A similarity principle for locally solvable vector fields

AbstractThis paper establishes a weak similarity principle for the class of locally solvable complex vector fields in the plane. The main tool is a local solvability result in an appropriate space of bounded mean oscillation functions

Semi-automatic rubble counting system for superheated droplet detectors

Neutron dose rate measurements are normally performed by means of PADC, CR-39 and TLD detectors. Although, none of these devices can give instant reading of the neutron dose, recently new kind of detectors are being developed, based on the formation of tiny drops in a superheated liquid suspended in a polymer or gel solution, called superheated droplet detector (SDD) or also as bubble detectors (BD), with no response for gamma radiation. This work describes the experimental setup and the developed procedures for acquiring and processing digital images obtained with bubble detector spectrometer (BDS), developed by Bubble Technology Industries, for personal neutron dosimeter and/or neutron energy fluence measurements in nuclear facilities. The results of the neutron measurements obtained during the F-18 production, at the RDS-111 cyclotron, are presented. These neutron measurements were the first ones with this type of BDS detectors in a particle accelerator facility in Brazil and it was very important to estimate neutron dose rate received by occupationally exposed individuals

Dark energy, non-minimal couplings and the origin of cosmic magnetic fields

In this work we consider the most general electromagnetic theory in curved space-time leading to linear second order differential equations, including non-minimal couplings to the space-time curvature. We assume the presence of a temporal electromagnetic background whose energy density plays the role of dark energy, as has been recently suggested. Imposing the consistency of the theory in the weak-field limit, we show that it reduces to standard electromagnetism in the presence of an effective electromagnetic current which is generated by the momentum density of the matter/energy distribution, even for neutral sources. This implies that in the presence of dark energy, the motion of large-scale structures generates magnetic fields. Estimates of the present amplitude of the generated seed fields for typical spiral galaxies could reach $10^{-9}$ G without any amplification. In the case of compact rotating objects, the theory predicts their magnetic moments to be related to their angular momenta in the way suggested by the so called Schuster-Blackett conjecture.Comment: 5 pages, no figure

Preparation and characterization of starch-poly-epsilon-caprolactone microparticles incorporating bioactive agents for drug delivery and tissue engineering applications

One limitation associated with the delivery of bioactive agents concerns the short half-life of these molecules when administered intravenously, which results in their loss from the desired site. Incorporation of bioactive agents into depot vehicles provides a means to increase their persistence at the disease site. Major issues are involved in the development of a proper carrier system able to deliver the correct drug, at the desired dose, place and time. In this work, starch-poly-e-caprolactone (SPCL) microparticles were developed for use in drug delivery and tissue engineering (TE) applications. SPCL microparticles were prepared by using an emulsion solvent extraction/evaporation technique, which was demonstrated to be a successful procedure to obtain particles with a spherical shape (particle size between 5 and 900 lm) and exhibiting different surface morphologies. Their chemical structure was confirmed by Fourier transform infrared spectroscopy. To evaluate the potential of the developed microparticles as a drug delivery system, dexamethasone (DEX) was used as model drug. DEX, a well-known component of osteogenic differentiation media, was entrapped into SPCL microparticles at different percentages up to 93%. The encapsulation efficiency was found to be dependent on the polymer concentration and drug-to-polymer ratio. The initial DEX release seems to be governed mainly by diffusion, and it is expected that the remaining DEX will be released when the polymeric matrix starts to degrade. In this work it was demonstrated that SPCL microparticles containing DEX can be successfully prepared and that these microparticular systems seem to be quite promising for controlled release applications, namely as carriers of important differentiation agents in TE.E.R.B. thanks the Marie Curie Host Fellowships for Early Stage Research Training (EST) "Alea Jacta EST" (MEST-CT-2004-008104) for providing her with a PhD Fellowship. This work was partially supported by the European NoE EXPERTISSUES (NMP3-CT-2004-500283)

Uso da adubação orgânica e cobertura morta na cultura da calêndula (Calendula officinalis L.).

A calêndula representa fonte alternativa econômica principalmente para a agricultura familiar. O objetivo do presente trabalho foi avaliar os efeitos da adubação orgânica e do uso da cobertura morta sobre a produção de biomassa e teor de flavonóides totais em plantas de calêndula. O experimento foi realizado no Campus de Montes Claros da Universidade Federal de Minas Gerais, utilizando-se o delineamento em blocos casualizados em esquema fatorial 2x2x4 com quatro repetições: duas épocas de colheita, presença ou ausência de cobertura morta e quatro doses de composto orgânico (0, 30, 60 e 90 t ha-1). As maiores produções de biomassa e flavonóides totais foram verificadas com o aumento das doses de composto orgânico. Para os flavonóides totais o maior teor foi obtido na segunda colheita na presença de cobertura morta

On Aharonov-Casher bound states

In this work bound states for the Aharonov-Casher problem are considered. According to Hagen's work on the exact equivalence between spin-1/2 Aharonov-Bohm and Aharonov-Casher effects, is known that the $\boldsymbol{\nabla}\cdot\mathbf{E}$ term cannot be neglected in the Hamiltonian if the spin of particle is considered. This term leads to the existence of a singular potential at the origin. By modeling the problem by boundary conditions at the origin which arises by the self-adjoint extension of the Hamiltonian, we derive for the first time an expression for the bound state energy of the Aharonov-Casher problem. As an application, we consider the Aharonov-Casher plus a two-dimensional harmonic oscillator. We derive the expression for the harmonic oscillator energies and compare it with the expression obtained in the case without singularity. At the end, an approach for determination of the self-adjoint extension parameter is given. In our approach, the parameter is obtained essentially in terms of physics of the problem.Comment: 11 pages, matches published versio

Effect of the divertor configuration on the JET edge radial electric field

The role of the divertor configuration and divertor plasma physics on the L???H transition is poorly understood, leading to large uncertainties in predicting the L???H power threshold in future devices. This contribution reports on edge perpendicular plasma flow measurements by Doppler backscattering in JET L???H transition experiments with the outer divertor strike-point at different positions: horizontal target (HT), vertical target (VT), and in the corner configuration (between the HT and VTs). The edge perpendicular flow was found to be significantly affected by changes in the divertor configuration in the region inside the separatrix. Our results do not show evidence for the existence of a critical edge flow shear needed to achieve H-mode for different divertor configurations, with a larger shear observed for the VT configuration. No significant change in the shear flow and in the density fluctuation level is measured preceding the L???H transition in the region just inside the separatrix. The dynamics of the L???H transitions are also influenced by the divertor configuration with divertor oscillations (DOs) observed only in the HT configuration. Interestingly, DOs are associated with marked changes in the edge perpendicular flow around the separatrix

Structure of the JET edge radial electric field in He and D plasmas

El primer autor es Carlos Silva, experto en medidas del plasma por reflectometr??a. Soy la segunda autora, ya que se estudian mis experimentos. Se acababa de instalar en JET un sistema de reflectometr??a Doppler que permite medir la velocidad de las fluctuaciones de densidad del plasma en la direcci??n perpendicular a la l??nea de campo magn??tico loca, v_perp. Tal velocidad tiene una componente dominante debida al campo el??ctrico radial local (E_r) del plasma. En el borde del plasma se observa que el perfil de E_r o v_perp a menudo tiene un pozo muy localizado en la zona del gradiente de densidad, dentro de la separatriz que delimita al plasma, y una colina centrada en la separatriz. Hay muchos modelos de transici??n L-H que se basan en la suposici??n de que el gradiente de la rotaci??n perpendicular rasga los remolinos de turbulencia que dan lugar al transporte elevado en el modo L (bajo confinamiento). Se ha llegado a decir que la transici??n L-H requiere un valor critico del pozo de E_r. En este art??culo se estudia el perfil de v_perp en plasmas de Deuterio y de Helio justo antes de la transici??n L-H (experimentos descritos en la aportaci??n 1). En primer lugar se estudian plasmas con calentamiento por inyecci??n de part??culas r??pidas neutras (Neutral Beam Injection, NBI). Tanto en plasmas de Deuterio como de Helio se observa que para valores de densidad bajos el perfil radial de v_perp apenas tiene pozo, y tiene una colina elevada. Seg??n sube la densidad la colina decrece hasta desaparecer y se forma un pozo cada vez m??s profundo. Plasmas de Deuterio calentados con ondas (Ion Cyclotron Resonant Heating, ICRH) muestran perfiles cualitativamente semejantes a los de NBI, pero con una variaci??n de la profundidad del pozo mucho m??s d??bil en funci??n de la densidad. Se concluye que no hay un valor cr??tico del pozo, ni de la colina, necesarios para la transici??n L-H. El resultado m??s interesante que se presenta es un estudio de la evoluci??n del perfil de v_perp seg??n aumenta la potencia de calentamiento hasta que ocurre la transici??n. La mayor??a de los modelos de transici??n L-H suponen que el pozo de v_perp se hace paulatinamente m??s profundo seg??n aumenta el calentamiento, hasta llegar al valor cr??tico. Aqu?? se muestra (Fig. 7) que ??ste no es el caso. En cu??nto se entra en modo L (con calentamiento por ondas) el plasma tiene b??sicamente el mismo perfil de v_perp. Si acaso la profundidad del pozo decrece muy despacio. La ??nica carencia de este estudio es que la resoluci??n temporal es limitada: se necesitan 300 ms para medir un perfil de v_perp. El tiempo de confinamiento del plasma es de ??se orden, y la rampa de potencia es muy lenta, del orden de 1MW/s. Por lo tanto no podemos medir c??mo cambia v_perp justo antes de la transici??n a escalas de tiempo m??s cortas. A pesar de eso es evidente que el modelo convencional de la transici??n no se ajusta a nuestras observaciones.Perpendicular velocity, v???, measurements have been obtained in JET experiments designed to investigate the underlying mechanisms influencing the L???H power threshold. L???H transitions were induced by using both NBI and ICRH in deuterium and helium plasmas. The v??? profile in the low density branch of the L???H transition has a modest or even no well and a marked peak near the separatrix in NBI heated discharges for both D and He plasmas, with a sharper SOL peak for He plasmas. As the line-averaged density increases, the SOL v??? peak decreases, in agreement with the modifications in the electron temperature profile at the divertor target, while the v??? well becomes deeper. Nevertheless, even in the high density branch, a shallow v??? well is found at the L???H transition, v??? ??? 1???2 km s???1, which is lower by a factor of about two than the contribution from the diamagnetic term. No evidence for the existence of a critical value in v??? is found at JET, particularly for helium plasmas. This may be explained by the existence of an edge toroidal flow relevant mainly at low density where the power threshold is high. In addition, no significant change in the edge v??? is measured preceding the L???H transition

Sludge Treatment Evaluation: 1992 Technical progress

This report documents Fiscal Year 1992 technical progress on the Sludge Treatment Evaluation Task, which is being conducted by Pacific Northwest Laboratory. The objective of this task is to develop a capability to predict the performance of pretreatment processes for mixed radioactive and hazardous waste stored at Hanford and other US Department of Energy (DOE) sites. Significant cost savings can be achieved if radionuclides and other undesirable constituents can be effectively separated from the bulk waste prior to final treatment and disposal. This work is initially focused on chemical equilibrium prediction of water washing and acid or base dissolution of Hanford single-shell tank (SST) sludges, but may also be applied to other steps in pretreatment processes or to other wastes. Although SST wastes contain many chemical species, there are relatively few constituents -- Na, Al, NO[sub 3], NO[sub 2], PO[sub 4], SO[sub 4], and F -- contained in the majority of the waste. These constituents comprise 86% and 74% of samples from B-110 and U-110 SSTS, respectively. The major radionuclides of interest (Cs, Sr, Tc, U) are present in the sludge in small molal quantities. For these constituents, and other important components that are present in small molal quantities, the specific ion-interaction terms used in the Pitzer or NRTL equations may be assumed to be zero for a first approximation. Model development can also be accelerated by considering only the acid or base conditions that apply for the key pretreatment steps. This significantly reduces the number of chemical species and chemical reactions that need to be considered. Therefore, significant progress can be made by developing all the specific ion interactions for a base model and an acid dissolution model

High throughput toxicity screening and intracellular detection of nanomaterials

EC FP7 NANoREG (Grant Agreement NMP4-LA-2013-310584)Free PMC Article: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5215403/With the growing numbers of nanomaterials (NMs), there is a great demand for rapid and reliable ways of testing NM safety—preferably using in vitro approaches, to avoid the ethical dilemmas associated with animal research. Data are needed for developing intelligent testing strategies for risk assessment of NMs, based on grouping and read-across approaches. The adoption of high throughput screening (HTS) and high content analysis (HCA) for NM toxicity testing allows the testing of numerous materials at different concentrations and on different types of cells, reduces the effect of inter-experimental variation, and makes substantial savings in time and cost.info:eu-repo/semantics/publishedVersio