Transmission wavefront shearing interferometry for photoelastic materials

A general analysis and experimental validation of transmission wavefront shearing interferometry for photoelastic materials are presented. These interferometers applied to optically isotropic materials produce a single interference pattern related to one phase term, but when applied to photoelastic materials, they produce the sum of two different interference patterns with phase terms that are the sum and difference, respectively, of two stress-related phase terms. The two stress-related phase terms may be separated using phase shifting and polarization optics. These concepts are experimentally demonstrated using coherent gradient sensing in full field for a compressed polycarbonate plate with a V-shaped notch with good agreement with theoretical data. The analysis may be applied to any wavefront shearing interferometer by modifying parameters describing the wavefront shearing distance

Shock Wave Structure in Particulate Composites

An experimental study of shock wave profiles in particulate composites of various compositions is undertaken to determine how shock width and rise times depend on the mean particulate size. The composites under examination serve as a model for concrete or polymer bonded explosives, based upon the impedance mismatch between the relatively stiff particulates and compliant matrix. Polymethyl Methacrylate (PMMA) and glass spheres ranging in size from 100 μm to 1000 μm are used in concentrations of 30% and 40% glass by volume for experiments with a single bead size, and up to 50% glass by volume for multi-mode particle size distributions. A linear change in shock wave rise time is observed as a function of mean particulate diameter

Fracture through cavitation in a metallic glass

The fracture surfaces of a Zr-based bulk metallic glass exhibit exotic multi-affine isotropic scaling properties. The study of the mismatch between the two facing fracture surfaces as a function of their distance shows that fracture occurs mostly through the growth and coalescence of damage cavities. The fractal nature of these damage cavities is shown to control the roughness of the fracture surfaces

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Study on Bacteriological profile of Wound Infections in Tertiary Care Hospital.

INTRODUCTION : Skin, the largest organ in the human body, plays a crucial role in the sustenance of life through the regulation of water and electrolyte balance, thermoregulation, and by acting as a barrier to external noxious agents including microorganisms, however , when the epithelial integrity of skin is disrupted, a wound results. A wound is breach in the skin and the exposure of subcutaneous tissue following loss of skin integrity provides a moist, warm and nutritive environment that is conducive to microbial colonization and proliferation. In developing countries like India, large number of people die daily of preventable and curable diseases such as wound infections. Wound infections are one of the most common hospital acquired infections and are an important cause of morbidity and account for 70-80% mortality. The importance of wound infections, in both economic and human terms, should not be underestimated. In a study on an average, patients with an infected wound stay about 6-10 days more than if the wounds heal without infections. The wound infection depends on a complex interaction between host factors like immunity, nutritional status and age , wound related factors like magnitude of trauma, dead space, devitalization and presence of hematoma and microbial factors like toxins, invasion and resistance to antibiotics. Most wound infections can be classified into two major categories, skin and soft tissue infections, although they often overlap as a consequence of disease progression. AIMS AND OBJECTIVES : 1. To isolate and identify the organism causing wound infections. 2. To detect the antimicrobial susceptibility pattern of the bacterial isolates. 3. To find out the incidence of Methicillin Resistant Staphylococcus aureus. 4. To find out the incidence of Extended Spectrum Beta Lactamase producers among Enterobacteriaceae isolates. 5. To select appropriate antibiotic for effective treatment. MATERIALS AND METHODS : A total of 289 patients with wound infection attending as outpatient and inpatient in Kilpauk Medical College and Hospital ,Chennai were included in the study. Study period: March 2009 to February 2010. Clinical samples like pus, tissue material and discharge from the incised lesions or ulcers were analyzed for bacteriological profile and antimicrobial susceptibility pattern. Staphylococcus aureus strains were analyzed for MRSA and Enterobacteriaceae isolates obtained were analyzed for ESBL production. The methodology included, 1. Collection of specimen, 2. Specimen processing, 3. Identification of pathogens, 4. Antimicrobial susceptibility testing, 5. Double disk synergy test for ESBL, 6. Minimum inhibitory concentration, 7. Phenotypic confirmatory test for MRSA. RESULTS : Specimens obtained from patients with wound infection attending Surgical, Orthopaedic, Burns ward, OG, IMCU, Plastic surgery departments as OP and IP were studied from March 2009 to Feb 2010 to identify the bacteriological profile of wound infection, antimicrobial susceptibility pattern of the organisms isolated ,incidence of MRSA and ESBL producing Enterobacteriaceae among them. Study included patients of both sexes and up to 80 years of age .Specimen included were pus, wound swab. Wound swabs from 289 patients were analyzed in the study. Male patients constituted 143(49.48%), Female patients constituted 146(50.51%), age ranged from 3 months to 80 years. Bacterial isolates were found in 164 (56.74%). The isolation rate was significantly higher in females (51.21%), compared to males (48.78%). The predominant isolates were Gram positive bacteria 96(58.53%). The most frequently isolated organisms were Staphylococcus aureus 89(54.26), followed by Klebsiella pneumoniae (24.39%), Pseudomonas aeruginosa 22(13.41%), Escherichia coli 5(3.04%), Enterococci 5(3.04%), Coagulase negative Staphylococcus 2(1.21%), Acinetobacter 1(0.60%). CONCLUSION : The predominant isolate was found to be Gram positive bacteria 96 (58.53%) than Gram negative bacteria 68 (41.46%).However Staphylococcus aureus 89 (54.26%) was seen as the most common bacterial pathogen followed by Klebsiella pneumoniae 40 (24.39%) and Pseudomonas aeruginosa 22 (13.41%) • Among the Staphylococcus aureus 36 (40.44%) were found to be MRSA and were susceptible to vancomycin (100%), levofloxacin (97.2%), amikacin (94.4%). • Detection of MRSA were found to be high with cefoxitin disk than oxacillin screen agar . • Among Enterobacteriaceae isolates 19 (42.2%) were found to be ESBL producers and were susceptible to amikacin (89.5%). • By employing standard microbiological techniques meticulously the causative agents can be isolated and antimicrobial sensitivity can be assessed for proper management of wound infection. • Essential infection control practices including hand washing by hospital personnel and provides better control of antibiotic resistant strains

Single particle and collective orientational relaxation in an anisotropic liquid near the isotropic-nematic transition

We report molecular dynamics simulation results for the single particle and collective orientational correlations for Gay-Berne fluid of anisotropy parameters κ = 3 and κ' = 5. The following significant results are reported. (i) The decay of collective orientational relaxation of rank two is found to slow down appreciably while approaching the isotropic-nematic (I-N) transition. It eventually becomes even slower than the single particle orientational relaxation of rank one. Surprisingly, even the latter shows a marked slowing down near the I-N transition. (ii) Analysis of the long-time behavior shows a breakdown of the rank dependence predicted by the Debye law in the same region. (iii) An analysis of the memory functions of the orientational time-correlation functions shows that for the collective relaxation surprisingly approaches a Markovian behavior near the I-N transition

Plastic Deformation in Laser-Induced Shock Compression of Monocrystalline Copper

Copper monocrystals were subjected to shock compression at pressures of 10–60 GPa by a short (3 ns initial) duration laser pulse. Transmission electron microscopy revealed features consistent with previous observations of shock-compressed copper, albeit at pulse durations in the µs regime. The results suggest that the defect structure is generated at the shock front. A mechanism for dislocation generation is presented, providing a realistic prediction of dislocation density as a function of pressure. The threshold stress for deformation twinning in shock compression is calculated from the constitutive equations for slip, twinning, and the Swegle-Grady relationship

MOLECULAR ANALYSIS OF THE CAMP- RESPONSE ELEMENT [CRE] ELEMENTS IN THE PROMOTER REGION AND EXON 1 OF THE SURVIVAL OF MOTOR NEURON 2 [SMN2] GENE IN MALAYSIAN SPINAL MUSCULAR ATROPHY PATIENTS; TO ELUCIDATE THEIR ROLE IN CIRCUMSCRIBING THE CLINICAL SEVERITY

Objective: In the Spinal muscular atrophy [SMA] genes [SMN1 and SMN2 genes]; the CRE-II elements at -400 bp in the promoter region of the SMN genes and CRE-I element at +108 bp in the exon 1 of the SMN genes, are reported to have a role in c-AMP induce expression of the SMN genes through its binding affinity to CREB-1. This study was designed to determine the role of CRE sites in the circumscribing the clinical severity of SMA. Methods: Direct sequencing was performed for the PCR products of the promoter regions of the SMA patients with homozygous deletion of SMN1, different copy number of SMN2 and NAIP non deletion. Results: No variation among the CRE-I and CRE-II sites was found in all the clinical types as compare to normal healthy control showing no role of CRE sites in circumscribing the clinical severity of SMA. Conclusion: There was no sequence variation found in the CRE binding sites in the three different clinical types of SMA reflecting no role of CRE binding sites in circumscribing the clinical severity of SMA