Wakes in a Collisional Quark-Gluon Plasma

Wakes created by a parton moving through a static and infinitely extended quark-gluon plasma are considered. In contrast to former investigations collisions within the quark-gluon plasma are taken into account using a transport theoretical approach (Boltzmann equation) with a Bhatnagar-Gross-Krook collision term. Within this model it is shown that the wake structure changes significantly compared to the collisionless case.Comment: 16 pages, 4 figures, high resolution figures available from the authors, final version to be published in J. Phys.

A radical mediated approach to the stereoselective formal total synthesis of (+)-Sch 642305

A formal total synthesis of (+)-Sch-642305 is described. The synthesis, which commenced from a simple chiral synthon (5S)-5-(hydroxymethyl)dihydrofuran-2(3H)-one, employed, as a key step, a radical mediated opening of a chiral epoxy alcohol intermediate with Cp2Ti(III)Cl following an efficient method developed by us earlier. The resultant intermediate radical was intramolecularly trapped by the electron deficient double bond present in the molecule to give rise to its highly functionalized six-membered carbocyclic ring in stereoselective manner

Ti(III)-mediated radical cyclization of β-aminoacrylate containing epoxy alcohol moieties: synthesis of highly substituted azacycles

Ti(III)-mediated radical cyclization of β-aminoacrylate containing 2,3-epoxy alcohol moieties led to the formation of highly substituted piperidine and pyrrolidine rings. The pyrrolidine ring system was then transformed into an indolizidine framework present in many natural products

Endoscopic Repair of Spontaneous CSF Rhinorrhoea: Results from 21 Cases

Introduction Surgery to close the skull base defect is the treatment of choice in persistent spontaneous cerebrospinal fluid rhinorrhoea with endoscopic endonasal repair being the method of choice.  This study analysed the demographics of presentation, optimal diagnostic and localisation strategies and the effectiveness of transnasal endoscopic treatment strategies  with post-operative follow-up of CSF rhinorrhoea patients in a tertiary care institution   . Materials and Methods  A prospective longitudinal study was conducted on 21 CSF rhinorrhoea patients operated on between August 2014 and August 2018 and results documented. Results CSF rhinorrhoea was found most commonly in middle aged female patients in our study. HRCT PNS was capable of identifying a leak site in 66% of the cases. All patients were operated endoscopically with no major intra-operative or post-operative complications. Resolution of CSF leak occurred in 85% of cases. Conclusion CSF rhinorrhoea can be diagnosed and endoscopic repair can be effectively performed in our existing tertiary care set-ups with good results

Extensive vasculitis in tuberculous meningitis

Tuberculous meningitis causes substantial morbidity and mortality in tropical countries. The various complications reported are hydrocephalus, vasculitic infarcts, tuberculomas, abscesses, and optochiasmatic arachnoiditis. Vasculitis in tuberculosis is basically at the level of lenticulostriate arteries supplying the basal ganglia and terminal cortical branches. In this case report, we present a rare case of tuberculous meningitis with extensive vasculopathy. During hospitalization, she developed acute onset right-sided classical hemiplegia with the inability to speak due to left internal carotid artery occlusion on imaging. The cerebrospinal fluid depicted very high protein levels. The exact pathogenesis of such extensive involvement in tuberculous meningitis substantiates the need for further studies

Resolving puzzles in conjugated polymer photophysics: nanoseconds to microseconds

Thesis (Ph. D.)--University of Rochester. Department of Materials Science, 2017.Conjugated polymers are active candidates of research for their potential applications in organic electronic devices. This thesis contains experimental results of the photophysical behaviour of Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) in the nanoseconds timescale. It is generally accepted that quantum yield of films are less than their solution counterparts and has a non-exponential “temporal tail” in the decay dynamics. This thesis reports the spectroscopy, excitation wavelength dependence, temperature dependence and electric field quenching of the temporal tail of the photoluminescence in MEH-PPV on a nanosecond timescale. We try to understand if a correlation exists between the “temporal tail” and quantum yield in films. We conclude that the tail represents emission from H-like aggregated regions in the polymer. Using a simple model of the photophysics, we estimate the formation yield of the aggregates responsible for the tail emission and conclude that they cannot account for the large reduction in fluorescence observed in densely packed films relative to that in solution. If recombination of injected charges in an OLED follows quantum spin statistics and all recombination forms the lowest excited states in a spin manifold, then the ratio of formed singlet to triplet exciton would be 1:3 setting an efficiency limit of 25% to the EL emission. However, in conjugated polymers, various studies have reported the formation ratio of singlet to triplet excitons to be greater than 1:3. These results have ambiguity due to issues of magnetoresistance, TTA, charge trapping, outcoupling etc. We try to reexamine the singlet-triplet branching ratio in Poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt- (benzo [2,1,3] thiadiazol-4,8-diyl) (F8BT) along with MEH-PPV with the hope of circumventing these problems. This approach involves simultaneous detection of singlet and triplet state luminescence and then estimate the recombination branching ratios directly from the change in singlet and triplet signals produced by applying magnetic fields. The role of PP in F8BT films are addressed based on studying the effect of external magnetic field on the DF and triplet signals of gold nanoparticle doped films. This work is unique and important because it includes a delay dependent magnetic field effect study of the DF suggesting that spin randomization of charge pairs is a fast process that occurs on the several hundred nanoseconds time scale. The magnetic field effect on the fluorescence persists to tens of microseconds and we argue that this apparent inconsistency implies the existence of an intermediate state in the recombination process that has implications for measurements and theoretical treatments of the singlet recombination fraction in electroluminescent conjugated polymers

Parametric Optimization of Nd:YAG Laser Beam Machining Process Using Artificial Bee Colony Algorithm

Nd:YAG laser beam machining (LBM) process has a great potential to manufacture intricate shaped microproducts with its unique characteristics. In practical applications, such as drilling, grooving, cutting, or scribing, the optimal combination of Nd:YAG LBM process parameters needs to be sought out to provide the desired machining performance. Several mathematical techniques, like Taguchi method, desirability function, grey relational analysis, and genetic algorithm, have already been applied for parametric optimization of Nd:YAG LBM processes, but in most of the cases, suboptimal or near optimal solutions have been reached. This paper focuses on the application of artificial bee colony (ABC) algorithm to determine the optimal Nd:YAG LBM process parameters while considering both single and multiobjective optimization of the responses. A comparative study with other population-based algorithms, like genetic algorithm, particle swarm optimization, and ant colony optimization algorithm, proves the global applicability and acceptability of ABC algorithm for parametric optimization. In this algorithm, exchange of information amongst the onlooker bees minimizes the search iteration for the global optimal and avoids generation of suboptimal solutions. The results of two sample paired t-tests also demonstrate its superiority over the other optimization algorithms