171 research outputs found
Advanced channel coding for space mission telecommand links
We investigate and compare different options for updating the error
correcting code currently used in space mission telecommand links. Taking as a
reference the solutions recently emerged as the most promising ones, based on
Low-Density Parity-Check codes, we explore the behavior of alternative schemes,
based on parallel concatenated turbo codes and soft-decision decoded BCH codes.
Our analysis shows that these further options can offer similar or even better
performance.Comment: 5 pages, 7 figures, presented at IEEE VTC 2013 Fall, Las Vegas, USA,
Sep. 2013 Proc. IEEE Vehicular Technology Conference (VTC 2013 Fall), ISBN
978-1-6185-9, Las Vegas, USA, Sep. 201
Age and growth determination by skeletochronology in loggerhead sea turtles (<i>Caretta caretta</i>) from the Mediterranean Sea
La esclerocronología se aplicaba a los huesos de los húmeros para determinar la edad y las tasas de crecimiento de la tortuga boba Caretta caretta del Mediterráneo. Cincuenta y cinco tortugas bobas muertas de 24 a 86.5 cm de longitud de la curvatura del caparazón (CCL) fueron recogidas del Mediterráneo central. Secciones de los húmeros fueron procesados histológicamente para analizar las marcas anuales de crecimiento. Se aplicaron dos aproximaciones para determinar el crecimiento somático utilizando la función de crecimiento de von Bertalanffy. La primera aproximación se basaba en el número total de marcas de crecimiento, correspondiendo a la edad de las tortugas en el momento de la muerte. La segunda aproximación era una estimación de la longitud del caparazón en las marcas de crecimiento más antiguas, con la intención de saber la tasa de crecimiento de cada tortuga. Las tasas de crecimiento individual observadas, oscilaban entre 1.4 y 6.2 cm año–1, mostrando una elevada diversidad individual intra e interanual, posiblemente ligada a la variabilidad ambiental experimentada por las tortugas bobas durante su vida. Ambas aproximaciones dieron resultados similares y sugieren que la tortuga mediterránea tarda 14.5-28.5 años en alcanzar un tamaño de 66.5-84.7 cm de CCL. Este tamaño corresponde al tamaño medio de las tortugas bobas hembras nidificantes, encontradas en la mayoría de lugares nidificantes del Mediterráneo y puede ser considerado el tamaño aproximado de la madurez
Determinación de la edad y el crecimiento por esclerocronología en la tortuga boba marina Caretta caretta del mar Mediterráneo
Skeletochronology was applied to humerus bones to assess the age and growth rates of loggerhead sea turtles (Caretta caretta) in the Mediterranean Sea. Fifty-five dead turtles with curved carapace lengths (CCL) ranging from 24 to 86.5 cm were collected from the central Mediterranean. Sections of humeri were histologically processed to analyze annual growth marks. Two approaches were used to estimate the somatic growth in the form of a von Bertalanffy growth function. The first approach was based on calculating the total number of growth marks, which corresponds to the age of turtles at death. The second approach estimates the carapace length at old growth marks in order to provide the growth rate of each turtle. The observed individual growth rates ranged from 1.4 to 6.2 cm yr–1, and showed both elevated inter- and intra-individual variability possibly related to the environmental variability experienced by turtles during their lifetime. Both approaches gave similar results and suggest that Mediterranean loggerhead turtles take 14.9 to 28.5 years to reach a CCL of 66.5 to 84.7 cm. This size corresponds to the average size of nesting females found in the most important Mediterranean nesting sites and can be considered the approximate size at maturity.La esclerocronología se aplicaba a los huesos de los húmeros para determinar la edad y las tasas de crecimiento de la tortuga boba Caretta caretta del Mediterráneo. Cincuenta y cinco tortugas bobas muertas de 24 a 86.5 cm de longitud de la curvatura del caparazón (CCL) fueron recogidas del Mediterráneo central. Secciones de los húmeros fueron procesados histológicamente para analizar las marcas anuales de crecimiento. Se aplicaron dos aproximaciones para determinar el crecimiento somático utilizando la función de crecimiento de von Bertalanffy. La primera aproximación se basaba en el número total de marcas de crecimiento, correspondiendo a la edad de las tortugas en el momento de la muerte. La segunda aproximación era una estimación de la longitud del caparazón en las marcas de crecimiento más antiguas, con la intención de saber la tasa de crecimiento de cada tortuga. Las tasas de crecimiento individual observadas, oscilaban entre 1.4 y 6.2 cm año–1, mostrando una elevada diversidad individual intra e interanual, posiblemente ligada a la variabilidad ambiental experimentada por las tortugas bobas durante su vida. Ambas aproximaciones dieron resultados similares y sugieren que la tortuga mediterránea tarda 14.5-28.5 años en alcanzar un tamaño de 66.5-84.7 cm de CCL. Este tamaño corresponde al tamaño medio de las tortugas bobas hembras nidificantes, encontradas en la mayoría de lugares nidificantes del Mediterráneo y puede ser considerado el tamaño aproximado de la madurez
The 75-Gram Glucose Load in Pregnancy
OBJECTIVE—To investigate, in pregnant women without gestational diabetes mellitus (GDM), the relation among obstetric/demographic characteristics; fasting, 1-h, and 2-h plasma glucose values resulting from a 75-g glucose load; and the risk of abnormal neonatal anthropometric features and then to verify the presence of a threshold glucose value for a 75-g glucose load above which there is an increased risk for abnormal neonatal anthropometric characteristics.
RESEARCH DESIGN AND METHODS—The study group consisted of 829 Caucasian pregnant women with singleton pregnancy who had no history of pregestational diabetes or GDM, who were tested for GDM with a 75-g, 2-h glucose load, used as a glucose challenge test, in two periods of pregnancy (early, 16–20 weeks; late, 26–30 weeks), and who did not meet the criteria for a GDM diagnosis. In the newborns, the following abnormal anthropometric characteristics were considered as outcome measures: cranial/thoracic circumference (CC/TC) ratio ≤10th percentile for gestational age (GA), ponderal index (birth weight/length3 × 100) ≥90th percentile for GA, and macrosomia (birth weight ≥90th percentile for GA), on the basis of growth standard development for our population. For the first part of the objective, logistic regression models were used to identify 75-g glucose load values as well as obstetric and demographic variables as markers for abnormal neonatal anthropometric characteristics. For the second part, the receiver operating characteristic (ROC) curve was performed for the 75-g glucose load values to determine the plasma glucose threshold value that yielded the highest combined sensitivity and specificity for the prediction of abnormal neonatal anthropometric characteristics.
RESULTS—In both early and late periods, maternal age >35 years was a predictor of neonatal CC/TC ratio ≤10th percentile and macrosomia, with fasting 75-g glucose load values being independent predictors of neonatal CC/TC ratio ≤10th percentile. In both periods, 1-h values gave a strong association with all abnormal neonatal anthropometric characteristics chosen as outcome measures, with maternal age >35 years being an independent predictor for macrosomia. The 2-h, 75-g glucose load values were significantly associated in both periods with neonatal CC/TC ratio ≤10th percentile and ponderal index ≥90th percentile, whereas maternal age >35 years was an independent predictor of both neonatal CC/TC ratio ≤10th percentile and macrosomia. In the ROC curves for the prediction of neonatal CC/TC ratio ≤10th percentile for GA in both early and late periods of pregnancy, inflection points were identified for a 1-h, 75-g glucose load threshold value of 150 mg/dl in the early period and 160 mg/dl in the late period.
CONCLUSIONS—This study documented a significant association, seen even in the early period of pregnancy, between 1-h, 75-g glucose load values and abnormal neonatal anthropometric features, and provided evidence of a threshold relation between 75-g glucose load results and clinical outcome. Our results would therefore suggest the possibility of using a 75-g, 1-h oral glucose load as a single test for the diagnosis of GDM, adopting a threshold value of 150 mg/dl at 16–20 weeks and 160 mg/dl at 26–30 weeks
Geomorphology of Mount Ararat/Ağri Daği (Ağri Daği Milli Parki, Eastern Anatolia, Turkey)
This paper presents a geomorphological map of Mount Ararat/Ağri Daği in Eastern Anatolia (Turkey). Mount Ararat/Ağri Daği is a volcanic complex covered by a unique ice cap in the Near East. The massif is the result of multiple volcanic phases, and present day landforms are the result of subsequent and overlapping glacial, periglacial, and slope processes. The geomorphological mapping of Mount Ararat/Ağri Daği was firstly performed on the basis of desktop studies, by applying remote-sensing investigations using high-resolution satellite imagery (PLEIADES and SPOT images). A preliminary draft of the map was crosschecked and validated in the field as part of an interdisciplinary campaign carried out in the 2014 summer season. All the collected data suggest that the Mount Ararat/Ağri Daği glaciation played a crucial role in the evolution of the landscape and that even today glaciers are significant features in this area. Currently, ice bodies cover 7.28 km2 and include peculiar glacier types. Among these are three well-developed debris-covered glaciers, flowing down along the flanks of the volcano
The VMC Survey -- L. Type II Cepheids in the Magellanic Clouds
Type II Cepheids (T2C) are less frequently used counterparts of classical
Cepheids which provide the primary calibration of the distance ladder for
measuring in the local Universe. In the era of the Hubble Tension, T2C
variables with the RR Lyrae stars (RRL) and the tip of the red giant branch
(TRGB) can potentially provide classical Cepheid independent calibration of the
cosmic distance ladder. Our goal is to provide an absolute calibration of the
Period-Luminosity, Period-Luminosity-Color and Period-Wesenheit
relations(PL,PLC and PW) of T2Cs in the Large Magellanic Cloud (LMC). We
exploited time-series photometry in the near-infrared (NIR) bands for a sample
of more than 320 T2Cs in the Magellanic Clouds (MC). These observations were
acquired during 2009-2018 in the context of the VMC ESO public survey (The
VISTA near-infrared YJKs survey of the Magellanic System). The NIR photometry
was supplemented with well-sampled optical light curves and accurate pulsation
periods from the OGLE IV survey and the Gaia mission. We used the best-quality
NIR light curves to generate custom templates for modelling sparsely sampled
light curves in YJKs bands; in turn, we derived accurate and precise
intensity-averaged mean magnitudes and pulsation amplitudes of 339 T2Cs in the
MC. We used optical and NIR mean magnitudes to derive PL/PLC/PW relations for
T2Cs in multiple bands, which were calibrated with the geometric distance to
the LMC and with the Gaia parallaxes. We used our new empirical calibrations of
PL/PW relations to obtain distances to 22 T2C-host Galactic globular clusters,
which were found to be systematically smaller by 0.1 mag and 0.03-0.06 mag
compared with the literature. A better agreement is found between our distances
and those based on RRLs in globular clusters, providing strong support for
using these population II stars with the TRGB for future distance scale
studies
The VMC Survey -- XXXV. Model fitting of LMC Cepheid light curves
We present the results of the light curve model fitting technique applied to
optical and near-infrared photometric data for a sample of 18 Classical
Cepheids (11 fundamentals and 7 first overtones) in the Large Magellanic Cloud
(LMC). We use optical photometry from the OGLE III database and near--infrared
photometry obtained by the European Southern bservatory public survey "VISTA
near--infrared survey of the Magellanic Clouds system". Iso--periodic nonlinear
convective model sequences have been computed for each selected Cepheid in
order to reproduce the multi--filter light curve amplitudes and shape details.
The inferred individual distances provide an intrinsic weighted mean value for
the LMC distance modulus of mag with a standard deviation of 0.13
mag. We derive also the Period--Radius, the Period--Luminosity and the
Period--Wesenheit relations that are consistent with similar relations in the
literature. The intrinsic masses and luminosities of the best--fitting models
show that all the investigated pulsators are brighter than the redictions of
the canonical evolutionary mass--luminosity relation, suggesting a significant
efficiency of non--canonical phenomena, such as overshooting, mass loss and/or
rotation.Comment: 14 pages, 10 figures, MNRAS accepte
Cost-effectiveness analysis of personalised versus standard dosimetry for selective internal radiation therapy with TheraSphere in patients with hepatocellular carcinoma
Aims: To perform a cost-effectiveness analysis (CEA) comparing personalised dosimetry with standard dosimetry in the context of selective internal radiation therapy (SIRT) with TheraSphere for the management of adult patients with locally advanced hepatocellular carcinoma (HCC) from the Italian Healthcare Service perspective.
Materials and methods: A partition survival model was developed to project costs and the quality-adjusted life years (QALYs) over a lifetime horizon. Clinical inputs were retrieved from a published randomised controlled trial. Health resource utilisation inputs were extracted from the questionnaires administered to clinicians in three oncology centres in Italy, respectively. Cost parameters were based on Italian official tariffs.
Results: Over a lifetime horizon, the model estimated the average QALYs of 1.292 and 0.578, respectively, for patients undergoing personalised and standard dosimetry approaches. The estimated mean costs per patient were €23,487 and €19,877, respectively. The incremental cost-utility ratio (ICUR) of personalised versus standard dosimetry approaches was €5,056/QALY.
Conclusions: Personalised dosimetry may be considered a cost-effective option compared to standard dosimetry for patients undergoing SIRT for HCC in Italy. These findings provide evidence for clinicians and payers on the value of personalised dosimetry as a treatment option for patients with HCC
5G NTN LEO Based Demonstrator Using OpenAirInterface5G
peer reviewed3GPP Release-17 formally recognizes Non-
Terrestrial Network (NTN) components as an integral part of
future telecom networks. The integration of 5G with NTN has
gained significant traction due to the joint effort from academia,
industry, and government space agencies. The first phase of
5G-NTN prototype development has been successful using GEO
satellites. Moving ahead, LEO satellites can provide higher
data rates and lower latency compared to GEO. In this paper,
we discuss the ongoing activities, and planned experiments
related to the project 5G-LEO (OpenAirInterface5G Extension
for 5G Satellite Links). 5G-LEO aims to provide direct access
of 5G services to a ground UE via a transparent payload
LEO satellite. To the best of our knowledge, 5G-LEO is the
first work involving the adaptation of 5G protocol addressing
the challenges presented by the LEO satellite channel for
example high and time-varying Doppler and frequent handover.
Open-source 5G-NR protocol stack OpenAirInterface5G has
been taken as the baseline and 3GPP Release 17 compliant
adaptations have been done in all the layers for this purpose.
An end-to-end hardware demonstrator has been developed for
in-lab validation. The results of the experiments using the LEO
satellite channel emulator will be summarised in the full paper
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