Bio-preservation Potential of Sediment in Eberswalde crater, Mars

Within Eberswalde crater, Mars, is one of the most well-preserved river delta deposits identified within Mars’ rock record, and visually traceable from the deposit, is the partially-intact watershed that fed the paleo-lake that once resided within the crater basin. Aqueous alteration minerals, smectite clays and opaline silica, have been previously identified within the deposit, however the origin of those minerals is not well understood. Through analysis of topographic and hyperspectral data, we seek to ascertain the origin and provenance of these minerals to better understand their formative conditions and formation age. We will also assess Eberswalde crater’s potential as a site to explore for preserved evidence of past life on planet Mars. Using hyperspectral data to compare the minima positions of particular absorption features (e.g., ~2.3 µm for metal-OH absorptions in smectite clays) from multiple regions, including the river delta deposit, the watershed, the adjacent Northwest Noachis Terra plateau, we test the hypothesis that the smectites found within the Eberswalde crater deposit are fluvial detritus transported there during the Hesperian age (i.e., 3.5-2.0 Ga). We find that the spectra from these three regions are consistent with each other, and most consistent with lab spectra of Fe/Mg smectite clays, namely nontronite and saponite. The similar CRISM signature, and the fluvial relationship between the rocks within the watershed and the preserved putative delta stratigraphy point to a detrital origin for the smectite clays observed within Eberswalde crater. A detrital origin indicates that the clays formed prior to transport during the late Noachian (i.e., 4.0-3.5 Ga), and possibly within the subsurface, which previous studies indicate may have been the time period and location most amenable to the preservation of evidence of past life on Mars. Furthermore, the presence of detrital clays within the deposit indicate that, during the period when a lake existed within Eberswalde crater and a river delta was forming therein (i.e., during the late Hesperian and/or early Amazonian), the lake was ~neutral-pH and a habitable environment. Taken together, these observations indicate that: (1) within Eberswalde crater is a river delta deposit that formed in a habitable environment, (2) that deposit is made up of layers of sediment composed of minerals that formed during the most habitable period in Mars’ ancient history, and (3) those minerals formed in an environment thought to be most likely to preserve evidence of past life. Furthermore, this high concentration of high-biosignature preservation features are within a small rover-accessible locale, so Eberswalde crater represents a strong candidate for consideration for future missions exploring Mars for past habitability. And, the similarities between the Eberswalde crater fluvial system and the Jezero crater system make it a compelling site as a standard of comparison for analyses by the upcoming NASA Perseverance rover mission

Overexpression of Mcl-1 exacerbates lymphocyte accumulation and autoimmune kidney disease in lpr mice

Cell death by apoptosis has a critical role during embryonic development and in maintaining tissue homeostasis. In mammals, there are two converging apoptosis pathways: the ‘extrinsic’ pathway, which is triggered by engagement of cell surface ‘death receptors’ such as Fas/APO-1; and the ‘intrinsic’ pathway, which is triggered by diverse cellular stresses, and is regulated by prosurvival and pro-apoptotic members of the Bcl-2 family of proteins. Pro-survival Mcl-1, which can block activation of the proapoptotic proteins, Bax and Bak, appears critical for the survival and maintenance of multiple haemopoietic cell types. To investigate the impact on haemopoiesis of simultaneously inhibiting both apoptosis pathways, we introduced the vavP-Mcl-1 transgene, which causes overexpression of Mcl-1 protein in all haemopoietic lineages, into Faslpr/lpr mice, which lack functional Fas and are prone to autoimmunity. The combined mutations had a modest impact on myelopoiesis, primarily an increase in the macrophage/monocyte population in Mcl-1tg/lpr mice compared with lpr or Mcl-1tg mice. The impact on lymphopoiesis was striking, with a marked elevation in all major lymphoid subsets, including the non-conventional double-negative (DN) T cells (TCRβ+ CD4– CD8– B220+ ) characteristic of Faslpr/lpr mice. Of note, the onset of autoimmunity was markedly accelerated in Mcl-1tg/lpr mice compared with lpr mice, and this was preceded by an increase in immunoglobulin (Ig)-producing cells and circulating autoantibodies. This degree of impact was surprising, given the relatively mild phenotype conferred by the vavP-Mcl-1 transgene by itself: a two- to threefold elevation of peripheral B and T cells, no significant increase in the non-conventional DN T-cell population and no autoimmune disease. Comparison of the phenotype with that of other susceptible mice suggests that the development of autoimmune disease in Mcl-1tg/lpr mice may be influenced not only by Ig-producing cells but also other haemopoietic cell types

The anatomy of exhumed river-channel belts: Bedform to belt‐scale river kinematics of the Ruby Ranch Member, Cretaceous Cedar Mountain Formation, Utah, USA

Many published interpretations of ancient fluvial systems have relied on observations of extensive outcrops of thick successions. This paper, in contrast, demonstrates that a regional understanding of palaeoriver kinematics, depositional setting and sedimentation rates can be interpreted from local sedimentological measurements of bedform and barform strata. Dune and bar strata, channel planform geometry and bed topography are measured within exhumed fluvial strata exposed as ridges in the Ruby Ranch Member of the Cretaceous Cedar Mountain Formation, Utah, USA. The ridges are composed of lithified stacked channel belts, representing at least five or six re‐occupations of a single‐strand channel. Lateral sections reveal well‐preserved barforms constructed of subaqueous dune cross‐sets. The topography of palaeobarforms is preserved along the top surface of the outcrops. Comparisons of the channel‐belt centreline to local palaeotransport directions indicate that channel planform geometry was preserved through the re‐occupations, rather than being obscured by lateral migration. Rapid avulsions preserved the state of the active channel bed and its individual bars at the time of abandonment. Inferred minimum sedimentation durations for the preserved elements, inferred from cross‐set thickness distributions and assumed bedform migration rates, vary within a belt from one to ten days. Using only these local sedimentological measurements, the depositional setting is interpreted as a fluvial megafan, given the similarity in river kinematics. This paper provides a systematic methodology for the future synthesis of vertical and planview data, including the drone‐equipped 2020 Mars Rover mission, to exhumed fluvial and deltaic strata

Quantum Computers and Quantum Coherence

If the states of spins in solids can be created, manipulated, and measured at the single-quantum level, an entirely new form of information processing, quantum computing, will be possible. We first give an overview of quantum information processing, showing that the famous Shor speedup of integer factoring is just one of a host of important applications for qubits, including cryptography, counterfeit protection, channel capacity enhancement, distributed computing, and others. We review our proposed spin-quantum dot architecture for a quantum computer, and we indicate a variety of first generation materials, optical, and electrical measurements which should be considered. We analyze the efficiency of a two-dot device as a transmitter of quantum information via the ballistic propagation of carriers in a Fermi sea.Comment: 13 pages, latex, one eps figure. Prepared for special issue of J. Mag. Magn. Matl., "Magnetism beyond 2000". Version 2: small revisions and correction

Overexpression of Mcl-1 exacerbates lymphocyte accumulation and autoimmune kidney disease in lpr mice

Cell death by apoptosis has a critical role during embryonic development and in maintaining tissue homeostasis. In mammals, there are two converging apoptosis pathways: the ‘extrinsic’ pathway, which is triggered by engagement of cell surface ‘death receptors’ such as Fas/APO-1; and the ‘intrinsic’ pathway, which is triggered by diverse cellular stresses, and is regulated by prosurvival and pro-apoptotic members of the Bcl-2 family of proteins. Pro-survival Mcl-1, which can block activation of the proapoptotic proteins, Bax and Bak, appears critical for the survival and maintenance of multiple haemopoietic cell types. To investigate the impact on haemopoiesis of simultaneously inhibiting both apoptosis pathways, we introduced the vavP-Mcl-1 transgene, which causes overexpression of Mcl-1 protein in all haemopoietic lineages, into Faslpr/lpr mice, which lack functional Fas and are prone to autoimmunity. The combined mutations had a modest impact on myelopoiesis, primarily an increase in the macrophage/monocyte population in Mcl-1tg/lpr mice compared with lpr or Mcl-1tg mice. The impact on lymphopoiesis was striking, with a marked elevation in all major lymphoid subsets, including the non-conventional double-negative (DN) T cells (TCRβ+ CD4– CD8– B220+ ) characteristic of Faslpr/lpr mice. Of note, the onset of autoimmunity was markedly accelerated in Mcl-1tg/lpr mice compared with lpr mice, and this was preceded by an increase in immunoglobulin (Ig)-producing cells and circulating autoantibodies. This degree of impact was surprising, given the relatively mild phenotype conferred by the vavP-Mcl-1 transgene by itself: a two- to threefold elevation of peripheral B and T cells, no significant increase in the non-conventional DN T-cell population and no autoimmune disease. Comparison of the phenotype with that of other susceptible mice suggests that the development of autoimmune disease in Mcl-1tg/lpr mice may be influenced not only by Ig-producing cells but also other haemopoietic cell types

Control of Decoherence: Dynamical Decoupling versus Quantum Zeno Effect - a case study for trapped ions

The control of thermal decoherence via dynamical decoupling and via the quantum Zeno effect (Zeno control) is investigated for a model of trapped ion, where the dynamics of two low lying hyperfine states undergoes decoherence due to the thermal interaction with an excited state. Dynamical decoupling is a procedure that consists in periodically driving the excited state, while the Zeno control consists in frequently measuring it. When the control frequency is high enough, decoherence is shown to be suppressed. Otherwise, both controls may accelerate decoherence.Comment: 24 pages, 8 figure

The Big Five Across Socioeconomic Status: Measurement Invariance, Relationships, and Age Trends

24 pagesAssociations between socioeconomic status (SES) and personality traits have important implications for theory and application. Progress in understanding these associations depends on valid measurement, unbiased estimation, and careful assessment of generalizability. In this registered report, we used data from AIID, a large online study, to address three basic questions about personality and SES. First, we evaluated the measurement invariance of a common measure of personality, the Big Five Inventory, across indicators of educational attainment, income, and occupational prestige. Fit indices showed some instances of detectable noninvariance, but with little practical impact on substantive results. Second, we estimated associations between SES and personality. Results showed that personality and SES were largely independent (most rs < .1), in contrast to predictions derived from several previous studies. Third, we tested whether age trends in personality were moderated by SES. Results did not support predictions from social investment theory, but they did suggest that age trends were largely generalizable across SES. We discuss the implications of these findings for developing and validating personality measures for use in diverse samples. We also discuss the implications for theories that propose that the Big Five are responsive to, or partially responsible for, people’s economic and social conditions