What effect does network size have on NRTK positioning?

The Network Real Time Kinematic (NRTK) positioning is nowadays a very common practice not only in academia but also in the professional world. To support the users several networks of Continuous Operating Reference Stations (CORSs) were born. These networks offer real-time services for NRTK positioning, providing a centimetric positioning accuracy with an average distance of 25-35 kms between the reference stations. But what is the effective distance between reference stations that allows to achieve the precision required for real-time positioning, using both geodetic and GIS receivers? How the positional accuracy changes with increasing distances between CORS? Can a service of geostationary satellites, such as the European EGNOS, be an alternative to the network positioning for medium-low cost receivers? These are only some of the questions that the Authors try to answer in this articl

Earthquake forecasting: a possible solution considering the GPS ionospheric delay

Abstract. The recent earthquakes in L'Aquila (Italy) and in Japan have dramatically emphasized the problem of natural disasters and their correct forecasting. One of the aims of the research community is to find a possible and reliable forecasting method, considering all the available technologies and tools. Starting from the recently developed research concerning this topic and considering that the number of GPS reference stations around the world is continuously increasing, this study is an attempt to investigate whether it is possible to use GPS data in order to enhance earthquake forecasting. In some cases, ionospheric activity level increases just before to an earthquake event and shows a different behaviour 5–10 days before the event, when the seismic event has a magnitude greater than 4–4.5 degrees. Considering the GPS data from the reference stations located around the L'Aquila area (Italy), an analysis of the daily variations of the ionospheric signal delay has been carried out in order to evaluate a possible correlation between seismic events and unexpected variations of ionospheric activities. Many different scenarios have been tested, in particular considering the elevation angles, the visibility lengths and the time of day (morning, afternoon or night) of the satellites. In this paper, the contribution of the ionospheric impact has been shown: a realistic correlation between ionospheric delay and earthquake can be seen about one week before the seismic event

Doppler measurement integration for kinematic real-time GPS positioning

The present paper discusses the advantages of the use of Doppler shift measurements in a Kalman filter estimator in order to improve the kinematic stand-alone global positioning system positioning performance. Tests conducted in an urban environment using a single-frequency receiver demonstrate the real advantages of the proposed real- time computation technique

Size-dependent resistivity in a micro-processed YBa2Cu3O7-δ superconducting whisker

We report the results of a detailed geometrical and electrical study which has been performed on a YBa2Cu3O7-δ superconducting whisker. This sample has undergone three subsequent steps of micro-machining by means of a focused ion beam (FIB) instrument, in order to progressively decrease its cross-sectional area from ~77 to ~4 µm2, over a length of about 150 µm. A simple analytical model based on the exact shape both of the electrical contacts and of the micro-machined material has been proposed for the voltage drop; besides, an accurate geometrical characterization of all of the sample details has been performed by means of SEM microscopy. This enabled us to extract accurate electrical resistivity curves from the resistance versus temperature characteristics for each of the fabrication steps of the whisker, showing an increase of the sheet resistivity with decreasing cross-sectional area. Among the possible physical reasons for such behaviour, inelastic electron scattering at the sample surfaces has been ruled out because of the very short mean free path of carriers in YBCO. On the other hand, oxygen out-diffusion and Ga ion implantation due to the FIB processing are most likely to be responsible for the observed resistivity trend

Markers of insulin resistance and carotid atherosclerosis. A comparison of the homeostasis model assessment and triglyceride glucose index.

Summary Aims The present investigation was designed to test the association between carotid atherosclerosis and two simple markers of insulin resistance, i.e. HOMA-Index and TyG-Index. Materials and methods The study was performed in two different cohorts. In the first cohort, 330 individuals were enrolled. Blood pressure, lipids, glucose, waist and cigarette smoking were evaluated. HOMA-IR and TyG-Index were calculated as markers of prevalent hepatic and muscular insulin resistance respectively. Carotid atherosclerosis was assessed by Doppler ultrasonography. The association between cardiovascular risk factors, markers of insulin resistance and carotid atherosclerosis was assessed by multiple logistic regression analyses. In the second cohort, limited to the evaluation of TyG-Index, 1432 subjects were studied. Results In the first cohort, TyG-Index was significantly associated with carotid atherosclerosis in a model including age, sex, diabetes, cigarette smoking and LDL cholesterol, while HOMA-IR was not. When components of metabolic syndrome were added to the model as dichotomous variables (absent/present), TyG-Index retained its predictive power. The same result was obtained when the metabolic syndrome was added to the model (absence/presence). The association between TyG-Index and carotid atherosclerosis was confirmed in the second cohort. Conclusions The present findings suggest that TyG-Index is better associated with carotid atherosclerosis than HOMA-IR

Antibody Recognition of Cancer-Related Gangliosides and Their Mimics Investigated Using in silico Site Mapping

Modified gangliosides may be overexpressed in certain types of cancer, thus, they are considered a valuable target in cancer immunotherapy. Structural knowledge of their interaction with antibodies is currently limited, due to the large size and high flexibility of these ligands. In this study, we apply our previously developed site mapping technique to investigate the recognition of cancer-related gangliosides by anti-ganglioside antibodies. The results reveal a potential ganglioside-binding motif in the four antibodies studied, suggesting the possibility of structural convergence in the anti-ganglioside immune response. The structural basis of the recognition of ganglioside-mimetic peptides is also investigated using site mapping and compared to ganglioside recognition. The peptides are shown to act as structural mimics of gangliosides by interacting with many of the same binding site residues as the cognate carbohydrate epitopes. These studies provide important clues as to the structural basis of immunological mimicry of carbohydrates

Depressive and subthreshold depressive symptomatology among older adults in a socioeconomically deprived area in Brazil

Depressive and subthreshold depressive symptomatology are common but often neglected in older adults. / Objective: This study aimed to assess rates of depressive and subthreshold depressive symptomatology, and the characteristics associated, among older adults living in a socioeconomically deprived area of Brazil. / Methods: This study is part of the PROACTIVE cluster randomised controlled trial. 3356 adults aged 60+ years and registered in 20 primary health clinics were screened for depressive symptomatology with the Patient Health Questionnaire-9 (PHQ-9). Depressive status was classified according to the total PHQ-9 score and the presence of core depressive symptoms (depressed mood and anhedonia) as follows: no depressive symptomatology (PHQ-9 score 0–4, or 5–9 but with no core depressive symptom); subthreshold depressive symptomatology (PHQ-9 score 5–9 and at least one core depressive symptom); and depressive symptomatology (PHQ-9 score ≥ 10). Sociodemographic information and self-reported chronic conditions were collected. Relative risk ratios and 95% CIs were obtained using a multinomial regression model. / Results: Depressive and subthreshold depressive symptomatology were present in 30% and 14% of the screened sample. Depressive symptomatology was associated with female gender, low socioeconomic conditions and presence of chronic conditions, whereas subthreshold depressive symptomatology was only associated with female gender and having hypertension. / Conclusions: Depressive and subthreshold depressive symptomatology is highly prevalent in this population registered with primary care clinics. Strategies managed by primary care non-mental health specialists can be a first step for improving this alarming and neglected situation among older adults

Solar neutrino detection in a large volume double-phase liquid argon experiment

Precision measurements of solar neutrinos emitted by specific nuclear reaction chains in the Sun are of great interest for developing an improved understanding of star formation and evolution. Given the expected neutrino fluxes and known detection reactions, such measurements require detectors capable of collecting neutrino-electron scattering data in exposures on the order of 1 ktonne yr, with good energy resolution and extremely low background. Two-phase liquid argon time projection chambers (LAr TPCs) are under development for direct Dark Matter WIMP searches, which possess very large sensitive mass, high scintillation light yield, good energy resolution, and good spatial resolution in all three cartesian directions. While enabling Dark Matter searches with sensitivity extending to the "neutrino floor" (given by the rate of nuclear recoil events from solar neutrino coherent scattering), such detectors could also enable precision measurements of solar neutrino fluxes using the neutrino-electron elastic scattering events. Modeling results are presented for the cosmogenic and radiogenic backgrounds affecting solar neutrino detection in a 300 tonne (100 tonne fiducial) LAr TPC operating at LNGS depth (3,800 meters of water equivalent). The results show that such a detector could measure the CNO neutrino rate with ~15% precision, and significantly improve the precision of the 7Be and pep neutrino rates compared to the currently available results from the Borexino organic liquid scintillator detector.Comment: 21 pages, 7 figures, 6 table