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1.
Phys Rev E ; 101(2-1): 022901, 2020 Feb.
Article in English | MEDLINE | ID: mdl-32168580

ABSTRACT

We study how the presence of obstacles in a confined system of monodisperse disks affects their discharge through an aperture. The disks are driven by a horizontal conveyor belt that moves at constant velocity. The mean packing fraction at the outlet decreases as the distance between the obstacles and the aperture decreases. The obstacles organize the dynamics of the stagnant zones in two characteristic behaviors that differ mainly in the magnitude of the fluctuations of the fraction of stagnant disks in the system. It is shown that the effective aperture is reduced by the presence of obstacles.

2.
Neotrop Entomol ; 49(3): 369-391, 2020 Jun.
Article in English | MEDLINE | ID: mdl-31997282

ABSTRACT

Primary and secondary parasitoids of Hypogeococcus spp. (Hemiptera: Pseudococcidae) on Cactaceae, Amaranthaceae, and Portulacaceae were reported from field surveys conducted in Puerto Rico, USA, since 2009. Resident natural enemies of the Harrisia cactus mealybug (HCM), Hypogeococcus sp., which is devastating native cacti in Puerto Rico and threatening cacti in the adjacent Caribbean islands, were documented prior to the planned introductions of non-native biological control agents from South America against this pest. Two species of Encyrtidae (Hymenoptera: Chalcidoidea) were recorded as primary parasitoids of the HCM on Cactaceae: Leptomastidea hypogeococci Triapitsyn, which was the most common, and Anagyrus quilmes Triapitsyn, Logarzo & Aguirre. Another primary parasitoid, Acerophagus sp. near nubilipennis Dozier (Encyrtidae), was also reared from a different Hypogeococcus sp. on Amaranthaceae and Portulacaceae. Hyperparasitoids, usually via L. hypogeococci, included Prochiloneurus narendrani Noyes & Triapitsyn (Encyrtidae), Pachyneuron sp. (Hymenoptera: Pteromalidae), Chartocerus elongatus (Girault), and Chartocerus niger (Ashmead) (Hymenoptera: Signiphoridae). Cheiloneurus chrisiantorresi Triapitsyn sp. n. (Encyrtidae) is newly described and illustrated; its status as a suspect hyperparasitoid of Hypogeococcus sp. on Amaranthaceae and Portulacaceae, along with that of Cheiloneurus sp., will need to be verified. The recorded HCM predators include one species of Chamaemyiidae (Diptera), Leucopina bella (Loew), and three species of Coccinellidae (Coleoptera): Cryptolaemus montrouzieri Mulsant, Decadiomus austrinus (Gordon), and Scymnobius flavifrons (Melsheimer).


Subject(s)
Diptera/parasitology , Hymenoptera/physiology , Pest Control, Biological , Animals , Cactaceae , Female , Male , Puerto Rico
3.
Nanotechnology ; 31(15): 155204, 2020 Apr 10.
Article in English | MEDLINE | ID: mdl-31860894

ABSTRACT

The development of novel devices for neuromorphic computing and non-traditional logic operations largely relies on the fabrication of well controlled memristive systems with functionalities beyond standard bipolar behavior and digital ON-OFF states. In the present work we demonstrate for Ta2O5-based devices that it is possible to selectively activate/deactivate two series memristive interfaces in order to obtain clockwise or counter-clockwise multilevel squared remanent resistance loops, just by controlling both the electroforming process and the (a)symmetry of the applied stimuli, and independently of the nature of the used metallic electrodes. Based on our thorough characterization, analysis and modeling, we show that the physical origin of this electrical behavior relies on controlled oxygen vacancies electromigration between three different nanoscopic zones of the active Ta2O5-x layer: a central one and two quasi-symmetric interfaces with reduced TaO2-h(y) layers. Our devices fabrication process is rather simple as it implies the room temperature deposition of only one CMOS compatible oxide-Ta-oxide-and one metal, suggesting that it might be possible to take advantage of these properties at low cost and with easy scability. The tunable opposite remanent resistance loops circulations with multiple-analogic-intermediate stable states allows mimicking the adaptable synaptic weight of biological systems and presents potential for non-standard logic devices.

4.
Gen Comp Endocrinol ; 285: 113230, 2020 01 01.
Article in English | MEDLINE | ID: mdl-31348955

ABSTRACT

During the ovarian ontogeny in birds, five fundamental events can be recognized: migration and colonization of the primordial germ cells, differentiation and proliferation of oogonies, an organization of germinal nests, beginning of the meiotic process and folliculogenesis. The knowledge of these events is fundamental for the interpretation of the processes involved in the differentiation of female gametes. However, there are only references for some model species such as Gallus gallus domesticus and Coturnix coturnix. In a previous study, the histological structure of embryonic ovaries of Columba livia was revealed. Therefore, the objective of this work is to characterize the processes of meiosis and folliculogenesis C. livia from the analysis of the expression of the GnRH receptor, the 3ßHSD enzyme and the cell proliferation protein PCNA in embryonic and postnatal ovaries. Therefore, the expression of GnRHR, 3ßHSD, and PCNA was revealed in histological testicular and ovarian preparations in embryos (stages 41-43) and neonates (2, 5, 7, 10 and 75 days post-hatching). The present study demonstrates that the fate of germline cells is dictated by their location during gonadal development. Thus, the germline cells located in the cortex of the left gonad enter meiosis, while those in the right gonad and those in the medulla of the left ovary fail to go into meiosis. This indicates that somatic signals, instead of an autonomous cellular mechanism, regulate the entry of the germline cells into meiosis in the C. livia embryo. Future studies will be focused on the analysis of proteins associated with meiotic events and folliculogenesis in embryonic and neonatal ovaries of C. livia, to evaluate the regulation of meiosis in vitro.


Subject(s)
3-Hydroxysteroid Dehydrogenases/metabolism , Columbidae/metabolism , Meiosis , Ovarian Follicle/growth & development , Receptors, LHRH/metabolism , Animals , Cell Proliferation , Columbidae/embryology , Embryo, Nonmammalian/cytology , Female , Germ Cells/metabolism , Immunohistochemistry , Oocytes/cytology , Oocytes/metabolism , Ovarian Follicle/metabolism , Proliferating Cell Nuclear Antigen/metabolism
5.
Acta Histochem ; 121(3): 354-360, 2019 Apr.
Article in English | MEDLINE | ID: mdl-30826091

ABSTRACT

The spatial organization of cells during tissue differentiation is a crucial process in the morphogenesis of vertebrates. This process involves the movement, separation, and connection of cells. It is essential to elucidate the molecular mechanisms involved in these processes for the understanding of animal morphogenesis. Cell-cell adhesion molecules, called cadherins, are involved in the selective adhesion of cells. In the case of birds, the expression of these molecules in various organ systems during embryonic development has been reported in Gallus gallus domesticus. In this work, we present the immunohistochemical analysis of the differential expression of E and N-cadherin binding molecules in Columba livia embryos at various stages of gonadal morphogenesis. The expression of E and N-cadherin in embryos corresponding to the stages 41, 43 and in neonates of 2, 5, 7 and 75 post-hatching days were assessed by immunohistochemistry. Results revealed the expression of N-cadherin in the plasma membrane and the perinuclear zone of germline cells in ovaries and testes. However, the expression of E-cadherin was noticed with similar immunoreactivity pattern, in Sertoli cells and in the cells of the follicular nests. The differential expression of follicular cells and Sertoli cells positive for E-cadherin and germline cell N-cadherin positive cells were evidenced in the present work at the cell-cell interaction level. Future studies will focus on determining the expression of E and N-cadherin molecules during the migration of the primordial germ cells and the colonization of the genital ridge.


Subject(s)
Cadherins/metabolism , Chickens/metabolism , Morphogenesis/physiology , Testis/metabolism , Animals , Columbiformes , Female , Immunohistochemistry/methods , Male , Ovary/metabolism , Sertoli Cells/cytology
6.
Acta Histochem ; 120(5): 446-455, 2018 Jul.
Article in English | MEDLINE | ID: mdl-29776745

ABSTRACT

In this work, testicular ontogeny is analyzed at the anatomical, histological and immunohistochemical levels; the latter through the detection of GnRHR and PCNA in the testicles of embryos, neonates and juveniles of Columba livia. We analyzed 150 embryos, 25 neonates and 5 juveniles by means of observations under a stereoscopic magnifying glass and scanning electron microscope (SEM). The histological analysis was performed using hematoxylin-eosin staining techniques and the PAS reaction. For the immunohistochemical analysis, the expression of GnRHR and PCNA in embryos corresponding to stages 41, 43 and in neonates of 2, 5, 7 and 75 days post-hatch was revealed in testicular histological preparations. That gonadal outline is evident in stage 18. In stage 29, the testes are constituted of a medulla in which the PGCs are surrounded by the Sertoli cells, constituting the seminiferous tubules. From stage 37 a greater organization of the tubules is visualized and at the time of hatching the testicle is constituted of the closed seminiferous tubules, formed of the PGCs and Sertoli cells. The Leydig cells are evident outside the tubules. In the juvenile stages, the differentiation of germline cells and the organization of small vessels that irrigate the developing testicle begin to be visible. In the analyzed stages, the immunodetection of the GnRHR receptor and PCNA revealed specific marking in the plasma membrane and in the perinuclear zone for GnRHR and in the nucleus of the germline cells in juvenile testicles for PCNA. These results can be used as a basis for further study of endocrine regulation events during testicular ontogeny in avian species.


Subject(s)
Receptors, LHRH/metabolism , Testis/growth & development , Animals , Columbiformes , Immunohistochemistry , Male , Proliferating Cell Nuclear Antigen/metabolism , Testis/anatomy & histology , Testis/embryology
7.
Article in English | MEDLINE | ID: mdl-29108814

ABSTRACT

OBJECTIVE: To determine the predictors and prevalence of metabolic syndrome (MS) and the presence of vascular inflammation in apparently-normal children (10-15 years) of both sexes in Guayaquil, Ecuador. STUDY DESIGN AND METHODS: We included 395 apparently-healthy students from a middle-income school in a cross-sectional survey. Informed consent was obtained from students and parents. Anthropometric measurements including blood pressure (BP), body mass index (BMI) and waist-to-height ratio (WHtR), and blood tests were recorded. Vascular inflammation parameters were assessed. Percentiles of the different parameters were used, and MS was defined according to National Cholesterol Education Program Adult Treatment Panel III criteria (NCEP-ATPIII). Waist circumference>P 75, blood pressure>P 90, glucose>100mg/dl, triglycerides>100mg/dl, HDL<45mg/dl. If 3 of the 5 criteria were present, this was considered MS. RESULTS: The mean age was 12 years (186 boys, 209 girls). The overall prevalence of MS was 9.37% (6.33% in girls, 3.04% in boys). Sustained hypertension was detected in 6.6% of children and pre-hypertension in 7.1%. Obesity was found in 1.8% of subjects, and overweight in 15.2%. Triglycerides has a RR 2.34 (1.97-2.76); HOMA index has a RR 1.97(1.62-2.40); HDL cholesterol has a RR 1.84(1.58-2.13); Insulin level has a RR 1.53(1.40-1.67) and interleukin 6 has RR 1.83(1.20-2.79). Serum glucose, total cholesterol and LDL-Cholesterol had no association with the metabolic syndrome. HDL-Cholesterol<45mg/dl and triglyceride>100mg/dl were present in 70% of subjects with MS. The WHtR threshold≥0.5 was 100% sensitive in both sexes (67% specificity in boys and 69% in girls). There were significant associations between the WHtR and pre-hypertension and sedentary lifestyle (P<0.001 and P<0.003 respectively). A WHtR value of ≥0.50 indicated a 2.2-fold increased risk of MS compared with normal WHtR, and normal weight. CONCLUSIONS: A WHtR≥0.5 was 100% sensitive in detecting MS in 10-15 year-old boys and girls in the normal or overweight range of the BMI. This assessment is a simple and practical tool for use in population-based studies of cardiovascular risk. When combined with pre-hypertension and a sedentary lifestyle, the WHtR is highly sensitive in predicting MS.

9.
Rev Saude Publica ; 51(0): 39, 2017 Apr 27.
Article in English, Spanish | MEDLINE | ID: mdl-28489187

ABSTRACT

OBJECTIVE: Determine the perception of university students regarding interprofessional and interdependent work between team members in their inclusion in primary care. METHODS: Analytical cross-sectional study. The sampling had a probabilistic, stratified random type with 95% confidence and 5% margin of error. Seven-hundred and four students of Public Universities in Santiago (Chile) answered self-administered questionnaire. RESULTS: Ninety-seven point eight of students say that interprofessional work is important; 27.1% of them declare that their university did not seem to show that their study plans were important. The professionals listed as most important in teams are physicians and nurses. CONCLUSIONS: Spaces for development and institutional support are key elements to promote interprofessional work. If this competence can involve each academic unit in their different formative spaces there will be a significant contribution to said promotion. Teamwork is a pending task. OBJETIVO: Determinar la percepción de estudiantes universitarios respecto al trabajo interprofesional e interdependencia entre los miembros del equipo en su inserción en la atención primaria. MÉTODOS: Estudio de tipo analítico y transversal. El muestreo fue de tipo aleatorio, probabilístico estratificado con un 95% de confianza y un 5% de margen de error. Se utilizó un cuestionario auto-administrado en 704 estudiantes de Universidades del Estado en Santiago de Chile. RESULTADOS: Un 97,8% de los estudiantes opinan que el trabajo interprofesional es importante; un 27,1% de ellos declara que su universidad no le ha entregado importancia en sus planes de estudios. Los profesionales mencionados como más importantes en el equipo son los médicos y enfermeras. CONCLUSIONES: Espacios de desarrollo y respaldo institucional son elementos claves para promover el trabajo interprofesional. Que esta competencia logre involucrar a cada unidad académica en sus diferentes espacios formativos será un aporte significativo en aquello. Trabajo en equipo es una tarea pendiente.


Subject(s)
Interprofessional Relations , Patient Care Team , Primary Health Care , Students, Health Occupations , Chile , Cross-Sectional Studies , Female , Humans , Male , Surveys and Questionnaires
10.
Rev. saúde pública (Online) ; 51(39): 1-10, 2017. ilus, tab, graf
Article in English, Spanish | LILACS, RHS Repository | ID: biblio-981933

ABSTRACT

La educación médica se ha enfocado, históricamente, en el desempeño individual de los profesionales de la salud. Sin embargo, ante los cambios en el foco, estructura y necesidades de los sistemas de atención en salud, el foco se ha redirigido hacia el trabajo en equipo. Esta concepción implica una acción coordinada, llevada a cabo por dos o más individuos, lo que implica metas acordadas en conjunto, y exige entendimiento claro y respeto de los roles y las funciones de cada miembro. El trabajo en equipo, más que un fin, es un proceso y requiere la habilidad de trabajar como colegas, en vez de superior-subordinado. En este sentido, se entiende por multiprofesionalismo al trabajo común realizado por profesionales de las diferentes categorías, en las que su contribución individual conduce a un producto final que satisface los requerimientos únicos de cada parte en la solución de los problemas identificados. Tanto la construcción colectiva del trabajo a realizar por el equipo multidisciplinario cuanto las posibilidades de incorporar la atención a las prácticas profesionales, indican la necesidad de identificar y desarrollar dimensiones comunicativas en los sujetos involucrados en el cuidado (trabajadores y usuarios). Los equipos multidisciplinarios deben superar los acuerdos y articulaciones centradas solo en las relaciones. La Organización Mundial de la Salud señala que la práctica colaborativa optimiza los resultados de la atención en salud entregando una atención integral a los pacientes, sus familias, cuidadores y comunidades. Los profesionales preparados para la práctica colaborativa han aprendido a trabajar en un equipo interprofesional mediante entrenamiento efectivo en educación interprofesional; esta educación ocurre cuando estudiantes de dos o más profesiones aprenden sobre, de y entre ellos mismos para permitir una colaboración efectiva. (AU)


Subject(s)
Humans , Patient Care Team/trends , Health Human Resource Evaluation , Interprofessional Relations , Social Perception , Students, Health Occupations , Health Knowledge, Attitudes, Practice , Public Health , Interdisciplinary Communication , Health Human Resource Training
11.
J Insect Sci ; 16(1)2016.
Article in English | MEDLINE | ID: mdl-27324585

ABSTRACT

Hypogeococcus pungens Granara de Willink, sensu stricto, is a serious pest of cacti in Puerto Rico threating many Caribbean islands. A classical biological control program for H. pungens was initiated for Puerto Rico in 2010 with a survey for natural enemies of H. pungens in its native range of Argentina. Biological differences were observed between populations of H. pungens sampled on Amaranthaceae and Cactaceae. Molecular studies suggested that H. pungens populations from different host plant families are likely a complex of species. Our objective was to study the biology of H. pungens sensu stricto on specimens collected in the same locality and host plant as the holotype [Tucumán Province, Argentina; Alternanthera pungens Kunth (Amaranthaceae)]. We were interested in the reproductive biology of females, longevity and survival of adults, the effect of temperature on the development, and nymph performance (survival and development) on five Cactaceae species. We found that H. pungens s.s showed marked biological differences from the populations collected on Cactaceae and exported to Australia for the biological control of the cactus Harrisia spp. The main differences were the presence of deuterotoky parthenogenesis and the fact that H. pungens did not attack Cactaceae in the laboratory. Our results provide biological evidence that H. pungens is a species complex. We propose that the population introduced to Australia is neither Hypogeococcus festerianus Lizer y Trelles nor H. pungens, but an undescribed species with three circuli, and that the Hypogeococcus pest of cacti in Puerto Rico is not H. pungens.


Subject(s)
Cactaceae , Hemiptera/classification , Hemiptera/physiology , Herbivory , Animals , Argentina , Female , Fertility , Hemiptera/growth & development , Longevity , Male , Nymph/classification , Nymph/growth & development , Nymph/physiology , Puerto Rico , Reproduction , Temperature
12.
Rev. Fac. Med. Univ. Nac. Nordeste ; 36(1): 6-17, 2016. ilus, tab
Article in Spanish | LILACS | ID: biblio-1045908

ABSTRACT

El objetivo del presente estudio fue optimizar la implementación de cultivos primarios a partir de muestras de carcinoma renal de células claras (CRCC) para comprobar la conservación del fenotipo lipogénico contra cortes fijados del mismo origen. Se utilizaron muestras de pacientes con CRCC, evaluándose diversas metodologías y condiciones experimentales de digestión de muestras, adherencia y despegue celular, fenotipo lipogénico, potencial de clonación, proliferación y capacidad de migración. El mayor rendimiento y viabilidad celular se verificó mediante digestión con colagenasa. La adherencia inicial se logró a las 24 hs de incubación, utilizando placas plásticas de cultivo, recubiertas con colágeno comercial y gelatina 0,2% en la mayoría de las muestras analizadas (60% de los casos). Se obtuvieron monocapas, con potencial de migración, en un 40% de los casos, tras 5 ± 1 días de incubación. El promedio de subcultivos fue de 3 ± 1. Este estudio permitió estandarizar cultivos primarios de CRCC comprobándose la conservación de la fenotipia lipogénica, logrando de dicha manera una herramienta importante y útil para el estudio de la biología tumoral y el ensayo de nuevas terapéuticas


The aim of this study was to optimize the implementation of primary cultures from samples of renal clear cell carcinoma (CRCC) to check the conservation of the lipogenic phenotype. CRCC Patient samples were used, in order to evaluate different methodologies and the experimental conditions of sample digestion, cell adhesion and lipogenic phenotype, proliferation and migration ability. The highest yield in cell number and viability was assessed using collagenase digestion. The initial adhesion was achieved after 24 hours of incubation in plastic plates recoverd with commercial collagen or 0.2% gelatin (60% of cases). Monolayers, with migration potential, were obtained in 40% of all cases, after 5 ± 1 days of incubation. The subcultures average was 3 ± 1. This study allowed us to standardize primary cultures of CRCC and check the conservation of the lipogenic phenotyping, achieving in this way an important and useful tool to study the tumor biology.


O objetivo deste trabalho foi otimizar a implementação de culturas primárias de amostras de carcinoma de células claras renal (CRCC) para verificar conservação fenótipo lipogenic contra os cortes previstos a mesma origem. As amostras dos pacientes foram utilizados CRCC, avaliando diferentes metodologias e as condições experimentais da digestão de amostras, adesão celular e fenótipo clonagem potencial take-lipogenic, proliferação e capacidade de migração. O maior rendimento e a viabilidade celular foi avaliada por digestão com colagenase. A adesão inicial foi obtida após 24 horas de incubação com colagénio e gelatina comercial 0,2% em 60% dos casos. As monocamadas foram obtidos em 40% após 5 ± 1 dias de incubação com o potencial de migração. As subculturas média foi de 3 ± 1. Este estudo nos permitiu padronizar culturas primárias de CRCC são verificados quanto à conservação da fenotipagem lipogenic, conseguindo desta forma um importante e útil para o estudo da biologia do tumor e teste de nova ferramenta terapêutica


Subject(s)
Humans , Carcinoma, Renal Cell/diagnosis , Kidney Neoplasms/diagnosis , Culture Techniques/methods , Primary Cell Culture/methods
13.
Rev. MVZ Córdoba ; 20(2): 4564-4571, May-Aug. 2015. ilus, tab
Article in English | LILACS | ID: biblio-957305

ABSTRACT

Objective. Evaluate the productivity and composition of fatty acids in chicks fed diets enriched with neem Azadirachta indica A. Juss seed flour. Materials and methods. 80 mixed broiler chicks of Arbor Acres stock and levels 0, 1, 3 and 5% neem seed flour added to a commercial diet were evaluated. 20 experimental units were included in each treatment for five weeks. The consumption and weight gain were recorded, as well as the composition of fatty acids in the fat by means of alkaline transesterification. Data was statistically analyzed by a completely random procedure and the measurements were compared with the Tukey test(p≤0.05). Results. The greatest weight gain, consumption and best feed conversion were found in the treatment that contains 1% neem seed flour. It also produced the increase in the proportion of polyunsaturated fatty acids, especially linoleic acid (C18:2 Omega-6) and eicosapentaenoic acid (C20:5 omega-3), and the proportion of palmitic acid (C16:0). The consumption of feed diminished when 5% of neem flour was added. Conclusions. It was demonstrated that incorporating 1% neem seed flour in the diet of broiler chicks modifies the consumption of fatty acids without harming its productive behavior.


Objetivo. Evaluar la productividad y composición de ácidos grasos en pollos alimentados con dietas adicionadas con harina de semilla de neem Azadirachta indica A. Juss. Materiales y métodos. Se emplearon 80 pollos mixtos de la estirpe Arbor Acres de engorda y se evaluaron los niveles 0, 1, 3 y 5% de harina de semilla de neem añadidos a una dieta comercial. En cada tratamiento se tuvieron 20 unidades experimentales con una duración de cinco semanas. Se registró el consumo y la ganancia de peso, así como la composición de los ácidos grasos de la grasa mediante transesterificación alcalina. Los datos se analizaron estadísticamente por el procedimiento completamente al azar y las medias se compararon con la prueba de Tukey (p≤ 0.05). Resultados. La mayor ganancia de peso, consumo y la mejor conversión alimenticia correspondió al tratamiento que contenia 1% de harina de semilla de neem. También propició el aumento en la proporción de ácidos grasos poliinsaturados especialmente en el ácido linoleico, (C18:2 omega-6) y en el ácido eicosapentaenoico (C20:5 omega-3), y de manera concomitante se redujo la proporción del ácido palmítico (C16:0). El consumo de alimento disminuyó al adicionar 5% de harina de neem. Conclusiones. Se demostró que la incorporación de 1% de harina de semilla de neem en la dieta de los pollos de engorda modifica la composición de ácidos grasos sin perjudicar su comportamiento productivo.

14.
Nanoscale ; 7(15): 6667-74, 2015 Apr 21.
Article in English | MEDLINE | ID: mdl-25797852

ABSTRACT

Plasmonic nanostructures comprising Au and ZnO nanoparticles synthesized by the spontaneous reduction of HAuCl4 in ethylene glycol were used to assess the possibility of modulating the direction of the electron transfer processes at the interface. One electron UV reduction and visible oxidation of the reversible couple TEMPOL/TEMPOL-H was confirmed by EPR spectroscopy. The apparent quantum yield for TEMPOL-H conversion under continuous wave visible excitation depends on the irradiation wavelength, being 0.57% and 0.27% at 450 ± 12 and 530 ± 12 nm, respectively. These results indicate that both the surface plasmon resonance and the interband transition from the 5d to the 6s level of Au nanoparticles contribute to the visible activity of the nanostructure. In addition, by detecting free electron conduction band electrons in ZnO, after the visible excitation of Au/ZnO nanostructures, we provide direct evidence of the photoexcited electron transfer from gold nanoparticles to ZnO.

15.
Soft Matter ; 11(17): 3367-72, 2015 May 07.
Article in English | MEDLINE | ID: mdl-25809584

ABSTRACT

Recently, Roht et al. [J. Contam. Hydrol., 2013, 145, 10-16] observed that the presence of suspended non-Brownian macroscopic particles decreased the dispersivity of a passive solute, for a pressure-driven flow in a narrow parallel-plate channel at low Reynolds numbers. This result contradicts the idea that the streamline distortion caused by the random diffusive motion of the particles increases the dispersion and mixing of the solute. Therefore, to estimate the influence of this motion on the dispersivity of the solute, and investigate the origin of the reported decrease, we experimentally studied the probability density function (pdf) of the particle velocities, and spatio-temporal correlations, in the same experimental configuration. We observed that, as the mean suspension velocity exceeds a critical value, the pdf of the streamwise velocity of the particles markedly changes from a symmetric distribution to an asymmetric one strongly skewed to high velocities and with a peak of the most probable velocity close to the maximum velocity. The latter observations and the analysis of the suspension microstructure indicate that the observed decrease in the dispersivity of the solute is due to particle migration to the mid-plane of the channel, and consequent flattening of the velocity profile. Moreover, we estimated the contribution of particle diffusive motion to the solute dispersivity to be three orders of magnitude smaller than the reported decrease, and thus negligible. Solute dispersion is then much more affected by how particles modify the flow velocity profile across the channel than by their random diffusive motion.

16.
Article in English | MEDLINE | ID: mdl-25122295

ABSTRACT

For the last 50 years, the flow of a granular material through an aperture has been intensely studied in gravity-driven vertical systems (e.g., silos and hoppers). Nevertheless, in many industrial applications, grains are horizontally transported at constant velocity, lying on conveyor belts or floating on the surface of flowing liquids. Unlike fluid flows, that are controlled by the pressure, granular flow is not sensitive to the local pressure but rather to the local velocity of the grains at the outlet. We can also expect the flow rate to depend on the local density of the grains. Indeed, vertical systems are packed in dense configurations by gravity, but, in contrast, in horizontal systems the density can take a large range of values, potentially very small, which may significantly alter the flow rate. In the present article, we study, for different initial packing fractions, the discharge through an orifice of monodisperse grains driven at constant velocity by a horizontal conveyor belt. We report how, during the discharge, the packing fraction is modified by the presence of the outlet, and we analyze how changes in the packing fraction induce variations in the flow rate. We observe that variations of packing fraction do not affect the velocity of the grains at the outlet, and, therefore, we establish that flow-rate variations are directly related to changes in the packing fraction.


Subject(s)
Models, Theoretical , Motion , Particle Size
17.
Rev. MVZ Córdoba ; 18(supl.1): 3612-3617, dic. 2013. ilus, tab
Article in English | LILACS, COLNAL | ID: lil-701787

ABSTRACT

Objective. Was to evaluate the effect of GnRH and D-Chloprostenol application on pregnancy and prolificacy rates on Pelibuey ewes. Materials and methods. Forty five ewes were randomly allocated to one of three treatments: T1(n=15), day 0: sponges with 65 mg medroxyprogesterone acetate (MPA) + 200 IU equine chorionic gonadotropin (eCG) and sponge removal (day 12) + breeding by natural mating (days 12-15); T2 (n=15), day 0: 50 µg gonadotropin releasing hormone (GnRH) + 7.5 mg D-Chloprostenol (day 5) + 50 µg GnRH (day 7) + insemination at fixed time (AIFT) 12 to 14 h after last injection of GnRH; T3 (n=15), 100 µg GnRH (day 0) + 7.5 mg D-Chloprostenol (day 5) + 100 µg GnRH (day 7) + AIFT 12 to 14 h after last injection of GnRH. Results. The average concentration of progesterone (P4) in blood was 1.22 ± 0.74 ng/mL, which was used to verify ovarian activity at the beginning of the treatments. 100% of the T1 ewes presented estrus, beginning at 38.4±9.56 h after sponge removal. There were differences (p<0.05) for pregnancy rates, of 60, 33.33 and 46.66% respectively, among the treatments. Prolificacy was no different (p>0.05) among the treatments where the values were 1.2, 1.4 and 1.4 lambs/ewe for T1, T2 and T3, Conclusions. The results of this study show that the use of GnRH and D-Chloprostenol did improve pregnancy rates but did not improve prolificacy in tropical ewes.


Objetivo. Fue evaluar el efecto de la aplicación de GnRH y D-Cloprostenol en la tasa de gestación y prolificidad en ovejas Pelibuey. Materiales y métodos. Cuarenta y cinco ovejas fueron asignadas aleatoriamente a uno de tres tratamientos: T1(n=15), día 0: esponjas con 65 mg de acetato de medroxiprogesterona (MPA) + 200 UI de gonadotropina coriónica equina (eCG) al retirar las esponjas (día 12), servidas con monta natural (día 12-15); T2 (n=15), día 0: 50 µg de hormona liberadora de gonadotropinas (GnRH) + 7.5 mg de D-Cloprostenol (día 5) + 50 µg de GnRH (día 7) + inseminación a tiempo fijo (IATF) 12 a 14 h después de la segunda inyección de GnRH; T3 (n=15), 100 µg de GnRH (día 0) + 7.5 mg de D-Cloprostenol (día 5) + 100 µg de GnRH (día 7)+IATF 12 a 14 h después de la segunda inyección de GnRH. Resultados. La concentración promedio de progesterona (P4) en sangre fue 1.22 ± 0.74 ng/mL, que demostró actividad ovárica. El 100% de las ovejas de T1 presentaron estro, iniciando a las 38.4 ± 9.56 h del retiro de esponjas. El porcentaje de gestación fue diferente (p<0.05) entre T1, T2 y T3, siendo 60, 33.33 y 46.66%, respectivamente. La prolificidad no presentó diferencias (p>0.05) para T1, T2 y T3, siendo 1.2, 1.4 y 1.4 corderos/oveja parida, respectivamente. Conclusiones. Los resultados de este estudio indican que bajo condiciones tropicales el uso de GnRH y D-Cloprostenol, mejoró el porcentaje de gestación pero no la prolificidad.


Subject(s)
Estrus Synchronization , Gonadotropin-Releasing Hormone , Pregnancy
18.
Article in English | MEDLINE | ID: mdl-24483555

ABSTRACT

An experimental and theoretical study of the flow of liquid films around a stationary horizontal cylinder is reported. The film presents two different behaviors: The flow is stable in the upper zone (up to ∼150° with the vertical) and Rayleigh-Taylor-like instabilities appear in the lower zone. For the stable region, film thickness evolution could be described by numerically integrating an evolution equation obtained using a lubrication approximation. For the unstable region, a linear stability analysis allows us to determine the maximum growth wavelength for the Rayleigh-Taylor instability. Approximate analytical solutions were obtained for generatrices at an angle with the vertical θ=0 (stable region) and θ=π (where the instability appears).

19.
Acta Ortop Mex ; 27(6): 396-401, 2013.
Article in Spanish | MEDLINE | ID: mdl-24716372

ABSTRACT

BACKGROUND: The prognosis of late onset Perthes cases is usually poor and the proposed treatments vary based on the surgeon's preferences and experience, as well as on the available resources. Most of them are salvage procedures with a short follow-up and non-standardized application criteria. METHODS: Hip arthroscopy and arthrodiastasis with external fixator are indicated for certain situations in Perthes disease. Based on the results obtained with each of these techniques separately, both of them were used to treat a case of Perthes disease involving a poor prognosis. RESULTS: Results two years after surgery are good. CONCLUSIONS: The use of both techniques together may produce a good result in these patients.


Subject(s)
Arthroscopy , External Fixators , Legg-Calve-Perthes Disease/surgery , Adolescent , Age Factors , Humans , Male , Orthopedic Procedures/methods
20.
Rev. Fac. Med. Univ. Nac. Nordeste ; 32(2): 22-24, jun.-dic. 2012. ilus
Article in Spanish | LILACS | ID: lil-722443

ABSTRACT

RESUMEN:Se denomina accidente bothrópico al cuadro clínico producido por el veneno inoculado por ofidios del género Bothrops(Yarará). Este se caracteriza por ser proteolítico, coagulante y hemorragíparo, y ocasiona en las víctimasefectos locales y sistémicos.Las complicaciones incluyen: tendinitis, fascitis, infección bacteriana, abscesos y síndrome compartimental. Esteúltimo tiene una incidencia inferior...


SUMMARY:Clinical simptoms produced by venom of Bothrops (Yarará) are called ophidism. The poison of these snakes hasproteolitic, coagulant action and causes hemorrage. It causes local and systemic effects.Complications include: tendinitis, fasciitis, bacterial infection, abscesses and compartment syndrome...


Chama-se acidente botrï ao quadro clínico produzidos pelo veneno de Bothrops ophidia. Recaracteriza por ser proteolítica,coagulante e hemorragiparo e causas das vítimas em efeitos locais e sistêmicos. No sítio da inoculação ocorreum dano tecidual imediatamente com mionecrose, hemorragia e edema.Complicações incluem: tendinite, fasciíte plantar, infecção bacteriana, abscesso, e síndrome compartimental...


Subject(s)
Humans , Amputation, Surgical , Anterior Compartment Syndrome , Argentina , Bothrops
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