Global component analysis of errors in three satellite-only global precipitation estimates

Revealing the error components of satellite-only precipitation products (SPPs) can help algorithm developers and end-users understand their error features and improve retrieval algorithms. Here, two error decomposition schemes are employed to explore the error components of the IMERG-Late, GSMaP-MVK, and PERSIANN-CCS SPPs over different seasons, rainfall intensities, and topography classes. Global maps of the total bias (total mean squared error) and its three (two) independent components are depicted for the first time. The evaluation results for similar regions are discussed, and it is found that the evaluation results for one region cannot be extended to another similar region. Hit and/or false biases are the major components of the total bias in most overland regions globally. The systematic error contributes less than 20 % of the total error in most areas. Large systematic errors are primarily due to missed precipitation. It is found that the SPPs show different topographic patterns in terms of systematic and random errors. Notably, among the SPPs, GSMaP-MVK shows the strongest topographic dependency of the four bias scores. A novel metric, namely the normalized error component (NEC), is proposed as a means to isolate the impact of topography on the systematic and random errors. Potential methods of improving satellite precipitation retrievals and error adjustment models are discussed.</p

A computational evaluation of over-representation of regulatory motifs in the promoter regions of differentially expressed genes

BACKGROUND: Observed co-expression of a group of genes is frequently attributed to co-regulation by shared transcription factors. This assumption has led to the hypothesis that promoters of co-expressed genes should share common regulatory motifs, which forms the basis for numerous computational tools that search for these motifs. While frequently explored for yeast, the validity of the underlying hypothesis has not been assessed systematically in mammals. This demonstrates the need for a systematic and quantitative evaluation to what degree co-expressed genes share over-represented motifs for mammals. RESULTS: We identified 33 experiments for human and mouse in the ArrayExpress Database where transcription factors were manipulated and which exhibited a significant number of differentially expressed genes. We checked for over-representation of transcription factor binding sites in up- or down-regulated genes using the over-representation analysis tool oPOSSUM. In 25 out of 33 experiments, this procedure identified the binding matrices of the affected transcription factors. We also carried out de novo prediction of regulatory motifs shared by differentially expressed genes. Again, the detected motifs shared significant similarity with the matrices of the affected transcription factors. CONCLUSIONS: Our results support the claim that functional regulatory motifs are over-represented in sets of differentially expressed genes and that they can be detected with computational methods

γ-Catenin is overexpressed in acute myeloid leukemia and promotes the stabilization and nuclear localization of β-catenin

Canonical Wnt signaling regulates the transcription of T-cell factor (TCF)-responsive genes through the stabilization and nuclear translocation of the transcriptional co-activator, β-catenin. Overexpression of β-catenin features prominently in acute myeloid leukemia (AML) and has previously been associated with poor clinical outcome. Overexpression of γ-catenin mRNA (a close homologue of β-catenin) has also been reported in AML and has been linked to the pathogenesis of this disease, however, the relative roles of these catenins in leukemia remains unclear. Here we report that overexpression and aberrant nuclear localization of γ-catenin is frequent in AML. Significantly, γ-catenin expression was associated with β-catenin stabilization and nuclear localization. Consistent with this, we found that ectopic γ-catenin expression promoted the stabilization and nuclear translocation of β-catenin in leukemia cells. β-Catenin knockdown demonstrated that both γ- and β-catenin contribute to TCF-dependent transcription in leukemia cells. These data indicate that γ-catenin expression is a significant factor in the stabilization of β-catenin in AML. We also show that although normal cells exclude nuclear translocation of both γ- and β-catenin, this level of regulation is lost in the majority of AML patients and cell lines, which allow nuclear accumulation of these catenins and inappropriate TCF-dependent transcription

Helios Is Associated with CD4 T Cells Differentiating to T Helper 2 and Follicular Helper T Cells In Vivo Independently of Foxp3 Expression

Although in vitro IL-4 directs CD4 T cells to produce T helper 2 (Th2)-cytokines, these cytokines can be induced in vivo in the absence of IL-4-signalling. Thus, mechanism(s), different from the in vitro pathway for Th2-induction, contribute to in vivo Th2-differentiation. The pathway for in vivo IL-4-independent Th2-differentiation has yet to be characterized. - upregulate Th1 features - T-bet and IFN-γ - but not Helios. In addition, CD4 T cells induced to produce Th2 cytokines in vitro do not express Helios. The kinetics of Helios mRNA and protein induction mirrors that of GATA-3. The induction of IL-4, IL-13 and CXCR5 by alumOVA requires NF-κB1 and this is also needed for Helios upregulation. Importantly, Helios is induced in Th2 and TFh cells without parallel upregulation of Foxp3. These findings suggested a key role for Helios in Th2 and TFh development in response to alum-protein vaccines. We tested this possibility using Helios-deficient OTII cells and found this deficiency had no discernable impact on Th2 and TFh differentiation in response to alumOVA.Helios is selectively upregulated in CD4 T cells during Th2 and TFh responses to alum-protein vaccines in vivo, but the functional significance of this upregulation remains uncertain

On the diurnal cycle of atmospheric relative humidity in the intertropical regions

International audienceThe heat engine of climate is the atmospheric water cycle. The relationships between clouds and the atmospheric water vapor are key to improve our understanding of climate variability. Recent advances in space-borne remote sensing provide new opportunities to investigate the clouds-moisture interactions at regional and global scales. We focus on the joint diurnal variations of vertical profiles of tropospheric water vapor and collocated cloud categories in the intertropical region. Water vapor profiles are retrieved from the SAPHIR/Megha-Tropiques microwave sounder and cloud types are obtained from infrared and visible sensors onboard geostationary satellites. Environmental parameters such as SST and air temperature are extracted from the ERA-5 reanalysis. Winter and summer seasons are contrasted over the tropical oceans. The diurnal and seasonal variations of water vapor is analyzed conditionally to five cloud types. The diurnal cycle of water vapor evolves from the bottom to the top of the troposphere and strongly depends on the cloud type, with a modulation according to the season. This analysis is a first step toward a more general endeavor to improve our understanding of the atmospheric water cycle

On the diurnal cycle of atmospheric relative humidity in the intertropical regions

International audienceThe heat engine of climate is the atmospheric water cycle. The relationships between clouds and the atmospheric water vapor are key to improve our understanding of climate variability. Recent advances in space-borne remote sensing provide new opportunities to investigate the clouds-moisture interactions at regional and global scales. We focus on the joint diurnal variations of vertical profiles of tropospheric water vapor and collocated cloud categories in the intertropical region. Water vapor profiles are retrieved from the SAPHIR/Megha-Tropiques microwave sounder and cloud types are obtained from infrared and visible sensors onboard geostationary satellites. Environmental parameters such as SST and air temperature are extracted from the ERA-5 reanalysis. Winter and summer seasons are contrasted over the tropical oceans. The diurnal and seasonal variations of water vapor is analyzed conditionally to five cloud types. The diurnal cycle of water vapor evolves from the bottom to the top of the troposphere and strongly depends on the cloud type, with a modulation according to the season. This analysis is a first step toward a more general endeavor to improve our understanding of the atmospheric water cycle

Potential of Doppler radar on a stratospheric platform for dynamical studies.

International audienceHigh Altitude Platforms could offer an interesting alternative to both ground- and space-borne instruments when neither configuration offers an optimal solution. Specifically, for Doppler radar measurement of meteorological targets, ground-based radars are incredibly useful but limited in their area of deployment and space-based instruments providing a 3D sampling are particularly challenging to design. Stratospheric balloons could offer some very interesting possibilities to build a reference database of the dynamical properties of convective clouds. In the case of radar, this is a particularly interesting prospect because a platform at an altitude of 20 km offers power performances close to that of a ground system. Likewise, the possible speed of displacement of the platform is in order of magnitude close to the sought-after Doppler shifts. The main disadvantage of drifting balloons is their random trajectory (to a certain extent) and in the fact that in the upper part of the tropopause or in the lower stratosphere, the currents are rather divergent from the convective cores which could tend to move the instrument away from the most intense events.In the tropics, an altitude of 20 km is probably not optimal since deep convective systems will influence the trajectory due to the divergence at the top of the towers which will repel the balloon. However, a balloon flying at an altitude of 20 km will still be able to observe significant convective activity. Two concepts are being studied. The first one is a radar on an Open Stratospheric Ballons in order to follow events (squall lines) over short durations. The second one is a radar on a Pressurised Stratospheric Balloon , capable of staying between 20 and 30 km altitude for up to a few weeks. It is a free-moving system caught up in the stratospheric circulation in the Tropics for instance. If flown for a long-enough duration, the radar could gather enough measurements to build a database of limited size that could provide reference properties of dynamics and microphysics in regions inaccessible to ground based systems. This would also complement and validate satellite measurements (EarthCare, Aeolus) on critical areas for which there are no measurements. A rapid study showed encouraging results for tracking the flight of a Pressurised Stratospheric Balloon (PSB) in the tropics