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A number of recent articles have demonstrated the use of active control to mitigate the effects of combustion instability in afterburner and dump combustor applications. In these applications, cyclic injection of small quantities of control fuel has been proposed to counteract the periodic heat release that contributes to undesired pressure oscillations. This same technique may also be useful to mitigate oscillations in gas turbine combustors, especially in test rig combustors characterized by acoustic modes that do not exist in the final engine configuration. To address this issue, the present paper reports on active control of a subscale, atmospheric pressure nozzle/combustor arrangement. The fuel is natural gas. Cyclic injection of 14 percent control fuel in a premix fuel nozzle is shown to reduce oscillating pressure amplitude by a factor of 0.30 (i.e., -10 dB) at 300 Hz. Measurement of the oscillating heat release is also reported.

Patients with the autoimmune disease multiple sclerosis (MS) typically present with the clinically isolated syndromes (CIS) transverse myelitis (TM) or optic neuritis (ON). B-cell disturbances have been well documented in patients with MS and CIS patients with ON, but not in CIS patients with TM, despite the fact that these patients have the worst clinical outcome of all CIS types. The goal of this study was to characterize the B-cell populations and immunoglobulin genetics in TM patients. We found a unique expansion of CD27high plasmablasts in both the cerebrospinal fluid and periphery of TM patients that is not present in ON patients. Additionally, plasmablasts from TM patients show evidence for positive selection with increased somatic hypermutation accumulation in VH4+ B cells and receptor editing that is not observed in ON patients. These characteristics unique to TM patients may impact disease severity and progression. [ABSTRACT FROM AUTHOR]

T cell receptor genes are assembled in developing T lymphocytes from discrete V, D, and J genes by a site-specific somatic rearrangement mechanism. A flanking recombination signal, composed of a conserved heptamer and a semiconserved nonamer separated by 12 or 23 variable nucleotides, targets the activity of the rearrangement machinery to the adjoining V, D, and J genes. Following the rearrangement of V, D, or J genes, their respective recombination signals are ligated together. Although these signal joints are allegedly invariant, created by the head-to-head abuttal of the heptamers, some do exhibit junctional diversity. Recombination signals were initially identified by comparison and alignment of germ-line sequences with the sequence of rearranged genes. However, their overall low level of sequence conservation makes their characterization solely from sequence data difficult. Recently, computational analysis unraveled correlations between nucleotides at several positions scattered within the spacer and recombination activity, so that it is now possible to identify putative recombination signals and determine and predict their recombination efficiency. In this paper, we analyzed the variability introduced in signal joints generated after rearrangement of the TRDD1 and TRDD2 genes in murine thymocytes. The recurrent presence of identical nucleotides inserted in these signal joints led us to reconsider the location and sequence of the TRDD1 recombination signal. By combining molecular characterization and computational analysis, we show that the functional TRDD1 recombination signal is shifted inside the putative coding sequence of the TRDD1 gene and, consequently, that this gene is shorter than indicated in the databases. [ABSTRACT FROM AUTHOR]