Isometric Skeletal Muscle Contractile Properties in Common Strains of Male Laboratory Mice

Assessing contractile function of skeletal muscle in murine models is a commonly employed laboratory technique that investigators utilize to measure the impact of genetic manipulations, drug efficacy, or other therapeutic interventions. Often overlooked is the potential for the strain of the mouse to influence the functional properties of the skeletal muscle. Thus, we sought to characterize commonly assessed isometric force measures in the hindlimb muscles across a variety of mouse strains. Using 6-8-week-old male mice, we measured isometric force, fatigue susceptibility, relaxation kinetics, muscle mass, myofiber cross-sectional area, and fiber type composition of the extensor digitorum longus (EDL) and soleus muscles in C57BL/6NJ, BALB/cJ, FVB/NJ, C57BL/6J, and C57BL/10 mice. The data demonstrate both unique differences and a number of similarities between both muscles in the various genetic backgrounds of mice. Soleus muscle specific force (i.e., force per unit size) exhibited higher variation across strains while specific force of the EDL muscle exhibited minimal variation. In contrast, absolute force differed only in a few mouse strains whereas analysis of muscle morphology revealed many distinctions when compared across all the groups. Collectively, the data suggest that the strain of the mouse can potentially influence the measured biological outcome and may possibly promote a synergistic effect with any genetic manipulation or therapeutic intervention. Thus, it is critical for the investigator to carefully consider the genetic background of the mouse used in the experimental design and precisely document the strain of mouse employed during publication

Kinetic model for ozonation of toxic water contaminants

Issued as Annual report, Project no. E-20-W03 (continued by E-20-E03

Bilateral Deficit in Common Resistant Training Exercises

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Deepwater Horizon oil slick characterization with UAVSAR: Continuing investigations

In June 2010, the UAVSAR platform was deployed to the Gulf of Mexico in response to the Deepwater Horizon (DWH) oil spill. We have analyzed the quad-polarized L-band SAR data collected over the main oil slick to develop and validate algorithms for improved discrimination of oil slicks on water and identification of oil properties. Our results show that radar backscatter from both clean water and oil in the slick is predominantly from a single surface scatterer, consistent with the tilted Bragg scattering mechanism across the incidence angle range of 26-60°. We find that the change of backscatter over the main slick is due to both a damping of the ocean wave spectral components by the oil and an effective redn. of the dielec. const. resulting from a mixt. of 65-90% oil with water in the surface layer. These results support the use of synthetic aperture radar in quantifying oil volumetric concn. in a thick slick of emulsified oil. Our results are unique in that they quantify specific properties of thicker emulsified oil rather than simple slick extent, so are potentially useful for guiding spill clean-up. The improved sensitivity of UAVSAR compared to other aircraft and satellite SAR is due primarily to the low noise floor of ∼-50 dB, which is at least 20 dB below that of most radars in use over the DWH spill. With UAVSAR we can discriminate small variations in the radar signature within the oil slick, from which we have extd. bulk ests. of the volumetric concn. of the surface oil.This research was conducted in part at the Jet Propulsion Lab., California Institute of Technol., under contract with the National Aeronautics and Space Administration

Deepwater Horizon Oil Slick Characterization with UAVSAR

No abstract availabl

On the Use of Simulated Airborne Compact Polarimetric SAR for Characterizing Oil–Water Mixing of the Deepwater Horizon Oil Spill

Compact polarimetry (CP) synthetic aperture radar (SAR) is a form of coherent dual-pol SAR that has been shown to have great potential for maritime surveillance applications such as ship and ice detection. In this paper, we demonstrate the potential of CP data for oil spill characterization. As the availability of CP data is limited at this time, we simulate CP image data from UAVSAR L-Band quad-polarized images. We reconstruct quad-pol SAR data (termed pseudo-quad) from these simulated CP SAR data, and calculate an oil-water mixing index, termed Mdex. We show that the differences between the pseudo-quad and quad-pol Mdex maps are negligible. This contributes to the case that CP SAR has great potential for multiple applications in maritime surveillance

Oil slick detection in the offshore domain: evaluation of polarization-dependent SAR parameters

Remote sensing technology is an essential link in the global monitoring of the ocean surface and radars are efficient sensors for detecting marine pollution. When used operationally, a tradeoff must usually be made between the covered area and the quantity of information collected by the radar. To identify the most appropriate imaging mode, a methodology based on Receiver Operating Characteristic (ROC) curve analysis has been applied to an original dataset collected by an airborne system, SETHI, characterized by a very low instrument noise floor. The dataset was acquired during an oil spill clean-up exercise carried out in 2015 in the North Sea. Various polarization-dependent quantities are investigated and a relative ordering of the main polarimetric parameters is reported. VV offers the best tradeoff between the benefit of detection performance and the instrument and data requirements. When the sensor has a sufficiently low noise floor, HV is also recommended because it provides strong slick-sea contrast. Among all the investigated quad-polarimetric settings, no significant added value compared to single-polarized data was found

Plastic bed beneath Hofsjökull ice cap, central Iceland, and the sensitivity of ice flow to surface meltwater flux

The mechanical properties of glacier beds play a fundamental role in regulating the sensitivity of glaciers to environmental forcing across a wide range of timescales. Glaciers are commonly underlain by deformable till whose mechanical properties and influence on ice flow are not well understood but are critical for reliable projections of future glacier states. Using synoptic-scale observations of glacier motion in different seasons to constrain numerical ice flow models, we study the mechanics of the bed beneath Hofsjökull, a land-terminating ice cap in central Iceland. Our results indicate that the bed deforms plastically and weakens following incipient summertime surface melt. Combining the inferred basal shear traction fields with a Coulomb-plastic bed model, we estimate the spatially distributed effective basal water pressure and show that changes in basal water pressure and glacier accelerations are non-local and non-linear. These results motivate an idealized physical model relating mean basal water pressure and basal slip rate wherein the sensitivity of glacier flow to changes in basal water pressure is inversely related to the ice surface slope

Image1_Isometric skeletal muscle contractile properties in common strains of male laboratory mice.JPEG

Assessing contractile function of skeletal muscle in murine models is a commonly employed laboratory technique that investigators utilize to measure the impact of genetic manipulations, drug efficacy, or other therapeutic interventions. Often overlooked is the potential for the strain of the mouse to influence the functional properties of the skeletal muscle. Thus, we sought to characterize commonly assessed isometric force measures in the hindlimb muscles across a variety of mouse strains. Using 6-8-week-old male mice, we measured isometric force, fatigue susceptibility, relaxation kinetics, muscle mass, myofiber cross-sectional area, and fiber type composition of the extensor digitorum longus (EDL) and soleus muscles in C57BL/6NJ, BALB/cJ, FVB/NJ, C57BL/6J, and C57BL/10 mice. The data demonstrate both unique differences and a number of similarities between both muscles in the various genetic backgrounds of mice. Soleus muscle specific force (i.e., force per unit size) exhibited higher variation across strains while specific force of the EDL muscle exhibited minimal variation. In contrast, absolute force differed only in a few mouse strains whereas analysis of muscle morphology revealed many distinctions when compared across all the groups. Collectively, the data suggest that the strain of the mouse can potentially influence the measured biological outcome and may possibly promote a synergistic effect with any genetic manipulation or therapeutic intervention. Thus, it is critical for the investigator to carefully consider the genetic background of the mouse used in the experimental design and precisely document the strain of mouse employed during publication.</p