The Impact of Interference on GNSS Receiver Observables – A Running Digital Sum Based Simple Jammer Detector

A GNSS-based navigation system relies on externally received information via a space-based Radio Frequency (RF) link. This poses susceptibility to RF Interference (RFI) and may initiate failure states ranging from degraded navigation accuracy to a complete signal loss condition. To guarantee the integrity of the received GNSS signal, the receiver should either be able to function in the presence of RFI without generating misleading information (i.e., offering a navigation solution within an accuracy limit), or the receiver must detect RFI so that some other means could be used as a countermeasure in order to ensure robust and accurate navigation. Therefore, it is of utmost importance to identify an interference occurrence and not to confuse it with other signal conditions, for example, indoor or deep urban canyon, both of which have somewhat similar impact on the navigation performance. Hence, in this paper, the objective is to investigate the effect of interference on different GNSS receiver observables in two different environments: i. an interference scenario with an inexpensive car jammer, and ii. an outdoor-indoor scenario without any intentional interference. The investigated observables include the Automatic Gain Control (AGC) measurements, the digitized IF (Intermediate Frequency) signal levels, the Delay Locked Loop and the Phase Locked Loop discriminator variances, and the Carrier-to-noise density ratio (C/N0) measurements. The behavioral pattern of these receiver observables is perceived in these two different scenarios in order to comprehend which of those observables would be able to separate an interference situation from an indoor scenario, since in both the cases, the resulting positioning accuracy and/or availability are affected somewhat similarly. A new Running Digital Sum (RDS) -based interference detection method is also proposed herein that can be used as an alternate to AGC-based interference detection. It is shown in this paper that it is not at all wise to consider certain receiver observables for interference detection (i.e., C/N0); rather it is beneficial to utilize certain specific observables, such as the RDS of raw digitized signal levels or the AGC-based observables that can uniquely identify a critical malicious interference occurrence

Synthesis, Structure, and Ferromagnetism of a New Oxygen Defect Pyrochlore System Lu2V2O_{7-x} (x = 0.40-0.65)

A new fcc oxygen defect pyrochlore structure system Lu2V2O_{7-x} with x = 0.40 to 0.65 was synthesized from the known fcc ferromagnetic semiconductor pyrochlore compound Lu2V2O7 which can be written as Lu2V2O6O' with two inequivalent oxygen sites O and O'. Rietveld x-ray diffraction refinements showed significant Lu-V antisite disorder for x >= 0.5. The lattice parameter versus x (including x = 0) shows a distinct maximum at x ~ 0.4. We propose that these observations can be explained if the oxygen defects are on the O' sublattice of the structure. The magnetic susceptibility versus temperature exhibits Curie-Weiss behavior above 150 K for all x, with a Curie constant C that increases with x as expected in an ionic model. However, the magnetization measurements also show that the (ferromagnetic) Weiss temperature theta and the ferromagnetic ordering temperature T_C both strongly decrease with increasing x instead of increasing as expected from C(x). The T_C decreases from 73 K for x = 0 to 21 K for x = 0.65. Furthermore, the saturation moment at a field of 5.5 T at 5 K is nearly independent of x, with the value expected for a fixed spin 1/2 per V. The latter three observations suggest that Lu2V2O_{7-x} may contain localized spin 1/2 vanadium moments in a metallic background that is induced by oxygen defect doping, instead of being a semiconductor as suggested by the C(x) dependence.Comment: 9 pages including 7 figures, 3 table

Superconductivity in Pr2Ba4Cu7O15-delta with metallic double chains

We report superconductivity with $T_{c,onset}$=$\sim$10K in Pr$_{2}$Ba$_{4}$Cu$_{7}$O$_{15-\delta}$ compound possessing metallic double chains. A reduction treatment on as-sintered samples causes not only the enhanced metallic conduction but also the appearance of superconductivity accompanied by the c-axis elongation due to oxygen deficiency

Synthesis and properties of lanthanide-exchanged Preyssler`s heteropolyanions

Na{sup +} in the Preyssler heteropolytungstate anion [NaP{sub 5}W{sub 30}O{sub 110}]{sup 14{minus}} can be exchanged for a trivalent lanthanide ion. The potential significance of this new class of lanthanide heteropolyanions relates to their applications in catalysis science. This view follows from the fact that Keggin heteropolyanions and their free acids are used as heterogeneous solid catalysts and homogeneous solution catalysts. The authors describe synthetic conditions that lead to the incorporation of Ce{sup 3+} and Pr{sup 3+} within the Preyssler anion, and the coprecipitation of Ce{sup 3+} and the Preyssler anion. Initial studies indicate that the latter, coprecipitated, material deserves study for bifunctional catalytic activity

Functional Electrical Stimulation following nerve injury in a Large Animal Model.

INTRODUCTION: Controversy exists over the effects of functional electrical stimulation (FES) on reinnervation. We hypothesized that intramuscular FES would not delay reinnervation after recurrent laryngeal nerve (RLn) axonotmesis. METHODS: RLn cryo-injury and electrode implantation in ipsilateral posterior cricoarytenoid muscle (PCA) were performed in horses. PCA was stimulated for 20 weeks in eight animals; seven served as controls. Reinnervation was monitored through muscle response to hypercapnia, electrical stimulation and exercise. Ultimately, muscle fiber type proportions and minimum fiber diameters, and RLn axon number and degree of myelination were determined. RESULTS: Laryngeal function returned to normal in both groups within 22 weeks. FES improved muscle strength and geometry, and induced increased type I:II fiber proportion (p=0.038) in the stimulated PCA. FES showed no deleterious effects on reinnervation. DISCUSSION: Intramuscular electrical stimulation did not delay PCA reinnervation after axonotmesis. FES can represent a supportive treatment to promote laryngeal functional recovery after RLn injury. This article is protected by copyright. All rights reserved

Molecular Genetic Approaches to Disease of Neural Development

This study utilized novel genetic techniques in order to find causative gene mutations that underlie diseases of neural development. Our laboratory has collected 175 cases of malformations of cortical development (MCD) from the United States and Europe. Four of these cases are the focus of this manuscript: two familial cases of infantile neuroaxonal dystrophy (INAD), a familial case of hereditary spastic paraparesis (HSP), and a sporadic case of Greig cephalopolysyndactyly (GCPS) and cerebral cavernous malformations (CCMs). The techniques utilized to study the affected patients include microarray-based single nucleotide polymorphism (SNP) genotyping and copy number variation (CNV) analysis, both of which are powerful tools in the hunt for disease-causing gene mutations. In the familial cases of INAD, we report two novel mutations in the PLA2G6 gene, previously shown to cause INAD when mutated. In the familial case of HSP, we demonstrate linkage to the SPG11 locus on chromosome 15q. Finally, in the sporadic case of GCPS and CCM, we published the first report on this novel syndrome along with a genetic analysis that demonstrates a microdeletion on chromosome 7p, resulting in heterozygous loss of both the GLI3 and CCM2 genes. The three studies presented in this manuscript demonstrate the utility of SNP genotyping and CNV analysis in revealing the genetic mutations that underlie diseases of neural development

Temperature-dependent spin gap and singlet ground state in BaCuSi2O6

Bulk magnetic measurements and inelastic neutron scattering were used to investigate the spin-singlet ground state and magnetic gap excitations in BaCuSi2O6, a quasi-2-dimensional antiferromagnet with a bilayer structure. The results are well described by a model based on weakly interacting antiferromagnetic dimers. A strongly temperature-dependent dispersion in the gap modes was found. We suggest that the observed excitations are analogous to magneto-excitons in light rare-earth compounds, but are an intrinsic property of a simple Heisenberg Hamiltonian for the S=1/2 magnetic bilayer.Comment: 10 pages, 4 figures, REVTeX and PS for text, PS for figures direct download: http://papillon.phy.bnl.gov/preprints/bacusio.htm

Actinide speciation in glass leach-layers: An EXAFS study

Uranium L{sub 3} X-ray absorption data were obtained from two borosilicate glasses, which are considered as models for radioactive wasteforms, both before and after leaching. Surface sensitivity to uranium speciation was attained by a novel application of simultaneous fluorescence and electron-yield detection. Changes in speciation are clearly discernible, from U(VI) in the bulk to (UO{sub 2}){sup 2+}-uranyl in the leach layer. The leach-layer uranium concentration variations with leaching times are also determined from the data

Group A Streptococcus M1T1 Intracellular Infection of Primary Tonsil Epithelial Cells Dampens Levels of Secreted IL-8 Through the Action of SpyCEP.

Streptococcus pyogenes (Group A Streptococcus; GAS) commonly causes pharyngitis in children and adults, with severe invasive disease and immune sequelae being an infrequent consequence. The ability of GAS to invade the host and establish infection likely involves subversion of host immune defenses. However, the signaling pathways and innate immune responses of epithelial cells to GAS are not well-understood. In this study, we utilized RNAseq to characterize the inflammatory responses of primary human tonsil epithelial (TEpi) cells to infection with the laboratory-adapted M6 strain JRS4 and the M1T1 clinical isolate 5448. Both strains induced the expression of genes encoding a wide range of inflammatory mediators, including IL-8. Pathway analysis revealed differentially expressed genes between mock and JRS4- or 5448-infected TEpi cells were enriched in transcription factor networks that regulate IL-8 expression, such as AP-1, ATF-2, and NFAT. While JRS4 infection resulted in high levels of secreted IL-8, 5448 infection did not, suggesting that 5448 may post-transcriptionally dampen IL-8 production. Infection with 5448ΔcepA, an isogenic mutant lacking the IL-8 protease SpyCEP, resulted in IL-8 secretion levels comparable to JRS4 infection. Complementation of 5448ΔcepA and JRS4 with a plasmid encoding 5448-derived SpyCEP significantly reduced IL-8 secretion by TEpi cells. Our results suggest that intracellular infection with the pathogenic GAS M1T1 clone induces a strong pro-inflammatory response in primary tonsil epithelial cells, but modulates this host response by selectively degrading the neutrophil-recruiting chemokine IL-8 to benefit infection