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The colonial legacy in France : fracture, rupture, and apartheid
\"Debates about the legacy of colonialism in France are not new, but they have taken on new urgency in the wake of recent terrorist attacks. Responding to acts of religious and racial violence in 2005, 2010, and 2015 and beyond, the essays in this volume pit French ideals against government-sponsored revisionist decrees that have exacerbated tensions, complicated the process of establishing and recording national memory, and triggered divisive debates on what it means to identify as French. As they document the checkered legacy of French colonialism, the contributors raise questions about France and the contemporary role of Islam, the banlieues, immigration, race, history, pedagogy, and the future of the Republic. This innovative volume reconsiders the cultural, economic, political, and social realities facing global French citizens today and includes contributions by Achille Mbembe, Benjamin Stora, Franًcoise Vergلes, Alec Hargreaves, Elsa Dorlin, and Alain Mabanckou, among others\"--Provided by publisher.
Book
Dust-to-Gas and Refractory-to-Ice Mass Ratios of Comet 67P/Churyumov-Gerasimenko from Rosetta Observations
This chapter reviews the estimates of the dust-to-gas and refractory-to-ice mass ratios derived from
Rosetta
measurements in the lost materials and the nucleus of 67P/Churyumov-Gerasimenko, respectively. First, the measurements by
Rosetta
instruments are described, as well as relevant characteristics of 67P. The complex picture of the activity of 67P, with its extreme North-South seasonal asymmetry, is presented. Individual estimates of the dust-to-gas and refractory-to-ice mass ratios are then presented and compared, showing wide ranges of plausible values.
Rosetta
’s wealth of information suggests that estimates of the dust-to-gas mass ratio made in cometary comae at a single point in time may not be fully representative of the refractory-to-ice mass ratio within the cometary nuclei being observed.
Journal Article
Deciphering the bone marrow microenvironment’s role in multiple myeloma immunotherapy resistance
Multiple Myeloma (MM) is a malignant monoclonal gammopathy characterized by the proliferation of plasma cells (PC) in the bone marrow (BM). The tight cross-talk between the BM microenvironment and PC is the hallmark of MM. The BM microenvironment comprises a cellular compartment, consisting of hematopoietic and non-hematopoietic cells. The first includes myeloid cells, T- and B-lymphocytes, natural killer (NK) cells, macrophages, and osteoclasts (OCs). In contrast, non-hematopoietic cell types include BM-derived mesenchymal stromal cells (MSCs), osteoblasts, adipocytes and endothelial cells. Besides the cellular compartment, there is a non-cellular compartment that includes extracellular matrix, growth factors, chemokines, and several cytokines. All these members play distinctive but interacting roles in the progression of MM and the drug response. MM remains an incurable disease, but in the last years immunotherapy has emerged as an important tool in the treatment of MM. The involvement of the BM microenvironment is a relevant barrier in the response to immunotherapy and in generating resistance. In this review, we provide an overview of the BM microenvironment perturbation in MM patients and how it can determine the possible resistance to immunotherapy, including monoclonal antibodies (mAbs), antibody-drug conjugates, chimeric antigen receptor T-cell (CAR-T), and bispecific T-cell engagers (BsAbs).
Journal Article
Ammonium salts are a reservoir of nitrogen on a cometary nucleus and possibly on some asteroids
The distribution of carbon and nitrogen in the Solar System is thought to reflect the stability of carbon- and nitrogen-bearing molecules when exposed to the heat of the forming Sun. Comets have a low nitrogen-to-carbon ratio, which is contrary to expectations because they originate in the outer Solar System where nitrogen species should be common. Poch et al. used laboratory experiments to simulate cometary surfaces and compared the resulting spectra with comet 67P/Churyumov-Gerasimenko. They assigned a previously unidentified infrared absorption band to nitrogen-containing ammonium salts. The salts could contain enough nitrogen to bring the comet's nitrogen-to-carbon ratio in line with the Sun's. Science , this issue p. eaaw7462 Laboratory experiments show that comet 67P contains ammonium salts, which may dominate its nitrogen content. The measured nitrogen-to-carbon ratio in comets is lower than for the Sun, a discrepancy which could be alleviated if there is an unknown reservoir of nitrogen in comets. The nucleus of comet 67P/Churyumov-Gerasimenko exhibits an unidentified broad spectral reflectance feature around 3.2 micrometers, which is ubiquitous across its surface. On the basis of laboratory experiments, we attribute this absorption band to ammonium salts mixed with dust on the surface. The depth of the band indicates that semivolatile ammonium salts are a substantial reservoir of nitrogen in the comet, potentially dominating over refractory organic matter and more volatile species. Similar absorption features appear in the spectra of some asteroids, implying a compositional link between asteroids, comets, and the parent interstellar cloud.
Journal Article
Detection of ferrihydrite in Martian red dust records ancient cold and wet conditions on Mars
Iron oxide-hydroxide minerals in Martian dust provide crucial insights into Mars’ past climate and habitability. Previous studies attributed Mars’ red color to anhydrous hematite formed through recent weathering. Here, we show that poorly crystalline ferrihydrite (Fe
5
O
8
H · nH
2
O) is the dominant iron oxide-bearing phase in Martian dust, based on combined analyses of orbital, in-situ, and laboratory visible near-infrared spectra. Spectroscopic analyses indicate that a hyperfine mixture of ferrihydrite, basalt and sulfate best matches Martian dust observations. Through laboratory experiments and kinetic calculations, we demonstrate that ferrihydrite remains stable under present-day Martian conditions, preserving its poorly crystalline structure. The persistence of ferrihydrite suggests it formed during a cold, wet period on early Mars under oxidative conditions, followed by a transition to the current hyper-arid environment. This finding challenges previous models of continuous dry oxidation and indicates that ancient Mars experienced aqueous alteration before transitioning to its current desert state.
Mars’ distinctive red colour attributed to ferrihydrite, a type of rust mineral. This finding suggests Mars experienced a cold and wet environment before transitioning to its current desert state.
Journal Article
Transgenic Expression of the Dicotyledonous Pattern Recognition Receptor EFR in Rice Leads to Ligand-Dependent Activation of Defense Responses
Plant plasma membrane localized pattern recognition receptors (PRRs) detect extracellular pathogen-associated molecules. PRRs such as Arabidopsis EFR and rice XA21 are taxonomically restricted and are absent from most plant genomes. Here we show that rice plants expressing EFR or the chimeric receptor EFR::XA21, containing the EFR ectodomain and the XA21 intracellular domain, sense both Escherichia coli- and Xanthomonas oryzae pv. oryzae (Xoo)-derived elf18 peptides at sub-nanomolar concentrations. Treatment of EFR and EFR::XA21 rice leaf tissue with elf18 leads to MAP kinase activation, reactive oxygen production and defense gene expression. Although expression of EFR does not lead to robust enhanced resistance to fully virulent Xoo isolates, it does lead to quantitatively enhanced resistance to weakly virulent Xoo isolates. EFR interacts with OsSERK2 and the XA21 binding protein 24 (XB24), two key components of the rice XA21-mediated immune response. Rice-EFR plants silenced for OsSERK2, or overexpressing rice XB24 are compromised in elf18-induced reactive oxygen production and defense gene expression indicating that these proteins are also important for EFR-mediated signaling in transgenic rice. Taken together, our results demonstrate the potential feasibility of enhancing disease resistance in rice and possibly other monocotyledonous crop species by expression of dicotyledonous PRRs. Our results also suggest that Arabidopsis EFR utilizes at least a subset of the known endogenous rice XA21 signaling components.
Journal Article
Seasonal Flows on Warm Martian Slopes
Water probably flowed across ancient Mars, but whether it ever exists as a liquid on the surface today remains debatable. Recurring slope lineae (RSL) are narrow (0.5 to 5 meters), relatively dark markings on steep (25° to 40°) slopes; repeat images from the Mars Reconnaissance Orbiter High Resolution Imaging Science Experiment show them to appear and incrementally grow during warm seasons and fade in cold seasons. They extend downslope from bedrock outcrops, often associated with small channels, and hundreds of them form in some rare locations. RSL appear and lengthen in the late southern spring and summer from 48°S to 32°S latitudes favoring equator-facing slopes, which are times and places with peak surface temperatures from ∼250 to 300 kelvin. Liquid brines near the surface might explain this activity, but the exact mechanism and source of water are not understood.
Journal Article
Spectral Clustering of CRISM Datasets in Jezero Crater Using UMAP and k-Means
In this paper, we expand upon our previous research on unsupervised learning algorithms to map the spectral parameters of the Martian surface. Previously, we focused on the VIS-NIR range of hyperspectral data from the CRISM imaging spectrometer instrument onboard NASA’s Mars Reconnaissance Orbiter to relate to other correspondent imager data sources. In this study, we generate spectral cluster maps on a selected CRISM datacube in a NIR range of 1050–2550 nm. This range is suitable for identifying most dominate mineralogy formed in ancient wet environment such as phyllosilicates, pyroxene and smectites. In the machine learning community, the UMAP method for dimensionality reduction has recently gained attention because of its computing efficiency and speed. We apply this algorithm in combination with k-Means to data from Jezero Crater. Such studies of Jezero Crater are of priority to support the planning of the current NASA’s Perseversance rover mission. We compare our results with other methodologies based on a suitable metric and can identify an optimal cluster size of six for the selected datacube. Our proposed approach outperforms comparable methods in efficiency and speed. To show the geological relevance of the different clusters, the so-called “summary products” derived from the hyperspectral data are used to correlate each cluster with its mineralogical properties. We show that clustered regions relate to different mineralogical compositions (e.g., carbonates and pyroxene). Finally the generated spectral cluster map shows a qualitatively strong resemblance with a given manually compositional expert map. As a conclusion, the presented method can be implemented for automated region-based analysis to extend our understanding of Martian geological history.
Journal Article