Unambiguous Tracking Method Based on Combined Correlation Functions for sine/cosine-BOC CBOC and AltBOC Modulated Signals

Unambiguous tracking for Binary Offset Carrier (BOC) modulated signals is an important requirement of modern Global Navigation Satellite System (GNSS) receivers. An unambiguous tracking method based on combined correlation functions for even/odd order sine/cosine-BOC, Composite BOC(CBOC) and Alternate BOC(AltBOC) modulated signals is proposed. Firstly, a unitary mathematical formulation for all kinds of BOC modulations is introduced. Then an unambiguous tracking method is proposed based on the formulation and the idea of pseudo correlation function (PCF) method. Finally, the tracking loop based on the proposed method is designed. Simulation results indicate that the proposed method can remove side peaks while retaining the sharp main peak for all kinds of BOC modulations. The tracking performance for AltBOC is examined and the results show that the proposed method has better performance in thermal noise and long-delay multipath mitigation than the traditional unambiguous tracking methods

Three protected tetrapeptides

The structures of three protected tetrapeptides, containing the Boc-Gly-Gly-Phe-X-OMe chain, tert-butoxycarbonyl-glycy-glycl-phenylalanine-leucine methyl ester dihydrate, Boc-Gly-Gly-L-Phe-D-Leu-OMe, C25H38N4O7·2H2O, tert-butoxycarbonyl-glycy-glycl-phenylalanine-methionine methyl ester dihydrate, Boc-Gly Gly-L-Phe-D-Met-OMe, C24H36N4O7S.2H2O and tert-butoxycarbonyl-glycy-glycl-phenylalanine-norleucine methyl ester dihydrate, Boc-Gly-Gly-D-Phe-L-Nle-OMe, C25H38N4O7.2H2O, are described. The three molecules have the same conformation of the Boc-Gly Gly Phe-X-OMe tetrapeptide chain and display the same packing, consisting of couples of molecules linked head-to-tail by two hydrogen (N-HO) bonds; other hydrogen bonds, also involving two water molecules of crystallization, link these couples together, and give rise to a planar structure

Total synthesis of (±)-paroxetine by diastereoconvergent cobalt-catalysed arylation

A total synthesis of paroxetine is reported, with a diastereoselective and diastereoconvergent cobalt-catalysed sp3–sp2 coupling reaction involving a 3-substituted 4-bromo-N-Boc-piperidine (Boc = tert-butoxycarbonyl) substrate as a key step. A 9:1 diastereoselectivity was obtained, while a control experiment involving a conformationally locked 3-substituted 4-bromo-tert-butyl cyclohexane ring proceeded with essentially complete stereoselectivit

The 5'-3' exoribonuclease pacman is required for epithelial sheet sealing in Drosophila and genetically interacts with the phosphatase puckered

Background information. Ribonucleases have been well studied in yeast and bacteria, but their biological significance to developmental processes in multicellular organisms is not well understood. However, there is increasing evidence that specific timed transcript degradation is critical for regulation of many cellular processes, including translational repression, nonsense-mediated decay and RNA interference. The Drosophila gene pacman is highly homologous to the major yeast exoribonuclease XRN1 and is the only known cytoplasmic 5′–3′ exoribonuclease in eukaryotes. To determine the effects of this exoribonuclease in development we have constructed a number of mutations in pacman by P-element excision and characterized the resulting phenotypes. Results. Mutations in pacman resulted in flies with a number of specific phenotypes, such as low viability, dull wings, crooked legs, failure of correct dorsal/thorax closure and defects in wound healing. The epithelial sheet movement involved in dorsal/thorax closure is a conserved morphogenetic process which is similar to that of hind-brain closure in vertebrates and wound healing in humans. As the JNK (c-Jun N-terminal kinase) signalling pathway is known to be involved in dorsal/thorax closure and wound healing, we tested whether pacman affects JNK signalling. Our experiments demonstrate that pacman genetically interacts with puckered, a phosphatase that negatively regulates the JNK signalling pathway. Conclusions. These results reveal that the 5′–3′ exoribonuclease pacman is required for a critical aspect of epithelial sheet sealing in Drosophila. Since these mutations result in specific phenotypes, our data suggest that the exoribonuclease Pacman targets a specific subset of mRNAs involved in this process. One of these targets could be a member of the JNK signalling pathway, although it is possible that a parallel pathway may instead be affected. The exoribonuclease pacman is highly conserved in all eukaryotes, therefore it is likely that it is involved in similar morphological processes, such as wound healing in human cells

Unambiguous Acquisition and Tracking Technique for General BOC Signals

This article presents a new unambiguous acquisition and tracking technique for general Binary Offset Carrier (BOC) ranging signals, which will be used in modern GPS, European Galileo system and Chinese BeiDou system. The test criterion employed in this technique is based on a synthesized correlation function which completely removes positive side peaks while keeping the sharp main peak. Simulation results indicate that the proposed technique completely removes the ambiguity threat in the acquisition process while maintaining relatively higher acquisition performance for low order BOC signals. The potential false lock points in the tracking phase for any order BOC signals are avoided by using the proposed method. Impacts of thermal noise and multipath on the proposed technique are investigated; the simulation results show that the new method allows the removal of false lock points with slightly degraded tracking performance. In addition, this method is convenient to implement via logic circuits

Ptch2/Gas1 and Ptch1/Boc differentially regulate Hedgehog signalling in murine primordial germ cell migration.

Gas1 and Boc/Cdon act as co-receptors in the vertebrate Hedgehog signalling pathway, but the nature of their interaction with the primary Ptch1/2 receptors remains unclear. Here we demonstrate, using primordial germ cell migration in mouse as a developmental model, that specific hetero-complexes of Ptch2/Gas1 and Ptch1/Boc mediate the process of Smo de-repression with different kinetics, through distinct modes of Hedgehog ligand reception. Moreover, Ptch2-mediated Hedgehog signalling induces the phosphorylation of Creb and Src proteins in parallel to Gli induction, identifying a previously unknown Ptch2-specific signal pathway. We propose that although Ptch1 and Ptch2 functionally overlap in the sequestration of Smo, the spatiotemporal expression of Boc and Gas1 may determine the outcome of Hedgehog signalling through compartmentalisation and modulation of Smo-downstream signalling. Our study identifies the existence of a divergent Hedgehog signal pathway mediated by Ptch2 and provides a mechanism for differential interpretation of Hedgehog signalling in the germ cell niche

Activation and regioselectivity of five-membered cyclic thionocarbamates to nucleophilic attack

The cyclic thionocarbamate of alaninol undergoes nucleophilic attack by sulfur nucleophiles at 5-C to give 1-thiopropyl-2-amine derivatives when derivatised on nitrogen with a Boc group. Iodide under microwave conditions causes a rearrangement to the isomeric thiazolidinone, while "hard" nucleophiles react at the thione group to yield a variety of product types by subsequent C–N or C–O cleavage. X-ray crystallography studies showed that the N-Boc group reduces delocalisation of electron density from nitrogen into the thione group, and thus promotes activation of the ring to nucleophilic attack