Metallic hot wire anemometer

A hot wire anemometer is described which has a body formed of heat resistant metal such as an alloy high in nickel content which supports a probe wire disposed in a V groove in the body. The V groove contains a high temperature ceramic adhesive that partially encompasses the downstream side of the probe wire. Mechanical and electrical connection to the probe wire is achieved through conductive support rods that are constructed of the same high temperature metal, insulation between the body and the conductor rods being provided by a coating of an oxide of the same material which coating is formed in situ. The oxide coating insulates the conductor rods from the body, mechanically fixes the conductors within the body, and maintains its integrity at elevated temperatures

A Quantum Cosmological Model With Static and Dynamic Wormholes

Quantization is performed of a Friedmann-Robertson-Walker universe filled with a conformally invariant scalar field and a perfect fluid with equation of state $p=\alpha \rho$. A well-known discrete set of static quantum wormholes is shown to exist for radiation ($\alpha =1/3$), and a novel continuous set is found for cosmic strings ($\alpha = -1/3$), the latter states having throat radii of any size. In both cases wave-packet solutions to the Wheeler-DeWitt equation are obtained with all the properties of evolving quantum wormholes. In the case of a radiation fluid, a detailed analysis of the quantum dynamics is made in the context of the Bohm-de Broglie interpretation. It is shown that a repulsive quantum force inversely proportional to the cube of the scale factor prevents singularities in the quantum domain. For the states considered, there are no particle horizons either.Comment: LaTex file, 13 pages. To appear in General Relativity and Gravitatio

Gravitational collapse to toroidal, cylindrical and planar black holes

Gravitational collapse of non-spherical symmetric matter leads inevitably to non-static external spacetimes. It is shown here that gravitational collapse of matter with toroidal topology in a toroidal anti-de Sitter background proceeds to form a toroidal black hole. According to the analytical model presented, the collapsing matter absorbs energy in the form of radiation (be it scalar, neutrinos, electromagnetic, or gravitational) from the exterior spacetime. Upon decompactification of one or two coordinates of the torus one gets collapsing solutions of cylindrical or planar matter onto black strings or black membranes, respectively. The results have implications on the hoop conjecture.Comment: 6 pages, Revtex, modifications in the title and in the interpretation of some results, to appear in Physical Review

EFFECTS OF TURBULENCE-RADIATION INTERACTIONS IN A NON-PREMIXED TURBULENT METHANE-AIR FLAME

This work studied a turbulent flame and analyzed the interaction between turbulence and radiation (TRI). The problem consists of a non-premixed turbulent methane flame surrounded by a low-velocity air coflow identified as Flame DLR-A. The steady laminar diffusion flamelet (SLDF) model is used to solve the chemical kinetics. To generate the flamelet library, turbulence-chemistry interaction is taken into account through previously assumed probability density functions (PDF) of mean scalars. Radiative heat flux is calculated with the discrete ordinates method, considering the Gray Gas model (GG). Turbulence is solved with k-ε Standard model and TRI methodology is based on temperature self-correlation. The solution is obtained using ANSYS/Fluent code coupled with user-defined functions (UDFs). Results indicated that the temperature and chemical species predictions are little affected by TRI, while the radiative quantities (radiative heat flux on the domain wall) are importantly affect by TRI effects

Pair creation of higher dimensional black holes on a de Sitter background

We study in detail the quantum process in which a pair of black holes is created in a higher D-dimensional de Sitter (dS) background. The energy to materialize and accelerate the pair comes from the positive cosmological constant. The instantons that describe the process are obtained from the Tangherlini black hole solutions. Our pair creation rates reduce to the pair creation rate for Reissner-Nordstrom-dS solutions when D=4. Pair creation of black holes in the dS background becomes less suppressed when the dimension of the spacetime increases. The dS space is the only background in which we can discuss analytically the pair creation process of higher dimensional black holes, since the C-metric and the Ernst solutions, that describe respectively a pair accelerated by a string and by an electromagnetic field, are not know yet in a higher dimensional spacetime.Comment: 10 pages; 1 figure included; RexTeX4. v2: References added. Published version. v3: Typo in equation (46) fixe

Balanço auxina/citocinina para multiplicação in vitro de pimenteira-do-reino (Piper nigrum L.).

As técnicas de cultura de tecidos têm sido empregadas de diferentes formas no desenvolvimento de cultivares superiores de plantas, podendo oferecer novas alternativas aos programas de melhoramento em suas diferentes fases. O trabalho consiste na micropropagação da cultivar de pimenteira-do-reino Balankota, cujos explantes utilizados foram gemas apicais e axilares inoculadas em meio de cultura Murashige & Skoog (MS), com 3% de sacarose, vitaminas MS, suplementados com diferentes combinações de auxina (AIA) e citocininas (cinetina e BAP) e solidificado com 0,2% de Phytagel. Os explantes foram mantidos em condições controladas de cultivo por 6 semanas. O delineamento experimental utilizado foi inteiramente casualizado e os resultados foram analisados pela ANOVA com teste de Tukey ao nível de 5% de probabilidade. As avaliações foram quanto ao número de gemas e brotos por explante e grau de oxidação. Concentrações inferiores de cinetina emitiram maiores números de gemas, e todas as combinações apresentaram elevado grau de oxidação e média semelhantes para número de brotos. O balanço Cinetina/AIA promove a diferenciação de novas gemas com destaque para 0,5μM de cinetina e 0,2μM de AIA. Independente do balanço ocorre elevado grau de oxidação dos explantes

Effect of Water Content on the Thermal Inactivation Kinetics of Horseradish Peroxidase Freeze-Dried from Alkaline pH

The thermal inactivation of horseradish peroxidase freeze-dried from solutions of different pH (8, 10 and 11.5, measured at 25 C) and equilibrated to different water contents was studied in the temperature range from 110 to 150 C. The water contents studied (0.0, 1.4, 16.2 and 25.6 g water per 100 g of dry enzyme) corresponded to water activities of 0.0, 0.11, 0.76 and 0.88 at 4 C. The kinetics were well described by a double exponential model. The enzyme was generally more stable the lower the pH of the original solution, and for all pH values, the maximum stability was obtained at 1.4 g water/100 g dry enzyme. Values of z were generally independent of water content and of the pH of the original solution, and in the range of 15–25 °C, usually found in neutral conditions, with the exception of the enzyme freeze dried from pH 11.5 and equilibrated with phosphorus pentoxide, where a z-value of the stable fraction close to 10 C was found

Two-dimensional gravitation and Sine-Gordon-Solitons

Some aspects of two-dimensional gravity coupled to matter fields, especially to the Sine-Gordon-model are examined. General properties and boundary conditions of possible soliton-solutions are considered. Analytic soliton-solutions are discovered and the structure of the induced space-time geometry is discussed. These solutions have interesting features and may serve as a starting point for further investigations.Comment: 23 pages, latex, references added, to appear in Phys.Rev.

Proliferação de brotos de cultivares de bananeira em cinco subcultivos em diferentes concentrações de benzilaminopurina a cada subcultivo.

Mudas de bananeira de qualidade que proporcionem eficiência e segurança nos projetos de implantação ou substituições de bananais é um dos principais gargalos da cadeia produtiva da banana. A muda micropropagada permite alcança a qualidade desejada, pois tem qualidade genética e fitossanitária, além do considerável aumento do número de plantas dentro de curto espaço de tempo. O objetivo foi avaliar o comportamento de três cultivares de bananeira em cinco subcultivos de multiplicação de brotos usando concentrações diferentes de BAP a cada subcultivo. O experimento foi realizado no laboratório de biotecnologia e recursos genéticos da Embrapa Amazônia Oriental. A cultura foi estabelecida em meio básico de estabelecimento (1⁄2MS + BAP 2,5 mg.L-1 + PVP 0,4 %, solidificado com Phytagel 0,2 % + Sulfato de Estreptomicina 100 mg.L-1 e pH 6,1). Após 72 horas foi feita a transferência dos explantes intumescidos para meio de cultura de indução de brotos, MS completo com diferentes concentrações de benzilaminopurina (BAP 4,0 mg.L-1; 3,5 mg.L-1; 3,0 mg.L- 1 ; 2,5 mg.L-1; 2,0 mg.L-1) que corresponderam respectivamente, às concentrações de BAP no primeiro, segundo, terceiro, quarto e quinto subcultivo. O tempo de cultivo em cada subcultivo de multiplicação dos brotos foi de quatro a seis semanas. A taxa média de brotos para as três cultivares foi de 1,25; 2,56; 2,52; 2,47; 2,50 respectivamente, nos cinco subcultivos realizados, não havendo diferença significativa de número de brotos entre cultivares e subcultivos nas diferentes concentrações de BAP.PIBIC-2011