On Velocity Measurements in Non-Isothermal Turbulent Flows

Turbulent velocity measurements in non-isothermal flows are conventionally performed by constant current hot-wire anemometry. The procedure involved however is cumbersome, the output signals are nonlinear and more critically a continuous signal of velocity fluctuations is not provided. The method described here utilizes two orthogonal wires situated a fraction of a millimeter apart. The upstream wire is operated in a low overheat, constant-current compensated mode thus providing a signal proportional to temperature while the down-stream wire, practically unaffected by the thermal wake of the first wire is operated in the constant temperature mode. Compensation for the effects of local temperature on the downstream wire is accomplished by the temperature signal obtained from the first wire. Variations of Kramers\u27 law coefficients (both being functions of density and thermal conductivities) due to temperature variations are compensated through an analog circuit at the input of the logarithmic amplifiers of the linearizer. By this method, linear and separate signals of the velocity and local temperature are thus obtained simultaneously and continuously. Advantages accruing from this method are readily adapted to cross-wire configuration thus permitting direct measurements of momentum and heat transfer in turbulent heated flows

SYNZIP Protein Interaction Toolbox: in Vitro and in Vivo Specifications of Heterospecific Coiled-Coil Interaction Domains

The synthetic biology toolkit contains a growing number of parts for regulating transcription and translation, but very few that can be used to control protein association. Here we report characterization of 22 previously published heterospecific synthetic coiled-coil peptides called SYNZIPs. We present biophysical analysis of the oligomerization states, helix orientations, and affinities of 27 SYNZIP pairs. SYNZIP pairs were also tested for interaction in two cell-based assays. In a yeast two-hybrid screen, >85% of 253 comparable interactions were consistent with prior in vitro measurements made using coiled-coil microarrays. In a yeast-signaling assay controlled by coiled-coil mediated scaffolding, 12 SYNZIP pairs were successfully used to down-regulate the expression of a reporter gene following treatment with α-factor. Characterization of these interaction modules dramatically increases the number of available protein interaction parts for synthetic biology and should facilitate a wide range of molecular engineering applications. Summary characteristics of 27 SYNZIP peptide pairs are reported in specification sheets available in the Supporting Information and at the SYNZIP Web site [http://keatingweb.mit.edu/SYNZIP/].National Science Foundation (U.S.) (NSF award MCB 0950233)National Institutes of Health (U.S.) (grant RO1 GM55040)National Institutes of Health (U.S.) (grant PN2 EY016546)National Institutes of Health (U.S.) (grant P50 GMO81879)National Science Foundation (U.S.). Synthetic Biology Engineering Research CenterHoward Hughes Medical Institut

The Gracilis Myocutaneous Free Flap: A Quantitative Analysis of the Fasciocutaneous Blood Supply and Implications for Autologous Breast Reconstruction

BACKGROUND: Mastectomies are one of the most common surgical procedures in women of the developed world. The gracilis myocutaneous flap is favoured by many reconstructive surgeons due to the donor site profile and speed of dissection. The distal component of the longitudinal skin paddle of the gracilis myocutaneous flap is unreliable. This study quantifies the fasciocutaneous vascular territories of the gracilis flap and offers the potential to reconstruct breasts of all sizes. METHODS: Twenty-seven human cadaver dissections were performed and injected using lead oxide into the gracilis vascular pedicles, followed by radiographic studies to identify the muscular and fasciocutaneous perforator patterns. The vascular territories and choke zones were characterized quantitatively using the 'Lymphatic Vessel Analysis Protocol' (LVAP) plug-in for Image J® software. RESULTS: We found a step-wise decrease in the average vessel density from the upper to middle and lower thirds of both the gracilis muscle and the overlying skin paddle with a significantly higher average vessel density in the skin compared to the muscle. The average vessel width was greater in the muscle. Distal to the main pedicle, there were either one (7/27 cases), two (14/27 cases) or three (6/27 cases) minor pedicles. The gracilis angiosome was T-shaped and the maximum cutaneous vascular territory for the main and first minor pedicle was 35 × 19 cm and 34 × 10 cm, respectively. CONCLUSION: Our findings support the concept that small volume breast reconstructions can be performed on suitable patients, based on septocutaneous perforators from the minor pedicle without the need to harvest any muscle, further reducing donor site morbidity. For large reconstructions, if a 'T' or tri-lobed flap with an extended vertical component is needed, it is important to establish if three territories are present. Flap reliability and size may be optimized following computed tomographic angiography and surgical delay

Chemical reaction and turbulence. Progress report, June 1, 1980-May 31, 1981. [O/sub 3/+NO reaction]

The experimental techniques to be used to carry out the measurements have been developed both for the velocity and concentration fluctuation measurements. The calculations of the reacting mixing layer indicate that the region of interest, where finite rates play a role, is 0.3 shown on figures 5 and 6 also indicate that this quantity is not very sensitive to the modelling of the finite-rate reaction. The difference of 20% is most likely less than the combined uncertainty in the measurements and the turbulence mode. On the other hand, the profile of and R/sub cf/ shows some interesting trends which are likely to depend on the details of the modelling. These quantities, then, can be expected to be the more useful results of the experiment

Chemical reaction and turbulence. Progress report, June 1, 1979-May 31, 1980

This corresponds to the first year of our investigation into the interaction of chemical reactions and turbulence. During this time, construction of a special purpose wind tunnel was completed, the fiber optics probe for concentration measurements was designed and constructed, and the general method of attack on the theoretical front was set up by first looking at the problem of total dispersion of a scalar in turbulent flows and independently setting up a scheme to model directly the equations describing the evolution of the probability density function of the species concentrations in the free shear layer. All the aforementioned tasks were performed on schedule according to the time chart originally proposed