Orbital magnetism in axially deformed sodium clusters: From scissors mode to dia-para magnetic anisotropy

Low-energy orbital magnetic dipole excitations, known as scissors mode (SM), are studied in alkali metal clusters. Subsequent dynamic and static effects are explored. The treatment is based on a self-consistent microscopic approach using the jellium approximation for the ionic background and the Kohn-Sham mean field for the electrons. The microscopic origin of SM and its main features (structure of the mode in light and medium clusters, separation into low- and high-energy plasmons, coupling high-energy M1 scissors and E2 quadrupole plasmons, contributions of shape isomers, etc) are discussed. The scissors M1 strength acquires large values with increasing cluster size. The mode is responsible for the van Vleck paramagnetism of spin-saturated clusters. Quantum shell effects induce a fragile interplay between Langevin diamagnetism and van Vleck paramagnetism and lead to a remarkable dia-para anisotropy in magnetic susceptibility of particular light clusters. Finally, several routes for observing the SM experimentally are discussed.Comment: 21 pages, 7 figure

Orbital Magnetic Dipole Mode in Deformed Clusters: A Fully Microscopic Analysis

The orbital M1 collective mode predicted for deformed clusters in a schematic model is studied in a self-consistent random-phase-approximation approach which fully exploits the shell structure of the clusters. The microscopic mechanism of the excitation is clarified and the close correlation with E2 mode established. The study shows that the M1 strength of the mode is fragmented over a large energy interval. In spite of that, the fraction remaining at low energy, well below the overwhelming dipole plasmon resonance, is comparable to the strength predicted in the schematic model. The importance of this result in view of future experiments is stressed.Comment: 10 pages, 3 Postscript figures, uses revte

Classes of exact wavefunctions for general time-dependent Dirac Hamiltonians in 1+1 dimensions

In this work we construct two classes of exact solutions for the most general time-dependent Dirac Hamiltonian in 1+1 dimensions. Some problems regarding to some formal solutions in the literature are discussed. Finally the existence of a generalized Lewis-Riesenfeld invariant connected with such solutions is discussed

Travelers' vaccinations: experience from the Travelers' Clinic of Hospital das Clínicas, University of São Paulo School of Medicine

O perfil dos indivíduos, a situação vacinal e as vacinas recomendadas aos viajantes que procuram o serviço médico de orientação pré-viagem do Ambulatório dos Viajantes do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo foram analisados no presente estudo. Dos 445 viajantes estudados, 51% eram mulheres; a mediana de idade foi de 33,5 anos; 51% viajavam a trabalho e 39,5% por lazer. Destinos mais procurados: África (47%); Ásia (31,7%); América do Sul (21,4%). Trezentos e oitenta e cinco (86,5%) viajantes tiveram indicação de vacinação para viagem. Principais vacinas recomendadas: febre tifóide (55,7%), difteria-tétano (54,1%), hepatite A (46,1%), hepatite B (44,2%), febre amarela (24,7%). A orientação pré-viagem mostrou-se importante não só para indicar as vacinas recomendadas para a viagem, mas também como oportunidade para atualização das vacinas de rotina.TThe profile and vaccination status of travelers seeking pre-travel medical advice at the Travelers' Clinic of Hospital das Clínicas, University of São Paulo School of Medicine, and the vaccines recommended for them, were analyzed in the present study. Among the 445 travelers who were studied, 51% were women, the median age was 33.5 years, 51% were traveling on business and 39.5% were traveling for leisure purposes. The destinations most sought were Africa (47%), Asia (31.7%) and South America (21.4%). Vaccination before traveling was recommended for 385 (86.5%) of the travelers. The main vaccines recommended were against typhoid fever (55.7%), diphtheria-tetanus (54.1%), hepatitis A (46.1%), hepatitis B (44.2%) and yellow fever (24.7%). The pre-travel guidance was shown to be important not only for indicating the vaccines recommended for the trip, but also as an opportunity to update routine vaccinations

Robustness area technique developing guidelines for power system restoration

This paper proposes a novel energy based technique called the Robustness Area (RA) technique that measures power system robustness levels, as a helper for planning Power System Restorations (PSRs). The motivation is on account of the latest blackouts in Brazil, where the local Independent System Operator (ISO) encountered difficulties related to circuit disconnections during the restoration. The technique identifies vulnerable and robust buses, pointing out system areas that should be firstly reinforced during PSR, in order to enhance system stability. A Brazilian power system restoration area is used to compare the guidelines adopted by the ISO with a more suitable new plan indicated by the RA tool. Active power and reactive power load margin and standing phase angle show the method efficiency as a result of a well balanced system configuration, enhancing the restoration performance. Time domain simulations for loop closures and severe events also show the positive impact that the proposed tool brings to PSRs

Foamy polystyrene trays for fresh-meat packaging: Life-cycle inventory data collection and environmental impact assessment

Abstract: ood packaging systems are designed to perform series of functions mainly aimed at containing and protecting foods during their shelf-lives. However, to perform those functions a package causes environmental impacts that affect food supply chains and that come from its life-cycle phases. Therefore, package design should be done based upon not only the issues of cost, food shelf-life and safety, as well as practicality, but also of environ- mental sustainability. For this purpose, Life Cycle Assessment (LCA) can be applied in the packaging fi eld with the aim of highlighting environmental hotspots and improvement potentials, thus enabling more eco-friendly prod- ucts. In this context, an LCA of foamy polystyrene (PS) trays used for fresh meat packaging was performed here. The study highlighted that the highest environmental impacts come from PS-granule production and electricity consumption. In this regard, the authors underscored that there are no margins for improvement in the produc- tion of the granules and in the transport of the material inputs involved as well as of the trays to users. On the contrary, changing the energy source into a renewable one (by installing, for instance, a wind power plant) would enable a 14% damage reduction. In this way, the authors documented that alternative ways can be found for global environmental improvement of the system analysed and so for enhanced environmental sustainability of food packaging systems

Mineralização dos resíduos provenientes da secagem da pimenta-do-reino quando aplicados ao solo

The use of residues from the black pepper bean drying process as fertilizer for agricultural crops implies the need to know the dynamics of their decomposition and release of the nutrients to guide it’s management, especially regarding the best time of its application in the soil. This study aimed to evaluate the dynamics of organic carbon and nitrogen during the mineralization process of this residue. The experiment was conducted in a completely randomized design with ten treatments related to different post-disposal periods to the soil (0, 7, 13, 20, 27, 34, 48, 69, 98, 147 days). Samples were collected to quantify easily oxidized organic carbon (OCeo), organic nitrogen (ON) and the determinations of their respective mineralized fractions. The evaluation of OCeo mineralization, being more stable and less susceptible to climatic variations, was the most appropriate for estimating the mineralized fraction of the residue. The application of the residue in dystrophic Yellow Red Latosol soil during the month of August provides, after 140 days, OCeo and ON mineralized fractions around 99 and 60%, respectively, in the climatic conditions of Espirito Santo state, Brazil.A utilização de resíduos do processo de secagem de pimenta-do-reino como fertilizante de lavouras deve considerar a dinâmica de sua decomposição e liberação dos nutrientes, para orientar o seu manejo, principalmente quanto à melhor época de sua aplicação no solo. Este estudo teve como objetivo avaliar a dinâmica do carbono orgânico e do nitrogênio durante o processo de mineralização desse resíduo. O experimento foi conduzido em delineamento inteiramente casualizado com dez tratamentos, correspondentes ao tempo de pós-disposição ao solo (0, 7, 13, 20, 27, 34, 48, 69, 98, 147 dias), quando amostras foram coletadas para a determinação de carbono orgânico facilmente oxidado (OCeo), nitrogênio orgânico (ON) e suas respectivas frações mineralizadas. A avaliação da mineralização do OCeo, por ser mais estável e menos suscetível às variações climáticas, foi a mais apropriada para a estimativa da fração mineralizada do resíduo. A aplicação do resíduo em solo de Latossolo Vermelho Amarelo distrófico durante o mês de agosto proporciona, após 140 dias, frações mineralizadas OCeo e ON em torno de 99 e 60%, respectivamente, nas condições climáticas do estado do Espírito Santo, Brasil

Agricultural wastes incorporated to the substrate in the production of scarlet eggplant seedlings

The use of agricultural residues for seedlings production stands out as an effective sustainable alternative in the production of vegetables. This research aimed to evaluate the effect of increasing concentrations of wastes from the coffee beans drying process (moinha) on substrates composed of coconut fiber, eggshell and commercial substrate in the emergence and quality of scarlet eggplant seedlings. We carried out the experiment with five treatments, as the following: T0 – commercial substrate BioplantÒ; T1- 15% of moinha  (MO) + 15% of coconut fiber (FC) + 5% of eggshells (CO) + 65% of commercial substrate (SC); T2 - 30% MO + 15% FC + 5% CO+ 50% SC; T3 - 45% MO + 15% FC + 5% CO + 35% SC; and T4 - 60% MO + 15% FC + 5% CO + 20% SC. We evaluated the emergency speed index, seed emergency, seedling height, stem diameter, shoot, root and total dry mass, Dickson’s Quality Index and the electrical conductivity of the substrates. The addition of moinha concentrations above 15% promotes an increase in electrical conductivity compared to the control and negatively affects the seedlings emergency. Among all treatments, 38% of moinha promotes an increase in the number of leaves, 15% of moinha results in higher plant height, stem diameter, and the highest dry mass accumulation. The alternative substrate containing 15% MO + 15% FC + 5% CO + 65% SC promotes a better development for scarlet eggplants seedlings, being an alternative to the exclusive use of the commercial substrate

Inclusion items and financial risk assessment in systems with grazing sheep under the concentrated supplementation

xxxThe aim of this study was to evaluate the sensitivity and financial risk in two production systems of beef sheep, in grazing, with and without the use of concentrate, in Santa Teresa County - Espírito Santo State, Brazil. A cash flow spreadsheet was prepared. Through the sensitivity analysis it was shown that greater attention should be directed to the sale of finished animals and their acquisition. These, in descending order of relevance, followed by labor, in the system with no concentrate, and concentrated supplementation, in the system where it was present. Then, the Monte Carlo simulation was performed. Probabilities of 37.9 and 33.3% that the systems without and with the concentrate, respectively, were financially unfeasible were observed. Considering the alternative remuneration of 6%, there is a considerable risk for both options, perhaps because the proposed scenarios consider the need to implement all the infrastructure for the activity, in addition to the reduced size of the production module. The strategic use of concentrated supplement as a complement to pasture presents itself as an alternative that can reduce financial risk and increase income in intensive systems of production of beef sheep in grazing. The labor efficiency is an item that affects the financial efficiency of beef sheep production systems on pasture, especially in situations of weight gain of animals without the use of concentrated supplementation. The reduction of financial risk with the use of concentrated supplementation. Intensive grazing sheep production systems can be financially advantageous and the strategic use of concentrate can result in increased income and reduced financial risk associated with this type of production

Twist Mode in Spherical Alkali Metal Clusters

A remarkable orbital quadrupole magnetic resonance, so-called twist mode, is predicted in alkali metal clusters where it is represented by $I^{\pi}=2^-$ low-energy excitations of valence electrons with strong M2 transitions to the ground state. We treat the twist by both macroscopic and microscopic ways. In the latter case, the shell structure of clusters is fully exploited, which is crucial for the considered size region ($8\le N_e\le 1314$). The energy-weighted sum rule is derived for the pseudo-Hamiltonian. In medium and heavy spherical clusters the twist dominates over its spin-dipole counterpart and becomes the most strong multipole magnetic mode.Comment: 8 pages, 4 figures, to be published in Phys. Rev. Lett., v.85, n.15, 200