859 research outputs found

    Spinning flavour branes and fermion pairing instabilities

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    We consider probe Dp-branes, p=3,5,7, in global AdS_5 x S^5, rotating along an internal direction in the S^5. These are dual to strongly interacting N=4 SYM on S^3 with massless fundamental flavours, in the presence of an R-symmetry chemical potential for flavour fermions. For massless, "AdS-filling" Dp-brane embeddings at zero temperature, we find an infinite set of threshold values of the chemical potential at which instabilities are triggered. The onset of instability is always preceded by metastability of the zero density state. From the onset values of the chemical potential, we infer that unstable directions favour a homogeneous condensate of a bilinear made from fermion harmonics, or Cooper pairing. We confirm this picture both numerically and analytically. The linearized analysis showing the appearance of instabilities involves a charged scalar in global AdS space coupled to a (large) constant background gauge potential. The resulting frequency space correlator of the fermion bilinear at strong coupling displays poles in the upper half plane. In contrast, the correlator at zero coupling exhibits Pauli blocking due to occupation of states below the Fermi level, but no instabilities. The end-point of the strong coupling instability is not visible in our setup.Comment: 44 pages, 10 figures, uses late

    Thermal N = 4 SYM theory as a 2D Coulomb gas

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    We consider N = 4 supersymmetric Yang-Mills theory with SU(N) gauge group at large N and at finite temperature on a spatial S^3. We show that, at finite weak 't Hooft coupling, the theory is naturally described as a two dimensional Coulomb gas of complex eigenvalues of the Polyakov-Maldacena loop, valued on the cylinder. In the low temperature confined phase the eigenvalues condense onto a strip encircling the cylinder, while the high temperature deconfined phase is characterised by an ellipsoidal droplet of eigenvalues.Comment: 1+10 pages. 2 figure

    Reaction of the polycross progenies to two major leaf diseases of rubber (Hevea brasiliensis)

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    A three-year study was undertaken to evaluate the polycross progeny of prepotent clones for their tolerance/susceptibility for abnormal leaf fall (ALF) disease caused by Phytophthora spp. and powdery mildew (PM) disease caused by Oidium heveae at the Central Experiment Station of Rubber Research Institute of India at Chethackal in Ranni. The clones were evaluated during 11th to 13th year after planting. The data obtained were analysed and computed progeny wise and clone wise. The pooled data of three years showed that for ALF disease, the clone P 128 (progeny of AVT 73) was superior over other clones with leaf retention of 76 per cent followed by the clones P 75 (progeny of PB 217) and P 69 (progeny of PB 252) showing leaf retention of 75 per cent. However, the evaluation of the progenies and clones within each progeny against PM disease were not encouraging as lot of variation was observed among the progenies and clones and the disease intensity in general, was very high. The pooled data of three years of assessment on PM disease revealed that the clone P60 evolved from the progeny of RRII 105 and the clones P 54 and P 104 evolved from the progeny of 5/76 showed less than 25 per cent of PDI and thus, were tolerant. The ALF disease tolerant clones P 132, P 69 and P 128 are also reported to be promising in terms of latex and timber yield

    Optical-fiber source of polarization-entangled photon pairs in the 1550nm telecom band

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    We present a fiber based source of polarization-entangled photon pairs that is well suited for quantum communication applications in the 1550nm band of standard fiber-optic telecommunications. Polarization entanglement is created by pumping a nonlinear-fiber Sagnac interferometer with two time-delayed orthogonally-polarized pump pulses and subsequently removing the time distinguishability by passing the parametrically scattered signal-idler photon pairs through a piece of birefringent fiber. Coincidence detection of the signal-idler photons yields biphoton interference with visibility greater than 90%, while no interference is observed in direct detection of either the signal or the idler photons. All four Bell states can be prepared with our setup and we demonstrate violations of CHSH form of Bell's inequalities by up to 10 standard deviations of measurement uncertainty.Comment: 12 pages, 4 figures, to be submitted to Phys. Rev. Lett. See also paper QTuB4 in QELS'03 Technical Digest (OSA, Washington, D.C., 2003). This is a more complete versio

    A study on incidence of Incidental Gallbladder Carcinoma in simple Cholecystectomy Specimen by histopathology, management and follow-up

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    INTRODUCTION: Cholecystectomy is the most common major abdominal procedure performed worldwide. Carcinoma of gallbladder is the 5th most common cancer of digestive tract and the most common malignancy of the biliary tract.The clinical manifestations of gall bladder carcinoma are generally indistinguishable from those associated with cholecystitis or cholelithiasis. Around 90% of GB (Gall bladder) carcinoma have accompanying stone.Stones and chronic inflammation are the risk factors for carcinoma of gallbladder. Most of the cases of GB carcinoma are diagnosed during or after surgery performed for stones or benign biliary diseases. Despite advancements in various diagnostic procedures, preoperative diagnosis of early GB carcinoma is very difficult to diagnose. Advanced stage of the disease because of delayed diagnosis leads to its poor prognosis. AIMS AND OBJECTIVES: The purpose of the present study is to find the incidence of Incidental Gallbladder Carcinoma in simple Cholecystectomy Specimen by histopathology, management and follow-up. study design: prospective observational study. materials: 100 patients. study & follow-up period : One year. Inclusion criteria: All patients with undergoing simple cholecystectomy for gall stone and benign biliary disease. Exclusion criteria: Patients with pre diagnosed Gallbladder malignancy, Gallbladder mass, Empyema Gallbladder and Gallstones associated with obstructive jaundice were excluded. MATERIALS AND METHODS: Patient presenting with right hypochondrial pain, jaundice, dyspepsia will be taken detailed history, clinical examination and necessary investigations including blood complete picture, liver function tests and ultrasound abdomen. Patients who are diagnosed as having gall stones and other benign biliary disease who require simple cholecystectomy are subjected to open/laparoscopic cholecystectomy and the gallbladder specimens will be sent for histopathological study. Patients with positive histology for carcinoma will be called up and managed depending upon the stage of disease and followed up for one year. Data will be collected and analyzed through SPSS version 16. DISCUSSION: Gallbladder Carcinoma (GBC) is the most common malignancy of the biliary tract and the sixth most common malignancy of the gastrointestinal tract worldwide. It is an aggressive and a late symptomatic disease and most of the patients are treated at advanced stages. The prognosis is usually dismal and the 5 year survival rates have been reported to be less than 5% for the more advanced stages. The countries with a high incidence of gallbladder cancer include Chile, Poland, India and Japan. A very high incidence of this cancer has been reported among women in northern India (21.5/100,000) and among female Native American Indians (14.5/1000,000). The early-stage carcinoma is typically diagnosed incidentally because of the inflammatory symptoms which are related to the coexistent cholelithiasis or cholecystitis. CONCLUSION: • incidence of Incidental GBC found in my study is 2%. • Incidental GBC is becoming more common due to the wide spread use of LC procedures being carried out for benign GB disease • However, this may be decreasing due to use of ultrasound scanning for upper abdominal symptoms suggestive of GB disease • Open or L C is adequate treatment for pTis and pT1 • Given the high rate of residual disease , therefore re-resection still the only curative treatment ,and should be strongly considered for pT2 and pT3, but no CBD resection • Although the type of hepatic resection does not appear to affect the outcome, it is essential to achieve tumour-free surgical margins. • The prognosis is usually dismal and the 5 year survival rates have been reported to be less than 5% for the more advanced stages

    PM Emission From a Commercial Jet Engine -- Project APEX

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    Project APEX (Aircraft Particle Emissions eXperiment) was a multi-agency commercial aircraft emission characterization and technology demonstration experiment. Its objective was to characterize particle and trace gas precursor species in the emissions from a NASA DC-8 aircraft with General Electric CFM56-2C1 engines at the engine exit plane as well as selected down stream locations. This was to advance the understanding of particle emissions and their evolution in the atmosphere from a current in-service turbofan engine. The test was conducted at the NASA Dryden Flight Research Center at Edwards Air Force Base California during April 15-30, 2004. Participants included the National Aeronautics and Space Administration, Environmental Protection Agency, Federal Aviation Administration, Department of Defense, the aviation industry (General Electric, Pratt and Whitney, and Boeing), and the research community (Aerodyne Research Inc., Massachusetts Institute of Technology, Process Metrix, University of California-Riverside, and University of Missouri-Rolla)

    Emissions from Alternate Aviation Fuels and their Environmental Impact

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    Track II: Transportation and BiofuelsIncludes audio file (19 min.)The anticipated growth in commercial air traffic, rising fuel costs, and an increasing desire to reduce reliance on fossil fuels produced in politically unstable regions, has driven research into alternate renewable fuels, either from biomass (Biofuels) or synthesis from coal, natural gas and other renewable feedstocks (Fischer-Tropsch (FT) fuels). Industry and government has recently sponsored (Dec 07, Jan 09) two engine emission tests led in part by the Missouri S&T team. The tests focused on burning alternative and conventional fuels and associated blends in CFM56-type commercial gas turbine engines. The CFM56 engine type is the most common engine in the global commercial fleet powering greater than 70% of the US domestic fleet. The purpose of these emission tests was to quantify any differences in particulate matter (PM) and hazardous air pollutants (HAP) emissions observed between the different fuels, and assess the environmental impacts that may result from these differences. The PM measurements indicate that, especially for the 100% F-T fuel, PM number and mass are diminished at all powers relative to conventional fuels. Some significant differences in hydro-carbon speciation were also observed for the 100% F-T fuel. Differences were less pronounce for the blends. This paper will present a concise summary of the results of these measurement campaigns along with an assessment of any associated environmental impact changes, focusing mainly on airport local air quality and the global atmosphere
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