain of 1.08%. For large lobsters, a 45 minutes immersion in 6% brine produced a weight gain of 3.87%, and cooking a weight gain of 1.62%.O presente estudo propõe alternativas aos métodos convencionais de processamento da lagosta inteira-cozida. Para a paralisação de 60 kg de lagosta com aplicação de choque elétrico, foram consumidos 10,526 x 10-3 kWh, valor significativamente inferior aos 11 kWh requeridos pelo método tradicional de choque térmico. Um maior ganho de peso foi obtido pela imersão de lagostas paralisadas em salmoura antes do cozimento. Experimentos combinando as concentrações de salmoura a 3, 6 e 9% com os tempos de imersão de 15, 30 ou 45 minutos foram realizados. Um modelo matemático foi ajustado para predizer o rendimento de peso de lagostas de diferentes tamanhos para as combinações de tratamentos testadas. Para lagostas pequenas, um tempo de imersão de 45 minutos em salmoura a 6% apresentou a melhor resposta em termos de ganho de peso (4,7%) e o cozimento produziu uma perda de peso de somente 1,34% em relação ao peso da lagosta fresca. Para lagostas de tamanho médio, um tempo de imersão em salmoura a 9% produziu um ganho de peso de 2,64%, e o cozimento, um ganho de peso de 1,08%. Para lagostas grandes, uma imersão de 45 minutos em salmoura a 6% produziu um ganho de peso de 3,87%, e o cozimento, um ganho de peso de 1,62%