Photonic Crystal Directional Coupler Based Optomechanical Sensor

An extremely small ($6.5\times6.5\mu$m) optomechanical sensor is proposed that utilizes a photonic crystal (PC) etched onto silicon-on-insulator (SOI) using adapted complimentary metal-oxide-semiconductor fabrication technology. The destructive interference of light with the periodic structure can forbid its propagation inside the crystal across a range of frequencies and can be used to confine light near edge of a PC slab. By placing two PC edges near each other, a directional coupler is formed where light is periodically exchanged between the two waveguides. Wet-etching away the buried oxide residing beneath the photonic crystal directional coupler (PCDC), a membrane is formed. Exerting force on the PCDC alters the separation between the two PC edges and modulates the observed transmission at the coupler outputs. Buckle-mitigating structures are also demonstrated here which relieve the unpredictable compressive stress built into the top silicon layer of SOI during wafer fabrication. The PCDC sensors attempt to overcome some of the shortcomings of existing micromechanical sensors such as area constraints, material restrictions, stiction, and EM interference. PCDC sensors are also highly parallelizable due to their small size and wide optical bandwidth. PCDC sensors are envisaged to be used in microfluidic integration and are capable of 149kPa full scale pressure measurement ranges

Self-similar structure and experimental signatures of suprathermal ion distribution in inertial confinement fusion implosions

The distribution function of suprathermal ions is found to be self-similar under conditions relevant to inertial confinement fusion hot-spots. By utilizing this feature, interference between the hydro-instabilities and kinetic effects is for the first time assessed quantitatively to find that the instabilities substantially aggravate the fusion reactivity reduction. The ion tail depletion is also shown to lower the experimentally inferred ion temperature, a novel kinetic effect that may explain the discrepancy between the exploding pusher experiments and rad-hydro simulations and contribute to the observation that temperature inferred from DD reaction products is lower than from DT at National Ignition Facility.Comment: Revised version accepted for publication in PRL. "Copyright (2015) by the American Physical Society.

Influência da irrigação na salinização e sodificação dos solos do Projeto de Irrigação de São Gonçalo.

Para esclarecer a influencia da irrigacao e as condicoes de drenagem no desenvolvimento de problemas de salinidade e sodicidade nos solos do Projeto de Irrigacao de Sao Goncalo, foram escolhidos 25 pontos fixos de amostragens permanentes distribuidas na area em operacao do Projeto. Durante quatro anos seguidos foram tomadas amostras de solo ate 90 cm de profundidade, para determinacao de pH, condutividade eletrica e cations trocaveis. Tambem foram feitas observacoes mensais do lencol freatico durante um ano em todos os pontos de amostragens. A agua de irrigacao foi tambem amostrada e analisada periodicamente. Com base nos resultados das analises nao foi possivel identificar aumento da salinidade nem da sodicidade do solo. Aparentemente isto parece ser devido a boa qualidade da agua de irrigacao em combinacao com certo grau de drenagem natural do rio Piranhas.bitstream/item/68365/1/Gilberto-1.pdfTrabalho apresentado no I Simpósio Brasileiro do Trópico Semi-Árido, Olinda, ago. 1982

The Wnt Co-Receptor Lrp6 Is Required for Normal Mouse Mammary Gland Development

Canonical Wnt signals are transduced through a Frizzled receptor and either the LRP5 or LRP6 co-receptor; such signals play central roles during development and in disease. We have previously shown that Lrp5 is required for ductal stem cell activity and that loss of Lrp5 delays normal mammary development and Wnt1-induced tumorigenesis. Here we show that canonical Wnt signals through the Lrp6 co-receptor are also required for normal mouse mammary gland development. Loss of Lrp6 compromises Wnt/β-catenin signaling and interferes with mammary placode, fat pad, and branching development during embryogenesis. Heterozygosity for an inactivating mutation in Lrp6 is associated with a reduced number of terminal end buds and branches during postnatal development. While Lrp6 is expressed in both the basal and luminal mammary epithelium during embryogenesis, Lrp6 expression later becomes restricted to cells residing in the basal epithelial layer. Interestingly, these cells also express mammary stem cell markers. In humans, increased Lrp6 expression is associated with basal-like breast cancer. Taken together, our results suggest both overlapping and specific functions for Lrp5 and Lrp6 in the mammary gland

Irrigation water quality on the salinity and sodicity of soils in the São Gonçalo project

Para esclarecer a influência da irrigação e as condições de drenagem no desenvolvimento de problemas de salinidade e sodicidade nos solos aluviais do Projeto de Irrigação de São Gonçalo, foram escolhidos 25 pontos fixos de amostragem permanente distribuídos na área em operação do projeto. Uma vez por ano e durante quatro anos seguidos foram tomadas amostras de solo até 90 cm de profundidade, para determinação de pH, condutividade elétrica (CE) e cátions trocáveis. Também foram feitas observações mensais do lençol freático durante um ano em todos os pontos de amostragens. A água de irrigação foi também amostrada e analisada periodicamente. Com base nos resultados das análises, não foi possível identificar aumento da salinidade nem da sodicidade do solo. Aparentemente, isto deve-se a um equilíbrio de sais provavelmente atingido, favorecido por certo grau de drenagem natural subterrânea ao rio Piranhas, e à relativamente boa qualidade da água de irrigação.  In order to explain the influence of irrigation and drainage conditions on the salinity and sodicity built up on the alluvial soils of São Gonçalo Irrigation Project, some 25 points were selected widespread all over the area under operation for permanent sampling. Soil sampling, from 90 cm of depth, took place once a year during four consecutive years for determining the pH, CE and exchange cations. Ground (phreatic) water depth was also recorded once a month during a year in all the sampling sites, as well as irrigation water quality. No change was observed on the soil salinity and sodicity at the end of the study period. This is due, possibly, to a salt equilibrium achieved in the soil profile as a consequence of a certain degree of natural underground drainage towards the Piranhas river and to the relative good quality of the irrigation water

Integrating multiple perspectives on the human-nature relationship: A reply to Fletcher 2017

The concept of “connectedness with nature” is increasingly used in environmental and sustainability discourse. However, this construct has also been critiqued and proponents charged with harboring an ambivalence that paradoxically reinforces a sense of separation from “nature”. We respond to one critique by demonstrating that whilst problematizing aspects of “connectedness with nature” has merit, selective use of examples misconstrues efforts in this field, undermines common ground and conflates theoretical conceptualizations with practical implementation. In addressing problems of perception and praxis, we emphasize the primacy of direct experience in shaping ways of knowing and recommend integral ecology (based on Wilber’s integral theory) as an inclusive framework for attending to multiple perspectives on the human-nature relationship