69 research outputs found
Tropospheric delay performance for GNSS integrated water vapor estimation by using GPT2w model, ECMWF's IFS operational model and in situ meteorological data
Tropospheric delay comprises one of the most important error sources in
satellite navigation and is caused when radio signals broadcasted by GPS
satellites propagate into the atmosphere. It is usually projected onto zenith
direction by using mapping functions named as Zenith Tropospheric Delay
(ZTD). ZTD is described as the sum of the Zenith Hydrostatic Delay (ZHD) and
the Zenith Wet Delay (ZWD) and with the aid of surface pressure and
temperature the integrated water vapor can be estimated. The main objective
of this study is to evaluate the tropospheric delay performance for GNSS
integrated water vapor estimation by using GPT2w model, ECMWF's IFS (ECMWF
stands for the European Centre for Medium-Range Weather Forecasts) reanalysis
model and ground meteorological data from two stations of the permanent
network of Cyprus and Greece. The period from 27 May to 3 June 2018 is
characterized by two different synoptic conditions: high pressure with fair
weather in central Mediterranean (Greece), on the one hand, and high
instability over the upper levels of the atmosphere that resulted in
thunderstorms inland and mountainous areas during midday over the Eastern
Mediterranean (Cyprus), on the other hand. In general, the results show that
both the empirical blind model GPT2w and the ECMWF (IFS) operational model
perform well in particular over Nicosia when used for the retrieval of
Integrated Water Vapor (IWV) from GNSS measurements, although appreciable
deviations were observed between ECMWF (IFS)-retrieved IWV and the one
retrieved from GNSS observations by using meteorological measurements. A
sharp increase of IWV prior to the abrupt rainfall events during noon on 30 and 31Â May over Nicosia was also found.</p
Atmospheric Temperature anomalies as manifestation of the dark Universe
We are investigating the possible origin of small-scale anomalies, like the
annual stratospheric temperature anomalies. Unexpectedly within known physics,
their observed planetary "dependency", does not match concurrent solar
activity, whose impact on the atmosphere is unequivocal; this points at an
additional energy source of exo-solar origin. A viable concept behind such
observations is based on possible gravitational focusing by the Sun and its
planets towards the Earth of low-speed invisible streaming matter; its influx
towards the Earth gets temporally enhanced. Only a somehow "strongly"
interacting invisible streaming matter with the small upper atmospheric
screening can be behind the observed temperature excursions. Ordinary dark
matter (DM) candidates like axions or WIMPs, cannot have any noticeable impact.
The associated energy deposition is . The atmosphere has been
uninterruptedly monitored for decades. Therefore, the upper atmosphere can
serve as a novel (low-threshold) detector for the dark Universe, with built-in
spatiotemporal resolution while the solar system gravity acts temporally as a
signal amplifier. Interestingly, the anomalous ionosphere shows a relationship
with the inner earth activity like earthquakes. Similarly investigating the
transient sudden stratospheric warmings within the same reasoning, the nature
of the assumed "invisible streams" could be deciphered.Comment: 8 pages, 7 figures, Published in the proceedings of the "15th
International Conference on Meteorology, Climatology and Atmospheric Physics
(COMECAP 2021)" see
https://www.conferre.gr/allevents/comecap2020/Proceedings_Final.pd
Development of a genotyping microarray for Usher syndrome
BACKGROUND: Usher syndrome, a combination of retinitis pigmentosa (RP) and sensorineural hearing loss with or without vestibular dysfunction, displays a high degree of clinical and genetic heterogeneity. Three clinical subtypes can be distinguished, based on the age of onset and severity of the hearing impairment, and the presence or absence of vestibular abnormalities. Thus far, eight genes have been implicated in the syndrome, together comprising 347 protein-coding exons. METHODS: To improve DNA diagnostics for patients with Usher syndrome, we developed a genotyping microarray based on the arrayed primer extension (APEX) method. Allele-specific oligonucleotides corresponding to all 298 Usher syndrome-associated sequence variants known to date, 76 of which are novel, were arrayed. RESULTS: Approximately half of these variants were validated using original patient DNAs, which yielded an accuracy of >98%. The efficiency of the Usher genotyping microarray was tested using DNAs from 370 unrelated European and American patients with Usher syndrome. Sequence variants were identified in 64/140 (46%) patients with Usher syndrome type I, 45/189 (24%) patients with Usher syndrome type II, 6/21 (29%) patients with Usher syndrome type III and 6/20 (30%) patients with atypical Usher syndrome. The chip also identified two novel sequence variants, c.400C>T (p.R134X) in PCDH15 and c.1606T>C (p.C536S) in USH2A. CONCLUSION: The Usher genotyping microarray is a versatile and affordable screening tool for Usher syndrome. Its efficiency will improve with the addition of novel sequence variants with minimal extra costs, making it a very useful first-pass screening tool
Common TNF-α, IL-1β, PAI-1, uPA, CD14 and TLR4 polymorphisms are not associated with disease severity or outcome from Gram negative sepsis
<p>Abstract</p> <p>Background</p> <p>Several studies have investigated single nucleotide polymorphisms (SNPs) in candidate genes associated with sepsis and septic shock with conflicting results. Only few studies have combined the analysis of multiple SNPs in the same population.</p> <p>Methods</p> <p>Clinical data and DNA from consecutive adult patients with culture proven Gram negative bacteremia admitted to a Danish hospital between 2000 and 2002. Analysis for commonly described SNPs of tumor necrosis-α, (TNF-α), interleukin-1β (IL-1β), plasminogen activator-1 (PAI-1), urokinase plasminogen activator (uPA), CD14 and toll-like receptor 4 (TLR4) was done.</p> <p>Results</p> <p>Of 319 adults, 74% had sepsis, 19% had severe sepsis and 7% were in septic shock. No correlation between severity or outcome of sepsis was observed for the analyzed SNPs of TNF-α, IL-1β, PAI-1, uPA, CD14 or TLR-4. In multivariate Cox proportional hazard regression analysis, increasing age, polymicrobial infection and haemoglobin levels were associated with in-hospital mortality.</p> <p>Conclusion</p> <p>We did not find any association between TNF-α, IL-1β, PAI-1, uPA, CD14 and TLR4 polymorphisms and outcome of Gram negative sepsis. Other host factors appear to be more important than the genotypes studied here in determining the severity and outcome of Gram negative sepsis.</p
Observations of quiet-time moderate midlatitude L-band scintillation in association with plasma bubbles
Observations of moderate night time amplitude scintillation on the GPS L1C/A signal were recorded at the midlatitude station of Nicosia, corresponding geographic latitude and longitude of 35.18˚N and 33.38˚E respectively, on a geomagnetically quiet day. The variations of slant total electron content (STEC) and amplitude scintillation index (S4) on the night of June 12, 2014, indicate the presence of electron density depletions accompanying scintillation occurrence. The estimated apparent horizontal drift velocity and propagation direction of the plasma depletions are consistent with those observed for the equatorial plasma bubbles, thus suggesting that the moderate amplitude L-band scintillation observed over Nicosia may be associated with the extension of such plasma bubbles. The L-band scintillation occurrence was concurrent with the observations of range spread F on the ionograms recorded by the digisonde at Nicosia. The height–time–intensity plot generated using the ionogram data also showed features which can be attributed to off-angle reflections from electron density depletions, thus corroborating the STEC observations. This observation suggests that the midlatitude ionosphere is more active even during geomagnetically quiet days than previously thought and that further studies are necessary. This is particularly relevant for the GNSS user community and related applications
Multilocus Microsatellite Typing (MLMT) of Strains from Turkey and Cyprus Reveals a Novel Monophyletic L. donovani Sensu Lato Group
In eastern Mediterranean, leishmaniasis represents a major public health problem with considerable impact on morbidity and potential to spread. Cutaneous leishmaniasis (CL) caused by L. major or L. tropica accounts for most cases in this region although visceral leishmaniasis (VL) caused by L. infantum is also common. New foci of human CL caused by L. donovani complex strains were recently described in Cyprus and Turkey. Herein we analyzed Turkish strains from human CL foci in Çukurova region (north of Cyprus) and a human VL case in Kuşadasi. These were compared to Cypriot strains that were previously typed by Multilocus Enzyme Electrophoresis (MLEE) as L. donovani MON-37. Nevertheless, they were found genetically distinct from MON-37 strains of other regions and therefore their origin remained enigmatic. A population study was performed by Multilocus Microsatellite Typing (MLMT) and the profile of the Turkish strains was compared to previously analyzed L. donovani complex strains. Our results revealed close genetic relationship between Turkish and Cypriot strains, which form a genetically distinct L. infantum monophyletic group, suggesting that Cypriot strains may originate from Turkey. Our analysis indicates that the epidemiology of leishmaniasis in this region is more complicated than originally thought
The Role of Host Genetics in Susceptibility to Influenza: A Systematic Review
Background: The World Health Organization has identified studies of the role of host genetics on susceptibility to severe influenza as a priority. A systematic review was conducted to summarize the current state of evidence on the role of host genetics in susceptibility to influenza (PROSPERO registration number: CRD42011001380). Methods and Findings: PubMed, Web of Science, the Cochrane Library, and OpenSIGLE were searched using a pre-defined strategy for all entries up to the date of the search. Two reviewers independently screened the title and abstract of 1,371 unique articles, and 72 full text publications were selected for inclusion. Mouse models clearly demonstrate that host genetics plays a critical role in susceptibility to a range of human and avian influenza viruses. The Mx genes encoding interferon inducible proteins are the best studied but their relevance to susceptibility in humans is unknown. Although the MxA gene should be considered a candidate gene for further study in humans, over 100 other candidate genes have been proposed. There are however no data associating any of these candidate genes to susceptibility in humans, with the only published study in humans being under-powered. One genealogy study presents moderate evidence of a heritable component to the risk of influenza-associated death, and while the marked familial aggregation of H5N1 cases is suggestive of host genetic factors, this remains unproven. Conclusion: The fundamental question ‘‘Is susceptibility to severe influenza in humans heritable?’ ’ remains unanswered. No
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