Relaxation and breakup of an initially extended drop in an otherwise quiescent fluid

In this paper we examine some general features of the time-dependent dynamics of drop deformation and breakup at low Reynolds numbers. The first aspect of our study is a detailed numerical investigation of the ‘end-pinching’ behaviour reported in a previous experimental study. The numerics illustrate the effects of viscosity ratio and initial drop shape on the relaxation and/or breakup of highly elongated droplets in an otherwise quiescent fluid. In addition, the numerical procedure is used to study the simultaneous development of capillary-wave instabilities at the fluid-fluid interface of a very long, cylindrically shaped droplet with bulbous ends. Initially small disturbances evolve to finite amplitude and produce very regular drop breakup. The formation of satellite droplets, a nonlinear phenomenon, is also observed

A spherical particle straddling a fluid/gas interface in an axisymmetric straining flow

Numerical solutions, obtained via the boundary-integral technique, are used to consider the effect of a linear axisymmetric straining flow on the existence of steady-state configurations in which a neutrally buoyant spherical particle straddles a gas–liquid interface. The problem is directly applicable to predictions of the stability of particle capture in flotation processes, and is also of interest in the context of contact angle and surface tension measurements. A primary goal of the present study is a determination of the critical capillary number, Ca_c, beyond which an initially captured particle is pulled from the interface by the flow, and the dependence of Ca_c on the equilibrium contact angle θ_c. We also present equilibrium configurations for a wide range of contact angles and subcritical capillary numbers

The creeping motion of a spherical particle normal to a deformable interface

Numerical results are presented for the approach of a rigid sphere normal to a deformable fluid-fluid interface in the velocity range for which inertial effects may be neglected. Both the case of a sphere moving with constant velocity, and that of a sphere moving under the action of a constant non-hydrodynamic body force are considered for several values of the viscosity ratio, density difference and interfacial tension between the two fluids. Two distinct modes of interface deformation are demonstrated: a film drainage mode in which fluid drains away in front of the sphere leaving an ever-thinning film, and a tailing mode where the sphere passes several radii beyond the plane of the initially undeformed interface, while remaining encapsulated by the original surrounding fluid which is connected with its main body by a thin thread-like tail behind the sphere. We consider the influence of the viscosity ratio, density difference, interfacial tension and starting position of the sphere in deter-mining which of these two modes of deformation will occur

Magnetic Monopole in the Loop Representation

We quantize the electromagnetic field in the presence of a static magnetic monopole, within the loop-representation formalism. We find that the loop-dependent wave functional becomes multivalued, in the sense that it acquires a dependence on the surfaces bounded by the loop. This generalizes what occurs in quantum mechanics in multiply connected spaces. When Dirac's quantization condition holds, this surface-dependence disappears, together with the effect of the monopole on the electromagnetic field.Comment: reference and comment adde

Feno de pastagem nativa da "Zona de mimoso", como opcao para suplementacao do rebanho, na epoca seca.

Entre os diversos tipos de vegetacao do Piaui, a pastagem nativa da "zona de mimoso" e considerada uma das mais importantes do Estado. O maior problema enfrentado pelo pecuarista da regiao e a falta de forragempara o rebanho, na seca, ja que a pastagem cultivada e insignificante.Neste periodo a pastagem nativa seca totalmente e parte dela e carregada pelos ventos, tornando-se escassa a disponibilidade de forragem. Noperiodo chuvoso, a pastagem nativa chega a ser abundante e, as vezes excedendo o consumo animal. A producao de feno do excedente da pastagemnativa e uma opcao para suplementacao do gado na epoca critica. A UEPAE de Teresina produziu na "zona de mimoso" cerca de 9,0 t de feno parasuplementacao de seu rebanho. O trabalho foi realizado em marco de 1982, quando havia excedentes de forragem. Foram usados dois sistemas: 1)Todas as operacoes (roco, enleiramento e enfaradmento) forma executados manualmente. 2)Foi realizado roco mecanico, e enleiramento manual. Em ambos o enfardamento foi manual em prensa de feno. A maior producao de feno no sistema totalmente manual foi devido a altura de corte das plantas ter sido mais baixa. O feno produzido em Campo Maior tinha 7,85% de proteina bruta e 0,08% de fosforo, com base na materia seca. Este dados mostram que o teor de proteina e superior as necessidades de mantenca dos bovinos, que e de 7,0%. Quanto ao fosforo, esta abaixo de suas necessidades, precisando portanto, de suplementacao mineral.bitstream/item/95804/1/CT190001.pd

Tratamiento y control de la diabetes con intervención de estilo de vida en pacientes ambulatorios: Serie de Casos y Actualización: Diabetes treatment and control using lifestyle intervention in outpatient setting: Case Series and Update

The prevalence of diabetes demands the identification of more efficient long-term methods to achieve good patient control. This paper reports the progress of 4 patients diagnosed with previously poorly controlled diabetes and prediabetes with comorbidities that were attended in an outpatient clinic, they received orientation regarding lifestyle change and were instructed to increase consumption of dietary fiber and physical activity. Body composition and biochemical markers were followed and changes were reported. In a 5 month period Patient 1 achieved criterion for controlled diabetes and was able to suspend oral hypoglycemic agents, reducing his body weight by 10%. Within a 8 week period Patient 2 experienced a 50% decrease of HOMA IR and was able to achieve criteria of controlled diabetes. Furthermore a 3 kg increase in lean body mass and a 4 kg body weight decrease were documented. These findings were accompanied by a 23% and 38% decrease in total cholesterol and triglycerides respectively. Patient 3 achieved criteria for type 2 diabetes remission within a 18 month time span(Inicial HBA1C 11.4% Final HBA1C 5.3). Patient 4 progressed to remission of prediabetes and a decrease of 5.9% in total body weight in a 3 month period.Las cifras de prevalencia de la diabetes nos obligan a identificar métodos más eficientes a largo plazo para lograr el buen control de los pacientes. En este trabajo se reporta el curso clínico de 4 pacientes con diagnóstico de diabetes y prediabetes quienes fueron atendidos en la consulta externa y recibieron asistencia no intensiva para cambio de comportamiento en salud, orientada a aumentar consumo de fibra alimentaria y a aumentar sus niveles de actividad física.  Se reportan cambios en indicadores bioquímicos y antropométricos. El paciente 1 en 5 meses logró suspender hipoglucemiantes orales, disminuyendo un 10% de su peso corporal y logrando criterios de prediabetes (remisión parcial). El paciente 2 en un período de 8 semanas logró alcanzar criterios de diabetes controlada, disminuyendo en 50% el índice HOMA IR.  Además, se documentó pérdida de 4 kg de masa grasa corporal con ganancia de 3 kg de masa magra.  Lo anterior se acompañó de una disminución del 23% del colesterol total y 38% de triglicéridos. La paciente 3 alcanzó criterios de remisión de DM2 durante un seguimiento de 18 meses(HBA1C 11.4% inicial y 5.3% final). La paciente 4 evolucionó a remisión de prediabetes y disminución de 5.9% de peso corporal total en un periodo de 3 meses

Modelling of epitaxial film growth with a Ehrlich-Schwoebel barrier dependent on the step height

The formation of mounded surfaces in epitaxial growth is attributed to the presence of barriers against interlayer diffusion in the terrace edges, known as Ehrlich-Schwoebel (ES) barriers. We investigate a model for epitaxial growth using a ES barrier explicitly dependent on the step height. Our model has an intrinsic topological step barrier even in the absence of an explicit ES barrier. We show that mounded morphologies can be obtained even for a small barrier while a self-affine growth, consistent with the Villain-Lai-Das Sarma equation, is observed in absence of an explicit step barrier. The mounded surfaces are described by a super-roughness dynamical scaling characterized by locally smooth (faceted) surfaces and a global roughness exponent $\alpha>1$. The thin film limit is featured by surfaces with self-assembled three-dimensional structures having an aspect ratio (height/width) that may increase or decrease with temperature depending on the strength of step barrier.Comment: To appear in J. Phys. Cond. Matter; 3 movies as supplementary materia

Análise de nitrogênio total em amostras de tecido vegetal pelos métodos de Dumas e Kjeldahl.

O objetivo deste trabalho é comparar os resultados obtidos pelos dois métodos utilizados para análise de nitrogênio total (Nt), que são os métodos de Kjeldhal e Dumas, em algumas amostras de tecido vegetal e grãos normalmente analisadas na rotina do laboratório

Potentially Hygroreceptive Sensilla on the Anal Stylus of the Glassy-Winged Sharpshooter, Homalodisca vitripennis

This study begins to elucidate the cues and mechanisms by which the glassy-winged sharpshooter, Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae), select host plants for feeding and oviposition. The electrophysiological response of the anal styli of male and female H. vitripennis to water vapor was examined using a modified electroantennography (EAG) device (stylogram). A strong electrophysiological response of the anal stylus to water vapor was found. Scanning electron microscopic examination of the anal stylus revealed the presence of long mechanosensory hairs, many small coeloconic-type sensilla, and masses of secretory granules termed brochosomes. Each coeloconic sensillum is located in a pit from which protrude finger-like projections. The pit is often blocked by masses of brochosomes and an unidentified dense material. Based on the electrophysiological response of the anal stylus to water vapor, we hypothesize that the coeloconic sensilla on the stylus may be hygroreceptors. H. vitripennis are xylem feeders and may use the sensilla to assist in host selection for the purpose of feeding or oviposition based on detected plant water status. Furthermore, H. vitripennis oviposit into the leaf epidermis, and may use these sensilla to evaluate moisture content to determine host suitability for both oviposition and subsequent feeding of emerged progeny. Understanding the cues and underlying mechanisms of host selection is an important consideration for predicting the movement of H. vitripennis between crops and disease epidemiology