1,612 research outputs found

    Quantum Mechanics on Manifolds Embedded in Euclidean Space

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    Quantum particles confined to surfaces in higher dimensional spaces are acted upon by forces that exist only as a result of the surface geometry and the quantum mechanical nature of the system. The dynamics are particularly rich when confinement is implemented by forces that act normal to the surface. We review this confining potential formalism applied to the confinement of a particle to an arbitrary manifold embedded in a higher dimensional Euclidean space. We devote special attention to the geometrically induced gauge potential that appears in the effective Hamiltonian for motion on the surface. We emphasize that the gauge potential is only present when the space of states describing the degrees of freedom normal to the surface is degenerate. We also distinguish between the effects of the intrinsic and extrinsic geometry on the effective Hamiltonian and provide simple expressions for the induced scalar potential. We discuss examples including the case of a 3-dimensional manifold embedded in a 5-dimensional Euclidean space.Comment: 12 pages, LaTe

    Oriented Tailoring of Plastic Antibodies for Prostate Specific Antigen and Application of the Imprinted Material as Ionophore in Potentiometric Detection

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    Poster, presented at Nanobio Europe, Varese, Italy, 18 - 20 June, 2012.Prostate Specific Antigen (PSA) is the biomarker of choice for screening prostate cancer throughout the population, with PSA values above 10 ng/mL pointing out a high probability of associated cancer1. According to the most recent World Health Organization (WHO) data, prostate cancer is the commonest form of cancer in men in Europe2. Early detection of prostate cancer is thus very important and is currently made by screening PSA in men over 45 years old, combined with other alterations in serum and urine parameters. PSA is a glycoprotein with a molecular mass of approximately 32 kDa consisting of one polypeptide chain, which is produced by the secretory epithelium of human prostate. Currently, the standard methods available for PSA screening are immunoassays like Enzyme-Linked Immunoabsorbent Assay (ELISA). These methods are highly sensitive and specific for the detection of PSA, but they require expensive laboratory facilities and high qualify personal resources. Other highly sensitive and specific methods for the detection of PSA have also become available and are in its majority immunobiosensors1,3-5, relying on antibodies. Less expensive methods producing quicker responses are thus needed, which may be achieved by synthesizing artificial antibodies by means of molecular imprinting techniques. These should also be coupled to simple and low cost devices, such as those of the potentiometric kind, one approach that has been proven successful6. Potentiometric sensors offer the advantage of selectivity and portability for use in point-of-care and have been widely recognized as potential analytical tools in this field. The inherent method is simple, precise, accurate and inexpensive regarding reagent consumption and equipment involved. Thus, this work proposes a new plastic antibody for PSA, designed over the surface of graphene layers extracted from graphite. Charged monomers were used to enable an oriented tailoring of the PSA rebinding sites. Uncharged monomers were used as control. These materials were used as ionophores in conventional solid-contact graphite electrodes. The obtained results showed that the imprinted materials displayed a selective response to PSA. The electrodes with charged monomers showed a more stable and sensitive response, with an average slope of -44.2 mV/decade and a detection limit of 5.8X10-11 mol/L (2 ng/mL). The corresponding non-imprinted sensors showed smaller sensitivity, with average slopes of -24.8 mV/decade. The best sensors were successfully applied to the analysis of serum samples, with percentage recoveries of 106.5% and relatives errors of 6.5%

    Repercussions of growth path on carcass characteristics, meat colour and shear force in Alentejana bulls

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    The aim of this study was to evaluate the carcass and meat characteristics of eight muscles from bulls with distinct growth paths. A total of 40 Alentejana male calves were allocated to two distinct feeding regimes. In the continuous growth (CG) system, the animals were fed concentrates plus hay and were slaughtered at 18 months of age. On the other hand, in the discontinuous growth (DG) system, the animals were fed hay until 15 months of age; the cattle were then fed the same diet provided to the CG group from 15 to 24 months of age. The DG reduced hot carcass weight, fatness and dressing %, but the proportions of fat, bone and muscle tissues in the leg were not affected. In contrast, there was a positive impact of compensatory growth on supraspinatus, triceps brachii, semitendinosus, biceps femoris muscle tenderness, overcoming the negative effects of age at slaughter. The reasons for such improvement in meat tenderness were not related to intra-muscular fat content or myofibrillar protein degradation values. An association between tenderness and muscle collagen properties was not established. The results indicate that the compensatory growth has a muscle-dependent effect

    New Approaches to Preparation of SnO2-Based Varistors — Chemical Synthesis, Dopants, and Microwave Sintering

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    Tin oxides have applications such as sensors, solar cells, transistors, and varistors, which are being studied to replace ZnO varistors due to similar electrical properties, simpler microstructure, no formation of secondary phases, and lower concentration of agent modifiers to promote the varistor characteristics and densification. Varistors are ceramic with a high concentration of structural and electronics defects. The type and the amount of defects are related with agent modifiers and processing steps employed. The study in materials processing aims to improve the ceramics properties. Chemical synthesis ensures the homogeneous distribution of dopants used to promote electrical and structural properties. Microwave sintering appears as processing to optimize time and sintering temperature. Varistor application is linked to its breakdown voltage, which should be larger than the operating voltage. In an operating range of 1 kV to 1 MV, the varistors are used in electricity transmission networks. In a range of 24–1000 V, the application occurs in electronics and appliances and in a range smaller than 24 V, as protective of automotive electronics and computers. This chapter aims to provide information on new processing steps for the production of SnO2 varistors and to show the possibility to get electrical properties with non-ohmic characteristic for technological applications

    Comparison of ibuprofen release from minitablets and capsules containing ibuprofen: β-Cyclodextrin complex

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    NOTICE: this is the author’s version of a work that was accepted for publication in European Journal of Pharmaceutics and Biopharmaceutics. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Eur J Pharm Biopharm. 2011 May;78(1):58-66. Epub 2010 Dec 30.Mixtures containing ibuprofen (IB) complexed with b-cyclodextrin (bCD) obtained by two complexation methods [suspension/solution (with water removed by air stream, spray- and freeze-drying) and kneading technique] were processed into pharmaceutical dosage forms (minitablets and capsules). Powders (IB, bCD and IBbCD) were characterized for moisture content, densities (true and bulk), angle of repose and Carr’s index, X-ray and NMR. From physical mixtures and IBbCD complexes without other excipients were prepared 2.5-mm-diameter minitablets and capsules. Minitablets were characterized for the energy of compaction, tensile strength, friability, density and IB release (at pH 1.0 and 7.2), whereby capsules were characterized for IB release. The results from the release of IB were analyzed using different parameters, namely, the similarity factor (f2), the dissolution efficiency (DE) and the amounts released at a certain time (30, 60 and 180 min) and compared statistically (a = 0.05). The release of IB from the minitablets showed no dependency on the amount of water used in the formation of the complexes. Differences were due to the compaction force used or the presence of a shell for the capsules. The differences observed were mostly due to the characteristics of the particles (dependent on the method considered on the formation of the complexes) and neither to the dosage form nor to the complex of the IB

    Expectativa De Enfermeiros Brasileiros Acerca Do Acolhimento Realizado Na Atenção Primária Em Saúde

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    Objective: To know the expectations of Brazilians nurses in relation to the reception held for them at the Primary Health Care. Method: This is a qualitative study based on the social phenomenology by Alfred Schutz. Results: The nurses report that the host is something far from their reality, dependent on policy, management, population and physical structure of the workplace. Conclusion: The findings of this study showed that the reality of care performed by nurses in primary health care is characterized by calls for the evaluation of acute complaints, and that the solution to the host be ideal, providing changes in the relationship between him and the user they require far capabilities of its reality, which was called in this study magic output. It was evident that for nurses the reorganization of the host and their work process depends only on external factors to their actions, forgetting its commitment to provide a humanized care and based on the application of its relational competence. © 2016, Universidad Nacional de Colombia. All rights reserved.18574675

    Population overlap and habitat segregation in wintering Black-tailed Godwits Limosa limosa

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    Distinct breeding populations of migratory species may overlap both spatially and temporally, but differ in patterns of habitat use. This has important implications for population monitoring and conservation. To quantify the extent to which two distinct breeding populations of a migratory shorebird, the Black-tailed Godwit Limosa limosa, overlap spatially, temporally and in their use of different habitats during winter. We use mid-winter counts between 1990 and 2001 to identify the most important sites in Iberia for Black-tailed Godwits. Monthly surveys of estuarine mudflats and rice-fields at one major site, the Tejo estuary in Portugal in 2005-2007, together with detailed tracking of colour-ringed individuals, are used to explore patterns of habitat use and segregation of the Icelandic subspecies L. l. islandica and the nominate continental subspecies L. l. limosa. In the period 1990-2001, over 66 000 Black-tailed Godwits were counted on average in Iberia during mid-winter (January), of which 80% occurred at just four sites: Tejo and Sado lower basins in Portugal, and Coto Dontildeana and Ebro Delta in Spain. Icelandic Black-tailed Godwits are present throughout the winter and forage primarily in estuarine habitats. Continental Black-tailed Godwits are present from December to March and primarily use rice-fields. Iberia supports about 30% of the Icelandic population in winter and most of the continental population during spring passage. While the Icelandic population is currently increasing, the continental population is declining rapidly. Although the estuarine habitats used by Icelandic godwits are largely protected as Natura 2000 sites, the habitat segregation means that conservation actions for the decreasing numbers of continental godwits should focus on protection of rice-fields and re-establishment of freshwater wetlands

    Critical behavior of the planar magnet model in three dimensions

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    We use a hybrid Monte Carlo algorithm in which a single-cluster update is combined with the over-relaxation and Metropolis spin re-orientation algorithm. Periodic boundary conditions were applied in all directions. We have calculated the fourth-order cumulant in finite size lattices using the single-histogram re-weighting method. Using finite-size scaling theory, we obtained the critical temperature which is very different from that of the usual XY model. At the critical temperature, we calculated the susceptibility and the magnetization on lattices of size up to 42342^3. Using finite-size scaling theory we accurately determine the critical exponents of the model and find that ν\nu=0.670(7), γ/ν\gamma/\nu=1.9696(37), and β/ν\beta/\nu=0.515(2). Thus, we conclude that the model belongs to the same universality class with the XY model, as expected.Comment: 11 pages, 5 figure

    Qualidade nutricional de plântulas de cultivares de trigo submetidas à inoculação com Azospirillum, bioestimulante e triadimenol

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    This study aimed to evaluate the nutritional quality of wheat seedlings subjected to treatments with biostimulant, triadimenol and Azospirillum brasilense. The experimental design was completely randomized, with four replications in a factorial scheme 3 x 8: three wheat cultivars and eight seed treatments. The cultivars used were CD-150, CD-116 and CD-104, and the treatments were a combination of the following: 150 g L-1 of triadimenol (TRI), 90 mg L-1 of kinetin + 50 mg L-1 of gibberellic acid + 50 mg L-1 of indolebutyric acid (KGA), and strains Ab-V5 and Ab-V6 of A. brasilense at the concentration of 2.0 x 108 viable cells mL-1, organized as follows: control, TRI, KGA, AZO, TRI+KGA, TRI+AZO, AZO+KGA and TRI+KGA+AZO. Germination (%), shoot and root dry matter, and the levels of N and K in plant shoot and root were evaluated. The results showed that: TRI, KGA and AZO do not interfere with seed germination of CD-150, CD-116 and CD-104; germination of wheat cultivar CD-104 is greater than of the cultivars CD-150 and CD-116; nutritional quality is affected by the performance of triadimenol in wheat seedlings in both shoot and root, and the isolated use of CGA increases the dry matter portion of the cultivars CD-150, CD-116 and CD-104; treatment KGA+AZO raises the nitrogen levels in the shoot and root in wheat seedlings in the early development of wheat cultivar CD-116.Objetivou-se avaliar a qualidade nutricional de plântulas de trigo submetidas aos tratamentos com bioestimulante, triadimenol e bactéria Azospirillum brasilense. O delineamento utilizado foi inteiramente casualizado, quatro repetições, esquema fatorial 3 x 8 (três cultivares de trigo e oito tratamentos de sementes). As cultivares foram CD-150, CD-116 e CD-104, e os tratamentos foram obtidos da combinação entre: 150 g L-1 de triadimenol (TRI); 90 mg L-1 de cinetina + 50 mg L-1 de ácido giberélico + 50 mg L-1 de ácido indolbutírico (CGA) e estirpes Ab-V5 e Ab-V6 de A. brasilense na concentração de 2,0 x 108 células viáveis mL-1, organizados da seguinte forma: testemunha; TRI; CGA; AZO; TRI+CGA; TRI+AZO; CGA+AZO e TRI+CGA+AZO. Foram avaliadas a germinação (%), matéria seca da parte aérea e raiz e o teor de N e K na parte aérea e raiz. Os resultados evidenciaram que: TRI, CGA e AZO não interferem na germinação das sementes da CD-150, CD-116 e CD-104; a germinação da cultivar de trigo CD-104 é maior que as cultivares CD-150 e CD-116; a qualidade nutricional é prejudicada pela atuação do triadimenol em plântulas de trigo tanto na parte aérea como na raiz, e a utilização isolada de CGA incrementa a massa de matéria seca de parte nas cultivares CD-150, CD-116 e CD-104; O tratamento CGA+AZO eleva o conteúdo de nitrogênio na parte aérea e raiz em plântulas de trigo e no desenvolvimento inicial da cultivar CD-116 de trigo
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