551 research outputs found
Registration of Multisensor Images through a Conditional Generative Adversarial Network and a Correlation-Type Similarity Measure
The automatic registration of multisensor remote sensing images is a highly challenging task due to the inherently different physical, statistical, and textural characteristics of the input data. Information-theoretic measures are often used to favor comparing local intensity distributions in the images. In this paper, a novel method based on the combination of a deep learning architecture and a correlation-type area-based functional is proposed for the registration of a multisensor pair of images, including an optical image and a synthetic aperture radar (SAR) image. The method makes use of a conditional generative adversarial network (cGAN) in order to address image-to-image translation across the optical and SAR data sources. Then, once the optical and SAR data are brought to a common domain, an area-based â2 similarity measure is used together with the COBYLA constrained maximization algorithm for registration purposes. While correlation-type functionals are usually ineffective in the application to multisensor registration, exploiting the image-to-image translation capabilities of cGAN architectures allows moving the complexity of the comparison to the domain adaptation step, thus enabling the use of a simple â2 similarity measure, favoring high computational efficiency, and opening the possibility to process a large amount of data at runtime. Experiments with multispectral and panchromatic optical data combined with SAR images suggest the effectiveness of this strategy and the capability of the proposed method to achieve more accurate registration as compared to state-of-the-art approaches
Nonacceptability criteria and closure properties for the class of languages accepted by binary systolic tree automata
AbstractIn this paper a contribution is given to the solution of the problem of finding an inductive characterization of the class of languages accepted by binary systolic tree automata, L(BSTA), in terms of the closure of a class of languages with respect to certain operations. It is shown that L(BSTA) is closed with respect to some new operations: selective concatenation, restricted concatenation and restricted iteration. The known nonclosure of L(BSTA) with respect to classical language operations, like concatenation and Kleene iteration is proved here by using a new nonacceptability criterion
Polar cap arcs from the magnetosphere to the ionosphere: kinetic modelling and observations by Cluster and TIMED
On 1 April 2004 the GUVI imager onboard the TIMED spacecraft spots an
isolated and elongated polar cap arc. About 20 min later, the Cluster
satellites detect an isolated upflowing ion beam above the polar cap.
Cluster observations show that the ions are accelerated upward by a
quasi-stationary electric field. The field-aligned potential drop is
estimated to about 700 V and the upflowing ions are accompanied by a tenuous
population of isotropic protons with a temperature of about 500 eV.
<br><br>
The magnetic footpoints of the ion outflows observed by Cluster are situated
in the prolongation of the polar cap arc observed by TIMED GUVI. The
upflowing ion beam and the polar cap arc may be different signatures of the
same phenomenon, as suggested by a recent statistical study of polar cap ion
beams using Cluster data.
<br><br>
We use Cluster observations at high altitude as input to a quasi-stationary
magnetosphere-ionosphere (MI) coupling model. Using a Knight-type
current-voltage relationship and the current continuity at the topside
ionosphere, the model computes the energy spectrum of precipitating
electrons at the top of the ionosphere corresponding to the generator
electric field observed by Cluster. The MI coupling model provides a
field-aligned potential drop in agreement with Cluster observations of
upflowing ions and a spatial scale of the polar cap arc consistent with the
optical observations by TIMED. The computed energy spectrum of the
precipitating electrons is used as input to the Trans4 ionospheric transport
code. This 1-D model, based on Boltzmann's kinetic formalism, takes into
account ionospheric processes such as photoionization and electron/proton
precipitation, and computes the optical and UV emissions due to
precipitating electrons. The emission rates provided by the Trans4 code are
compared to the optical observations by TIMED. They are similar in size and
intensity. Data and modelling results are consistent with the scenario of
quasi-static acceleration of electrons that generate a polar cap arc as they
precipitate in the ionosphere. The detailed observations of the acceleration
region by Cluster and the large scale image of the polar cap arc provided by
TIMED are two different features of the same phenomenon. Combined together,
they bring new light on the configuration of the high-latitude magnetosphere
during prolonged periods of Northward IMF. Possible implications of the
modelling results for optical observations of polar cap arcs are also
discussed
Dasabuvir and Ombitasvir/Paritaprevir/Ritonavir with or without Ribavirin in Patients with HIV-HCV Coinfection. Real Life Interim Analysis of an Italian Multicentre Compassionate Use Program
Background and Aims: An HCV cure is now possible in a large proportion of HIV-HCV patient. We present real life results of a compassionate use program promoted by SIMIT (Infectious and Tropical Diseases Italian Society) of Dasabuvir and Ombitasvir/Paritaprevir/Ritonavir ± Ribavirin for 12 weeks in 213 HIV-HCV genotype 1 patients. Data on efficacy and tolerability of this strategy in HIV patients have been reported until now only in 43 non cirrhotic HIV subjects
Time spent with HIV-RNA †200 copies/ml in a cohort of people with HIV during the U=U era
Objective:
Zero risk of linked HIV transmission in sero-discordant couples when the HIV-infected partner had viral load (VL) <200 copies/mL (âU statusâ) was found in observational studies. We aimed at estimating the proportion of time in which âU statusâ was maintained and identifying factors associated with the risk of losing it. /
Design:
Observational cohort study. /
Methods:
We included participants in the ICONA cohort who had reached an established âU statusâ (VLâ€200 copies/mL for >6 months) as of December 2010. The outcome was the number of person-days of follow up (PDFU) above a VL>200 copies/ml, relative to the total number of PDFU observed. A logistic regression model was used to identify factors independently associated with the risk of losing âU statusâ. /
Results:
8,241 persons living with HIV were included in the analysis who contributed 12,670,888 PDFU. Of these, 1,648 (20%) were female, 768 (9%) were people who inject drugs (PWID), and 2,066 (25%) were foreing-born. The median of VL measurements was 9 (IQR: 4â15). Overall, only 3.1% of PDFU were observed when VL was >200 copies/mL. The proportion of PDFU with VL>200 cp/ml was higher than average in females (5.3%), unemployed (5.4%), PWID (4.7%), and in people with>3 previous virologic failures (6.3%). These variables were significant predictors of losing âU statusâ in the multivariable logistic regression. /
Conclusions:
Our results reinforce the validity of the U=U message in real-world setting. However, we identified subsets of our study population at higher risk of losing the âU statusâ for whom additional efforts are needed
A multi-satellite study of accelerated ionospheric ion beams above the polar cap
This paper presents a study of nearly field-aligned outflowing ion beams observed on the Cluster satellites over the polar cap. Data are taken at geocentric radial distances of the order of 5&ndash;9 <i>R<sub>E</sub></i>. The distinction is made between ion beams originating from the polar cusp/cleft and beams accelerated almost along the magnetic field line passing by the spacecraft. Polar cusp beams are characterized by nearly field-aligned proton and oxygen ions with an energy ratio E<sub>O+</sub> / E<sub>H+</sub>, of the order of 3 to 4, due to the ion energy repartition inside the source and to the latitudinal extension of the source. Rapid variations in the outflowing ion energy are linked with pulses/modifications of the convection electric field. Cluster data allow one to show that these perturbations of the convection velocity and the associated ion structures propagate at the convection velocity. <P style="line-height: 20px;"> In contrast, polar cap local ion beams are characterized by field-aligned proton and oxygen ions with similar energies. These beams show the typical inverted V structures usually observed in the auroral zone and are associated with a quasi-static converging electric field indicative of a field-aligned electric field. The field-aligned potential drop fits well the ion energy profile. The simultaneous observation of precipitating electrons and upflowing ions of similar energies at the Cluster orbit indicates that the spacecraft are crossing the mid-altitude part of the acceleration region. In the polar cap, the parallel electric field can thus extend to altitudes higher than 5&nbsp;Earth radii. A detailed analysis of the distribution functions shows that the ions are heated during their parallel acceleration and that energy is exchanged between H<sup>+</sup> and O<sup>+</sup>. Furthermore, intense electrostatic waves are observed simultaneously. These observations could be due to an ion-ion two-stream instability
Long-Term Durability of Tenofovir-Based Antiretroviral Therapy in Relation to the Co-Administration of Other Drug Classes in Routine Clinical Practice
BACKGROUND: In clinical trials, toxicity leading to tenofovir disoproxil fumarate (TDF) discontinuation is rare (3% by 2 years); however in clinical practice it seems to be higher, particularly when TDF is co-administered with ritonavir-boosted protease inhibitors (PI/r). Aims of this study were to assess the rate of TDF discontinuations in clinical practice and to identify factors associated with the risk of stopping TDF. METHODS: All antiretroviral treatment (ART)-naive patients initiating a TDF-based regimen were selected from the ICONA Foundation Study cohort. The primary outcome was TDF discontinuation regardless of the reason; secondary outcome measures were TDF discontinuation due to toxicity and selective TDF discontinuation (that is, TDF discontinuation or substitution, maintaining unchanged the remaining antiretroviral treatment). RESULTS: 3,618 ART-naĂŻve patients were included: 54% started a PI/r-based and 46% a NNRTI-based based regimen. Two-hundred-seventy-seven patients discontinued TDF and reintroduced ART within 30 days without TDF. The probability of TDF discontinuation regardless of the reason was of 7.4% (95%CI:6.4-8.5) by 2 years and 14.1% (95%CI:12.2-16.1) by 5 years. The 5-year KM estimates in the PI/r vs. NNRTI group were 20.4% vs. 7.6%, respectively (log-rank p = 0.0001), for the outcome of stopping regardless of the reason, and 10.7% vs. 4.7% (p = 0.0001) for discontinuation due to toxicity. PI/r use and lower eGFR were associated with an increased risk of discontinuing TDF. CONCLUSION: In our cohort, the frequency of TDF discontinuations was higher than that observed in clinical trials. Co-administration of TDF with PI/r was associated with an increased rate of TDF discontinuations. Further studies are needed to clarify the mechanisms that might have led to this outcome
Long-term durability of tenofovir-based antiretroviral therapy in relation to the co-administration of other drug classes in routine clinical practice
BACKGROUND: In clinical trials, toxicity leading to tenofovir disoproxil fumarate (TDF) discontinuation is rare (3% by 2 years); however in clinical practice it seems to be higher, particularly when TDF is co-administered with ritonavir-boosted protease inhibitors (PI/r). Aims of this study were to assess the rate of TDF discontinuations in clinical practice and to identify factors associated with the risk of stopping TDF.
METHODS: All antiretroviral treatment (ART)-naive patients initiating a TDF-based regimen were selected from the ICONA Foundation Study cohort. The primary outcome was TDF discontinuation regardless of the reason; secondary outcome measures were TDF discontinuation due to toxicity and selective TDF discontinuation (that is, TDF discontinuation or substitution, maintaining unchanged the remaining antiretroviral treatment).
RESULTS: 3,618 ART-naĂŻve patients were included: 54% started a PI/r-based and 46% a NNRTI-based based regimen. Two-hundred-seventy-seven patients discontinued TDF and reintroduced ART within 30 days without TDF. The probability of TDF discontinuation regardless of the reason was of 7.4% (95%CI:6.4-8.5) by 2 years and 14.1% (95%CI:12.2-16.1) by 5 years. The 5-year KM estimates in the PI/r vs. NNRTI group were 20.4% vs. 7.6%, respectively (log-rank p = 0.0001), for the outcome of stopping regardless of the reason, and 10.7% vs. 4.7% (p = 0.0001) for discontinuation due to toxicity. PI/r use and lower eGFR were associated with an increased risk of discontinuing TDF.
CONCLUSION: In our cohort, the frequency of TDF discontinuations was higher than that observed in clinical trials. Co-administration of TDF with PI/r was associated with an increased rate of TDF discontinuations. Further studies are needed to clarify the mechanisms that might have led to this outcome
Faire lâUnion. La refondation des parties de droite aprĂšs les Ă©lections de 2002
Un nouveau parti de droite, pour le moment dénommé UMP, a été mis en place entre des deux tours de
l'élection présidentielle. Cet article se donne pour objectif d'analyser les enjeux de cette transformation.
La genĂšse de l'UMP permet de saisir dans quelle mesure un parti poli-tique peut ĂȘtre conçu comme la
connexion d'un ensemble de systÚmes de coopération organisés autour de postes à conquérir. En effet,
l'impératif d'unification de la droite française est lié au décalage persistant existant entre les systÚmes
de coopération législatif et présidentiel. Mais les questions soulevées par cette fusion partisane (l'UMP
inclut le RPR, DL et une majeure partie de l'UDF) montrent que cette vision ne peut suffire et que les
partis ne sont pas seulement des systÚmes de coopération mais aussi des systÚmes de production.
DĂšs lors, leurs logiques d'organisation internes pĂšsent sur ce travail de transformation du social en
politique, de la plu-ralité en homogénéité. Dans le cas de l'UMP, il s'agit d'abord de mettre en commun
des modes de fonctionnement, en particulier de définir la place et la légitimité accordées
respectivement aux adhérents et aux élus, mais aussi d'organiser l'expression de la pluralité
idéologique par la mise en place de courants
- âŠ