Visualization of Complex Flow Patterns in Angiotensin II-Induced Dissecting Murine Abdominal Aortic Aneurysms with High Frequency Ultrasound

Abdominal aortic aneurysm (AAA) rupture is a common cause of mortality in the United States. Current treatments are only employed once the risk of rupture outweighs the risks associated with surgery. Murine models have been developed to characterize AAA pathogenesis in the hope that new treatments will be developed. For this study, angiotensin II (AngII) was infused subcutaneously into apolipoprotein E-deficient (ApoE-/-) mice using an osmotic mini-pump over 28 days. ApoE-/- mice (16-week-old, 3 females, 2 males) were imaged using a VisualSonics Vevo 2100 high frequency ultrasound before pump implantation and 3, 7, 14, 21, and 27 days following implantation. Images were acquired in the transverse and longitudinal planes from the suprarenal region of the aorta. Blood pressure measurements were taken using a tail-cuff system (CODA, Kent Scientific). Three mice (1 female, 2 male) developed aneurysms within the first 14 days of infusion. Pre-study abdominal aortas had a diastolic diameter of 0.84±0.09 mm and a systolic diameter of 0.96±0.08 mm. By day 21, AAAs had a diastolic diameter of 1.51±0.59 mm and a systolic diameter of 1.56±0.59 mm. Initially, mice had a systolic blood pressure of 111.94±6.53 mmHg and a diastolic pressure of 82.38±5.13 mmHg. These pressures steadily elevated but eventually began to plateau. By day 27, systolic pressure had risen to 154.92±11.43 mmHg and diastolic pressure to 115.77±10.25 mmHg. Color Doppler images revealed complex, recirculating flow within the aneurysms, a phenomenon which could affect vessel remodeling. In conclusion, this study utilized in vivo sonographic methods to characterize AAA development

In Vivo Flow Measurements of Murine Renal Arteries and Veins with High Frequency Ultrasound

The number of glomeruli in the kidneys has been shown to have an effect on the decline in renal function over time (Brenner, Garcia, Anderson 1988). Furthermore, flow in the renal arteries and veins may depend on the number of glomeruli in the kidney. Consistent in vivo measurements of volumetric flow in the renal arteries and veins are difficult to obtain. Thus, the purpose of this study was to develop non-invasive imaging techniques capable of estimating arterial and venous flow to kidneys. A high-frequency small animal ultrasound system was chosen based upon its excellent spatial and temporal resolution when imaging mice (Vevo 2100, VisualSonics, Inc.). Velocity profiles of the renal arteries and veins in C57BL/6 male mice (n=4) were measured. Motion, color Doppler, and pulsed wave Doppler data were acquired and used to determine renal diameter, maximum velocity, mean velocity, and volumetric flow for both kidneys. For the renal artery the average volumetric flow was 33.31±7.16 mm3/s and for the renal vein it was 30.23±4.58 mm3/s. The next step will be imaging the same animals multiple times to ensure that these measurements are consistent over prolonged periods of time. Then data will be collected from different breeds of mice to conclude whether or not differences in glomeruli number affect renal flow. Measurement of volumetric flow in the renal arteries and veins can lead to important insights into how the glomeruli density in kidneys relates to renal flow and function

Internal solitary waves in the Coastal Mixing and Optics 1996 experiment : multimodal structure and resuspension

Observations of internal solitary waves (ISWs) and of their role in sediment resuspension during the Coastal Mixing and Optics 1996 (CMO 96) experiment are reported. The largest resuspension events observed in the experiment can be related to retarded flow under the wave footprint. Two distinctly different periods of resuspension events could be distinguished based on the prevailing atmospheric conditions: a calm period, which we consider characteristic of nominal conditions, and an energetic period, during which two major storms occurred. ISWs arrived at the mooring site from a variety of sources, though a common intermodal dynamics seemed to occur repeatedly. Both mode 1 and mode 2 ISWs have been observed. The present analysis of the month-long portion of the CMO 96 data set constitutes the first reported observations, insofar as we are aware, of mode 2 waves on the continental shelf. Both mode 1 and mode 2 ISWs were found to stimulate resuspension. The mode 2 waves seem to be generated locally by resonant or topographic interactions with mode 1 ISWs. Internal wave fields of the type described here are expected to exist in a variety of other shallow seas as well

On the Nature of the Frontal Zone of the Choctawhatchee Bay Plume in the Gulf of Mexico

River plumes often feature turbulent processes in the frontal zone and interfacial region at base of the plume, which ultimately impact spreading and mixing rates with the ambient coastal ocean. The degree to which these processes govern overall plume mixing is yet to be quantified with microstructure observations. A field campaign was conducted in a river plume in the northeast Gulf of Mexico in December 2013, in order to assess mixing processes that could potentially impact transport and dispersion of surface material near coastal regions. Current velocity, density, and Turbulent Kinetic Energy Values, ε, were obtained using an Acoustic Doppler Current Profiler (ADCP), a Conductivity Temperature Depth (CTD) profiler, a Vertical Microstructure Profiler (VMP), and two Acoustic Doppler Velocimeters (ADVs). The frontal region contained ε values on the order of 10−5 m2 s−3, which were markedly larger than in the ambient water beneath (O 10−9 m2s−3). An energetic wake of moderate ε values (O 10−6 m2 s−3) was observed trailing the frontal edge. The interfacial region of an interior section of the plume featured opposing horizontal velocities and a ε value on the order of 10−6 m2 s−3. A simplified mixing budget was used under significant assumptions to compare contributions from wind, tides, and frontal regions of the plume. The results from this order of magnitude analysis indicated that frontal processes (59%) dominated in overall mixing. This emphasizes the importance of adequate parameterization of river plume frontal processes in coastal predictive models

Giant Monopole Resonance in Transitional and Deformed-Nuclei

Journals published by the American Physical Society can be found at http://publish.aps.org

SeaSoar spectral light absorption and attenuation observations during the coastal mixing and optics experiment : R/V Endeavor cruises from 14-Aug to 1-Sep 1996 and 25-Apr to 15-May 1997

This data report includes documentation of the Coastal Mixing and Optics (CMO) Experiment inherent optical property surveys on the continental shelf and slope in the Mid-Atlantic Bight south of Cape Cod, Massachusettes, USA. The surveys were conducted aboard the R/V Endeavor during two physical oceanography cruises: E9608 (14 August to 1 September 1996) and E9704 (25 April to 15 May 1997). The objective of the CMO Experiment was to rapidly survey a region in the Mid-Atlantic Bight (centered around 40.5°N, 70.5°W) to obtain three-dimensional, high-resolution measurements which would allow further elucidation of the lengthscales, distributions and relationships between hydrographic and optical properties. This report describes the installation and deployment of the optical instrumentation as well as the data acquisition, data processing and editing of the inherent optical property data. Vertical sections and maps of the inherent optical properties obtained from the surveys are also presented

Systematics of the Giant Monopole Resonance from Inelastic Alpha Scattering

Journals published by the American Physical Society can be found at http://publish.aps.org

Giant-Resonances in Ca-40

Journals published by the American Physical Society can be found at http://publish.aps.org

Optical measurement of rates of dissipation of temperature variance due to oceanic turbulence

Inhomogeneities in the refractive index induced by temperature fluctuations in turbulent flows have the effect of scattering light in near-forward angles. We have developed a method that extracts the rate of Temperature Variance Dissipation (TVD) and its spectrum from the properties of light scattering and have built an instrument - Optical Turbulence Sensor (OTS) - that implements the method. OTS uses a linear wavefront sensing Hartmann array and allows for nearly instantaneous measurements of temperature variance in turbulent flows. The instrument has been tested in an situ experiment carried out from a drifting vessel at a site off the coast of Newport, Oregon. Here we compare the temperature variance measured by OTS and its spectra with both theoretical predictions and with spectra obtained from a fast thermistor sensor.This paper was published in Optics Express and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsinfobase.org/oe/home.cfm. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.Keywords: Wave-front sensing, Turbulenc