All-optical endoscopic probe for high resolution 3D photoacoustic tomography

A novel all-optical forward-viewing photoacoustic probe using a flexible coherent fibre-optic bundle and a Fabry- Perot (FP) ultrasound sensor has been developed. The fibre bundle, along with the FP sensor at its distal end, synthesizes a high density 2D array of wideband ultrasound detectors. Photoacoustic waves arriving at the sensor are spatially mapped by optically scanning the proximal end face of the bundle in 2D with a CW wavelength-tunable interrogation laser. 3D images are formed from the detected signals using a time-reversal image reconstruction algorithm. The system has been characterized in terms of its PSF, noise-equivalent pressure and field of view. Finally, the high resolution 3D imaging capability has been demonstrated using arbitrary shaped phantoms and duck embryo

Multi-scale analysis of compressible viscous and rotating fluids

We study a singular limit for the compressible Navier-Stokes system when the Mach and Rossby numbers are proportional to certain powers of a small parameter \ep. If the Rossby number dominates the Mach number, the limit problem is represented by the 2-D incompressible Navier-Stokes system describing the horizontal motion of vertical averages of the velocity field. If they are of the same order then the limit problem turns out to be a linear, 2-D equation with a unique radially symmetric solution. The effect of the centrifugal force is taken into account

Field spectrometer to measure percent ground coverage and leaf area index of agriculture crops

Measurement of percent ground cover (PGC) and leaf area index (LAI) are required for crop modelling, yield estimation and for ground truth data in remote sensing studies. An instrument which traverses on a track above a crop and continuously measures the ratio of incident and reflected radiation at various wavelengths was developed and tested. Spectral irradiance and reflectance measurements were made at four wavelengths (647.8, 675.5, 739.9, 790.4 nm) at eight stages of growth of wheat and barley for three crop densities. Data provided information on the relations between spectral properties at selected wavelength and leaf area expansion at different growth stages. The spectral data were highly correlated with leaf area index measurements

Variations of crop canopy spectral reflectance measurements under changing sky conditions

The possibility of using reflectance data collected under both cloudy and sunny conditions is studied. Extrenle values of red and far-red reflectances measured directly over bare soil and crop canopies during intermittently cloudy conditions can differ by more than 100 percent and 60 percent, respectively. Eliminating the irradiance variations by using only data collected under sunny conditions reduced such variation to within 1 percent for bare soil and to within 8 percent and 20 percent for crop canopy red and far-red reflectances, respectively. In general, the reflectances measured under cloudy conditions with relatively constant irradiance values are constant and approximately 10 percent larger than the ones measured at similar sun angles during sunny conditions. This result is independent of the species and the spectral regions under study

FUM1—A Gene Required for Fumonisin Biosynthesis But Not for Maize Ear Rot and Ear Infection by Gibberella moniliformis in Field Tests

We have analyzed the role of fumonisins in infection of maize (Zea mays) by Gibberella moniliformis (anamorph Fusarium verticillioides) in field tests in Illinois and Iowa, United States. Fumonisin-nonproducing mutants were obtained by disrupting FUM1 (previouslyFUM5), the gene encoding a polyketide synthase required for fumonisin biosynthesis. Maize ear rot, ear infection, and fumonisin contamination were assessed by silk-channel injection in 1999 and 2000 and also by spray application onto maize silks, injection into maize stalks, and application with maize seeds at planting in 1999. Ear rot was evaluated by visual assessment of whole ears and by calculating percentage of symptomatic kernels by weight. Fumonisin levels in kernels were determined by high-performance liquid chromatography. The presence of applied strains in kernels was determined by analysis of recovered isolates for genetic markers and fumonisin production. Two independent fumonisin-nonproducing (fum1-3 and fum1-4) mutants were similar to their respective fumonisin-producing (FUM1-1) progenitor strains in ability to cause ear rot following silk-channel injection and also were similar in ability to infect maize ears following application by all four methods tested. This evidence confirms that fumonisins are not required for G. moniliformis to cause maize ear rot and ear infection

Field spectrometer to measure percent ground coverage and leaf area index of agriculture crops [remote sensing]

Measurement of percent ground cover (PGC) and leaf area index (LAI) are required for crop modelling, yield estimati-on and for ground truth data in remote sensing studies. An instrument which traverses on a track above a crop and continuously measures the ratio of incident and reflected radiation at various wavelengths was developed and tested. Spectral irradiance and reflectance measurements were made at four wavelengths (647.8 , 675.5 , 739.9 , 790.4 nm) at eight stages of growth of wheat and barley for three crop densities. Data provided information on the relations between spectral properties at selected wavelength and leaf area expansion at different growth stages. The spectral data were highly correlated with leaf area index measurements

Patient-specific polyvinyl alcohol phantom fabrication with ultrasound and x-ray contrast for brain tumor surgery planning

Phantoms are essential tools for clinical training, surgical planning and the development of novel medical devices. However, it is challenging to create anatomically accurate head phantoms with realistic brain imaging properties because standard fabrication methods are not optimized to replicate any patient-specific anatomical detail and 3D printing materials are not optimized for imaging properties. In order to test and validate a novel navigation system for use during brain tumor surgery, an anatomically accurate phantom with realistic imaging and mechanical properties was required. Therefore, a phantom was developed using real patient data as input and 3D printing of molds to fabricate a patient-specific head phantom comprising the skull, brain and tumor with both ultrasound and X-ray contrast. The phantom also had mechanical properties that allowed the phantom tissue to be manipulated in a similar manner to how human brain tissue is handled during surgery. The phantom was successfully tested during a surgical simulation in a virtual operating room. The phantom fabrication method uses commercially available materials and is easy to reproduce. The 3D printing files can be readily shared, and the technique can be adapted to encompass many different types of tumor

Stellar Populations in Compact Galaxy Groups: a Multi-Wavelength Study of HCGs 16, 22, and 42, their Star Clusters and Dwarf Galaxies

We present a multi-wavelength analysis of three compact galaxy groups, HCGs 16, 22, and 42, which describe a sequence in terms of gas richness, from space- (Swift, HST, Spitzer) and ground-based (LCO, CTIO) imaging and spectroscopy. We study various signs of past interactions including a faint, dusty tidal feature about HCG 16A, which we tentatively age-date at <1 Gyr. This represents the possible detection of a tidal feature at the end of its phase of optical observability. Our HST images also resolve what were thought to be double nuclei in HCG 16C and D into multiple, distinct sources, likely to be star clusters. Beyond our phenomenological treatment, we focus primarily on contrasting the stellar populations across these three groups. The star clusters show a remarkable intermediate-age population in HCG 22, and identify the time at which star formation was quenched in HCG 42. We also search for dwarf galaxies at accordant redshifts. The inclusion of 33 members and 27 'associates' (possible members) radically changes group dynamical masses, which in turn may affect previous evolutionary classifications. The extended membership paints a picture of relative isolation in HCGs 16 and 22, but shows HCG 42 to be part of a larger structure, following a dichotomy expected from recent studies. We conclude that (a) star cluster populations provide an excellent metric of evolutionary state, as they can age-date the past epochs of star formation; and (b) the extended dwarf galaxy population must be considered in assessing the dynamical state of a compact group.Comment: 29 pages, 13 figures. Accepted for publication in The Astrophysical Journa

Carbon content in amazonian oxisols after forest conversion to pasture.

O solo desempenha importante papel no ciclo do C, porém a substituição da floresta tropical por áreas cultivadas altera a dinâmica e o estoque desse elemento. Em uma frente pioneira de colonização no município de Itupiranga (PA), na Amazônia Oriental, foi desenvolvido este estudo com o objetivo de avaliar as consequências da substituição de floresta nativa por pastagens de Brachiaria brizantha no conteúdo de C de um Latossolo Amarelo distrófico. As amostras de solo foram coletadas em área de floresta nativa (FN), floresta secundária de 8?10 anos (FS), pastagens de 1?2 anos (P1-2), de 5?7 anos (P5?7) e de 10?12 anos (P10?12), nas camadas de 0?2, 2?5 e 5?10 cm, para avaliar os teores e o estoque de C e realizar um fracionamento granulométrico da matéria orgânica. Após o desmatamento, a densidade do solo aumentou até a profundidade de 5 cm, sendo esse aumento maior nas pastagens mais antigas. As maiores mudanças no conteúdo de C ocorreram na camada superior do solo, havendo aumento nesse conteúdo com o tempo de implantação das pastagens. Nas camadas de 2?5 e 5?10 cm, o conteúdo de C se mostrou estável entre os tipos de cobertura vegetal avaliados. As maiores concentrações de C foram encontradas na fração silte, mas os maiores conteúdos de C ocorreram na fração argila, independentemente do tipo de cobertura vegetal. Um aumento da quantidade de C associado à fração areia, na forma de resíduos orgânicos pouco decompostos, foi observado nas pastagens, confirmando a maior sensibilidade dessa fração às mudanças de uso do solo