Total posterior leg open wound management with free anterolateral thigh flap: case and literature review.

Soft tissue coverage of the exposed Achilles tendon is a unique reconstructive challenge. In this report, we describe the management of a large posterior leg wound with exposed Achilles tendon using a free anterolateral thigh (ALT) flap. A careful review of alternative reconstructive options is included, along with their respective advantages and disadvantages. A 32-year-old white man suffered a fulminant right lower extremity soft tissue infection requiring extensive debridement of the entire posterior surface of the right leg. The resulting large soft tissue defect included exposure of the Achilles tendon. Reconstruction of the defect was achieved with an ALT flap and split-thickness skin graft for coverage of the Achilles tendon and gastrocnemius muscle, respectively. The patient was able to ambulate independently within 2 months of the procedure

The rheology of dense, polydisperse granular fluids under shear

The solution of the Enskog equation for the one-body velocity distribution of a moderately dense, arbitrary mixture of inelastic hard spheres undergoing planar shear flow is described. A generalization of the Grad moment method, implemented by means of a novel generating function technique, is used so as to avoid any assumptions concerning the size of the shear rate. The result is illustrated by using it to calculate the pressure, normal stresses and shear viscosity of a model polydisperse granular fluid in which grain size, mass and coefficient of restitution varies amoungst the grains. The results are compared to a numerical solution of the Enskog equation as well as molecular dynamics simulations. Most bulk properties are well described by the Enskog theory and it is shown that the generalized moment method is more accurate than the simple (Grad) moment method. However, the description of the distribution of temperatures in the mixture predicted by Enskog theory does not compare well to simulation, even at relatively modest densities.Comment: 8 postscript figures Replaced with new version correcting an error in the SME calculations and misc. small corrections. Second replacement with final correction of SME calculation

The effect of epoxy resin in stone and slag concrete

In concrete construction, the weight of the structure represents a large portion of the total load carried; thus, there is considerable advantage in reducing the weight of the concrete. To obtain this result, there are at least three approaches (1). The first method of producing lightweight concrete is by means of substituting a porous lightweight aggregate of low specific gravity for the ordinary aggregate. The second method relies on introducing large voids within the concrete or mortar mass; this is known as aerated, cellular or gas concrete. The third method is simply to omit the fine aggregate from the mix in order to obtain a large number of voids in the concrete. For structural purposes, the first method is preferable to the others, since higher strengths can be achieved. The decrease in density or weight obtained with lightweight material is due to the presence of voids in the aggregate, but these voids will also reduce the strength of lightweight concrete as compared with normal weight concrete of the same paste content. However, it is possible by using a high cement content in lightweight concrete to obtain a high strength lightweight concrete. Recently, pure epoxy concrete has found application in construction because of its high compressive and tensile strengths as well as remarkable adhesive properties. The high cost has tended to limit extent of application. A recent investigation by Mr. Kuo Chu Hu has been made at this University where epoxy resin was used as an admixture in ordinary concrete and some improvement in properties were noted with respect to compressive strength under job curing conditions. Since it was thought that this improvement might be more significant with lightweight concrete, this investigation was initiated to determine the effects of the addition of small quantities of epoxy resin on expanded slag concrete. The investigation included three batches of stone concrete prepared with epoxy resin content at 0, 1 and 2% by volume, and a similar set for slag concrete making a total of 72 cylinders tested. Half of the specimens were cured under laboratory conditions and the other half cured under simulated job conditions. Compression and tensile strengths were determined in triplicate for all combinations of concrete type, epoxy content, and curing condition. In addition, duplicate tests of the modulus of elasticity were performed. --Introduction, pages 1-2

Unanticipated differences between α- and γ-diaminobutyric acid-linked hairpin polyamide-alkylator conjugates

Hairpin polyamide–chlorambucil conjugates containing an {alpha}-diaminobutyric acid ({alpha}-DABA) turn moiety are compared to their constitutional isomers containing the well-characterized {gamma}-DABA turn. Although the DNA-binding properties of unconjugated polyamides are similar, the {alpha}-DABA conjugates display increased alkylation specificity and decreased rate of reaction. Treatment of a human colon carcinoma cell line with {alpha}-DABA versus {gamma}-DABA hairpin conjugates shows only slight differences in toxicities while producing similar effects on cell morphology and G2/M stage cell cycle arrest. However, striking differences in animal toxicity between the two classes are observed. Although mice treated with an {alpha}-DABA hairpin polyamide do not differ significantly from control mice, the analogous {gamma}-DABA hairpin is lethal. This dramatic difference from a subtle structural change would not have been predicted

Chapman-Enskog expansion about nonequilibrium states: the sheared granular fluid

The Chapman-Enskog method of solution of kinetic equations, such as the Boltzmann equation, is based on an expansion in gradients of the deviations fo the hydrodynamic fields from a uniform reference state (e.g., local equilibrium). This paper presents an extension of the method so as to allow for expansions about \emph{arbitrary}, far-from equilibrium reference states. The primary result is a set of hydrodynamic equations for studying variations from the arbitrary reference state which, unlike the usual Navier-Stokes hydrodynamics, does not restrict the reference state in any way. The method is illustrated by application to a sheared granular gas which cannot be studied using the usual Navier-Stokes hydrodynamics.Comment: 23 pages, no figures. Submited to PRE Replaced to correct misc. errors Replaced to correct misc. errors, make notation more consistant, extend discussio

Protein structure similarity from principle component correlation analysis

BACKGROUND: Owing to rapid expansion of protein structure databases in recent years, methods of structure comparison are becoming increasingly effective and important in revealing novel information on functional properties of proteins and their roles in the grand scheme of evolutionary biology. Currently, the structural similarity between two proteins is measured by the root-mean-square-deviation (RMSD) in their best-superimposed atomic coordinates. RMSD is the golden rule of measuring structural similarity when the structures are nearly identical; it, however, fails to detect the higher order topological similarities in proteins evolved into different shapes. We propose new algorithms for extracting geometrical invariants of proteins that can be effectively used to identify homologous protein structures or topologies in order to quantify both close and remote structural similarities. RESULTS: We measure structural similarity between proteins by correlating the principle components of their secondary structure interaction matrix. In our approach, the Principle Component Correlation (PCC) analysis, a symmetric interaction matrix for a protein structure is constructed with relationship parameters between secondary elements that can take the form of distance, orientation, or other relevant structural invariants. When using a distance-based construction in the presence or absence of encoded N to C terminal sense, there are strong correlations between the principle components of interaction matrices of structurally or topologically similar proteins. CONCLUSION: The PCC method is extensively tested for protein structures that belong to the same topological class but are significantly different by RMSD measure. The PCC analysis can also differentiate proteins having similar shapes but different topological arrangements. Additionally, we demonstrate that when using two independently defined interaction matrices, comparison of their maximum eigenvalues can be highly effective in clustering structurally or topologically similar proteins. We believe that the PCC analysis of interaction matrix is highly flexible in adopting various structural parameters for protein structure comparison

A COMPARISON OF TWO CALIBRATION TECHNIQUES FOR LARGE VOLUME CALIBRATION

The purpose of this study was to compare results produced using two different large volume calibration techniques with those produced by using an optical motion capture system. A volume measuring 2.5x8x2 m. was calibrated using 4 survey poles, a multiphase calibration, and with a motion capture system. Reconstructions using the survey poles and multiphase calibration technique produced similar movement patterns as the motion capture system for both the position of a single marker and for tracking the whole body center of mass (COM). The multiphase calibration resulted in larger DLT errors for reconstruction of the control points, however, compared to the motion capture system, it also resulted in smaller RMS differences for both a single marker and for the COM