The internal structure of a debris-covered glacier on Mars revealed by gully incision

Viscous flow features (VFFs) in Mars' mid latitudes are analogous to debris-covered glaciers on Earth. They have complex, often curvilinear patterns on their surfaces, which probably record histories of ice flow. As is the case for glaciers on Earth, patterns on the surfaces of VFFs are likely to reflect complexities in their subsurface structure. Until now, orbital observations of VFF-internal structures have remained elusive. We present observations of internal structures within a small, kilometer-scale VFF in the Nereidum Montes region of Mars' southern mid latitudes, using images from the Context Camera (CTX) and High Resolution Imaging Science Experiment (HiRISE) instruments on Mars Reconnaissance Orbiter. The VFF-internal structures are revealed by a gully incision, which extends from the VFF headwall to its terminus and intersects curvilinear undulations and a crevasse field on the VFF surface. Near to the VFF terminus, the curvilinear VFF-surface undulations connect to the VFF-internal layers, which are inclined and extend down to the VFF's deep interior, and possibly all the way to the bed. Similar structures are common near to the termini of glaciers on Earth; they form under ice flow compression where ice thins and slows approaching the ice margin, and ice flow is forced up towards the surface. We performed 3D ice flow modeling which supports this analogy, revealing that the inclined VFF-internal structures, and associated curvilinear structures on the VFF surface, are located in a zone of strong ice flow compression where ice flow deviates upwards away from the bed. The inclined VFF-internal structures we observe could represent up-warped VFF-internal layering transported up to the surface from the VFF's deep interior, or thrust structures representing debris transport pathways between the VFF's bed and its surface. Our observations raise numerous considerations for future surface missions targeting Mars' mid-latitude subsurface ice deposits. Inclined layers formed under flow compression could reduce the requirement for high-cost, high-risk deep drilling to address high-priority science questions. They could allow futures missions to (a) access ice age sequences for palaeoenvironmental reconstruction via shallow sampling along transects of ice surfaces where layers of progressively older age outcrop, and/or (b) access samples of ice/lithics transported to shallow/surface positions from environments of astrobiological interest at/near glacier beds. However, our observations also raise considerations for potential drilling hazards associated with structural complexities and potential dust/debris layers within subsurface ice deposits on Mars. They highlight the importance of characterizing VFF-surface structures, and their relationships to VFF-internal structure and ice flow histories ahead of ice access missions to Mars

Bianchi type II models in the presence of perfect fluid and anisotropic dark energy

Spatially homogeneous but totally anisotropic and non-flat Bianchi type II cosmological model has been studied in general relativity in the presence of two minimally interacting fluids; a perfect fluid as the matter fluid and a hypothetical anisotropic fluid as the dark energy fluid. The Einstein's field equations have been solved by applying two kinematical ans\"{a}tze: we have assumed the variation law for the mean Hubble parameter that yields a constant value of deceleration parameter, and one of the components of the shear tensor has been considered proportional to the mean Hubble parameter. We have particularly dwelled on the accelerating models with non-divergent expansion anisotropy as the Universe evolves. Yielding anisotropic pressure, the fluid we consider in the context of dark energy, can produce results that can be produced in the presence of isotropic fluid in accordance with the \Lambda CDM cosmology. However, the derived model gives additional opportunities by being able to allow kinematics that cannot be produced in the presence of fluids that yield only isotropic pressure. We have obtained well behaving cases where the anisotropy of the expansion and the anisotropy of the fluid converge to finite values (include zero) in the late Universe. We have also showed that although the metric we consider is totally anisotropic, the anisotropy of the dark energy is constrained to be axially symmetric, as long as the overall energy momentum tensor possesses zero shear stress.Comment: 15 pages; 5 figures; matches the version published in The European Physical Journal Plu

Non-vacuum Solutions of Bianchi Type VI_0 Universe in f(R) Gravity

In this paper, we solve the field equations in metric f(R) gravity for Bianchi type VI_0 spacetime and discuss evolution of the expanding universe. We find two types of non-vacuum solutions by taking isotropic and anisotropic fluids as the source of matter and dark energy. The physical behavior of these solutions is analyzed and compared in the future evolution with the help of some physical and geometrical parameters. It is concluded that in the presence of isotropic fluid, the model has singularity at $\tilde{t}=0$ and represents continuously expanding shearing universe currently entering into phantom phase. In anisotropic fluid, the model has no initial singularity and exhibits the uniform accelerating expansion. However, the spacetime does not achieve isotropy as $t\rightarrow\infty$ in both of these solutions.Comment: 20 pages, 5 figures, accepted for publication in Astrophys. Space Sc

Primordialists and Constructionists: a typology of theories of religion

This article adopts categories from nationalism theory to classify theories of religion. Primordialist explanations are grounded in evolutionary psychology and emphasize the innate human demand for religion. Primordialists predict that religion does not decline in the modern era but will endure in perpetuity. Constructionist theories argue that religious demand is a human construct. Modernity initially energizes religion, but subsequently undermines it. Unpacking these ideal types is necessary in order to describe actual theorists of religion. Three distinctions within primordialism and constructionism are relevant. Namely those distinguishing: a) materialist from symbolist forms of constructionism; b) theories of origins from those pertaining to the reproduction of religion; and c) within reproduction, between theories of religious persistence and secularization. This typology helps to make sense of theories of religion by classifying them on the basis of their causal mechanisms, chronology and effects. In so doing, it opens up new sightlines for theory and research

Paleobiology of titanosaurs: reproduction, development, histology, pneumaticity, locomotion and neuroanatomy from the South American fossil record

Fil: García, Rodolfo A.. Instituto de Investigación en Paleobiología y Geología. Museo Provincial Carlos Ameghino. Cipolletti; ArgentinaFil: Salgado, Leonardo. Instituto de Investigación en Paleobiología y Geología. General Roca. Río Negro; ArgentinaFil: Fernández, Mariela. Inibioma-Centro Regional Universitario Bariloche. Bariloche. Río Negro; ArgentinaFil: Cerda, Ignacio A.. Instituto de Investigación en Paleobiología y Geología. Museo Provincial Carlos Ameghino. Cipolletti; ArgentinaFil: Carabajal, Ariana Paulina. Museo Carmen Funes. Plaza Huincul. Neuquén; ArgentinaFil: Otero, Alejandro. Museo de La Plata. Universidad Nacional de La Plata; ArgentinaFil: Coria, Rodolfo A.. Instituto de Paleobiología y Geología. Universidad Nacional de Río Negro. Neuquén; ArgentinaFil: Fiorelli, Lucas E.. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica. Anillaco. La Rioja; Argentin

Risk profiles and one-year outcomes of patients with newly diagnosed atrial fibrillation in India: Insights from the GARFIELD-AF Registry.

BACKGROUND: The Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF) is an ongoing prospective noninterventional registry, which is providing important information on the baseline characteristics, treatment patterns, and 1-year outcomes in patients with newly diagnosed non-valvular atrial fibrillation (NVAF). This report describes data from Indian patients recruited in this registry. METHODS AND RESULTS: A total of 52,014 patients with newly diagnosed AF were enrolled globally; of these, 1388 patients were recruited from 26 sites within India (2012-2016). In India, the mean age was 65.8 years at diagnosis of NVAF. Hypertension was the most prevalent risk factor for AF, present in 68.5% of patients from India and in 76.3% of patients globally (P < 0.001). Diabetes and coronary artery disease (CAD) were prevalent in 36.2% and 28.1% of patients as compared with global prevalence of 22.2% and 21.6%, respectively (P < 0.001 for both). Antiplatelet therapy was the most common antithrombotic treatment in India. With increasing stroke risk, however, patients were more likely to receive oral anticoagulant therapy [mainly vitamin K antagonist (VKA)], but average international normalized ratio (INR) was lower among Indian patients [median INR value 1.6 (interquartile range {IQR}: 1.3-2.3) versus 2.3 (IQR 1.8-2.8) (P < 0.001)]. Compared with other countries, patients from India had markedly higher rates of all-cause mortality [7.68 per 100 person-years (95% confidence interval 6.32-9.35) vs 4.34 (4.16-4.53), P < 0.0001], while rates of stroke/systemic embolism and major bleeding were lower after 1 year of follow-up. CONCLUSION: Compared to previously published registries from India, the GARFIELD-AF registry describes clinical profiles and outcomes in Indian patients with AF of a different etiology. The registry data show that compared to the rest of the world, Indian AF patients are younger in age and have more diabetes and CAD. Patients with a higher stroke risk are more likely to receive anticoagulation therapy with VKA but are underdosed compared with the global average in the GARFIELD-AF. CLINICAL TRIAL REGISTRATION-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01090362