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See detailHST-FOC observations of a remarkable UV auroral event on Jupiter
Gérard, Jean-Claude ULg; Grodent, Denis ULg; Prangé, R. et al

in NASA STI/Recon Technical Report N (1994), 95

Two sets of UV (ultraviolet) images of the Jovian north aurora were obtained with the Faint Object Camera (FOC) on Hubble. The first series shows a very intense discrete arc in corotation with the planet ... [more ▼]

Two sets of UV (ultraviolet) images of the Jovian north aurora were obtained with the Faint Object Camera (FOC) on Hubble. The first series shows a very intense discrete arc in corotation with the planet. The maximum apparent H2 emission rate corresponds to an electron precipitation of approximately 1/sq Wm, a very large flux in comparison with the solar EUV (extreme ultraviolet) heating. The hugh particle heating rate of the auroral upper atmosphere of Jupiter is expected to cause a large transient temperature increase and generate strong thermospheric winds. Twenty hours later, the discrete arc had considerably decreased in brightness. The timescale and magnitude of the change in the UV aurora strongly suggests that the discrete Jovian auroral precipitation is related to large scale current system variations as are the Earth's discrete aurorae. [less ▲]

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See detailHST-STIS Observations of Jupiter's Aurora
Clarke, J. T.; Ajello, J.; Ballester, G. E. et al

in Bulletin of the American Astronomical Society (1998, September 01)

HST observations of the UV emissions from Jupiter's aurora have been obtained with the new Space Telescope Imaging Spectrograph (STIS) since July 1997. UV images of the aurora are now possible with an ... [more ▼]

HST observations of the UV emissions from Jupiter's aurora have been obtained with the new Space Telescope Imaging Spectrograph (STIS) since July 1997. UV images of the aurora are now possible with an order of magnitude higher sensitivity than possible with earlier cameras, and improved angular resolution from shorter exposures. Images have been obtained at 4 epochs since Sept. 1997, and reveal several new features of the auroral emission pattern. These include i) faint auroral emissions extending roughly 60 deg. in the wake or plasma flow direction beyond Io's magnetic footprint, ii) systematic motions of the main auroral oval both toward the pole and toward the equator at different local times and longitudes, and iii) clear identification of an auroral emission feature with Ganymede's magnetic footprint, from the relative motion of the feature remaining underneath Ganymede in a time series of images. Preliminary interpretations of these features will be presented. Spectra have also been obtained of auroral emission features including the northern and southern main ovals, the diffuse emission poleward of the main oval, and the northern and southern Io footprints. These spectra will be presented with estimates of the overlying hydrocarbon columns, the energy of the exciting electrons, the rotational temperature of the emitting hydrogen, and the overlying column of atomic hydrogen. This work was supported by NASA under grants GO-6743.01-95A and GO-7308.01-96A to the University of Michigan. [less ▲]

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See detailHST-STIS Observations of Jupiter's FUV Aurora During the Cassini-Jupiter Flyby
Grodent, Denis ULg; Clarke, J. T.; Kim, J.

Poster (2001, June 25)

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See detailHST/ACS UV Imaging of Saturn's Southern Aurora in a Quiet State
Wannawichian, S.; Clarke, J. T.; Gérard, Jean-Claude ULg et al

Conference (2005, December 01)

Prior observations of Saturn's aurora have suggested that the aurora are highly variable, with much of the activity controlled by conditions in the solar wind. Observations of Saturn's UV aurora on 17 ... [more ▼]

Prior observations of Saturn's aurora have suggested that the aurora are highly variable, with much of the activity controlled by conditions in the solar wind. Observations of Saturn's UV aurora on 17 February 2005 were performed with the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope (HST) to further test this. The UV Solar Blind Camera (SBC) imaged the UV emissions from 115.0 to 170.0 nm for a period of 5 HST orbits, or 8 hours, corresponding to 74% of a Saturn rotation. In that observation period, HST imaged the southern auroral region in sunlight, but not the northern auroral region because of the tilt of Saturn rotation axis. Saturn's aurora appeared in its most quiet state, comparable or fainter than those observed by HST's Space Telescope Imaging Spectrograph (STIS) in January 2004. Discrete emissions were detected, with some evidence of latitudinal variations of localized emissions and motions. At the same time, Cassini's Ultraviolet Imaging Spectrograph (UVIS) studied the intensity and spectral distribution of Saturn's northern night side emission region. With the benefit of simultaneous observations, we found that the characteristics of Saturn's emission region in the day side southern aurora appeared correlated with Saturn kilometric radio (SKR) emissions, charged particles and magnetic field measurements in the night side Saturn magnetosphere. The faint UV aurora are consistent with the previously reported correlation between radio and UV emissions, and the low disturbance in Saturn's magnetosphere observed by Cassini. In this quiet state, the auroral oval brightness is a few kilorayleighs (KR). The summed images show evidence of an offset auroral oval toward midnight responding to solar wind pressure and more diffuse features in the dusk side. The specific properties of Saturn's aurora in its minimum state will be presented, and compared with more active periods. [less ▲]

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See detailHST/GHRS ultraviolet spectroscopy and model diagnostics of the Jovian aurora.
Gérard, Jean-Claude ULg; Dols, V.; Gustin, Jacques ULg et al

in Bulletin of the American Astronomical Society (1999)

A model coupling a detailed synthetic spectrum of the H_2 Lyman and Werner band systems with an electron energy degradation code is applied to the analysis of 7 GHRS spectra of the 1200-1700 { Angstroms ... [more ▼]

A model coupling a detailed synthetic spectrum of the H_2 Lyman and Werner band systems with an electron energy degradation code is applied to the analysis of 7 GHRS spectra of the 1200-1700 { Angstroms} region obtained with a ~ 5 { Angstroms} resolution at various locations in the north and south Jovian aurora. The observed color ratios indicate that the characteristic energy of the assumed initial Maxwellian distribution ranges between 17 and 40 keV. A clear signature of acetylene is observed near the absorption peaks at 1520, 1480 and 1440 { Angstroms}. The C_2H_2 column overlying the emission peak varies from 0.02 to 0.2 of the methane column. A better fit is obtained for some spectra when ethane absorption is added. The changing mixing ratios relative to methane are attributed to perturbations by heat released by the fast electron thermalization and/or perturbations to the hydrocarbon chemistry resulting from the production of H atoms by the aurora. A spectrum of the Io magnetic footprint and its trailing tail shows ultraviolet color and hydrocarbon absorption charateristics quite similar to some of the main oval spectra. This observation implies that the electrons of the Io flux tube are energized to a few tens of keV, similar to the electron precipitated in the main ovals and polar caps. Echelle spectra between 1216 and 1220 { Angstroms} at 0.07 { Angstroms} resolution are also compared with the model best fitting the closely spaced in time mid-resolution spectrum. It is found that the effective H_2 rovibrational temperature associated with the Echelle spectra is significantly higher than predicted by the model. A steep temperature gradient near the methane homopause due to large heating by auroral precipitation is a plausible explanation for this difference. We acknowledge funding by NASA and the PRODEX program of the European Space Agency. [less ▲]

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See detailHST/STIS images of UV auroral footprints from Io, Europa, and Ganymede.
Clarke, J. T.; Ajello, J.; Ballester, G. E. et al

in Bulletin of the American Astronomical Society (1999)

Ultraviolet images of Jupiter's aurora have been obtained with the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope (HST) since September 1997 with much higher sensitivity than ... [more ▼]

Ultraviolet images of Jupiter's aurora have been obtained with the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope (HST) since September 1997 with much higher sensitivity than earlier cameras. Higher sensitivity permits shorter exposures, freezing Jupiter's rotation and providing the highest angular resolution obtained to date. This combination of sensitivity and resolution has revealed new emissions from the magnetic footprints of Io, Europa, and Ganymede, which will be reported and discussed. Io's auroral footprint, while well studied with earlier cameras, appears highly extended at a low brightness in the wake or plasma flow direction. Ganymede's auroral footprint emission is now well established from the repeated appearance of this feature under the magnetic field trace of Ganymede, and there is initial evidence for auroral emission at Europa's magnetic footprint. Ganymede's auroral footprint appears consistently equatorward of the main auroral oval, which clearly constrains the main oval auroral currents to originate from beyond about 20 R_J. The observation that the main oval emissions are observed to corotate with Jupiter's magnetic field further constrains the origin of these currents to be within about 30 R_J, so that the source region for the main oval auroral is now fairly well constrained to a region in Jupiter's middle magnetosphere and within the current sheet. This work was supported by NASA under grant GO-7308.01-96A to the University of Michigan. [less ▲]

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See detailHST/STIS Observations of a Dawn Auroral Storm on Jupiter
Clarke, J. T.; Gladstone, R.; Pryor, W. et al

in Bulletin of the American Astronomical Society (2000, October 01)

The HST/STIS recorded a detailed time series of images and spectra of the UV emissions from a dawn auroral storm on Jupiter on 21 Sept. 1999. The images show complex and evolving fine structure in the ... [more ▼]

The HST/STIS recorded a detailed time series of images and spectra of the UV emissions from a dawn auroral storm on Jupiter on 21 Sept. 1999. The images show complex and evolving fine structure in the storm, while the emission center remained along the main oval and near dawn in magnetic local time. We serendipitously recorded low resolution UV spectra of the north-south spatial distribution of the auroral emissions. These spectra show far stronger hydrocarbon absorptions than observed in any previous auroral spectra. This indicates an unusually deep penetration of the incident primary particles with respect to the neutral atmosphere, and correspondingly high energy of the primary particles. We can thus use these spectra to identify many complex hydrocarbons in Jupiter's auroral atmosphere which are not normally measured in auroral spectra. These results will be presented along with model fits to the spectra derived both from fitting the observed hydrocarbon absorption features and from comparison with a photochemical model for the expected composition of the auroral atmosphere. This research has been supported by grant GO-8171.01-97A from the Space Telescope Science Institute to the University of Michigan. [less ▲]

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See detailHST/STIS spectroscopy of the magnetic Of?p star HD 108: the low state at ultraviolet wavelengths
Marcolino, W. L. F.; Bouret, J.-C.; Walborn, N. R. et al

in Monthly Notices of the Royal Astronomical Society (2012), 422

We present the first ultraviolet spectrum of the peculiar, magnetic Of?p star HD 108 obtained in its spectroscopic low state. The new data, obtained with the Space Telescope Imaging Spectrograph (STIS) on ... [more ▼]

We present the first ultraviolet spectrum of the peculiar, magnetic Of?p star HD 108 obtained in its spectroscopic low state. The new data, obtained with the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope, reveal significant changes compared to IUE spectra obtained in the high state: N Vλ1240, Si IVλ1400 and C IVλ1550 present weaker P Cygni profiles (less absorption) in the new data, while N IVλ1718 absorption is deeper, without the clear wind signature evident in the high state. Such changes contrast with those found in other magnetic massive stars, where more absorption is observed in the resonance doublets when the sightline is close to the plane of the magnetic equator. The new data show also that the photospheric Fe IV forest, at ˜1600-1700 Å, has strengthened compared to previous observations. The ultraviolet variability is large compared to that found in typical, non-magnetic O stars, but moderate when compared to the high-/low-state changes reported in the optical spectrum of HD 108 over several decades. We use non-local thermodynamic equilibrium (non-LTE) expanding-atmosphere models to analyse the new STIS observations. Overall, the results are in accord with a scenario in which the optical variability is mainly produced by magnetically constrained gas, close to the photosphere. The relatively modest changes found in the main ultraviolet wind lines suggest that the stellar wind is not substantially variable on a global scale. Nonetheless, multidimensional radiative-transfer models may be needed to understand some of the phenomena observed. [less ▲]

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See detailHsv-1 Thymidine Kinase Gene Therapy for Colorectal Adenocarcinoma-Derived Peritoneal Carcinomatosis
Lechanteur, Chantal ULg; Princen, Frédéric; Lo Bue, S. et al

in Gene Therapy (1997), 4(11), 1189-94

Peritoneal carcinomatosis is a common clinical situation which, in most cases, cannot be eradicated by surgery or chemotherapy. The feasibility of an HSV-TK-based suicide gene therapy for peritoneal ... [more ▼]

Peritoneal carcinomatosis is a common clinical situation which, in most cases, cannot be eradicated by surgery or chemotherapy. The feasibility of an HSV-TK-based suicide gene therapy for peritoneal carcinomatosis induced by DHD/K12 colon carcinoma cells was investigated. DHD/K12 cells stably expressing the tk gene were killed in vitro in the presence of low concentrations of ganciclovir, they exhibited a 'bystander effect' when mixed with TK-negative cells. BD-IX rats injected intraperitoneally, either directly or after surgical peritoneal irritations, with DHD/K12 cells developed peritoneal carcinomatosis within 2 weeks. Ganciclovir treatment of animals injected with DHD/K12-TK cells allowed a significant reduction of the tumor volume as well as a prolonged survival. Of these animals 35-40% showed a long-term disease-free survival after ganciclovir therapy. Residual or relapsing tumors could be explained by a low expression of the transgene as demonstrated by RT-PCR. [less ▲]

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See detailHsv-1 Thymidine Kinase Gene Therapy for Peritoneal Carcinomatosis
Lechanteur, Chantal ULg; Princen, Frédéric; Lo Bue, S. et al

in Advances in Experimental Medicine and Biology (1998), 451

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See detailHTA résistante et cible tensionnelle chez le diabétique
Krzesinski, Jean-Marie ULg

Conference (2011, December 13)

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See detailHTLV-1 clonality during chronic infection and BLV clonality during primary infection
Gillet, N.; Hlela, C.; Verdonck, T. et al

in AIDS Research and Human Retroviruses (2011, June 06), 8(1), 185

HTLV-1 clonality during chronic infection and BLV clonality during primary infection Nicolas A Gillet1,2*, Carol Hlela1, Tine Verdonck3, Eduardo Gotuzzo3, Daniel Clark3, Sabrina Rodriguez2, Nirav Malani4 ... [more ▼]

HTLV-1 clonality during chronic infection and BLV clonality during primary infection Nicolas A Gillet1,2*, Carol Hlela1, Tine Verdonck3, Eduardo Gotuzzo3, Daniel Clark3, Sabrina Rodriguez2, Nirav Malani4, Anat Melamed1, Niall Gormley5, Richard Carter5, David Bentley5, Charles Berry6, Frederic D Bushman4, Graham P Taylor7, Luc Willems2, Charles R M Bangham1 1Department of Immunology, Wright-Fleming Institute, Imperial College London, London, W2 1PG, UK. 2Molecular and Cellular Epigenetics, Interdisciplinary Cluster for Applied Genoproteomics (GIGA) of University of Liège (ULg), Liège, 4000, Belgium. 3Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru. 4Department of Microbiology, University of Pennsylvania School of Medicine, Pennsylvania, Philadelphia, PA, 19104, USA. 5Illumina, Chesterford Research Park, Essex, Little Chesterford, CB10 1XL, UK. 6University of California, California, La Jolla San Diego, CA, 92093-0901, USA. 7Department of Genitourinary Medicine and Communicable Diseases, Wright-Fleming Institute, Imperial College London, London, W2 1PG, UK. HTLV-1 persists by driving clonal proliferation of infected T-lymphocytes. A high proviral load predisposes to the inflammatory and malignant diseases associated with HTLV-1. Yet the reasons for the remarkable variation within and between individuals in the abundance of HTLV-1-infected clones remain unknown. We demonstrate that negative selection dominates during chronic infection, favouring establishment of proviruses integrated in transcriptionally silenced DNA: this selection is significantly stronger in asymptomatic carriers. We postulated that this selection occurred mainly during the primary infection. We are testing this hypothesis in an animal model by studying the BLV clonality during the primary infection in cows. By measuring the proviral load, the anti-BLV immune response and the BLV clonality we aim to quantify the impact of the immune response on the rate of infectious spread and on the selection of proviruses inserted in a particular genomic environment. Co-infection with Strongyloides stercoralis or Staphylococcus appears to be another risk factor for the development of HTLV-1 associated diseases. We observed that HTLV-1 clonality is altered by co-infection with these pathogens with an increase of both the number and the abundance of the infected T-cell clones. The genomic characteristics of the proviral integration sites in the most abundant clones differ significantly between co-infected individuals and those with HTLV-1 alone, implying the existence of different selection forces in co-infected patients. The rate of appearance of new clones in patients co-infected with Strongyloides stercoralis is higher than in patients with HTLV-1 alone. By comparing skin lesions and blood samples from patients with Infective Dermatitis associated with HTLV-1 (IDH), we observed a significant proportion of distinct infected clones between the two compartments. The skin lesions seem to be a site for HTLV-1 infectious spread. [less ▲]

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See detailHTLV-1 positive and negative T cells cloned from infected individuals display telomerase and telomere genes deregulation that predominate in activated but untransformed CD4+ T cells.
Zane, Linda; Sibon, David; CAPRARO, Valérie ULg et al

in International Journal of Cancer = Journal International du Cancer (2012), 131(4), 821-33

Untransformed HTLV-1 positive CD4(+) cells from infected individuals are selected for expressing tax and displaying morphological features consistent with telomere dysfunctions. We show that in resting ... [more ▼]

Untransformed HTLV-1 positive CD4(+) cells from infected individuals are selected for expressing tax and displaying morphological features consistent with telomere dysfunctions. We show that in resting HTLV-1 positive CD4(+) cells cloned from patients, hTERT expression parallels tax expression and cell cycling. Upon activation, these cells dramatically augment tax expression, whereas their increase in telomerase activity is about 20 times lower than that of their uninfected counterpart. Activated HTLV-1 positive CD4(+) but not uninfected CD4(+) or CD8(+) clones also repress the transcription of TRF1, TPP1, TANK1, POT1, DNA-PKc and Ku80. Both infected and uninfected lymphocytes from infected individuals shared common telomere gene deregulations toward a pattern consistent with premature senescence. ATLL cells displayed the highest telomerase activity (TA) whereas recovered a telomere gene transcriptome close to that of normal CD4(+) cells. In conclusion HTLV-1-dependent telomere modulations seem involved in clonal expansion, immunosuppression, tumor initiation and progression. [less ▲]

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See detailHTLV-1 propels thymic human T cell development in "human immune system" Rag2(-)/(-) gamma c(-)/(-) mice.
Villaudy, Julien; Wencker, Melanie; Gadot, Nicolas et al

in PLoS Pathogens (2011), 7(9), 1002231

Alteration of early haematopoietic development is thought to be responsible for the onset of immature leukemias and lymphomas. We have previously demonstrated that Tax(HTLV-1) interferes with ss-selection ... [more ▼]

Alteration of early haematopoietic development is thought to be responsible for the onset of immature leukemias and lymphomas. We have previously demonstrated that Tax(HTLV-1) interferes with ss-selection, an important checkpoint of early thymopoiesis, indicating that human T-cell leukemia virus type 1 (HTLV-1) infection has the potential to perturb thymic human alphabeta T-cell development. To verify that inference and to clarify the impact of HTLV-1 infection on human T-cell development, we investigated the in vivo effects of HTLV-1 infection in a "Human Immune System" (HIS) Rag2(-)/(-)gamma(c)(-)/(-) mouse model. These mice were infected with HTLV-1, at a time when the three main subpopulations of human thymocytes have been detected. In all but two inoculated mice, the HTLV-1 provirus was found integrated in thymocytes; the proviral load increased with the length of the infection period. In the HTLV-1-infected mice we observed alterations in human T-cell development, the extent of which correlated with the proviral load. Thus, in the thymus of HTLV-1-infected HIS Rag2(-)/(-)gammac(-)/(-) mice, mature single-positive (SP) CD4(+) and CD8(+) cells were most numerous, at the expense of immature and double-positive (DP) thymocytes. These SP cells also accumulated in the spleen. Human lymphocytes from thymus and spleen were activated, as shown by the expression of CD25: this activation was correlated with the presence of tax mRNA and with increased expression of NF-kB dependent genes such as bfl-1, an anti-apoptotic gene, in thymocytes. Finally, hepato-splenomegaly, lymphadenopathy and lymphoma/thymoma, in which Tax was detected, were observed in HTLV-1-infected mice, several months after HTLV-1 infection. These results demonstrate the potential of the HIS Rag2(-)/(-)gamma(c)(-)/(-) animal model to elucidate the initial steps of the leukemogenic process induced by HTLV-1. [less ▲]

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See detailThe HTLV-1 Tax interactome.
Boxus, Mathieu ULg; Twizere, Jean-Claude ULg; Legros, Sebastien et al

in Retrovirology (2008), 5

The Tax1 oncoprotein encoded by Human T-lymphotropic virus type I is a major determinant of viral persistence and pathogenesis. Tax1 affects a wide variety of cellular signalling pathways leading to ... [more ▼]

The Tax1 oncoprotein encoded by Human T-lymphotropic virus type I is a major determinant of viral persistence and pathogenesis. Tax1 affects a wide variety of cellular signalling pathways leading to transcriptional activation, proliferation and ultimately transformation. To carry out these functions, Tax1 interacts with and modulates activity of a number of cellular proteins. In this review, we summarize the present knowledge of the Tax1 interactome and propose a rationale for the broad range of cellular proteins identified so far. [less ▲]

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See detailThe HTLV-1 Tax protein inhibits formation of stress granules by interacting with histone deacetylase 6.
Legros, S.; Boxus, Mathieu ULg; Gatot, J. S. et al

in Oncogene (2011)

Human T cell leukemia virus type-1 (HTLV-1) is the causative agent of a fatal adult T-cell leukemia. Through deregulation of multiple cellular signaling pathways the viral Tax protein has a pivotal role ... [more ▼]

Human T cell leukemia virus type-1 (HTLV-1) is the causative agent of a fatal adult T-cell leukemia. Through deregulation of multiple cellular signaling pathways the viral Tax protein has a pivotal role in T-cell transformation. In response to stressful stimuli, cells mount a cellular stress response to limit the damage that environmental forces inflict on DNA or proteins. During stress response, cells postpone the translation of most cellular mRNAs, which are gathered into cytoplasmic mRNA-silencing foci called stress granules (SGs) and allocate their available resources towards the production of dedicated stress-management proteins. Here we demonstrate that Tax controls the formation of SGs and interferes with the cellular stress response pathway. In agreement with previous reports, we observed that Tax relocates from the nucleus to the cytoplasm in response to environmental stress. We found that the presence of Tax in the cytoplasm of stressed cells prevents the formation of SGs and counteracts the shutoff of specific host proteins. Unexpectedly, nuclear localization of Tax promotes spontaneous aggregation of SGs, even in the absence of stress. Mutant analysis revealed that the SG inhibitory capacity of Tax is independent of its transcriptional abilities but relies on its interaction with histone deacetylase 6, a critical component of SGs. Importantly, the stress-protective effect of Tax was also observed in the context of HTLV-1 infected cells, which were shown to be less prone to form SGs and undergo apoptosis under arsenite exposure. These observations identify Tax as the first virally encoded inhibitory component of SGs and unravel a new strategy developed by HTLV-1 to deregulate normal cell processes. We postulate that inhibition of the stress response pathway by Tax would favor cell survival under stressful conditions and may have an important role in HTLV-1-induced cellular transformation.Oncogene advance online publication, 2 May 2011; doi:10.1038/onc.2011.120. [less ▲]

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See detailHu, Luojia , Estimation of a censored dynamic panel data model,Econometrica. Journal of the Econometric Society
Rochus, Pierre ULg

in Mathematical Reviews [=MR] (2002), 70(6), 2499--2517

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See detailHubble observations of Jupiter’s north–south conjugate ultraviolet aurora
Gérard, Jean-Claude ULg; Grodent, Denis ULg; Radioti, Aikaterini ULg et al

in Icarus (2013), 226

Comparisons of the northern and southern far ultraviolet (UV) auroral emissions of Jupiter from the Hubble Space Telescope (HST) or any other ultraviolet imager have mostly been made so far on a ... [more ▼]

Comparisons of the northern and southern far ultraviolet (UV) auroral emissions of Jupiter from the Hubble Space Telescope (HST) or any other ultraviolet imager have mostly been made so far on a statistical basis or were not obtained with high sensitivity and resolution. Such observations are important to discriminate between different mechanisms responsible for the electron acceleration of the different components of the aurora such as the satellite footprints, the «main oval» or the polar emissions. The field of view of the ACS and STIS cameras on board HST is not wide enough to provide images of the full jovian disk. We thus compare the morphology of the north and south aurora observed 55 min apart and we point out similarities and differences. On one occasion HST pointed successively the two polar regions and auroral images were seen separated by only 3 min. This makes it possible to compare the emission structure and the emitted FUV power of corresponding regions. We find that most morphological features identified in one hemisphere have a conjugate counterpart in the other hemisphere. However, the power associated with conjugate regions of the main oval, diffuse or discrete equatoward emission observed quasi-simultaneously may be different in the two hemispheres. It is not directly nor inversely proportional to the strength of the B-field as one might expect for diffuse precipitation or field-aligned acceleration with equal ionospheric electron density in both hemispheres. Finally, the lack of symmetry of some polar emissions suggests that some of them could be located on open magnetic field lines. [less ▲]

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See detailHubble sans COSTAR
Grodent, Denis ULg; Dols, Vincent

Scientific conference (1994, June 23)

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