First-order framework and domain-wall/brane-cosmology correspondence

AbstractWe address the possibility of finding domain wall solutions from cosmological solutions in brane cosmology. We find first-order equations for corresponding cosmology/domain wall solutions induced on 3-branes. The quadratic term of energy density in the induced Friedmann equation plays a non-standard role and we discuss the way the standard cosmological and domain wall models are recovered as the brane tension becomes large and show how they can be described by four-dimensional supergravity action in such a limit. Finally, we show that gravity on the 3-brane is locally localized as one moves away from the two-dimensional domain walls living on the brane

3D black holes on a 2-brane in 4D Minkowski space

We investigate three-dimensional black hole solutions in the realm of pure and new massive gravity in 2+1 dimensions induced on a 2-brane embedded in a flat four-dimensional spacetime. There is no cosmological constant neither on the brane nor on the four-dimensional bulk. Only gravitational fields are turned on and we indeed find vacuum solutions as black holes in 2+1 dimensions even in the absence of any cosmological solution. There is a crossover scale that controls how far the three- or four-dimensional gravity manifests on the 2-brane. Our solutions also indicate that local BTZ and SdS_3 solutions can flow to local four-dimensional Schwarzschild like black holes, as one probes from small to large distances, which is clearly a higher dimensional manifestation on the 2-brane. This is similar to the DGP scenario where the effects of extra dimensions for large probed distances along the brane manifest.Comment: 10 pages, 5 figures, to appear in PL

Chemical composition and toxicity of essential oils of Piper spp. against larvae of Aedes aegypti L. (Diptera: Culicidae)

Aedes aegypti L. é um dos vetores do dengue. No Brasil, tem ganhado muita atenção no setor da saúde pública, uma vez que esta doença tem se tornando mais agressiva na forma hemorrágica na popula- ção. Esse estudo teve como objetivo investigar o efeito de óleos essenciais de Piper aduncum, Piper marginatum e Piper nigrum contra larvas de Aedes aegypti. Em um esforço para encontrar uma maneira natural, eficaz e acessível para controlar esta doença endêmica, as atividades dos óleos essenciais, a partir das plantas, foram analisadas por comparação através da medida da CL50 . Os óleos essenciais obtidos por hidrodestilação foram analisados por CG/EM. Os principais componentes identificados foram: β-pineno (32,7%) e E-cariofileno (17,1%) em P. aduncum; isoelemecina (21,7%) e apiol (20,1%) em P. marginatum e E-cariofileno (24,2%) e Óxido-cariofileno (20,1%) em P. nigrum. Os resultados mostram que Piper marginatum apresentou CL50 de 8,29 μg/mL e este trabalho é o primeiro relato de atividade larvicida de P. aduncum. Estes resultados sugerem que os óleos essenciais de espécies do gênero Piper são promissores como larvicidas contra larvas de A. aegypti.Aedes aegypti L. is one of the vectors of dengue fever. In Brazil it has gain much attention in the Public Health sector since this disease has becoming more aggressive in the hemorrhagic form in the population. This study aimed to investigate the effect of Piper aduncum, Piper marginatum and Piper nigrum essential oils against Aedes aegypti larvae. In an effort to find a natural effective and affordable way to control this endemic disease, the larvicidal activities of essential oils from the plants were analyzed for activity comparison by measurement of their LC50 . The essential oils isolated by hydrodistillation were analyzed by GC/MS. The main components identified were: β-pinene (32.7%) and E-caryophyllene (17.1%) in P. aduncum; isoelemecin (21.7%) and apiole (20.1%) in P. marginatum and E-caryophyllene (24.2%) and caryophyllene oxide (20.1%) in P. nigrum. The results show that Piper marginatum presented the LC50 of 8.29 μg/mL and these are the first report about the larvicidal activity of P. aduncum. These results suggest that the essential oil of Piper species are promising as larvicide against A. aegypti larvae.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Actividad antifúngica de extractos de plantas contra cepas de Microsporum canis y Candida spp.

Con el objetivo de encontrar compuestos fitoterapéuticos para tratar las infecciones por hongos de los animales, plantas que se encuentran comúnmente en el noreste de Brasil se evaluaron in vitro frente a cepas de Microsporum canis y Candida spp. aisladas de perros y gatos. Los extractos etanólicos de hojas de Momordica charantia, Calotropis procera, Peschiera affinis y Piper tuberculatum y la decocción de Mangifera índica fueron evaluados inicialmente por el método de difusión en pocillos de agar. Cuatro extractos indujeron zonas de inhibición del crecimiento contra M. canis: P. tuberculatum (20 mm), M. índica (14 mm), M. charantia (13 mm) y P. affinis (11 mm). Ninguno de ellos fue activo contra Candida spp. Se realizaron pruebas de microdilución en caldo para las cepas de M. canis (n = 5), para encontrar la concentración mínima inhibitoria (CIM) y la concentración fungicida mínima (CFM). Las medias geométricas de los valores de CIM fueron 590, 370, 350, 170 mg/ml, y para los valores de CFM fueron 1.190, 750, 700, 340 mg/ml de M. charantia, P. affinis, P. tuberculatum y M. indica, respectivamente. Por lo tanto, los extractos de M. charantia, P. affinis, P. tuberculatum y M. indica son buenos candidatos para la producción de fitoterápicos antifúngicos ya que estos extractos demostraron una buena actividad contra M. canis