4,361 research outputs found
Schr\"odinger formalism for a particle constrained to a surface in
In this work it is studied the Schr\"odinger equation for a non-relativistic
particle restricted to move on a surface in a three-dimensional Minkowskian
medium , i.e., the space equipped with the
metric . After establishing the consistency of the
interpretative postulates for the new Schr\"odinger equation, namely the
conservation of probability and the hermiticity of the new Hamiltonian built
out of the Laplacian in , we investigate the confining
potential formalism in the new effective geometry. Like in the well-known
Euclidean case, it is found a geometry-induced potential acting on the dynamics
which, besides
the usual dependence on the mean () and Gaussian () curvatures of the
surface, has the remarkable feature of a dependence on the signature of the
induced metric of the surface: if the signature is ,
and if the signature is . Applications to surfaces of
revolution in are examined, and we provide examples where the
Schr\"odinger equation is exactly solvable. It is hoped that our formalism will
prove useful in the modeling of novel materials such as hyperbolic
metamaterials, which are characterized by a hyperbolic dispersion relation, in
contrast to the usual spherical (elliptic) dispersion typically found in
conventional materials.Comment: 26 pages, 1 figure; comments are welcom
Studies on Gene Expression and Developmental Competence of Bovine Embryos Produced Under Different Conditions of Heat Stress
Gene expression is required in all steps of embryonic development and therefore heat stress is known to reduce developmental competence after direct exposure of oocytes and embryos to different conditions of heat shock, by decreasing protein synthesis. Moreover, as in somatic cells, the heat stress befuddles the integration of RNA and posttranscriptional modification of RNA, the assumption was that during meiotic maturation heat shock may mutate RNA within oocytes, with the possibility of altering the surrounding cumulus cells, causing, thus, reductions in development. Heat shock proteins (HSP) are among the first proteins produced during embryonic development and are crucial to cell function. The HSP70 (HSPA14 gene) is an important part of the cell’s machinery for folding, unfolding, transport, localization of proteins and differentiation, regulation of the embryonic cell cycle and helping to protect cells from stress. Therefore, HSPA14 is an apoptotic gene induced by heat shock is associated with embryonic loss, playing an important role of control mechanism of processes involved in growth, cellular differentiation, and embryonic development. In addition the connexin proteins (e.g. Cx43), related to gap junctions, are expressed in numerous tissues including gonads, act as a mediator of heat stress effect on cells. In the present review, the effect of heat stress on bovine embryonic development in a physiologic and genetic point of view is fully discussed
Uma tipografia de base elíptica e outros cruzamentos do design com a geometria das curvas cónicas
Através de alguns exemplos práticos, pretende-se defender que o conhecimento geométrico e, em particular, o conhecimento das curvas cónicas e suas aplicações, pode potenciar o trabalho projetual dos designers, diminuir os custos de hardware e software no ensino e no trabalho profissional, diminuir a necessidade de recurso a meios sofisticados e caros, reduzir a necessidade de permanente atualização dos meios tecnológicos, e de utilização de software que implique formação especializada e, sobretudo, que necessite de longos períodos de formação. Temos em vista contribuir para o reconhecimento da importância do estudo destas curvas e das superfícies por elas geradas, em especial no ensino da Geometria em cursos de Design. De facto, a partir da sistematização do conhecimento existente em outras áreas, como, por exemplo, a arquitetura e as engenharias, pelo aprofundamento da adaptação de propriedades das cónicas e de conhecimentos de áreas, como a geometria analítica ou a projetiva para a linguagem dos traçados geométricos, e pela contribuição com a sugestão de novos traçados, pode desenvolver-se a capacidade dos designers e estudantes de design resolverem problemas, no âmbito do projeto, na representação técnica e na comunicação externa com não peritos.Through some examples, we intend to argue that the knowledge of geometry and, in particular, the knowledge of conic curves and their applications, may potentiate the project work of designers, reducing the costs of hardware and software in teaching and professional work, reducing also the need for sophisticated and expensive means, and its continuous updating, and the use of software which involves specialized training, and especially requiring long training periods. We want to contribute to the recognition of the importance of the study of these curves and surfaces generated by them, especially in the teaching of Geometry in Design courses. In fact, from the systematization of existing knowledge in other areas, such as architecture and engineering, developing the adaptation of properties of conic curves and also the knowledge of areas such as analytic or projective geometry to the geometric design and contributing by suggesting new ways to draw the curves, we can develop the ability of designers and design students to solve problems in the context of the project, and others such as technical representation and external communication with non-experts
Anomalous diffusion : a basic mechanism for the evolution of inhomogeneous systems
In this article we review classical and recent results in anomalous diffusion and provide mechanisms useful for the study of the fundamentals of certain processes, mainly in condensed matter physics, chemistry and biology. Emphasis will be given to some methods applied in the analysis and characterization of diffusive regimes through the memory function, the mixing condition (or irreversibility), and ergodicity. Those methods can be used in the study of small-scale systems, ranging in size from single-molecule to particle clusters and including among others polymers, proteins, ion channels and biological cells, whose diffusive properties have received much attention lately
Mathematical model of brain tumour with glia-neuron interactions and chemotherapy treatment
Acknowledgements This study was possible by partial financial support from the following Brazilian government agencies: Fundação Araucária, EPSRC-EP/I032606/1 and CNPq, CAPES and Science Without Borders Program Process nos. 17656125, 99999.010583/2013-00 and 245377/2012-3.Peer reviewedPreprin
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Initial Development toward Non-Invasive Drug Monitoring via Untargeted Mass Spectrometric Analysis of Human Skin.
Drug monitoring is crucial for providing accurate and effective care; however, current methods (e.g., blood draws) are inconvenient and unpleasant. We aim to develop a non-invasive method for the detection and monitoring of drugs via human skin. The initial development toward this aim required information about which drugs, taken orally, can be detected via the skin. Untargeted liquid chromatography-mass spectrometry (LC-MS) was used as it was unclear if drugs, known drug metabolites, or other transformation products were detectable. In accomplishing our aim, we analyzed samples obtained by swabbing the skin of 15 kidney transplant recipients in five locations (forehead, nasolabial area, axillary, backhand, and palm), bilaterally, on two different clinical visits. Untargeted LC-MS data were processed using molecular networking via the Global Natural Products Social Molecular Networking platform. Herein, we report the qualitative detection and location of drugs and drug metabolites. For example, escitalopram/citalopram and diphenhydramine, taken orally, were detected in forehead, nasolabial, and hand samples, whereas N-acetyl-sulfamethoxazole, a drug metabolite, was detected in axillary samples. In addition, chemicals associated with environmental exposure were also detected from the skin, which provides insight into the multifaceted chemical influences on our health. The proof-of-concept results presented support the finding that the LC-MS and data analysis methodology is currently capable of the qualitative assessment of the presence of drugs directly via human skin
Optimization of bacterial nanocellulose fermentation using lignocellulosic residues and development of novel BNC-starch composites
In papermaking industry, significant fraction of fibres that cannot be re-utilized are wasted, which raise economic and environmental concerns[1]. On the other hand, development of renewable polymeric materials became a priority for the sustainability of several industries. Bacterial nanocellulose (BNC), a biopolymer extruded by Gluconacetobacter xylinus as a 3D nanofibrillar network, provide interesting properties as high porosity, high water retention, biocompatibility, non-toxicity and biodegradability [2]. These properties have sustained promising applications in the biomedical field, papermaking, composites and foods. However, large-scale BNC production remains a challenge, due to ineffective fermentation systems and high operating costs [2-3]. Therefore, the production of BNC through lignocellulosic residues has been studied. Recycled-paper-sludge (RPS) composed of small fibres with 40% of carbohydrates were hydrolysed and used as a carbon source in culture media formulation. Then, a Response Surface Methodology (RSM) optimization with RPS was assessed in order to maximize BNC production, through static fermentation with K. hansenii ATCC 53582. Overall, the results suggest that RPS had potential to be an alternative carbon source for BNC production with a maximum BNC yield of 5 g/L.
BNC produced as described above was then used for the development of novel green thermoplastic nanocomposites, combined with starch. When mixed with water and glycerol (with heat and shear), starch undergoes spontaneous destructuring, forming thermoplastic starch (TPS). In particular to food packaging applications, BNC has remained unexploited in spite of being considered to have enormous potential [4-5]. In this work, two approaches for composite production were assessed. Firstly, BNC 3D membrane was filled with biodegradable bio-based thermoplastic starch (TPS), where the production was achieved in a two-step process: impregnation of TPS in the BNC membrane, followed by drying. Different thicknesses of BNC membrane were studied (1-5 mm) as two impregnation time (24h;72h). The second approach consisted on the use of glycerol-TPS as matrix, where different concentrations (0.05 -0.5% w/v) of cellulose (Plant (PC) and BNC) was added. TPS-BNC and TPS-PC films were prepared by solution casting method. All nanocomposites manufactured were then characterized in terms of mechanical properties, morphology and permeability to water vapor (WVT). Overall, enhanced mechanical and barrier properties were obtained with BNC-TPS composites. In comparison to TPS-BNC and TPS-PC films, higher young modulus and tensile strength was obtained with the BNC-TPS composites. Being longer andinfo:eu-repo/semantics/publishedVersio
Crystal Structures of 2-Phenyl-2H-1,2,3-Triazol-4-Carbaldehyde, an Active a-Glycosidase Inhibition Agent, and (1-Phenyl-1H-1,2,3-Triazol-4-yl)Methyl Benzoate and (2-(4-Fluorophenyl)-2H-1,2,3-Triazole-4-yl)Methanol, Two Moderately Active Compounds
The use of the NCS crystallographic service at Southampton and the valuable assistance of the staff there are gratefully acknowledged. JLW thanks FAPERJ, Brazil for support.Peer reviewedPublisher PD
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