On the Threat of Systematic Jamming of GNSS

This paper presents a study of the threat of malicious interference to GNSS and examines the special case where the jamming device is incrementally more sophisticated than a typical always-on interference source. The concept of a systematic jamming attack is considered, where the interference signal is intentionally synchronized with the GNSS signals, with the intention of causing maximum disruption with the minimum power expenditure. Various attack methodologies are examined for the case of a civilian L1 receiver. It is shown that, depending on the attack strategy, the target signal and the target receiver, data-recovery, navigation and timing can be denied to a user with some tens of decibels less average power than a traditional jamming attack. It is further shown that some attacks may be capable to effectively deny some receiver functionality in a subtle manner such that presence of the malicious interference goes undetected. Key signal and receiver features that expose a vulnerability are identified and some means of improving receiver robustness are provided

Getting better all the time - The Continued Evolution of the GNSS Software-Defined Radio

Software Defined Radio (SDR) has an infinite number of interpretations depending on the context in which it is designed and used. By way of a starting definition the authors choose to use that of ‘a reconfigurable radio system whose characteristics are partially or fully defined via software or firmware’. In various forms, SDR has permeated a wide range of user groups, from military, business, academia and to the amateur radio enthusiast

Survey on Signal Processing for GNSS under Ionospheric Scintillation: Detection, Monitoring, and Mitigation

Ionospheric scintillation is the physical phenomena affecting radio waves coming from the space through the ionosphere. Such disturbance is caused by ionospheric electron density irregularities and is a major threat in Global Navigation Satellite Systems (GNSS). From a signal processing perspective, scintillation is one of the most challenging propagation scenarios, particularly affecting high-precision GNSS receivers and safety critical applications where accuracy, availability, continuity and integrity are mandatory. Under scintillation, GNSS signals are affected by amplitude and phase variations, which mainly compromise the synchronization stage of the receiver. To counteract these effects, one must resort to advanced signal processing techniques such as adaptive/robust methods, machine learning or parameter estimation. This contribution reviews the signal processing landscape in GNSS receivers, with emphasis on different detection, monitoring and mitigation problems. New results using real data are provided to support the discussion. To conclude, future perspectives of interest to the GNSS community are discussed

Adolescent Experiences With Intrauterine Devices: A Qualitative Study

PURPOSE: The purpose of this study was to improve understanding of adolescents\u27 reasons for choosing an intrauterine device (IUD) and to explore experiences that led to continuation or discontinuation of the levonorgestrel intrauterine system (LNG-IUS) and the copper IUD (copper IUD). METHODS: We conducted focus groups (FGs) with adolescents and young women who were current or former IUD users stratified by IUD type and 12-month IUD continuation or discontinuation. All subjects were participants from the Contraceptive CHOICE Project. FG data were supplemented with in-depth interviews (IDIs). Data collection was continued until thematic saturation was reached. Transcripts were independently coded by two researchers, and interrater reliability was calculated using a Kappa coefficient. Analysis followed a standard text-analysis approach. RESULTS: Thirteen FGs and seven IDIs were conducted with 43 young women. Effectiveness, duration of use, convenience, and potential bleeding changes emerged as themes for both choosing and continuing IUDs. Some women chose the LNG-IUS to achieve amenorrhea, whereas copper IUD users wanted a nonhormonal method and continued menses. Copper IUD users cited expulsion and bleeding irregularities as reasons for discontinuation, whereas LNG-IUS users reported bleeding irregularities and continued pain as reasons for removal. IUD users noted an adjustment period of weeks to months in which side effects were present before lessening. CONCLUSIONS: Effectiveness, duration of use, convenience, and potential changes in bleeding patterns drove adolescents\u27 choice and continuation of an IUD. Bleeding changes and pain contributed to IUD discontinuation. Discussion of effectiveness, duration and convenience, and anticipatory guidance regarding post-insertion side effects may be important in counseling young women about IUDs

Interference and intrusion in wireless sensor networks

Wireless sensor network (WSN) systems for safety-critical, space and Internet of Things applications have recently begun to adopt open standards and commercial-off-the-shelf equipment, and persistently face challenges of malicious intrusion and spectrum coexistence. These threats are explored through Monte-Carlo simulation and benchtop testing, including matched protocol interference and sophisticated, interactive intrusion attacks. The need for expanding intrusion detection via a more holistic approach, whilst simultaneously improving WSN security, is illustrated. Discussions on WSN security, vulnerabilities, and attacks are also provided

cGAS-STING pathway targeted therapies and their applications in the treatment of high-grade glioma

Median survival of patients with glioblastoma (GBM) treated with standard of care which consists of maximal safe resection of the contrast-enhancing portion of the tumor followed by radiation therapy with concomitant adjuvant temozolomide (TMZ) remains 15 months. The tumor microenvironment (TME) is known to contain immune suppressive myeloid cells with minimal effector T cell infiltration. Stimulator of interferon genes (STING) is an important activator of immune response and results in production of Type 1 interferon and antigen presentation by myeloid cells. This review will discuss important developments in STING agonists, potential biomarkers for STING response, and new combinatorial therapeutic approaches in gliomas

The separation of between-person and within-person components of individual change over time: A latent curve model with structured residuals.

Although recent statistical and computational developments allow for the empirical testing of psychological theories in ways not previously possible, one particularly vexing challenge remains: how to optimally model the prospective, reciprocal relations between two constructs as they developmentally unfold over time. Several analytic methods currently exist that attempt to model these types of relations, and each approach is successful to varying degrees. However, none provide the unambiguous separation of between-person and within-person components of stability and change over time, components that are often hypothesized to exist in the psychological sciences. The goal of our paper is to propose and demonstrate a novel extension of the multivariate latent curve model to allow for the disaggregation of these effects

GRB 081203A: Swift UVOT captures the earliest ultraviolet spectrum of a gamma-ray burst

We present the earliest ultraviolet (UV) spectrum of a gamma-ray burst (GRB) as observed with the Swift Ultra-Violet/Optical Telescope (UVOT). The GRB 081203A spectrum was observed for 50 s with the UV-grism starting 251 s after the Swift-Burst-Alert-Telescope (BAT) trigger. During this time, the GRB was ≈13.4 mag (u filter) and was still rising to its peak optical brightness. In the UV-grism spectrum, we find a damped Lyα line, Lyβ and the Lyman continuum break at a redshift z= 2.05 ± 0.01. A model fit to the Lyman absorption implies a gas column density of log NH i= 22.0 ± 0.1 cm−2, which is typical of GRB host galaxies with damped Lyα absorbers. This observation of GRB 081203A demonstrates that for brighter GRBs (v≈ 14 mag) with moderate redshift (0.5 < z < 3.5) the UVOT is able to provide redshifts, and probe for damped Lyα absorbers within 4–6 min from the time of the Swift-BAT trigger