A Review on Advancements in Optical Communication System

Communication systems are revolutionized by the tremendous research being done in this direction. The need is the mother of the invention. The need of data transfer in increasing every day. There is the big demand for the fast optical communication systems. The optical fibers have the big potential of carrying the different channels which can transmit the data at amazing speed. In this work we have studied the research done in the field of technological development taking place in fiber communication system. The focus is on the use of fiber link as a modern medium of communication in the optical range.Communication system, Optical data transfer, Channel, Fiber link, Optical range

Stability of a high Mach number flow in a channel

Modal instabilities in a flow through a channel at high Reynolds and Mach numbers are studied for three-dimensional perturbations. In addition to the Tollmien-Schlichting modes, there exist higher modes in a channel flow that do not have a counterpart in the incompressible limit. The stability characteristics of these higher modes, obtained through numerical calculations, are compared with boundary layer and Couette flows that have been previously studied. The dominant higher mode instabilities in a channel flow are shown to be viscous in nature, in contrast to compressible boundary layer modes. For general compressible bounded-domain flows, a necessary condition for the existence of neutral modes in the inviscid limit is obtained. This criterion is used to construct a procedure to determine a critical value of Mach number below which the higher modes remain stable. This criterion also delineates a range of angles of inclination of the wave number with respect to the flow direction which could go unstable at a specified Mach number. Asymptotic analysis is carried out for the lower and upper branch of the stability curve in the limit of high Reynolds number. A common set of relations are identified for these exponents for the upper and lower branch for the continuation of the Tollmien-Schlichting modes and the compressible modes. The scalings for the Tollmien-Schlichting modes are identical to those for an incompressible flow. The scalings for the finite wave number modes are different; the wave speed $c$ scales as \mbox{Re}^{-\frac{1}{3}} for the lower branch and \mbox{Re}^{-\frac{1}{5}} for the upper branch, where \mbox{Re} is the Reynolds number. The asymptotic analysis shows that the stability boundaries for three-dimensional perturbations at high Reynolds numbers can be calculated from the strain rate and the temperature of the base flow at the wall.Comment: 59 pages, 10 figure

Ultraviolet Radiation Detection by Barium Titanate Thin Films Grown by Sol-gel Hydrothermal Method

AbstractFerroelectric Barium titanate, BaTiO3 (BTO) thin film has been prepared successfully by sol-gel hydrothermal method (SG-HT) which combines the basic sol-gel process with hydrothermal treatment. High resolution X-ray diffraction (HR-XRD) study reveals single phase polycrystalline tetragonal structure of the prepared BTO thin film. Optical properties were studied using UV- Visible spectroscopy and band gap was found to be 3.51eV. The I–V characteristics revealed a low dark current (Ioff) of 6.07 × 10-9 A for the prepared BTO thin film which increases to 4.06 × 10-6 A (Ion) by almost three orders of magnitude when illuminated with UV radiation (λ = 365nm, Intensity = 24μW/cm2). The photoconductive gain (K = Ion/Ioff), was found to be 6.7 × 102. It can be clearly seen that the prepared BTO film can be utilized as an efficient Ultraviolet photodetector

Comparison of safety and efficacy of tamsulosin, tadalafil, combinations and deflazacort in lower ureteric orifice negotiation by large size uretero- scope (8/9.8 Fr) prior to intracorporeal lithotripsy

Objective: To compare the safety and efficacy of tamsulosin, tadalafil, deflazacort and combination of tamsulosin with tadalafil in lower ureteric orifice negotiation by large size ureteroscope (8/9.8 Fr) prior to intracorporeal lithotripsy.Patients and methods: In this prospective study, 180 patients presented with ureteric stone of size 8–15 mm were randomly assigned to 5 groups: tamsulosin (group A), tadalafil (group B), deflazacort (group C), combination of tamsulosin with tadalafil (group D) and placebo (group E). After 10 days of drug therapy 168 patients were underwent ureteroscopy and findings like endoscopic configuration of ureteric orifice, need for ureteric dilatation, ureteroscope negotiation, operating time, drug related side effect and procedural complication were noted in each group.Results: All four groups (A, B, C, D) were significantly better than group E in terms of ureteric orifice appearance (wide) during endoscopy. Negotiation of ureteric orifice was easy in group A (70.59%), B (58.82%) and D (78.13%) as compare to group E (31.43%) which was statistically significant. Group A (32.35%) and D (34.38%) were statistically better with group E (62.86%) in terms of ureteral dilatation. Operative time was less in all four groups as compared to group E. All patients well tolerated the drugs with no serious side effects.Conclusion: Both tamsulosin and tamsulosin with tadalafil helps in forward propagation of large sizeureteroscope as compared to other groups with less operative time without any significant complications.So, we can conclude that tamsulosin alone can be helpful for lower ureteric orifice negotiation duringintracorporeal lithotripsy with minimal side effects.Keywords: Hematuria; Negotiation; Ureteroscop

Medial plantar artery flap: a versatile workhorse flap for foot reconstruction, our experience

Soft tissue defect in the foot is commonly seen as it is more prone to trophic ulcers since it is the main weight bearing area of the body. Reconstruction of the weight bearing area of the foot requires the provision of a stable, supple, durable and preferably sensate skin coverage. Following Sir Gilli’s principle of replacing like with like, medial plantar artery flap provides an anatomically similar, glabrous skin for coverage on the plantar surface. In the present study, we share our clinical experience with the use of medial plantar artery flap for coverage of soft tissue defect over sole of foot. At our institution, a total of 10 patients presented with soft tissue defect of the sole, underwent medial plantar artery flap coverage. All the 10 patients were diagnosed cases of type 2 DM. patient outcome was assessed according to patients’ age distribution, duration of surgery, hospital stay, and post operative complications. Out of all the 10 patients, 5 were male and 5 were female. All the flaps healed uneventfully without major complications like partial flap necrosis. Donor site was covered with split thickness skin graft. There was suture site dehience in 2 cases which healed with secondary healing. Medial plantar artery flap has been described as an optimal reconstructive option for this type of soft tissue defect.

Loss of Periodontal Attachment in HIV‐Seropositive Military Personnel

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141395/1/jper0421.pd

Use of dorsalis pedis artery flap in coverage of distal lower leg defects

Soft tissue defect in the distal one third of leg have always posed a challenge for reconstructive surgeons. Such wounds are difficult to manage due the tenuous blood supply, limited subcutaneous cover over the tendons and bones. The aim of our study is to investigate the outcome of Dorsalis pedis artery flap for the coverage of such defects. In the present study, we share our clinical experience with the use of dorsalis pedis artery flap for the coverage of defect in the distal one third leg. This is a series of 4 cases where dorsalis pedis artery flap was used to cover lower one third defect. One case had focal squamous cell carcinoma due to long standing post burns contracture in distal one third of leg anteriorly. Other 3 cases had chronic non healing ulcer in the malleolar region. Patient outcome was assessed according to patients’ age distribution, duration of surgery, hospital stay, and post-operative complications. All 4 patients had excellent outcome with no major donor site complications, infection, and graft loss. Donor site was closed with split thickness skin graft. One patient developed a minor raw area over the dorsum of foot which healed secondarily. Although a potential risk in applying this flap is insufficient venous drainage, no problems with blood inflow or outflow were encountered in the present case series. The flaps survived, and the patient had good postoperative outcome. Hence dorsalis pedis flap can be used for the coverage of the distal foot as a good option

Changes in expression of polyamines and ethylene biosynthesis genes in groundnut (Arachis hypogaea L.) genotypes during Sclerotium rolfsii infection

476-483Stem rot disease caused by fungal pathogen, Sclerotium rolfsii Sacc., is potential threat to groundnut production in warm and humid condition. After host-pathogen interaction, a multitude of plant resistance associated reactions are initiated. In the present investigation we studied the role of polyamines and ethylene during host-pathogen interaction in stem rot tolerant (CS319, GG17 and GG31) and susceptible (TG37A) groundnut genotypes at 24, 48 and 72 h after infection. Stem rot tolerant genotypes showed higher expression of polyamine biosynthesis genes ornithine decarboxylase (Ordec), spermine synthase (Sms) and lipoxygenase1 (LOX1) gene at 72 h after infection than that of susceptible genotype TG37A. The expression analysis of ethylene biosynthesis genes (1-aminocyclopropane-1-carboxylate oxidase: ACCO and (ACCS) showed up regulation in stem rot susceptible genotype TG37A than that of tolerant genotypes after infection at all stages (24, 48 and 72 h after infection). The expression of amine oxidase (AMO) gene was observed highest in stem rot susceptible genotype TG37A while minimum in GJG31. Expression of this gene was remarkably induced in TG37A which may leads to higher accumulation of H2O2. Higher content of a polyamine, putrescine was found in the leaves of stem rot tolerant genotypes at 48 and 72 h after infection. These results implied that tolerant genotypes induced higher polyamine biosynthesis which may involve in plant defense and impart tolerance/ resistance. While, susceptible genotype (TG37A), utilized higher flux of S-Adenosyl methionine (SAM) for ethylene biosynthesis which may leads to necrosis of plants. Thus, stem rot resistant genotypes may be developed through genetic manipulation of polyamine biosynthesis pathway