21 research outputs found
Physical lumping methods for developing linear reduced models for high speed propulsion systems
In gasdynamic systems, information travels in one direction for supersonic flow and in both directions for subsonic flow. A shock occurs at the transition from supersonic to subsonic flow. Thus, to simulate these systems, any simulation method implemented for the quasi-one-dimensional Euler equations must have the ability to capture the shock. In this paper, a technique combining both backward and central differencing is presented. The equations are subsequently linearized about an operating point and formulated into a linear state space model. After proper implementation of the boundary conditions, the model order is reduced from 123 to less than 10 using the Schur method of balancing. Simulations comparing frequency and step response of the reduced order model and the original system models are presented
Waveguide-integrated silicon T centres
The performance of modular, networked quantum technologies will be strongly
dependent upon the quality of their quantum light-matter interconnects.
Solid-state colour centres, and in particular T centres in silicon, offer
competitive technological and commercial advantages as the basis for quantum
networking technologies and distributed quantum computing. These newly
rediscovered silicon defects offer direct telecommunications-band photonic
emission, long-lived electron and nuclear spin qubits, and proven native
integration into industry-standard, CMOS-compatible, silicon-on-insulator (SOI)
photonic chips at scale. Here we demonstrate further levels of integration by
characterizing T centre spin ensembles in single-mode waveguides in SOI. In
addition to measuring long spin T_1 times, we report on the integrated centres'
optical properties. We find that the narrow homogeneous linewidth of these
waveguide-integrated emitters is already sufficiently low to predict the future
success of remote spin-entangling protocols with only modest cavity Purcell
enhancements. We show that further improvements may still be possible by
measuring nearly lifetime-limited homogeneous linewidths in isotopically pure
bulk crystals. In each case the measured linewidths are more than an order of
magnitude lower than previously reported and further support the view that
high-performance, large-scale distributed quantum technologies based upon T
centres in silicon may be attainable in the near term
Additional roles of a peripheral loop–loop interaction in the Neurospora VS ribozyme
Many RNAs contain tertiary interactions that contribute to folding the RNA into its functional 3D structure. In the VS ribozyme, a tertiary loop–loop kissing interaction involving stem–loops I and V is also required to rearrange the secondary structure of stem–loop I such that nucleotides at the base of stem I, which contains the cleavage–ligation site, can adopt the conformation required for activity. In the current work, we have used mutants that constitutively adopt the catalytically permissive conformation to search for additional roles of the kissing interaction in vitro. Using mutations that disrupt or restore the kissing interaction, we find that the kissing interaction contributes ∼1000-fold enhancement to the rates of cleavage and ligation. Large Mg2+-dependent effects on equilibrium were also observed: in the presence of the kissing interaction cleavage is favored >10-fold at micromolar concentrations of Mg2+; whereas ligation is favored >10-fold at millimolar concentrations of Mg2+. In the absence of the kissing interaction cleavage exceeds ligation at all concentrations of Mg2+. These data provide evidence that the kissing interaction strongly affects the observed cleavage and ligation rate constants and the cleavage–ligation equilibrium of the ribozyme
ARACHIDONIC-ACID CASCADE and PLATELET-ACTIVATING-FACTOR in the NETWORK of EYE INFLAMMATORY MEDIATORS - THERAPEUTIC IMPLICATIONS in UVEITIS
EYE EAR NOSE & THROAT HOSP,NEW ORLEANS,LA 70112ESCOLA PAULISTA MED SCH,BR-04023 São Paulo,BRAZILESCOLA PAULISTA MED SCH,BR-04023 São Paulo,BRAZILWeb of Scienc
The low information content of Neurospora splicing signals: implications for RNA splicing and intron origin.
When we expressed a small (0.9 kb) nonprotein-coding transcript derived from the mitochondrial VS plasmid in the nucleus of Neurospora we found that it was efficiently spliced at one or more of eight 5' splice sites and ten 3' splice sites, which are present apparently by chance in the sequence. Further experimental and bioinformatic analyses of other mitochondrial plasmids, random sequences, and natural nuclear genes in Neurospora and other fungi indicate that fungal spliceosomes recognize a wide range of 5' splice site and branchpoint sequences and predict introns to be present at high frequency in random sequence. In contrast, analysis of intronless fungal nuclear genes indicates that branchpoint, 5' splice site and 3' splice site consensus sequences are underrepresented compared with random sequences. This underrepresentation of splicing signals is sufficient to deplete the nuclear genome of splice sites at locations that do not comprise biologically relevant introns. Thus, the splicing machinery can recognize a wide range of splicing signal sequences, but splicing still occurs with great accuracy, not because the splicing machinery distinguishes correct from incorrect introns, but because incorrect introns are substantially depleted from the genome
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The low information content of Neurospora splicing signals: implications for RNA splicing and intron origin.
When we expressed a small (0.9 kb) nonprotein-coding transcript derived from the mitochondrial VS plasmid in the nucleus of Neurospora we found that it was efficiently spliced at one or more of eight 5' splice sites and ten 3' splice sites, which are present apparently by chance in the sequence. Further experimental and bioinformatic analyses of other mitochondrial plasmids, random sequences, and natural nuclear genes in Neurospora and other fungi indicate that fungal spliceosomes recognize a wide range of 5' splice site and branchpoint sequences and predict introns to be present at high frequency in random sequence. In contrast, analysis of intronless fungal nuclear genes indicates that branchpoint, 5' splice site and 3' splice site consensus sequences are underrepresented compared with random sequences. This underrepresentation of splicing signals is sufficient to deplete the nuclear genome of splice sites at locations that do not comprise biologically relevant introns. Thus, the splicing machinery can recognize a wide range of splicing signal sequences, but splicing still occurs with great accuracy, not because the splicing machinery distinguishes correct from incorrect introns, but because incorrect introns are substantially depleted from the genome
Congenital diaphragmatic Bochdaleck hernia: case report
Abstract
Congenital diaphragmatic Bochdaleck hernia is an anatomical defect of the diaphragm, which allows protrusion of abdominal viscera into the chest, causing serious pulmonary and cardiac complications in the neonate. In this study we aimed to present a case of congenital Bochdaleck hernia. We investigated a 40 weeks old child, with a pregnancy carried out in a public hospital in Passo Fundo, Rio Grande do Sul, Brazil. We suggest that if diagnosis occurs in the prenatal period, the prognosis of this disease improves. As a consequence, it allows the parity of the fetus to occur in a higher complexity center, optimizing the chances of survival