Role of Latissimus Dorsi Island Flap in Coverage of Mutilating Upper Limb Injuries in Pediatric Age Group

Background/Purpose: Latissimus dorsi muscle (LDM) is one of the most versatile muscles that is commonly used in different reconstructive procedures. Severe mutilating injuries of the upper limb in children represent a great challenge to reconstructive surgeons especially when important structures become exposed. Materials & Methods: we utilized LDM as an island flap to cover extensive soft tissue defects in the upper limb of pediatric patients. This work included 17 children (13 males and 4 females). All of them had extensive soft tissue loss of the upper limb with exposure of important structures. The cause of injury was road traffic accident in all patients. We analyzed the operative time, need for multi-stage surgery and the recorded complications. Finally, we recorded the ultimate functional and aesthetic outcome after a period of two years of follow up. Results: From the harvested seventeen flaps, none of them was lost. Split thickness skin graft was done one week after flap harvesting and insetting to cover the muscle flap. There were four cases with partial loss of the skin graft secondary to infection. Those four cases needed re-grafting after eradication of infection that needed almost two weeks of local wound care and dressing. Re-grafting was successful in the four cases. Conclusion: For complex upper extremity wounds in the pediatric age group, we advice aggressive debridement and early reconstruction with LDM pedicle flap with a split-thickness skin graft cover over it. The technique is reliable, with minimal donor site morbidity and very accepted functional and cosmetic outcome.Index Word: Latissimus dorsi muscle flap, complex trauma, pediatric age group

Theoretical analysis of the spatial variability in tillage forces for fatigue analysis of tillage machines

This paper presents a new theoretical model to describe the spatial variability in tillage forces for the purpose of fatigue analysis of tillage machines. The proposed model took into account both the variability in tillage system parameters (soil engineering properties, tool design parameters and operational conditions) and the cyclic effects of mechanical behavior of the soil during failure ahead of tillage tools on the spatial variability in tillage forces. The stress-based fatigue life approach was used to determine the life time of tillage machines, based on the fact that the applied stress on tillage machines is primarily within the elastic range of the material. Stress cycles with their mean values and amplitudes were determined by the rainflow algorithm. The damage friction caused by each cycle of stress was computed according to the Soderberg criterion and the total damage was calculated by the Miner's law. The proposed model was applied to determine the spatial variability in tillage forces on the shank of a chisel plough. The equivalent stress history resulted from these forces were calculated by means of a finite element model and the Von misses criterion. The histograms of mean stress and stress amplitude obtained by the rainflow algorithm showed significant dispersions. Although the equivalent stress is smaller than the yield stress of the material, the failure by fatigue will occur after a certain travel distance. The expected distance to failure was found to be df=0.825×106km. It is concluded that the spatial variability in tillage forces has significant effect on the life time of tillage machines and should be considered in the design analysis of tillage machines to predict the life time. Further investigations are required to correlate the results achieved by the proposed model with field tests and to validate the proposed assumptions to model the spatial variability in tillage force

Optical properties of absorbing and non-absorbing aerosols retrieved by cavity ring down (CRD) spectroscopy

International audienceApplication of cavity ring down (CRD) spectrometry for measuring the optical properties of pure and mixed laboratory-generated aerosols is presented. The extinction coefficient (?ext), extinction cross section (?ext) and extinction efficiency (Qext) were measured for polystyrene spheres (PSS), ammonium sulphate ((NH4)2(SO4), sodium chloride (NaCl), glutaric acid (GA), and Rhodamine-590 aerosols. The refractive indices of the different aerosols were retrieved by comparing the measured extinction efficiency of each aerosol type to the extinction predicted by Mie theory. Aerosols composed of sodium chloride and glutaric acid in different mixing ratios were used as model for mixed aerosols of two non-absorbing materials, and their extinction and complex refractive index were derived. Aerosols composed of Rhodamine-590 and ammonium sulphate in different mixing ratios were used as model for mixing of absorbing and non-absorbing species, and their optical properties were derived. The refractive indices of the mixed aerosols were also calculated by various optical mixing rules. We found that for non-absorbing mixtures, the linear rule, Maxwell-Garnett rule, and extended effective medium approximation (EEMA), give comparable results, with the linear mixing rule giving a slightly better fit than the others. Overall, calculations for the mixed aerosols are not as good as for single component aerosols. For absorbing mixtures, the differences between the refractive indices calculated using the mixing rules and those retrieved by CRD are generally higher

Sodium Bose-Einstein Condensates in an Optical Lattice

The phase transition from a superfluid to a Mott insulator has been observed in a $^{23}$Na Bose-Einstein condensate. A dye laser detuned $\approx 5$nm red of the Na $3^2$S$\to 3^2$P$_{1/2}$ transition was used to form the three dimensional optical lattice. The heating effects of the small detuning as well as the three-body decay processes constrained the timescale of the experiment. Certain lattice detunings were found to induce a large loss of atoms. These loss features were shown to be due to photoassociation of atoms to vibrational levels in the Na$_2$ $(1) ^3\Sigma_g^+$ state.Comment: Figures somewhat compromised due to size reductio

Measuring the condensate fraction of rapidly rotating trapped boson systems: off-diagonal order from the density

We demonstrate a direct connection between the density profile of a system of ultra-cold trapped bosonic particles in the rapid-rotation limit and its condensate fraction. This connection can be used to probe the crossover from condensed vortex-lattice states to uncondensed quantum fluid states that occurs in rapidly rotating boson systems as the particle density decreases or the rotation frequency increases. We illustrate our proposal with a series of examples, including ones based on models of realistic finite trap systems, and comment on its application to freely expanding boson density profile measurements.Comment: 4 pages, 3 figures, version accepted for publication in Phys. Rev. Let

Extinction efficiencies of coated absorbing aerosols measured by cavity ring down aerosol spectrometry

International audienceIn this study, we measure the extinction efficiency at 532 nm of absorbing aerosol particles coated with a non-absorbing solid and liquid organic shell with coating thickness varying between 5 and 100 nm using cavity ring down aerosol spectrometry. For this purpose, we use nigrosin, an organic black dye, as a model absorbing core and two non-absorbing organic substances as shells, glutaric acid (GA) and Di-Ethyl-Hexyl-Sebacate (DEHS). The measured behavior of the coated particles is consistent with Mie calculations of core-shell particles. Errors between measured and calculated values for nigrosin coated with GA and DEHS are between 0.5% and 10.5% and between 0.5% and 9%, respectively. However, it is evident that the calculations are in better agreement with the measured results for thinner coatings. Possible reasons for these discrepancies are discussed

Ligand-based design, synthesis, computational insights, and in vitro studies of novel N-(5-Nitrothiazol-2-yl)-carboxamido derivatives as potent inhibitors of SARS-CoV-2 main protease

The global outbreak of the COVID-19 pandemic provokes scientists to make a prompt development of new effective therapeutic interventions for the battle against SARS-CoV-2. A new series o

Two-dimensional Bose gas under extreme rotation

We show that a Bose-condensed gas under extreme rotation in a 2D anisotropic trap, forms a novel elongated quantum fluid which has a roton-maxon excitation spectrum. For a sufficiently large interaction strength, the roton energy reaches zero and the system undergoes a second order quantum transition to the state with a periodic structure - rows of vortices. The number of rows increases with the interaction, and the vortices eventually form a triangular Abrikosov lattice.Comment: typos corrected, ref. added, minor changes in the pape